Mercurial Hosting > luan
annotate website/src/manual.html.luan @ 508:9218f9cf45d3
various fixes
author | Franklin Schmidt <fschmidt@gmail.com> |
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date | Thu, 21 May 2015 20:20:54 -0600 |
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478 | 1 local Luan = require "luan:Luan" |
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2 local Io = require "luan:Io" |
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3 local Html = require "luan:Html" |
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4 local Http = require "luan:http/Http" |
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5 local Shared = require "site:/Shared" |
505
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6 local heading_options = Shared.heading_options |
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7 |
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8 |
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9 return function() |
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10 Io.stdout = Http.response.text_writer() |
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11 %> |
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12 <html> |
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13 <head> |
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14 <% Html.simply_html_head() %> |
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15 <title>Luan Reference Manual</title> |
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16 </head> |
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17 <body> |
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18 |
372 | 19 <div container> |
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20 <% Shared.header() %> |
372 | 21 |
22 <h1>Luan Reference Manual</h1> | |
23 | |
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24 <p> |
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25 <small> |
372 | 26 Original copyright © 2015 Lua.org, PUC-Rio. |
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27 Freely available under the terms of the |
372 | 28 <a href="http://www.lua.org/license.html">Lua license</a>. |
29 Modified for Luan. | |
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30 </small> |
372 | 31 </p> |
32 | |
33 <hr/> | |
34 | |
35 <h2>Contents</h2> | |
36 | |
37 <div margin-bottom="1em"><a href="#intro">Introduction</a></div> | |
38 | |
373 | 39 <div margin-bottom="1em"> |
40 <a href="#basic">Basic Concepts</a> | |
41 <ul> | |
42 <li><a href="#types">Values and Types</a></li> | |
43 <li><a href="#env">Environments</a></li> | |
44 <li><a href="#error">Error Handling</a></li> | |
45 <li><a href="#meta">Metatables and Metamethods</a></li> | |
380 | 46 <li><a href="#gc">Garbage Collection</a></li> |
47 </ul> | |
48 </div> | |
49 | |
50 <div margin-bottom="1em"> | |
51 <a href="#lang">The Language</a> | |
52 <ul> | |
53 <li><a href="#lex">Lexical Conventions</a></li> | |
54 <li><a href="#vars">Variables</a></li> | |
389 | 55 <li> |
56 <a href="#stmts">Statements</a> | |
57 <ul> | |
58 <li><a href="#blocks">Blocks</a></li> | |
395 | 59 <li><a href="#chunks">Chunks</a></li> |
60 <li><a href="#assignment">Assignment</a></li> | |
61 <li><a href="#control">Control Structures</a></li> | |
62 <li><a href="#for">For Statement</a></li> | |
63 <li><a href="#fn_stmt">Function Calls as Statements</a></li> | |
64 <li><a href="#local_stmt">Local Declarations</a></li> | |
465 | 65 <li><a href="#template_stmt">Template Statements</a></li> |
395 | 66 </ul> |
67 </li> | |
68 <li> | |
69 <a href="#expressions">Expressions</a> | |
70 <ul> | |
71 <li><a href="#arithmetic">Arithmetic Operators</a></li> | |
396 | 72 <li><a href="#conversions">Coercions and Conversions</a></li> |
73 <li><a href="#relational">Relational Operators</a></li> | |
74 <li><a href="#logical_ops">Logical Operators</a></li> | |
75 <li><a href="#concatenation">Concatenation</a></li> | |
76 <li><a href="#length">The Length Operator</a></li> | |
77 <li><a href="#precedence">Precedence</a></li> | |
78 <li><a href="#constructors">Table Constructors</a></li> | |
417 | 79 <li><a href="#fn_calls">Function Calls</a></li> |
80 <li><a href="#fn_def">Function Definitions</a></li> | |
465 | 81 <li><a href="#template_expr">Template Expressions</a></li> |
389 | 82 </ul> |
83 </li> | |
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84 <li><a href="#visibility">Visibility Rules</a></li> |
373 | 85 </ul> |
86 </div> | |
87 | |
468 | 88 <div margin-bottom="1em"> |
89 <a href="#libs">Standard Libraries</a> | |
90 <ul> | |
91 <li><a href="#default_lib">Default Environment</a></li> | |
470 | 92 <li><a href="#luan_lib">Basic Functions</a></li> |
476 | 93 <li><a href="#package_lib">Modules</a></li> |
468 | 94 </ul> |
95 </div> | |
96 | |
372 | 97 <hr/> |
98 | |
373 | 99 |
479
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100 <h2 <%=heading_options%> ><a name="intro">Introduction</a></h2> |
372 | 101 |
102 <p>Luan is a high level programming language based on <a href="http://www.lua.org">Lua</a>. A great strength of Lua is its simplicity and Luan takes this even further, being even simpler than Lua. The goal is to provide a simple programming language for the casual programmer with as few concepts as possible so that one can quickly learn the language and then easily understand any code written in Luan.</p> | |
103 | |
104 <p>Luan is implemented in Java and is tightly coupled with Java. So it makes a great scripting language for Java programmers.</p> | |
105 | |
106 <p>Unlike Lua which is meant to be embedded, Luan is meant to be a full scripting language. This done not by adding feature to Luan, but rather by providing a complete set of libraries.</p> | |
371
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107 |
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108 |
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109 <h2 <%=heading_options%> ><a name="basic">Basic Concepts</a></h2> |
373 | 110 |
111 <p>This section describes the basic concepts of the language.</p> | |
112 | |
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113 <h3 <%=heading_options%> ><a name="types">Values and Types</a></h3> |
373 | 114 |
115 <p> | |
116 Luan is a <i>dynamically typed language</i>. | |
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117 This means that |
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118 variables do not have types; only values do. |
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119 There are no type definitions in the language. |
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120 All values carry their own type. |
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121 |
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122 |
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123 <p> |
373 | 124 All values in Luan are <i>first-class values</i>. |
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125 This means that all values can be stored in variables, |
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126 passed as arguments to other functions, and returned as results. |
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127 |
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128 |
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129 <p> |
373 | 130 There are eight basic types in Luan: |
131 <i>nil</i>, <i>boolean</i>, <i>number</i>, | |
132 <i>string</i>, <i>binary</i>, <i>function</i>, <i>userdata</i>, | |
133 and <i>table</i>. | |
134 <i>Nil</i> is the type of the value <b>nil</b>, | |
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135 whose main property is to be different from any other value; |
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136 it usually represents the absence of a useful value. |
373 | 137 <i>Nil</i> is implemented as the Java value <i>null</i>. |
138 <i>Boolean</i> is the type of the values <b>false</b> and <b>true</b>. | |
139 <i>Boolean</i> is implemented as the Java class <i>Boolean</i>. | |
140 <i>Number</i> represents both | |
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141 integer numbers and real (floating-point) numbers. |
373 | 142 <i>Number</i> is implemented as the Java class <i>Number</i>. Any Java subclass of <i>Number</i> is allowed and this is invisible to the Luan user. Operations on numbers follow the same rules of |
143 the underlying Java implementation. | |
144 | |
145 <i>String</i> is implemented as the Java class <i>String</i>. | |
146 <i>Binary</i> is implemented as the Java type <i>byte[]</i>. | |
147 | |
148 | |
149 <p> | |
150 Luan can call (and manipulate) functions written in Luan and | |
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151 functions written in Java (see <a href="#fn_calls">Function Calls</a>). |
373 | 152 Both are represented by the type <i>function</i>. |
153 | |
154 | |
155 <p> | |
156 The type <i>userdata</i> is provided to allow arbitrary Java objects to | |
157 be stored in Luan variables. | |
158 A userdata value is a Java object that isn't one of the standard Luan types. | |
159 Userdata has no predefined operations in Luan, | |
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160 except assignment and identity test. |
373 | 161 Userdata is useful then Java access is enabled in Luan |
162 | |
163 | |
164 | |
165 <p> | |
166 The type <i>table</i> implements associative arrays, | |
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167 that is, arrays that can be indexed not only with numbers, |
373 | 168 but with any Luan value except <b>nil</b>. |
169 Tables can be <i>heterogeneous</i>; | |
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170 that is, they can contain values of all types (except <b>nil</b>). |
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171 Any key with value <b>nil</b> is not considered part of the table. |
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172 Conversely, any key that is not part of a table has |
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173 an associated value <b>nil</b>. |
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174 |
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175 |
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176 <p> |
373 | 177 Tables are the sole data-structuring mechanism in Luan; |
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178 they can be used to represent ordinary arrays, sequences, |
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179 symbol tables, sets, records, graphs, trees, etc. |
373 | 180 To represent records, Luan uses the field name as an index. |
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181 The language supports this representation by |
373 | 182 providing <tt>a.name</tt> as syntactic sugar for <tt>a["name"]</tt>. |
183 There are several convenient ways to create tables in Luan | |
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184 (see <a href="#constructors">Table Constructors</a>). |
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185 |
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186 |
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187 <p> |
373 | 188 We use the term <i>sequence</i> to denote a table where |
189 the set of all positive numeric keys is equal to {1..<i>n</i>} | |
190 for some non-negative integer <i>n</i>, | |
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191 which is called the length of the sequence (see <a href="#length">The Length Operator</a>). |
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192 |
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193 |
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194 <p> |
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195 Like indices, |
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196 the values of table fields can be of any type. |
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197 In particular, |
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198 because functions are first-class values, |
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199 table fields can contain functions. |
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200 Thus tables can also carry <i>methods</i> (see <a href="#fn_def">Function Definitions</a>). |
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201 |
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202 |
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203 <p> |
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204 The indexing of tables follows |
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205 the definition of raw equality in the language. |
373 | 206 The expressions <tt>a[i]</tt> and <tt>a[j]</tt> |
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207 denote the same table element |
373 | 208 if and only if <tt>i</tt> and <tt>j</tt> are raw equal |
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209 (that is, equal without metamethods). |
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210 In particular, floats with integral values |
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211 are equal to their respective integers |
373 | 212 (e.g., <tt>1.0 == 1</tt>). |
213 | |
214 | |
215 <p> | |
216 Luan values are <i>objects</i>: | |
217 variables do not actually <i>contain</i> values, | |
218 only <i>references</i> to them. | |
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219 Assignment, parameter passing, and function returns |
373 | 220 always manipulate references to values; |
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221 these operations do not imply any kind of copy. |
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222 |
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223 |
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224 <p> |
478 | 225 The library function <a href="#Luan.type"><tt>Luan.type</tt></a> returns a string describing the type |
226 of a given value. | |
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227 |
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228 |
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229 |
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230 |
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231 |
479
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232 <h3 <%=heading_options%> ><a name="env">Environments</a></h3> |
371
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233 |
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234 <p> |
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235 As will be discussed in <a href="#vars">Variables</a> and <a href=#assignment">Assignment</a>, |
371
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236 any reference to a free name |
373 | 237 (that is, a name not bound to any declaration) <tt>var</tt> |
238 is syntactically translated to <tt>_ENV.var</tt>. | |
371
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239 Moreover, every chunk is compiled in the scope of |
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240 an external local variable named <tt>_ENV</tt> (see <a href="#chunks">Chunks</a>), |
373 | 241 so <tt>_ENV</tt> itself is never a free name in a chunk. |
242 | |
243 | |
244 <p> | |
245 Despite the existence of this external <tt>_ENV</tt> variable and | |
371
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246 the translation of free names, |
373 | 247 <tt>_ENV</tt> is a completely regular name. |
371
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248 In particular, |
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249 you can define new variables and parameters with that name. |
373 | 250 Each reference to a free name uses the <tt>_ENV</tt> that is |
371
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251 visible at that point in the program, |
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252 following the usual visibility rules of Luan (see <a href="#visibility">Visibility Rules</a>). |
373 | 253 |
254 | |
255 <p> | |
256 Any table used as the value of <tt>_ENV</tt> is called an <i>environment</i>. | |
257 | |
258 | |
259 <p> | |
260 When Luan loads a chunk, | |
261 the default value for its <tt>_ENV</tt> is an empty table. | |
262 | |
263 <p> | |
264 Luan also provides all chunks with two other local values: <tt>require</tt> and <tt>java</tt>. These are functions used to load and access libraries and other modules. | |
265 | |
266 | |
267 | |
268 | |
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269 <h3 <%=heading_options%> ><a name="error">Error Handling</a></h3> |
373 | 270 |
271 <p> | |
272 Luan code can explicitly generate an error by calling the | |
478 | 273 <a href="#Luan.error"><tt>error</tt></a> function. |
373 | 274 If you need to catch errors in Luan, |
478 | 275 you can use <a href="#Luan.pcall"><tt>pcall</tt></a> or <a href="#Luan.try"><tt>try</tt></a> |
373 | 276 to call a given function in <i>protected mode</i>. |
371
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277 |
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278 |
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279 <p> |
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280 Whenever there is an error, |
482 | 281 an <i>error table</i> |
371
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282 is propagated with information about the error. |
482 | 283 See <a href="#Luan.new_error"><tt>Luan.new_error</tt></a>. |
373 | 284 |
285 | |
286 | |
479
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287 <h3 <%=heading_options%> ><a name="meta">Metatables and Metamethods</a></h3> |
373 | 288 |
289 <p> | |
290 Every table in Luan can have a <i>metatable</i>. | |
291 This <i>metatable</i> is an ordinary Luan table | |
371
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292 that defines the behavior of the original value |
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293 under certain special operations. |
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294 You can change several aspects of the behavior |
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295 of operations over a value by setting specific fields in its metatable. |
373 | 296 For instance, when a table is the operand of an addition, |
297 Luan checks for a function in the field "<tt>__add</tt>" of the table's metatable. | |
371
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298 If it finds one, |
373 | 299 Luan calls this function to perform the addition. |
300 | |
301 | |
302 <p> | |
303 The keys in a metatable are derived from the <i>event</i> names; | |
304 the corresponding values are called <ii>metamethods</i>. | |
305 In the previous example, the event is <tt>"add"</tt> | |
371
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306 and the metamethod is the function that performs the addition. |
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307 |
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308 |
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309 <p> |
373 | 310 You can query the metatable of any table |
478 | 311 using the <a href="#Luan.get_metatable"><tt>get_metatable</tt></a> function. |
371
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312 |
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313 |
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314 <p> |
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315 You can replace the metatable of tables |
478 | 316 using the <a href="#Luan.set_metatable"><tt>set_metatable</tt></a> function. |
373 | 317 |
318 | |
319 <p> | |
320 A metatable controls how a table behaves in | |
371
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321 arithmetic operations, bitwise operations, |
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322 order comparisons, concatenation, length operation, calls, and indexing. |
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323 |
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324 |
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325 <p> |
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326 A detailed list of events controlled by metatables is given next. |
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327 Each operation is identified by its corresponding event name. |
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328 The key for each event is a string with its name prefixed by |
373 | 329 two underscores, '<tt>__</tt>'; |
371
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330 for instance, the key for operation "add" is the |
373 | 331 string "<tt>__add</tt>". |
371
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332 Note that queries for metamethods are always raw; |
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333 the access to a metamethod does not invoke other metamethods. |
373 | 334 You can emulate how Luan queries a metamethod for an object <tt>obj</tt> |
371
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335 with the following code: |
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336 |
382 | 337 <p><tt><pre> |
373 | 338 raw_get(get_metatable(obj) or {}, "__" .. event_name) |
382 | 339 </pre></tt></p> |
373 | 340 |
341 <p> | |
342 Here are the events: | |
371
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343 |
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344 <ul> |
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345 |
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346 <li><p><b>"add": </b> |
373 | 347 the <tt>+</tt> operation. |
348 | |
349 If any operand for an addition is a table, | |
350 Luan will try to call a metamethod. | |
351 First, Luan will check the first operand (even if it is valid). | |
352 If that operand does not define a metamethod for the "<tt>__add</tt>" event, | |
353 then Luan will check the second operand. | |
354 If Luan can find a metamethod, | |
371
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355 it calls the metamethod with the two operands as arguments, |
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356 and the result of the call |
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357 (adjusted to one value) |
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358 is the result of the operation. |
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359 Otherwise, |
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360 it raises an error. |
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361 </li> |
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362 |
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363 <li><p><b>"sub": </b> |
373 | 364 the <tt>-</tt> operation. |
371
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365 |
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366 Behavior similar to the "add" operation. |
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367 </li> |
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368 |
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369 <li><p><b>"mul": </b> |
373 | 370 the <tt>*</tt> operation. |
371
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371 |
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372 Behavior similar to the "add" operation. |
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373 </li> |
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374 |
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375 <li><p><b>"div": </b> |
373 | 376 the <tt>/</tt> operation. |
371
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377 |
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378 Behavior similar to the "add" operation. |
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379 </li> |
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380 |
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381 <li><p><b>"mod": </b> |
373 | 382 the <tt>%</tt> operation. |
371
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383 |
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384 Behavior similar to the "add" operation. |
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385 </li> |
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386 |
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387 <li><p><b>"pow": </b> |
373 | 388 the <tt>^</tt> (exponentiation) operation. |
371
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389 |
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390 Behavior similar to the "add" operation. |
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391 </li> |
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392 |
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393 <li><p><b>"unm": </b> |
373 | 394 the <tt>-</tt> (unary minus) operation. |
371
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395 |
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396 Behavior similar to the "add" operation. |
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397 </li> |
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398 |
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399 <li><p><b>"concat": </b> |
373 | 400 the <tt>..</tt> (concatenation) operation. |
401 | |
402 Behavior similar to the "add" operation. | |
371
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403 </li> |
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404 |
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405 <li><p><b>"len": </b> |
373 | 406 the <tt>#</tt> (length) operation. |
407 | |
371
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408 If there is a metamethod, |
373 | 409 Luan calls it with the object as argument, |
371
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410 and the result of the call |
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411 (always adjusted to one value) |
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412 is the result of the operation. |
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413 If there is no metamethod but the object is a table, |
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414 then Luan uses the table length operation (see <a href="#length">The Length Operator</a>). |
373 | 415 Otherwise, Luan raises an error. |
371
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416 </li> |
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417 |
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418 <li><p><b>"eq": </b> |
373 | 419 the <tt>==</tt> (equal) operation. |
371
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420 |
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421 Behavior similar to the "add" operation, |
373 | 422 except that Luan will try a metamethod only when the values |
423 being compared are both tables | |
371
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424 and they are not primitively equal. |
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425 The result of the call is always converted to a boolean. |
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426 </li> |
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427 |
502
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428 <li><p><b>"lt": </b> |
373 | 429 the <tt><</tt> (less than) operation. |
430 | |
431 Behavior similar to the "add" operation. | |
371
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432 The result of the call is always converted to a boolean. |
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433 </li> |
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434 |
502
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435 <li><p><b>"le": </b> |
373 | 436 the <tt><=</tt> (less equal) operation. |
371
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437 |
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438 Unlike other operations, |
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439 The less-equal operation can use two different events. |
373 | 440 First, Luan looks for the "<tt>__le</tt>" metamethod in both operands, |
371
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441 like in the "lt" operation. |
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442 If it cannot find such a metamethod, |
373 | 443 then it will try the "<tt>__lt</tt>" event, |
444 assuming that <tt>a <= b</tt> is equivalent to <tt>not (b < a)</tt>. | |
371
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445 As with the other comparison operators, |
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446 the result is always a boolean. |
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447 </li> |
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448 |
502
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449 <li><p><b>"index": </b> |
373 | 450 The indexing access <tt>table[key]</tt>. |
451 | |
452 This event happens | |
453 when <tt>key</tt> is not present in <tt>table</tt>. | |
454 The metamethod is looked up in <tt>table</tt>. | |
371
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455 |
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456 |
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457 <p> |
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458 Despite the name, |
502
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459 the metamethod for this event can be any type. |
371
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460 If it is a function, |
373 | 461 it is called with <tt>table</tt> and <tt>key</tt> as arguments. |
502
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462 Otherwise |
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463 the final result is the result of indexing this metamethod object with <tt>key</tt>. |
371
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464 (This indexing is regular, not raw, |
502
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465 and therefore can trigger another metamethod if the metamethod object is a table.) |
371
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466 </li> |
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467 |
502
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468 <li><p><b>"new_index": </b> |
373 | 469 The indexing assignment <tt>table[key] = value</tt>. |
371
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470 |
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471 Like the index event, |
373 | 472 this event happens when |
473 when <tt>key</tt> is not present in <tt>table</tt>. | |
474 The metamethod is looked up in <tt>table</tt>. | |
371
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475 |
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476 |
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477 <p> |
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478 Like with indexing, |
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479 the metamethod for this event can be either a function or a table. |
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480 If it is a function, |
373 | 481 it is called with <tt>table</tt>, <tt>key</tt>, and <tt>value</tt> as arguments. |
371
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482 If it is a table, |
373 | 483 Luan does an indexing assignment to this table with the same key and value. |
371
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484 (This assignment is regular, not raw, |
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485 and therefore can trigger another metamethod.) |
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486 |
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487 |
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488 <p> |
428
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489 Whenever there is a "new_index" metamethod, |
373 | 490 Luan does not perform the primitive assignment. |
371
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491 (If necessary, |
478 | 492 the metamethod itself can call <a href="#Luan.raw_set"><tt>raw_set</tt></a> |
371
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493 to do the assignment.) |
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494 </li> |
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495 |
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496 <li><p><b>"call": </b> |
373 | 497 The call operation <tt>func(args)</tt>. |
498 | |
499 This event happens when Luan tries to call a table. | |
500 The metamethod is looked up in <tt>func</tt>. | |
371
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501 If present, |
373 | 502 the metamethod is called with <tt>func</tt> as its first argument, |
503 followed by the arguments of the original call (<tt>args</tt>). | |
371
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504 </li> |
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505 |
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506 </ul> |
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507 |
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508 |
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509 |
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510 |
479
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511 <h3 <%=heading_options%> ><a name="gc">Garbage Collection</a></h3> |
380 | 512 |
513 <p> | |
514 Luan uses Java's garbage collection. | |
515 | |
516 | |
517 | |
518 | |
519 | |
479
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520 <h2 <%=heading_options%> ><a name="lang">The Language</a></h2> |
380 | 521 |
522 <p> | |
523 This section describes the lexis, the syntax, and the semantics of Luan. | |
371
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524 In other words, |
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525 this section describes |
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526 which tokens are valid, |
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527 how they can be combined, |
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528 and what their combinations mean. |
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529 |
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530 |
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531 <p> |
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532 Language constructs will be explained using the usual extended BNF notation, |
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533 in which |
380 | 534 {<i>a</i>} means 0 or more <i>a</i>'s, and |
535 [<i>a</i>] means an optional <i>a</i>. | |
371
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536 Non-terminals are shown like non-terminal, |
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537 keywords are shown like <b>kword</b>, |
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538 and other terminal symbols are shown like ‘<b>=</b>’. |
380 | 539 The complete syntax of Luan can be found in <a href="#9">§9</a> |
371
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540 at the end of this manual. |
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541 |
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542 |
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543 |
479
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544 <h3 <%=heading_options%> ><a name="lex">Lexical Conventions</a></h3> |
380 | 545 |
546 <p> | |
547 Luan ignores spaces and comments | |
371
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548 between lexical elements (tokens), |
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549 except as delimiters between names and keywords. |
380 | 550 Luan generally considers the end of a line to be the end of a statement. This catches errors and encourages readability. The exception to this is in paranthesis ( <i>(...)</i>, <i>[...]</i>, and <i>{...}</i> ) where the end of line is treated as white space. |
551 | |
552 <p> | |
553 <i>Names</i> | |
554 (also called <i>identifiers</i>) | |
555 in Luan can be any string of letters, | |
371
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556 digits, and underscores, |
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557 not beginning with a digit. |
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558 Identifiers are used to name variables, table fields, and labels. |
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559 |
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560 |
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561 <p> |
380 | 562 The following <i>keywords</i> are reserved |
371
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563 and cannot be used as names: |
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564 |
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565 |
389 | 566 <p><tt><pre> |
371
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567 and break do else elseif end |
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568 false for function goto if in |
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569 local nil not or repeat return |
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570 then true until while |
389 | 571 </pre></tt></p> |
371
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572 |
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573 <p> |
380 | 574 Luan is a case-sensitive language: |
575 <tt>and</tt> is a reserved word, but <tt>And</tt> and <tt>AND</tt> | |
371
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576 are two different, valid names. |
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577 |
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578 |
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579 <p> |
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580 The following strings denote other tokens: |
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581 |
389 | 582 <p><tt><pre> |
371
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583 + - * / % ^ # |
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584 & ~ | << >> // |
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585 == ~= <= >= < > = |
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586 ( ) { } [ ] :: |
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587 ; : , . .. ... |
389 | 588 </pre></tt></p> |
371
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589 |
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590 <p> |
380 | 591 <i>Literal strings</i> |
371
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592 can be delimited by matching single or double quotes, |
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593 and can contain the following C-like escape sequences: |
380 | 594 '<tt>\a</tt>' (bell), |
595 '<tt>\b</tt>' (backspace), | |
596 '<tt>\f</tt>' (form feed), | |
597 '<tt>\n</tt>' (newline), | |
598 '<tt>\r</tt>' (carriage return), | |
599 '<tt>\t</tt>' (horizontal tab), | |
600 '<tt>\v</tt>' (vertical tab), | |
601 '<tt>\\</tt>' (backslash), | |
602 '<tt>\"</tt>' (quotation mark [double quote]), | |
603 and '<tt>\'</tt>' (apostrophe [single quote]). | |
371
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604 A backslash followed by a real newline |
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605 results in a newline in the string. |
380 | 606 The escape sequence '<tt>\z</tt>' skips the following span |
371
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607 of white-space characters, |
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608 including line breaks; |
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609 it is particularly useful to break and indent a long literal string |
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610 into multiple lines without adding the newlines and spaces |
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611 into the string contents. |
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612 |
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613 |
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614 <p> |
380 | 615 Luan can specify any character in a literal string by its numerical value. |
371
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616 This can be done |
380 | 617 with the escape sequence <tt>\x<i>XX</i></tt>, |
618 where <i>XX</i> is a sequence of exactly two hexadecimal digits, | |
619 or with the escape sequence <tt>\<i>ddd</i></tt>, | |
620 where <i>ddd</i> is a sequence of up to three decimal digits. | |
371
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621 (Note that if a decimal escape sequence is to be followed by a digit, |
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622 it must be expressed using exactly three digits.) |
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623 |
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624 |
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625 <p> |
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626 Literal strings can also be defined using a long format |
380 | 627 enclosed by <i>long brackets</i>. |
628 We define an <i>opening long bracket of level <i>n</i></i> as an opening | |
629 square bracket followed by <i>n</i> equal signs followed by another | |
371
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630 opening square bracket. |
380 | 631 So, an opening long bracket of level 0 is written as <tt>[[</tt>, |
632 an opening long bracket of level 1 is written as <tt>[=[</tt>, | |
371
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633 and so on. |
380 | 634 A <i>closing long bracket</i> is defined similarly; |
371
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635 for instance, |
380 | 636 a closing long bracket of level 4 is written as <tt>]====]</tt>. |
637 A <i>long literal</i> starts with an opening long bracket of any level and | |
371
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638 ends at the first closing long bracket of the same level. |
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639 It can contain any text except a closing bracket of the same level. |
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640 Literals in this bracketed form can run for several lines, |
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641 do not interpret any escape sequences, |
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642 and ignore long brackets of any other level. |
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643 Any kind of end-of-line sequence |
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644 (carriage return, newline, carriage return followed by newline, |
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645 or newline followed by carriage return) |
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646 is converted to a simple newline. |
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647 |
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648 |
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649 <p> |
380 | 650 Any character in a literal string not |
371
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651 explicitly affected by the previous rules represents itself. |
380 | 652 However, Luan opens files for parsing in text mode, |
371
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653 and the system file functions may have problems with |
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654 some control characters. |
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655 So, it is safer to represent |
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656 non-text data as a quoted literal with |
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657 explicit escape sequences for non-text characters. |
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658 |
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659 |
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660 <p> |
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661 For convenience, |
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662 when the opening long bracket is immediately followed by a newline, |
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663 the newline is not included in the string. |
380 | 664 As an example |
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665 the five literal strings below denote the same string: |
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666 |
389 | 667 <p><tt><pre> |
371
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668 a = 'alo\n123"' |
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669 a = "alo\n123\"" |
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670 a = '\97lo\10\04923"' |
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671 a = [[alo |
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672 123"]] |
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673 a = [==[ |
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674 alo |
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675 123"]==] |
389 | 676 </pre></tt></p> |
371
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677 |
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678 <p> |
380 | 679 A <i>numerical constant</i> (or <i>numeral</i>) |
371
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680 can be written with an optional fractional part |
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681 and an optional decimal exponent, |
380 | 682 marked by a letter '<tt>e</tt>' or '<tt>E</tt>'. |
683 Luan also accepts hexadecimal constants, | |
684 which start with <tt>0x</tt> or <tt>0X</tt>. | |
371
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685 Hexadecimal constants also accept an optional fractional part |
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686 plus an optional binary exponent, |
380 | 687 marked by a letter '<tt>p</tt>' or '<tt>P</tt>'. |
371
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688 A numeric constant with a fractional dot or an exponent |
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689 denotes a float; |
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690 otherwise it denotes an integer. |
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691 Examples of valid integer constants are |
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692 |
389 | 693 <p><tt><pre> |
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694 3 345 0xff 0xBEBADA |
389 | 695 </pre></tt></p> |
382 | 696 |
697 <p> | |
371
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698 Examples of valid float constants are |
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699 |
389 | 700 <p><tt><pre> |
371
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701 3.0 3.1416 314.16e-2 0.31416E1 34e1 |
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702 0x0.1E 0xA23p-4 0X1.921FB54442D18P+1 |
389 | 703 </pre></tt></p> |
371
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704 |
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705 <p> |
380 | 706 A <i>comment</i> starts with a double hyphen (<tt>--</tt>) |
371
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707 anywhere outside a string. |
380 | 708 If the text immediately after <tt>--</tt> is not an opening long bracket, |
709 the comment is a <i>short comment</i>, | |
371
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710 which runs until the end of the line. |
380 | 711 Otherwise, it is a <i>long comment</i>, |
371
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712 which runs until the corresponding closing long bracket. |
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713 Long comments are frequently used to disable code temporarily. |
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714 |
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715 |
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716 |
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717 |
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718 |
479
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719 <h3 <%=heading_options%> ><a name="vars">Variables</a></h3> |
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720 |
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721 <p> |
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722 Variables are places that store values. |
380 | 723 There are three kinds of variables in Luan: |
371
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724 global variables, local variables, and table fields. |
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725 |
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726 |
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727 <p> |
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728 A single name can denote a global variable or a local variable |
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729 (or a function's formal parameter, |
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730 which is a particular kind of local variable): |
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731 |
389 | 732 <p><tt><pre> |
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733 var ::= Name |
389 | 734 </pre></tt></p> |
382 | 735 |
736 <p> | |
464
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737 Name denotes identifiers, as defined in <a href="#lex">Lexical Conventions</a>. |
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738 |
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739 |
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740 <p> |
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741 Any variable name is assumed to be global unless explicitly declared |
464
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742 as a local (see <a href="#local_stmt">Local Declarations</a>). |
380 | 743 Local variables are <i>lexically scoped</i>: |
371
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744 local variables can be freely accessed by functions |
464
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745 defined inside their scope (see <a href="#visibility">Visibility Rules</a>). |
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746 |
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747 |
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748 <p> |
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749 Before the first assignment to a variable, its value is <b>nil</b>. |
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750 |
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751 |
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752 <p> |
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753 Square brackets are used to index a table: |
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754 |
389 | 755 <p><tt><pre> |
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756 var ::= prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ |
389 | 757 </pre></tt></p> |
382 | 758 |
759 <p> | |
371
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760 The meaning of accesses to table fields can be changed via metatables. |
380 | 761 An access to an indexed variable <tt>t[i]</tt> is equivalent to |
762 a call <tt>gettable_event(t,i)</tt>. | |
464
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763 (See <a href="#meta">Metatables and Metamethods</a> for a complete description of the |
380 | 764 <tt>gettable_event</tt> function. |
765 This function is not defined or callable in Luan. | |
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766 We use it here only for explanatory purposes.) |
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767 |
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768 |
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769 <p> |
380 | 770 The syntax <tt>var.Name</tt> is just syntactic sugar for |
771 <tt>var["Name"]</tt>: | |
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772 |
389 | 773 <p><tt><pre> |
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774 var ::= prefixexp ‘<b>.</b>’ Name |
389 | 775 </pre></tt></p> |
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776 |
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777 <p> |
380 | 778 An access to a global variable <tt>x</tt> |
779 is equivalent to <tt>_ENV.x</tt>. | |
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780 Due to the way that chunks are compiled, |
464
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781 <tt>_ENV</tt> is never a global name (see <a href="#env">Environments</a>). |
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782 |
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783 |
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784 |
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785 |
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786 |
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787 <h3 <%=heading_options%> ><a name="stmts">Statements</a></h3> |
389 | 788 |
789 <p> | |
790 Luan supports an almost conventional set of statements, | |
371
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791 similar to those in Pascal or C. |
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792 This set includes |
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793 assignments, control structures, function calls, |
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794 and variable declarations. |
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795 |
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796 |
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797 |
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798 <h4 <%=heading_options%> ><a name="blocks">Blocks</a></h4> |
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799 |
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800 <p> |
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801 A block is a list of statements, |
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802 which are executed sequentially: |
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803 |
389 | 804 <p><tt><pre> |
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805 block ::= {stat} |
389 | 806 </pre></tt></p> |
807 | |
808 <p> | |
809 Luan has <i>empty statements</i> | |
371
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810 that allow you to separate statements with semicolons, |
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811 start a block with a semicolon |
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812 or write two semicolons in sequence: |
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813 |
389 | 814 <p><tt><pre> |
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815 stat ::= ‘<b>;</b>’ |
389 | 816 </pre></tt></p> |
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817 |
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818 <p> |
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819 A block can be explicitly delimited to produce a single statement: |
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820 |
389 | 821 <p><tt><pre> |
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822 stat ::= <b>do</b> block <b>end</b> |
389 | 823 </pre></tt></p> |
824 | |
825 <p> | |
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826 Explicit blocks are useful |
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827 to control the scope of variable declarations. |
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828 Explicit blocks are also sometimes used to |
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829 add a <b>return</b> statement in the middle |
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830 of another block (see <a href="#control">Control Structures</a>). |
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831 |
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832 |
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833 |
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834 |
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835 |
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836 <h4 <%=heading_options%> ><a name="chunks">Chunks</a></h4> |
395 | 837 |
838 <p> | |
839 The unit of compilation of Luan is called a <i>chunk</i>. | |
371
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840 Syntactically, |
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841 a chunk is simply a block: |
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842 |
395 | 843 <p><tt><pre> |
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844 chunk ::= block |
395 | 845 </pre></tt></p> |
846 | |
847 <p> | |
848 Luan handles a chunk as the body of an anonymous function | |
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849 with a variable number of arguments |
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850 (see <a href="#fn_def">Function Definitions</a>). |
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851 As such, chunks can define local variables, |
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852 receive arguments, and return values. |
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853 |
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854 |
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855 <p> |
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856 A chunk can be stored in a file or in a string inside the host program. |
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857 To execute a chunk, |
395 | 858 Luan first <i>loads</i> it, |
859 compiling the chunk's code, | |
860 and then Luan executes the compiled code. | |
861 | |
862 | |
863 | |
864 | |
865 | |
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866 <h4 <%=heading_options%> ><a name="assignment">Assignment</a></h4> |
395 | 867 |
868 <p> | |
869 Luan allows multiple assignments. | |
371
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870 Therefore, the syntax for assignment |
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871 defines a list of variables on the left side |
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872 and a list of expressions on the right side. |
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873 The elements in both lists are separated by commas: |
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874 |
395 | 875 <p><tt><pre> |
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876 stat ::= varlist ‘<b>=</b>’ explist |
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877 varlist ::= var {‘<b>,</b>’ var} |
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878 explist ::= exp {‘<b>,</b>’ exp} |
395 | 879 </pre></tt></p> |
880 | |
881 <p> | |
464
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882 Expressions are discussed in <a href="#expressions">Expressions</a>. |
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883 |
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884 |
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885 <p> |
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886 Before the assignment, |
395 | 887 the list of values is <i>adjusted</i> to the length of |
371
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888 the list of variables. |
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889 If there are more values than needed, |
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890 the excess values are thrown away. |
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891 If there are fewer values than needed, |
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892 the list is extended with as many <b>nil</b>'s as needed. |
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893 If the list of expressions ends with a function call, |
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894 then all values returned by that call enter the list of values, |
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895 before the adjustment |
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896 (except when the call is enclosed in parentheses; see <a href="#expressions">Expressions</a>). |
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897 |
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898 |
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899 <p> |
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900 The assignment statement first evaluates all its expressions |
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901 and only then the assignments are performed. |
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902 Thus the code |
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903 |
395 | 904 <p><tt><pre> |
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905 i = 3 |
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906 i, a[i] = i+1, 20 |
395 | 907 </pre></tt></p> |
908 | |
909 <p> | |
910 sets <tt>a[3]</tt> to 20, without affecting <tt>a[4]</tt> | |
911 because the <tt>i</tt> in <tt>a[i]</tt> is evaluated (to 3) | |
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912 before it is assigned 4. |
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913 Similarly, the line |
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914 |
395 | 915 <p><tt><pre> |
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916 x, y = y, x |
395 | 917 </pre></tt></p> |
918 | |
919 <p> | |
920 exchanges the values of <tt>x</tt> and <tt>y</tt>, | |
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921 and |
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922 |
395 | 923 <p><tt><pre> |
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924 x, y, z = y, z, x |
395 | 925 </pre></tt></p> |
926 | |
927 <p> | |
928 cyclically permutes the values of <tt>x</tt>, <tt>y</tt>, and <tt>z</tt>. | |
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929 |
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930 |
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931 <p> |
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932 The meaning of assignments to global variables |
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933 and table fields can be changed via metatables. |
395 | 934 An assignment to an indexed variable <tt>t[i] = val</tt> is equivalent to |
935 <tt>settable_event(t,i,val)</tt>. | |
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936 (See <a href="#meta">Metatables and Metamethods</a> for a complete description of the |
395 | 937 <tt>settable_event</tt> function. |
938 This function is not defined or callable in Luan. | |
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939 We use it here only for explanatory purposes.) |
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940 |
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941 |
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942 <p> |
395 | 943 An assignment to a global name <tt>x = val</tt> |
371
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944 is equivalent to the assignment |
464
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945 <tt>_ENV.x = val</tt> (see <a href="#env">Environments</a>). |
395 | 946 |
947 | |
948 | |
949 | |
479
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950 <h4 <%=heading_options%> ><a name="control">Control Structures</a></h4> |
395 | 951 |
952 <p> | |
371
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953 The control structures |
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954 <b>if</b>, <b>while</b>, and <b>repeat</b> have the usual meaning and |
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955 familiar syntax: |
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956 |
395 | 957 <p><tt><pre> |
371
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958 stat ::= <b>while</b> exp <b>do</b> block <b>end</b> |
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959 stat ::= <b>repeat</b> block <b>until</b> exp |
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960 stat ::= <b>if</b> exp <b>then</b> block {<b>elseif</b> exp <b>then</b> block} [<b>else</b> block] <b>end</b> |
395 | 961 </pre></tt></p> |
962 | |
963 <p> | |
464
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964 Luan also has a <b>for</b> statement (see <a href="#for">For Statement</a>). |
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965 |
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966 |
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967 <p> |
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968 The condition expression of a |
395 | 969 control structure must be a boolean. |
970 Any other value type will produce an error. | |
971 This helps catch errors and makes code more readable. | |
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972 |
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973 |
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974 <p> |
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975 In the <b>repeat</b>–<b>until</b> loop, |
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976 the inner block does not end at the <b>until</b> keyword, |
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977 but only after the condition. |
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978 So, the condition can refer to local variables |
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979 declared inside the loop block. |
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980 |
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981 |
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982 <p> |
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983 The <b>break</b> statement terminates the execution of a |
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984 <b>while</b>, <b>repeat</b>, or <b>for</b> loop, |
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985 skipping to the next statement after the loop: |
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986 |
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987 |
395 | 988 <p><tt><pre> |
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989 stat ::= <b>break</b> |
395 | 990 </pre></tt></p> |
991 | |
992 <p> | |
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993 A <b>break</b> ends the innermost enclosing loop. |
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994 |
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995 |
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996 <p> |
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997 The <b>return</b> statement is used to return values |
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998 from a function or a chunk |
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999 (which is an anonymous function). |
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1000 |
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1001 Functions can return more than one value, |
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1002 so the syntax for the <b>return</b> statement is |
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1003 |
395 | 1004 <p><tt><pre> |
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1005 stat ::= <b>return</b> [explist] [‘<b>;</b>’] |
395 | 1006 </pre></tt></p> |
1007 | |
1008 | |
1009 | |
1010 | |
479
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1011 <h4 <%=heading_options%> ><a name="for">For Statement</a></h4> |
395 | 1012 |
1013 <p> | |
1014 The <b>for</b> statement works over functions, | |
1015 called <i>iterators</i>. | |
1016 On each iteration, the iterator function is called to produce a new value, | |
1017 stopping when this new value is <b>nil</b>. | |
1018 The <b>for</b> loop has the following syntax: | |
1019 | |
1020 <p><tt><pre> | |
1021 stat ::= <b>for</b> namelist <b>in</b> exp <b>do</b> block <b>end</b> | |
1022 namelist ::= Name {‘<b>,</b>’ Name} | |
1023 </pre></tt></p> | |
1024 | |
1025 <p> | |
1026 A <b>for</b> statement like | |
1027 | |
1028 <p><tt><pre> | |
1029 for <i>var_1</i>, ···, <i>var_n</i> in <i>exp</i> do <i>block</i> end | |
1030 </pre></tt></p> | |
1031 | |
1032 <p> | |
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1033 is equivalent to the code: |
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1034 |
395 | 1035 <p><tt><pre> |
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1036 do |
395 | 1037 local <i>f</i> = <i>exp</i> |
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1038 while true do |
395 | 1039 local <i>var_1</i>, ···, <i>var_n</i> = <i>f</i>() |
1040 if <i>var_1</i> == nil then break end | |
1041 <i>block</i> | |
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1042 end |
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1043 end |
395 | 1044 </pre></tt></p> |
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1045 |
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1046 <p> |
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1047 Note the following: |
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1048 |
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1049 <ul> |
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1050 |
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1051 <li> |
395 | 1052 <tt><i>exp</i></tt> is evaluated only once. |
1053 Its result is an <i>iterator</i> function. | |
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1054 </li> |
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1055 |
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1056 <li> |
395 | 1057 <tt><i>f</i></tt> is an invisible variable. |
1058 The name is here for explanatory purposes only. | |
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1059 </li> |
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1060 |
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1061 <li> |
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1062 You can use <b>break</b> to exit a <b>for</b> loop. |
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1063 </li> |
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1064 |
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1065 <li> |
395 | 1066 The loop variables <tt><i>var_i</i></tt> are local to the loop; |
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1067 you cannot use their values after the <b>for</b> ends. |
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1068 If you need these values, |
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1069 then assign them to other variables before breaking or exiting the loop. |
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1070 </li> |
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1071 |
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1072 </ul> |
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1073 |
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1074 |
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1075 |
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1076 |
479
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1077 <h4 <%=heading_options%> ><a name="fn_stmt">Function Calls as Statements</a></h4> |
395 | 1078 |
1079 <p> | |
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1080 To allow possible side-effects, |
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1081 function calls can be executed as statements: |
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1082 |
395 | 1083 <p><tt><pre> |
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1084 stat ::= functioncall |
395 | 1085 </pre></tt></p> |
1086 | |
1087 <p> | |
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1088 In this case, all returned values are thrown away. |
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1089 Function calls are explained in <a href="#fn_calls">Function Calls</a>. |
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1090 |
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1091 |
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1092 |
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1093 <h4 <%=heading_options%> ><a name="local_stmt">Local Declarations</a></h4> |
395 | 1094 |
1095 <p> | |
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1096 Local variables can be declared anywhere inside a block. |
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1097 The declaration can include an initial assignment: |
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1098 |
395 | 1099 <p><tt><pre> |
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1100 stat ::= <b>local</b> namelist [‘<b>=</b>’ explist] |
395 | 1101 </pre></tt></p> |
1102 | |
1103 <p> | |
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1104 If present, an initial assignment has the same semantics |
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1105 of a multiple assignment (see <a href="#assignment">Assignment</a>). |
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1106 Otherwise, all variables are initialized with <b>nil</b>. |
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1107 |
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1108 |
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1109 <p> |
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1110 A chunk is also a block (see <a href="#chunks">Chunks</a>), |
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1111 and so local variables can be declared in a chunk outside any explicit block. |
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1112 |
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1113 |
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1114 <p> |
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1115 The visibility rules for local variables are explained in <a href="#visibility">Visibility Rules</a>. |
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1116 |
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1117 |
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1118 <h4 <%=heading_options%> ><a name="template_stmt">Template Statements</a></h4> |
465 | 1119 |
1120 <p>Template statements are based on <a href="#template_expr">template exressions</a> and provide the full equivalent of <a href="http://en.wikipedia.org/wiki/JavaServer_Pages">JSP</a> but in a general way. Template statements write the equivalent template exression to standard output. For example:</p> | |
1121 | |
1122 <p><tt><pre><%=Html.encode[[ | |
1123 local name = "Bob" | |
1124 %> | |
469 | 1125 Hello <%= name %>! |
1126 Bye <%= name %>. | |
465 | 1127 <% |
1128 ]]%></pre></tt></p> | |
1129 | |
1130 <p>is equivalent to the code:</p> | |
1131 | |
1132 <p><tt><pre><%=Html.encode[[ | |
1133 local name = "Bob" | |
1134 require("luan:Io").stdout.write( %> | |
469 | 1135 Hello <%= name %>! |
1136 Bye <%= name %>. | |
465 | 1137 <% ) |
1138 ]]%></pre></tt></p> | |
1139 | |
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1140 |
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1141 |
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1142 <h3 <%=heading_options%> ><a name="expressions">Expressions</a></h3> |
395 | 1143 |
1144 <p> | |
1145 The basic expressions in Luan are the following: | |
1146 | |
1147 <p><tt><pre> | |
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1148 exp ::= prefixexp |
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1149 exp ::= <b>nil</b> | <b>false</b> | <b>true</b> |
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1150 exp ::= Numeral |
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1151 exp ::= LiteralString |
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1152 exp ::= functiondef |
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1153 exp ::= tableconstructor |
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1154 exp ::= ‘<b>...</b>’ |
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1155 exp ::= exp binop exp |
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1156 exp ::= unop exp |
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1157 prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ |
395 | 1158 </pre></tt></p> |
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1159 |
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1160 <p> |
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1161 Numerals and literal strings are explained in <a href="#lex">Lexical Conventions</a>; |
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1162 variables are explained in <a href="#vars">Variables</a>; |
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1163 function definitions are explained in <a href="#fn_def">Function Definitions</a>; |
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1164 function calls are explained in <a href="#fn_calls">Function Calls</a>; |
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1165 table constructors are explained in <a href="#constructors">Table Constructors</a>. |
371
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1166 Vararg expressions, |
395 | 1167 denoted by three dots ('<tt>...</tt>'), can only be used when |
371
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1168 directly inside a vararg function; |
464
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1169 they are explained in <a href="#fn_def">Function Definitions</a>. |
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1170 |
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1171 |
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1172 <p> |
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1173 Binary operators comprise arithmetic operators (see <a href="#arithmetic">Arithmetic Operators</a>), |
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1174 relational operators (see <a href="#relational">Relational Operators</a>), logical operators (see <a href="#logical_ops">Logical Operators</a>), |
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1175 and the concatenation operator (see <a href="#concatenation">Concatenation</a>). |
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1176 Unary operators comprise the unary minus (see <a href="#arithmetic">Arithmetic Operators</a>), |
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1177 the unary logical <b>not</b> (see <a href="#logical_ops">Logical Operators</a>), |
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1178 and the unary <em>length operator</em> (see <a href="#length">The Length Operator</a>). |
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1179 |
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1180 |
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1181 <p> |
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1182 Both function calls and vararg expressions can result in multiple values. |
464
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1183 If a function call is used as a statement (see <a href="#fn_stmt">Function Calls as Statements</a>), |
371
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1184 then its return list is adjusted to zero elements, |
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1185 thus discarding all returned values. |
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1186 If an expression is used as the last (or the only) element |
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1187 of a list of expressions, |
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1188 then no adjustment is made |
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1189 (unless the expression is enclosed in parentheses). |
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1190 In all other contexts, |
395 | 1191 Luan adjusts the result list to one element, |
371
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1192 either discarding all values except the first one |
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1193 or adding a single <b>nil</b> if there are no values. |
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1194 |
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1195 |
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1196 <p> |
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1197 Here are some examples: |
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1198 |
395 | 1199 <p><tt><pre> |
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1200 f() -- adjusted to 0 results |
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1201 g(f(), x) -- f() is adjusted to 1 result |
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1202 g(x, f()) -- g gets x plus all results from f() |
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1203 a,b,c = f(), x -- f() is adjusted to 1 result (c gets nil) |
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1204 a,b = ... -- a gets the first vararg parameter, b gets |
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1205 -- the second (both a and b can get nil if there |
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1206 -- is no corresponding vararg parameter) |
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1207 |
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1208 a,b,c = x, f() -- f() is adjusted to 2 results |
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1209 a,b,c = f() -- f() is adjusted to 3 results |
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1210 return f() -- returns all results from f() |
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1211 return ... -- returns all received vararg parameters |
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1212 return x,y,f() -- returns x, y, and all results from f() |
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1213 {f()} -- creates a list with all results from f() |
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1214 {...} -- creates a list with all vararg parameters |
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1215 {f(), nil} -- f() is adjusted to 1 result |
395 | 1216 </pre></tt></p> |
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1217 |
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1218 <p> |
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1219 Any expression enclosed in parentheses always results in only one value. |
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1220 Thus, |
395 | 1221 <tt>(f(x,y,z))</tt> is always a single value, |
1222 even if <tt>f</tt> returns several values. | |
1223 (The value of <tt>(f(x,y,z))</tt> is the first value returned by <tt>f</tt> | |
1224 or <b>nil</b> if <tt>f</tt> does not return any values.) | |
1225 | |
1226 | |
1227 | |
479
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1228 <h4 <%=heading_options%> ><a name="arithmetic">Arithmetic Operators</a></h4> |
395 | 1229 |
1230 <p> | |
1231 Luan supports the following arithmetic operators: | |
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1232 |
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1233 <ul> |
395 | 1234 <li><b><tt>+</tt>: </b>addition</li> |
1235 <li><b><tt>-</tt>: </b>subtraction</li> | |
1236 <li><b><tt>*</tt>: </b>multiplication</li> | |
1237 <li><b><tt>/</tt>: </b>division</li> | |
1238 <li><b><tt>%</tt>: </b>modulo</li> | |
1239 <li><b><tt>^</tt>: </b>exponentiation</li> | |
1240 <li><b><tt>-</tt>: </b>unary minus</li> | |
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1241 </ul> |
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1242 |
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1243 <p> |
395 | 1244 Addition, subtraction, multiplication, division, and unary minus are the same as these operators in Java. Exponentiation uses Java's <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Math.html#pow(double,%20double)">Math.pow</a> function. |
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1245 |
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1246 <p> |
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1247 Modulo is defined as the remainder of a division |
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1248 that rounds the quotient towards minus infinite (floor division). |
395 | 1249 (The Java modulo operator is not used.) |
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1250 |
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1251 |
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1252 |
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1253 <h4 <%=heading_options%> ><a name="conversions">Coercions and Conversions</a></h4> |
396 | 1254 |
1255 <p> | |
465 | 1256 Luan generally avoids automatic conversions. |
1257 String concatenation automatically converts all of its arguments to strings. | |
1258 | |
1259 <p> | |
1260 Luan provides library functions for explicit type conversions. | |
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1261 |
396 | 1262 |
1263 | |
1264 | |
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1265 <h4 <%=heading_options%> ><a name="relational">Relational Operators</a></h4> |
396 | 1266 |
1267 <p> | |
1268 Luan supports the following relational operators: | |
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1269 |
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1270 <ul> |
396 | 1271 <li><b><tt>==</tt>: </b>equality</li> |
1272 <li><b><tt>~=</tt>: </b>inequality</li> | |
1273 <li><b><tt><</tt>: </b>less than</li> | |
1274 <li><b><tt>></tt>: </b>greater than</li> | |
1275 <li><b><tt><=</tt>: </b>less or equal</li> | |
1276 <li><b><tt>>=</tt>: </b>greater or equal</li> | |
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1277 </ul><p> |
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1278 These operators always result in <b>false</b> or <b>true</b>. |
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1279 |
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1280 |
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1281 <p> |
396 | 1282 Equality (<tt>==</tt>) first compares the type of its operands. |
371
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1283 If the types are different, then the result is <b>false</b>. |
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1284 Otherwise, the values of the operands are compared. |
396 | 1285 Strings, numbers, and binary values are compared in the obvious way (by value). |
1286 | |
1287 <p> | |
1288 Tables | |
371
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1289 are compared by reference: |
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1290 two objects are considered equal only if they are the same object. |
396 | 1291 Every time you create a new table, |
1292 it is different from any previously existing table. | |
1293 Closures are also compared by reference. | |
1294 | |
1295 <p> | |
417 | 1296 You can change the way that Luan compares tables |
464
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1297 by using the "eq" metamethod (see <a href="#meta">Metatables and Metamethods</a>). |
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1298 |
396 | 1299 <p> |
1300 Userdata are Java objects. They are compared for equality with the Java <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#equals(java.lang.Object)"><tt>equals</tt></a> method. | |
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1301 |
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1302 <p> |
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1303 Equality comparisons do not convert strings to numbers |
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1304 or vice versa. |
396 | 1305 Thus, <tt>"0"==0</tt> evaluates to <b>false</b>, |
1306 and <tt>t[0]</tt> and <tt>t["0"]</tt> denote different | |
371
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1307 entries in a table. |
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1308 |
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1309 |
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1310 <p> |
396 | 1311 The operator <tt>~=</tt> is exactly the negation of equality (<tt>==</tt>). |
371
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1312 |
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1313 |
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1314 <p> |
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1315 The order operators work as follows. |
396 | 1316 |
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1317 If both arguments are numbers, |
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1318 then they are compared following |
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1319 the usual rule for binary operations. |
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1320 Otherwise, if both arguments are strings, |
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1321 then their values are compared according to the current locale. |
396 | 1322 Otherwise, Luan tries to call the "lt" or the "le" |
464
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1323 metamethod (see <a href="#meta">Metatables and Metamethods</a>). |
396 | 1324 A comparison <tt>a > b</tt> is translated to <tt>b < a</tt> |
1325 and <tt>a >= b</tt> is translated to <tt>b <= a</tt>. | |
1326 | |
1327 | |
1328 | |
1329 | |
1330 | |
479
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1331 <h4 <%=heading_options%> ><a name="logical_ops">Logical Operators</a></h4> |
396 | 1332 |
1333 <p> | |
1334 The logical operators in Luan are | |
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1335 <b>and</b>, <b>or</b>, and <b>not</b>. |
396 | 1336 The <b>and</b> and <b>or</b> operators consider both <b>false</b> and <b>nil</b> as false |
1337 and anything else as true. | |
464
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1338 Like the control structures (see <a href="#control">Control Structures</a>), |
396 | 1339 the <b>not</b> operator requires a boolean value. |
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1340 |
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1341 <p> |
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1342 The negation operator <b>not</b> always returns <b>false</b> or <b>true</b>. |
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1343 The conjunction operator <b>and</b> returns its first argument |
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1344 if this value is <b>false</b> or <b>nil</b>; |
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1345 otherwise, <b>and</b> returns its second argument. |
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1346 The disjunction operator <b>or</b> returns its first argument |
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1347 if this value is different from <b>nil</b> and <b>false</b>; |
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1348 otherwise, <b>or</b> returns its second argument. |
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1349 Both <b>and</b> and <b>or</b> use short-circuit evaluation; |
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1350 that is, |
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1351 the second operand is evaluated only if necessary. |
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1352 Here are some examples: |
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1353 |
396 | 1354 <p><tt><pre> |
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1355 10 or 20 --> 10 |
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1356 10 or error() --> 10 |
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1357 nil or "a" --> "a" |
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1358 nil and 10 --> nil |
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1359 false and error() --> false |
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1360 false and nil --> false |
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1361 false or nil --> nil |
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1362 10 and 20 --> 20 |
396 | 1363 </pre></tt></p> |
1364 | |
1365 <p> | |
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1366 (In this manual, |
396 | 1367 <tt>--></tt> indicates the result of the preceding expression.) |
1368 | |
1369 | |
1370 | |
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1371 <h4 <%=heading_options%> ><a name="concatenation">Concatenation</a></h4> |
396 | 1372 |
1373 <p> | |
1374 The string concatenation operator in Luan is | |
1375 denoted by two dots ('<tt>..</tt>'). | |
1376 All operands are converted to strings. | |
1377 | |
1378 | |
1379 | |
479
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1380 <h4 <%=heading_options%> ><a name="length">The Length Operator</a></h4> |
396 | 1381 |
1382 <p> | |
1383 The length operator is denoted by the unary prefix operator <tt>#</tt>. | |
1384 The length of a string is its number of characters. | |
1385 The length of a binary is its number of bytes. | |
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1386 |
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1387 |
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1388 <p> |
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1389 A program can modify the behavior of the length operator for |
464
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1390 any table through the <tt>__len</tt> metamethod (see <a href="#meta">Metatables and Metamethods</a>). |
396 | 1391 |
1392 | |
1393 <p> | |
1394 Unless a <tt>__len</tt> metamethod is given, | |
1395 the length of a table <tt>t</tt> is defined | |
1396 as the number of elements in <em>sequence</em>, | |
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1397 that is, |
396 | 1398 the size of the set of its positive numeric keys is equal to <em>{1..n}</em> |
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1399 for some non-negative integer <em>n</em>. |
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1400 In that case, <em>n</em> is its length. |
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1401 Note that a table like |
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1402 |
396 | 1403 <p><tt><pre> |
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1404 {10, 20, nil, 40} |
396 | 1405 </pre></tt></p> |
1406 | |
1407 <p> | |
1408 has a length of <tt>2</tt>, because that is the last key in sequence. | |
1409 | |
1410 | |
1411 | |
1412 | |
1413 | |
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1414 <h4 <%=heading_options%> ><a name="precedence">Precedence</a></h4> |
396 | 1415 |
1416 <p> | |
1417 Operator precedence in Luan follows the table below, | |
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1418 from lower to higher priority: |
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1419 |
396 | 1420 <p><tt><pre> |
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1421 or |
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1422 and |
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1423 < > <= >= ~= == |
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1424 .. |
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1425 + - |
396 | 1426 * / % |
1427 unary operators (not # -) | |
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1428 ^ |
396 | 1429 </pre></tt></p> |
1430 | |
1431 <p> | |
371
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1432 As usual, |
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1433 you can use parentheses to change the precedences of an expression. |
396 | 1434 The concatenation ('<tt>..</tt>') and exponentiation ('<tt>^</tt>') |
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1435 operators are right associative. |
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1436 All other binary operators are left associative. |
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1437 |
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1438 |
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1439 |
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1440 |
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1441 |
479
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1442 <h4 <%=heading_options%> ><a name="constructors">Table Constructors</a></h4> |
396 | 1443 |
1444 <p> | |
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1445 Table constructors are expressions that create tables. |
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1446 Every time a constructor is evaluated, a new table is created. |
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1447 A constructor can be used to create an empty table |
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1448 or to create a table and initialize some of its fields. |
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1449 The general syntax for constructors is |
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1450 |
396 | 1451 <p><tt><pre> |
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1452 tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ |
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1453 fieldlist ::= field {fieldsep field} [fieldsep] |
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1454 field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp |
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1455 fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ |
396 | 1456 </pre></tt></p> |
1457 | |
1458 <p> | |
1459 Each field of the form <tt>[exp1] = exp2</tt> adds to the new table an entry | |
1460 with key <tt>exp1</tt> and value <tt>exp2</tt>. | |
1461 A field of the form <tt>name = exp</tt> is equivalent to | |
1462 <tt>["name"] = exp</tt>. | |
1463 Finally, fields of the form <tt>exp</tt> are equivalent to | |
1464 <tt>[i] = exp</tt>, where <tt>i</tt> are consecutive integers | |
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1465 starting with 1. |
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1466 Fields in the other formats do not affect this counting. |
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1467 For example, |
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1468 |
396 | 1469 <p><tt><pre> |
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1470 a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 } |
396 | 1471 </pre></tt></p> |
1472 | |
1473 <p> | |
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1474 is equivalent to |
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1475 |
396 | 1476 <p><tt><pre> |
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1477 do |
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1478 local t = {} |
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1479 t[f(1)] = g |
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1480 t[1] = "x" -- 1st exp |
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1481 t[2] = "y" -- 2nd exp |
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1482 t.x = 1 -- t["x"] = 1 |
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1483 t[3] = f(x) -- 3rd exp |
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1484 t[30] = 23 |
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1485 t[4] = 45 -- 4th exp |
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1486 a = t |
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1487 end |
396 | 1488 </pre></tt></p> |
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1489 |
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1490 <p> |
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1491 The order of the assignments in a constructor is undefined. |
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1492 (This order would be relevant only when there are repeated keys.) |
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1493 |
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1494 |
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1495 <p> |
396 | 1496 If the last field in the list has the form <tt>exp</tt> |
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1497 and the expression is a function call or a vararg expression, |
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1498 then all values returned by this expression enter the list consecutively |
464
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1499 (see <a href="#fn_calls">Function Calls</a>). |
371
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1500 |
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1501 |
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1502 <p> |
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1503 The field list can have an optional trailing separator, |
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1504 as a convenience for machine-generated code. |
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1505 |
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1506 |
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1507 |
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1508 |
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1509 |
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1510 <h4 <%=heading_options%> ><a name="fn_calls">Function Calls</a></h4> |
417 | 1511 |
1512 <p> | |
1513 A function call in Luan has the following syntax: | |
1514 | |
1515 <p><tt><pre> | |
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1516 functioncall ::= prefixexp args |
417 | 1517 </pre></tt></p> |
1518 | |
1519 <p> | |
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1520 In a function call, |
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1521 first prefixexp and args are evaluated. |
417 | 1522 If the value of prefixexp has type <i>function</i>, |
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1523 then this function is called |
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1524 with the given arguments. |
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1525 Otherwise, the prefixexp "call" metamethod is called, |
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1526 having as first parameter the value of prefixexp, |
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1527 followed by the original call arguments |
464
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1528 (see <a href="#meta">Metatables and Metamethods</a>). |
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1529 |
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1530 |
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1531 <p> |
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1532 Arguments have the following syntax: |
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1533 |
417 | 1534 <p><tt><pre> |
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1535 args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ |
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1536 args ::= tableconstructor |
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1537 args ::= LiteralString |
417 | 1538 </pre></tt></p> |
1539 | |
1540 <p> | |
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1541 All argument expressions are evaluated before the call. |
417 | 1542 A call of the form <tt>f{<i>fields</i>}</tt> is |
1543 syntactic sugar for <tt>f({<i>fields</i>})</tt>; | |
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1544 that is, the argument list is a single new table. |
417 | 1545 A call of the form <tt>f'<i>string</i>'</tt> |
1546 (or <tt>f"<i>string</i>"</tt> or <tt>f[[<i>string</i>]]</tt>) | |
1547 is syntactic sugar for <tt>f('<i>string</i>')</tt>; | |
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1548 that is, the argument list is a single literal string. |
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1549 |
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1550 |
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1551 <p> |
417 | 1552 A call of the form <tt>return <i>functioncall</i></tt> is called |
1553 a <i>tail call</i>. | |
1554 Luan implements <i>proper tail calls</i> | |
1555 (or <i>proper tail recursion</i>): | |
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1556 in a tail call, |
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1557 the called function reuses the stack entry of the calling function. |
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1558 Therefore, there is no limit on the number of nested tail calls that |
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1559 a program can execute. |
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1560 However, a tail call erases any debug information about the |
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1561 calling function. |
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1562 Note that a tail call only happens with a particular syntax, |
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1563 where the <b>return</b> has one single function call as argument; |
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1564 this syntax makes the calling function return exactly |
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1565 the returns of the called function. |
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1566 So, none of the following examples are tail calls: |
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1567 |
417 | 1568 <p><tt><pre> |
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1569 return (f(x)) -- results adjusted to 1 |
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1570 return 2 * f(x) |
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1571 return x, f(x) -- additional results |
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1572 f(x); return -- results discarded |
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1573 return x or f(x) -- results adjusted to 1 |
417 | 1574 </pre></tt></p> |
1575 | |
1576 | |
1577 | |
1578 | |
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1579 <h4 <%=heading_options%> ><a name="fn_def">Function Definitions</a></h4> |
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1580 |
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1581 <p> |
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1582 The syntax for function definition is |
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1583 |
417 | 1584 <p><tt><pre> |
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1585 functiondef ::= <b>function</b> funcbody |
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1586 funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> |
417 | 1587 </pre></tt></p> |
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1588 |
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1589 <p> |
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1590 The following syntactic sugar simplifies function definitions: |
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1591 |
417 | 1592 <p><tt><pre> |
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1593 stat ::= <b>function</b> funcname funcbody |
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1594 stat ::= <b>local</b> <b>function</b> Name funcbody |
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1595 funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] |
417 | 1596 </pre></tt></p> |
1597 | |
1598 <p> | |
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1599 The statement |
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1600 |
417 | 1601 <p><tt><pre> |
1602 function f () <i>body</i> end | |
1603 </pre></tt></p> | |
1604 | |
1605 <p> | |
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1606 translates to |
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1607 |
417 | 1608 <p><tt><pre> |
1609 f = function () <i>body</i> end | |
1610 </pre></tt></p> | |
1611 | |
1612 <p> | |
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1613 The statement |
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1614 |
417 | 1615 <p><tt><pre> |
1616 function t.a.b.c.f () <i>body</i> end | |
1617 </pre></tt></p> | |
1618 | |
1619 <p> | |
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1620 translates to |
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1621 |
417 | 1622 <p><tt><pre> |
1623 t.a.b.c.f = function () <i>body</i> end | |
1624 </pre></tt></p> | |
1625 | |
1626 <p> | |
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1627 The statement |
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1628 |
417 | 1629 <p><tt><pre> |
1630 local function f () <i>body</i> end | |
1631 </pre></tt></p> | |
1632 | |
1633 <p> | |
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1634 translates to |
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1635 |
417 | 1636 <p><tt><pre> |
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1637 local f; f = function () <em>body</em> end |
417 | 1638 </pre></tt></p> |
1639 | |
1640 <p> | |
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1641 not to |
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1642 |
417 | 1643 <p><tt><pre> |
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1644 local f = function () <em>body</em> end |
417 | 1645 </pre></tt></p> |
1646 | |
1647 <p> | |
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1648 (This only makes a difference when the body of the function |
417 | 1649 contains references to <tt>f</tt>.) |
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1650 |
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1651 |
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1652 <p> |
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1653 A function definition is an executable expression, |
417 | 1654 whose value has type <i>function</i>. |
1655 When Luan precompiles a chunk, | |
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1656 all its function bodies are precompiled too. |
417 | 1657 Then, whenever Luan executes the function definition, |
1658 the function is <i>instantiated</i> (or <i>closed</i>). | |
1659 This function instance (or <i>closure</i>) | |
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1660 is the final value of the expression. |
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1661 |
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1662 |
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1663 <p> |
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1664 Parameters act as local variables that are |
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1665 initialized with the argument values: |
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1666 |
417 | 1667 <p><tt><pre> |
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1668 parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ |
417 | 1669 </pre></tt></p> |
1670 | |
1671 <p> | |
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1672 When a function is called, |
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1673 the list of arguments is adjusted to |
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1674 the length of the list of parameters, |
417 | 1675 unless the function is a <i>vararg function</i>, |
1676 which is indicated by three dots ('<tt>...</tt>') | |
371
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1677 at the end of its parameter list. |
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1678 A vararg function does not adjust its argument list; |
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1679 instead, it collects all extra arguments and supplies them |
417 | 1680 to the function through a <i>vararg expression</i>, |
371
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1681 which is also written as three dots. |
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1682 The value of this expression is a list of all actual extra arguments, |
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1683 similar to a function with multiple results. |
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1684 If a vararg expression is used inside another expression |
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1685 or in the middle of a list of expressions, |
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1686 then its return list is adjusted to one element. |
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1687 If the expression is used as the last element of a list of expressions, |
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1688 then no adjustment is made |
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1689 (unless that last expression is enclosed in parentheses). |
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1690 |
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1691 |
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1692 <p> |
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1693 As an example, consider the following definitions: |
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1694 |
417 | 1695 <p><tt><pre> |
371
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1696 function f(a, b) end |
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1697 function g(a, b, ...) end |
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1698 function r() return 1,2,3 end |
417 | 1699 </pre></tt></p> |
1700 | |
1701 <p> | |
371
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1702 Then, we have the following mapping from arguments to parameters and |
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1703 to the vararg expression: |
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1704 |
417 | 1705 <p><tt><pre> |
371
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1706 CALL PARAMETERS |
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1707 |
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1708 f(3) a=3, b=nil |
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1709 f(3, 4) a=3, b=4 |
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1710 f(3, 4, 5) a=3, b=4 |
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1711 f(r(), 10) a=1, b=10 |
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1712 f(r()) a=1, b=2 |
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1713 |
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1714 g(3) a=3, b=nil, ... --> (nothing) |
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1715 g(3, 4) a=3, b=4, ... --> (nothing) |
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1716 g(3, 4, 5, 8) a=3, b=4, ... --> 5 8 |
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1717 g(5, r()) a=5, b=1, ... --> 2 3 |
417 | 1718 </pre></tt></p> |
371
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1719 |
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1720 <p> |
464
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1721 Results are returned using the <b>return</b> statement (see <a href="#control">Control Structures</a>). |
371
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1722 If control reaches the end of a function |
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1723 without encountering a <b>return</b> statement, |
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1724 then the function returns with no results. |
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1725 |
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1726 |
479
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1727 <h4 <%=heading_options%> ><a name="template_expr">Template Expressions</a></h4> |
465 | 1728 |
1729 <p>Luan template expression are based on <a href="http://en.wikipedia.org/wiki/JavaServer_Pages">JSP</a>. Template expressions return multiple values. Here is an example:</p> | |
1730 | |
1731 <p><tt><pre><%=Html.encode[[ | |
1732 local name = "Bob" | |
469 | 1733 write( %>Hello <%= name %>!<% ) |
465 | 1734 ]]%></pre></tt></p> |
1735 | |
1736 <p>This is equivalent to the code:</p> | |
1737 | |
1738 <p><tt><pre> | |
1739 local name = "Bob" | |
1740 write( "Hello ", name, "!" ) | |
1741 </pre></tt></p> | |
1742 | |
1743 <p>The strings in template expressions may be multiple lines.</p> | |
1744 | |
417 | 1745 |
1746 | |
479
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1747 <h3 <%=heading_options%> ><a name="visibility">Visibility Rules</a></h3> |
417 | 1748 |
1749 <p> | |
1750 Luan is a lexically scoped language. | |
371
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1751 The scope of a local variable begins at the first statement after |
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1752 its declaration and lasts until the last non-void statement |
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1753 of the innermost block that includes the declaration. |
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1754 Consider the following example: |
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1755 |
417 | 1756 <p><tt><pre> |
371
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1757 x = 10 -- global variable |
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1758 do -- new block |
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1759 local x = x -- new 'x', with value 10 |
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1760 print(x) --> 10 |
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1761 x = x+1 |
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1762 do -- another block |
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1763 local x = x+1 -- another 'x' |
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1764 print(x) --> 12 |
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1765 end |
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1766 print(x) --> 11 |
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1767 end |
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1768 print(x) --> 10 (the global one) |
417 | 1769 </pre></tt></p> |
1770 | |
1771 <p> | |
1772 Notice that, in a declaration like <tt>local x = x</tt>, | |
1773 the new <tt>x</tt> being declared is not in scope yet, | |
1774 and so the second <tt>x</tt> refers to the outside variable. | |
371
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1775 |
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1776 |
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1777 <p> |
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1778 Because of the lexical scoping rules, |
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1779 local variables can be freely accessed by functions |
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1780 defined inside their scope. |
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1781 A local variable used by an inner function is called |
417 | 1782 an <i>upvalue</i>, or <i>external local variable</i>, |
371
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1783 inside the inner function. |
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1784 |
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1785 |
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1786 <p> |
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1787 Notice that each execution of a <b>local</b> statement |
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1788 defines new local variables. |
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1789 Consider the following example: |
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1790 |
417 | 1791 <p><tt><pre> |
371
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1792 a = {} |
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1793 local x = 20 |
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1794 for i=1,10 do |
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1795 local y = 0 |
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1796 a[i] = function () y=y+1; return x+y end |
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1797 end |
417 | 1798 </pre></tt></p> |
1799 | |
1800 <p> | |
371
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1801 The loop creates ten closures |
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1802 (that is, ten instances of the anonymous function). |
417 | 1803 Each of these closures uses a different <tt>y</tt> variable, |
1804 while all of them share the same <tt>x</tt>. | |
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1805 |
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1806 |
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1807 |
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1808 |
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1809 |
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1810 <h2 <%=heading_options%> ><a name="libs">Standard Libraries</a></h2> |
468 | 1811 |
1812 <p> | |
1813 The standard Luan libraries provide useful functions | |
1814 that are implemented both in Java and in Luan itself. | |
1815 How each function is implemented shouldn't matter to the user. | |
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1816 Some of these functions provide essential services to the language |
478 | 1817 (e.g., <a href="#Luan.type"><tt>type</tt></a> and <a href="#Luan.get_metatable"><tt>get_metatable</tt></a>); |
468 | 1818 others provide access to "outside" services (e.g., I/O). |
1819 | |
1820 | |
479
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1821 <h3 <%=heading_options%> ><a name="default_lib">Default Environment</a></h3> |
468 | 1822 |
1823 <p> | |
1824 These are provided by default as local variables for any Luan code as described in <a href="#env">Environments</a>. | |
1825 | |
470 | 1826 |
479
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1827 <h4 <%=heading_options%> ><a name="_ENV"><tt>_ENV</tt></a></h4> |
468 | 1828 |
1829 <p> | |
1830 This is a table that holds the global variables of a module as described in <a href="#env">Environments</a>. | |
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1831 |
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1832 |
479
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1833 <h4 <%=heading_options%> ><a name="require"><tt>java ()</tt></a></h4> |
470 | 1834 |
1835 <p> | |
1836 This function enables Java in the current chunk if that chunk has permission to use Java. If the chunk doesn't have permission to use Java, then an error is thrown. | |
1837 | |
1838 | |
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1839 <h4 <%=heading_options%> ><a name="require"><tt>require (mod_uri)</tt></a></h4> |
470 | 1840 |
1841 <p> | |
1842 Example use: | |
1843 | |
1844 <p><tt><pre> | |
1845 local Table = require "luan:Table" | |
1846 </pre></tt></p> | |
1847 | |
1848 <p> | |
1849 Could be defined as: | |
1850 | |
1851 <p><tt><pre> | |
1852 local function require(mod_name) | |
476 | 1853 return <a href="#Package.load">Package.load</a>(mod_name) or <a href="#Luan.error">Luan.error</a>("module '"..mod_name.."' not found") |
470 | 1854 end |
1855 </pre></tt></p> | |
1856 | |
1857 | |
479
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1858 <h3 <%=heading_options%> ><a name="luan_lib">Basic Functions</a></h3> |
470 | 1859 |
1860 <p> | |
1861 Include this library by: | |
1862 | |
1863 <p><tt><pre> | |
1864 local Luan = require "luan:Luan" | |
1865 </pre></tt></p> | |
1866 | |
476 | 1867 <p> |
470 | 1868 The basic library provides basic functions to Luan that don't depend on other libaries. |
1869 | |
1870 | |
479
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1871 <h4 <%=heading_options%> ><a name="Luan.assert"><tt>Luan.assert (v [, message])</tt></a></h4> |
470 | 1872 |
1873 <p> | |
1874 Could be defined as: | |
1875 | |
1876 <p><tt><pre> | |
1877 function Luan.assert(v,message) | |
472 | 1878 return v or <a href="#Luan.error">Luan.error</a>(message or "assertion failed!") |
470 | 1879 end |
1880 </pre></tt></p> | |
1881 | |
1882 | |
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1883 <h4 <%=heading_options%> ><a name="Luan.assert_binary"><tt>Luan.assert_binary (v)</tt></a></h4> |
470 | 1884 |
1885 <p> | |
1886 Could be defined as: | |
1887 | |
1888 <p><tt><pre> | |
1889 function Luan.assert_binary(v) | |
1890 local v_type = Luan.type(v) | |
472 | 1891 return v_type == "binary" and v or <a href="#Luan.error">Luan.error</a>("bad argument #1 (binary expected, got "..v_type..")") |
470 | 1892 end |
1893 </pre></tt></p> | |
1894 | |
1895 | |
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1896 <h4 <%=heading_options%> ><a name="Luan.assert_boolean"><tt>Luan.assert_boolean (v)</tt></a></h4> |
470 | 1897 |
1898 <p> | |
1899 Like <a href="#Luan.assert_binary"><tt>assert_binary</tt></a> but for type <tt>boolean</tt>. | |
1900 | |
1901 | |
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1902 <h4 <%=heading_options%> ><a name="Luan.assert_integer"><tt>Luan.assert_integer (v)</tt></a></h4> |
470 | 1903 |
1904 <p> | |
1905 Asserts that <tt>v</tt> can be converted to Java type <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html">Integer</a> and returns an Integer. | |
1906 | |
1907 | |
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1908 <h4 <%=heading_options%> ><a name="Luan.assert_long"><tt>Luan.assert_long (v)</tt></a></h4> |
470 | 1909 |
1910 <p> | |
1911 Asserts that <tt>v</tt> can be converted to Java type <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Long.html">Long</a> and returns a Long. | |
1912 | |
1913 | |
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1914 <h4 <%=heading_options%> ><a name="Luan.assert_number"><tt>Luan.assert_number (v)</tt></a></h4> |
470 | 1915 |
1916 <p> | |
1917 Like <a href="#Luan.assert_binary"><tt>assert_binary</tt></a> but for type <tt>number</tt>. | |
1918 | |
1919 | |
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1920 <h4 <%=heading_options%> ><a name="Luan.assert_string"><tt>Luan.assert_string (v)</tt></a></h4> |
470 | 1921 |
1922 <p> | |
1923 Like <a href="#Luan.assert_binary"><tt>assert_binary</tt></a> but for type <tt>string</tt>. | |
1924 | |
1925 | |
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1926 <h4 <%=heading_options%> ><a name="Luan.assert_table"><tt>Luan.assert_table (v)</tt></a></h4> |
470 | 1927 |
1928 <p> | |
1929 Like <a href="#Luan.assert_binary"><tt>assert_binary</tt></a> but for type <tt>table</tt>. | |
1930 | |
1931 | |
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1932 <h4 <%=heading_options%> ><a name="Luan.do_file"><tt>Luan.do_file ([uri])</tt></a></h4> |
470 | 1933 |
1934 <p> | |
1935 Could be defined as: | |
1936 | |
1937 <p><tt><pre> | |
1938 function Luan.do_file(uri) | |
474 | 1939 return <a href="#Luan.load_file">Luan.load_file</a>(uri)() |
470 | 1940 end |
1941 </pre></tt></p> | |
1942 | |
1943 | |
1944 | |
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1945 <h4 <%=heading_options%> ><a name="Luan.error"><tt>Luan.error (message)</tt></a></h4> |
470 | 1946 |
1947 <p> | |
482 | 1948 Throws an error containing the message. |
1949 | |
1950 <p> | |
1951 Could be defined as: | |
1952 | |
1953 <p><tt><pre> | |
1954 function Luan.error(message) | |
1955 <a href="#Luan.new_error">Luan.new_error</a>(message).throw() | |
1956 end | |
1957 </pre></tt></p> | |
1958 | |
470 | 1959 |
1960 | |
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1961 <h4 <%=heading_options%> ><a name="Luan.get_metatable"><tt>Luan.get_metatable (table)</tt></a></h4> |
470 | 1962 |
1963 <p> | |
1964 If <tt>table</tt> does not have a metatable, returns <b>nil</b>. | |
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1965 Otherwise, |
470 | 1966 if the table's metatable has a <tt>"__metatable"</tt> field, |
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1967 returns the associated value. |
470 | 1968 Otherwise, returns the metatable of the given table. |
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1969 |
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1970 |
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1971 <h4 <%=heading_options%> ><a name="Luan.ipairs"><tt>Luan.ipairs (t)</tt></a></h4> |
474 | 1972 |
1973 <p> | |
1974 Returns an iterator function | |
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1975 so that the construction |
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1976 |
474 | 1977 <p><tt><pre> |
1978 for i,v in ipairs(t) do <i>body</i> end | |
1979 </pre></tt></p> | |
1980 | |
1981 <p> | |
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1982 will iterate over the key–value pairs |
474 | 1983 (<tt>1,t[1]</tt>), (<tt>2,t[2]</tt>), ..., |
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1984 up to the first nil value. |
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1985 |
474 | 1986 <p> |
1987 Could be defined as: | |
1988 | |
1989 <p><tt><pre> | |
1990 function Luan.ipairs(t) | |
1991 local i = 0 | |
1992 return function() | |
1993 if i < #t then | |
1994 i = i + 1 | |
1995 return i, t[i] | |
1996 end | |
1997 end | |
1998 end | |
1999 </pre></tt></p> | |
2000 | |
2001 | |
2002 | |
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2003 <h4 <%=heading_options%> ><a name="Luan.load"><tt>Luan.load (text, source_name [env, [, allow_expression]])</tt></a></h4> |
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2004 |
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2005 <p> |
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2006 Loads a chunk. |
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2007 |
474 | 2008 <p> |
2009 The <tt>text</tt> is compiled. | |
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2010 If there are no syntactic errors, |
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2011 returns the compiled chunk as a function; |
474 | 2012 otherwise, throws an error. |
2013 | |
2014 <p> | |
2015 The <tt>source_name</tt> parameter is a string saying where the text came from. It is used to produce error messages. | |
2016 | |
2017 <p> | |
2018 If the <tt>env</tt> parameter is supplied, it becomes the <tt>_ENV</tt> of the chunk. | |
2019 | |
2020 <p> | |
2021 If the <tt>allow_expression</tt> parameter is <tt>true</tt> then the entire text can be nothing more than an expression in which case the chunk returns the value of this expression. | |
2022 | |
2023 | |
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2024 <h4 <%=heading_options%> ><a name="Luan.load_file"><tt>Luan.load_file (file_uri [, add_extension])</tt></a></h4> |
474 | 2025 |
2026 <p> | |
2027 Similar to <a href="#Luan.load"><tt>load</tt></a>, | |
2028 but gets the chunk from file <tt>file_uri</tt> | |
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2029 or from the standard input, |
474 | 2030 if no file uri is given. |
2031 | |
2032 <p> | |
2033 Could be defined as: | |
2034 | |
2035 <p><tt><pre> | |
2036 function Luan.load_file(file_uri,add_extension) | |
2037 file_uri = file_uri or "stdin:" | |
2038 local f = Io.uri(file_uri,add_extension) | |
2039 f.exists() or <a href="#Luan.error">Luan.error</a>("file '"..file_uri.."' not found") | |
2040 return <a href="#Luan.load">Luan.load</a>( f.read_text(), file_uri ) | |
2041 end | |
2042 </pre></tt></p> | |
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2043 |
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2044 |
482 | 2045 <h4 <%=heading_options%> ><a name="Luan.new_error"><tt>Luan.new_error (message)</tt></a></h4> |
2046 | |
2047 <p> | |
2048 Creates a new error table containing the message assigned to "<tt>message</tt>". The error table also contains a <tt>throw</tt> function which throws the error. The table also contains a list of stack trace elements where each stack trace element is a table containing "<tt>source</tt>", "<tt>line</tt>", and possible "<tt>call_to</tt>". The table also has a metatable containing "<tt>__to_string</tt>" to render the error. | |
2049 | |
2050 <p> | |
2051 To print the current stack trace, you could do: | |
2052 | |
2053 <p><tt><pre> | |
2054 Io.print( Luan.new_error "stack" ) | |
2055 </pre></tt></p> | |
2056 | |
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2057 |
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2058 <h4 <%=heading_options%> ><a name="Luan.pairs"><tt>Luan.pairs (t)</tt></a></h4> |
475 | 2059 |
2060 <p> | |
2061 If <tt>t</tt> has a metamethod <tt>__pairs</tt>, | |
2062 calls it with <tt>t</tt> as argument and returns the | |
2063 result from the call. | |
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2064 |
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2065 |
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2066 <p> |
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2067 Otherwise, |
475 | 2068 returns a function |
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2069 so that the construction |
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2070 |
475 | 2071 <p><tt><pre> |
2072 for k,v in pairs(t) do <i>body</i> end | |
2073 </pre></tt></p> | |
2074 | |
2075 <p> | |
2076 will iterate over all key–value pairs of table <tt>t</tt>. | |
2077 | |
2078 | |
2079 | |
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2080 <h4 <%=heading_options%> ><a name="Luan.pcall"><tt>Luan.pcall (f [, arg1, ···])</tt></a></h4> |
475 | 2081 |
2082 <p> | |
2083 Calls function <tt>f</tt> with | |
2084 the given arguments in <i>protected mode</i>. | |
2085 This means that any error inside <tt>f</tt> is not propagated; | |
2086 instead, <tt>pcall</tt> catches the error | |
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2087 and returns a status code. |
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2088 Its first result is the status code (a boolean), |
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2089 which is true if the call succeeds without errors. |
475 | 2090 In such case, <tt>pcall</tt> also returns all results from the call, |
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2091 after this first result. |
475 | 2092 In case of any error, <tt>pcall</tt> returns <b>false</b> plus the error. |
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2093 |
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2094 |
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2095 |
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2096 |
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2097 <p> |
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2098 <hr><h3><a name="pdf-print"><code>print (···)</code></a></h3> |
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2099 Receives any number of arguments |
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2100 and prints their values to <code>stdout</code>, |
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2101 using the <a href="#pdf-tostring"><code>tostring</code></a> function to convert each argument to a string. |
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2102 <code>print</code> is not intended for formatted output, |
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2103 but only as a quick way to show a value, |
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2104 for instance for debugging. |
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2105 For complete control over the output, |
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2106 use <a href="#pdf-string.format"><code>string.format</code></a> and <a href="#pdf-io.write"><code>io.write</code></a>. |
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2107 |
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2108 |
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2109 |
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2110 <h4 <%=heading_options%> ><a name="Luan.range"><tt>Luan.range (start, stop [, step])</tt></a></h4> |
476 | 2111 |
2112 <p> | |
2113 Based on <a href="https://docs.python.org/2/library/functions.html#range">the Python range() function</a>, this lets one iterate through a sequence of numbers. | |
2114 | |
2115 <p> | |
2116 Example use: | |
2117 | |
2118 <p><tt><pre> | |
2119 for i in range(1,10) do | |
2120 Io.print("count up:",i) | |
2121 end | |
2122 for i in range(10,0,-1) do | |
2123 Io.print("count down:",i) | |
2124 end | |
2125 </pre></tt></p> | |
2126 | |
2127 <p> | |
2128 Could be defined as: | |
2129 | |
2130 <p><tt><pre> | |
2131 function Luan.range(start, stop, step) | |
2132 step = step or 1 | |
478 | 2133 step == 0 and <a href="#Luan.error">Luan.error</a> "bad argument #3 (step may not be zero)" |
476 | 2134 local i = start |
2135 return function() | |
2136 if step > 0 and i <= stop or step < 0 and i >= stop then | |
2137 local rtn = i | |
2138 i = i + step | |
2139 return rtn | |
2140 end | |
2141 end | |
2142 end | |
2143 </pre></tt></p> | |
2144 | |
2145 | |
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2146 |
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2147 <h4 <%=heading_options%> ><a name="Luan.raw_equal"><tt>Luan.raw_equal (v1, v2)</tt></a></h4> |
475 | 2148 |
2149 <p> | |
2150 Checks whether <tt>v1</tt> is equal to <tt>v2</tt>, | |
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2151 without invoking any metamethod. |
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2152 Returns a boolean. |
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2153 |
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2154 |
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2155 |
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2156 <h4 <%=heading_options%> ><a name="Luan.raw_get"><tt>Luan.raw_get (table, index)</tt></a></h4> |
475 | 2157 |
2158 <p> | |
2159 Gets the real value of <tt>table[index]</tt>, | |
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2160 without invoking any metamethod. |
475 | 2161 <tt>table</tt> must be a table; |
2162 <tt>index</tt> may be any value. | |
2163 | |
2164 | |
2165 | |
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2166 <h4 <%=heading_options%> ><a name="Luan.raw_len"><tt>Luan.raw_len (v)</tt></a></h4> |
475 | 2167 |
2168 <p> | |
2169 Returns the length of the object <tt>v</tt>, | |
371
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2170 which must be a table or a string, |
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2171 without invoking any metamethod. |
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2172 Returns an integer. |
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2173 |
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2174 |
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2175 |
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2176 <h4 <%=heading_options%> ><a name="Luan.raw_set"><tt>Luan.raw_set (table, index, value)</tt></a></h4> |
475 | 2177 |
2178 <p> | |
2179 Sets the real value of <tt>table[index]</tt> to <tt>value</tt>, | |
371
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2180 without invoking any metamethod. |
475 | 2181 <tt>table</tt> must be a table, |
2182 <tt>index</tt> any value different from <b>nil</b>, | |
2183 and <tt>value</tt> any Lua value. | |
2184 | |
371
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2185 |
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2186 <h4 <%=heading_options%> ><a name="Luan.set_metatable"><tt>Luan.set_metatable (table, metatable)</tt></a></h4> |
371
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2187 |
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2188 <p> |
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2189 Sets the metatable for the given table. |
475 | 2190 If <tt>metatable</tt> is <b>nil</b>, |
371
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2191 removes the metatable of the given table. |
475 | 2192 If the original metatable has a <tt>"__metatable"</tt> field, |
371
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2193 raises an error. |
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2194 |
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2195 |
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2196 |
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2197 |
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2198 <p> |
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2199 <hr><h3><a name="pdf-tonumber"><code>tonumber (e [, base])</code></a></h3> |
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2200 |
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2201 |
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2202 <p> |
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2203 When called with no <code>base</code>, |
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2204 <code>tonumber</code> tries to convert its argument to a number. |
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2205 If the argument is already a number or |
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2206 a string convertible to a number, |
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2207 then <code>tonumber</code> returns this number; |
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2208 otherwise, it returns <b>nil</b>. |
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2209 |
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2210 |
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2211 <p> |
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2212 The conversion of strings can result in integers or floats, |
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2213 according to the lexical conventions of Lua (see <a href="#3.1">§3.1</a>). |
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2214 (The string may have leading and trailing spaces and a sign.) |
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2215 |
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2216 |
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2217 <p> |
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2218 When called with <code>base</code>, |
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2219 then <code>e</code> must be a string to be interpreted as |
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2220 an integer numeral in that base. |
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2221 The base may be any integer between 2 and 36, inclusive. |
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2222 In bases above 10, the letter '<code>A</code>' (in either upper or lower case) |
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2223 represents 10, '<code>B</code>' represents 11, and so forth, |
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2224 with '<code>Z</code>' representing 35. |
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2225 If the string <code>e</code> is not a valid numeral in the given base, |
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2226 the function returns <b>nil</b>. |
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2227 |
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2228 |
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2229 |
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2230 |
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2231 <h4 <%=heading_options%> ><a name="Luan.to_string"><tt>Luan.to_string (v)</tt></a></h4> |
475 | 2232 |
2233 <p> | |
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2234 Receives a value of any type and |
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2235 converts it to a string in a human-readable format. |
475 | 2236 |
2237 <p> | |
2238 If the metatable of <tt>v</tt> has a <tt>"__to_string"</tt> field, | |
2239 then <tt>to_string</tt> calls the corresponding value | |
2240 with <tt>v</tt> as argument, | |
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2241 and uses the result of the call as its result. |
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2242 |
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2243 |
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2244 |
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2245 <h4 <%=heading_options%> ><a name="Luan.try"><tt>Luan.try (t)</tt></a></h4> |
476 | 2246 |
2247 <p> | |
490 | 2248 Implements try-catch as found in other languages where each block is in table <tt>t</tt>. <tt>t[1]</tt> is the "try" block. The <tt>t.catch</tt> and <tt>t.finally</tt> blocks are optional. Returns the result of the "try" block or the "catch" block. |
476 | 2249 |
2250 <p> | |
2251 Example use: | |
2252 | |
2253 <p><tt><pre> | |
2254 try { | |
2255 function() | |
2256 a_dangerous_fn() | |
2257 end; | |
2258 catch = function(e) | |
2259 -- handle error | |
2260 end; | |
2261 finally = function() | |
2262 -- clean up | |
2263 end; | |
2264 } | |
2265 </pre></tt></p> | |
2266 | |
482 | 2267 <p> |
2268 Could be defined as: | |
2269 | |
2270 <p><tt><pre> | |
2271 function Luan.try(t) | |
2272 local r = { <a href="#Luan.pcall">Luan.pcall</a>(t[1]) } | |
2273 if r[1] then | |
2274 Table.remove(r,1) | |
2275 elseif t.catch ~= nil then | |
2276 r = { t.catch(r[2]) } | |
2277 else | |
2278 t.finally and t.finally() | |
2279 r[2].throw() | |
2280 end | |
2281 t.finally and t.finally() | |
2282 return Table.unpack(r) | |
2283 end | |
2284 </pre></tt></p> | |
476 | 2285 |
2286 | |
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2287 <h4 <%=heading_options%> ><a name="Luan.type"><tt>Luan.type (v)</tt></a></h4> |
475 | 2288 |
2289 <p> | |
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2290 Returns the type of its only argument, coded as a string. |
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2291 The possible results of this function are |
475 | 2292 "<tt>nil</tt>" (a string, not the value <b>nil</b>), |
2293 "<tt>number</tt>", | |
2294 "<tt>string</tt>", | |
2295 "<tt>binary</tt>", | |
2296 "<tt>boolean</tt>", | |
2297 "<tt>table</tt>", | |
2298 "<tt>function</tt>", | |
2299 and "<tt>userdata</tt>". | |
2300 | |
2301 | |
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2302 <h4 <%=heading_options%> ><a name="Luan.values"><tt>Luan.values (···)</tt></a></h4> |
476 | 2303 |
2304 <p> | |
2305 Returns a function so that the construction | |
2306 | |
2307 <p><tt><pre> | |
2308 for v in Luan.values(···) do <i>body</i> end | |
2309 </pre></tt></p> | |
2310 | |
2311 <p> | |
2312 will iterate over all values of <tt>···</tt>. | |
2313 | |
2314 | |
475 | 2315 |
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2316 <h4 <%=heading_options%> ><a name="Luan.VERSION"><tt>Luan.VERSION</tt></a></h4> |
475 | 2317 |
2318 <p> | |
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2319 A global variable (not a function) that |
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2320 holds a string containing the current interpreter version. |
478 | 2321 The current value of this variable is "<tt><%=Luan.VERSION%></tt>". |
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2322 |
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2323 |
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2324 |
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2325 |
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2326 |
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2327 |
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2328 <h3 <%=heading_options%> ><a name="package_lib">Modules</a></h3> |
476 | 2329 |
2330 <p> | |
2331 Include this library by: | |
2332 | |
2333 <p><tt><pre> | |
2334 local Package = require "luan:Package" | |
2335 </pre></tt></p> | |
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2336 |
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2337 <p> |
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2338 The package library provides basic |
476 | 2339 facilities for loading modules in Luan. |
2340 | |
2341 | |
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2342 <h4 <%=heading_options%> ><a name="Package.load"><tt>Package.load (mod_uri)</tt></a></h4> |
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2343 |
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2344 <p> |
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2345 Loads the given module. |
476 | 2346 The function starts by looking into the <a href="#Package.loaded"><tt>Package.loaded</tt></a> table |
2347 to determine whether <tt>mod_uri</tt> is already loaded. | |
2348 If it is, then <tt>Package.load</tt> returns the value stored | |
2349 at <tt>Package.loaded[mod_uri]</tt>. | |
2350 Otherwise, it tries to load a new value for the module. | |
2351 | |
2352 <p> | |
2353 To load a new value, <tt>Package.load</tt> first checks if <tt>mod_uri</tt> starts with "<b>java:</b>". If yes, then this is a Java class which is loaded by special Java code. | |
2354 | |
2355 <p> | |
2356 If <tt>mod_uri</tt> is not a Java class, then <tt>Package.load</tt> tries to read the text of the file referred to by <tt>mod_uri</tt> (using <tt>add_extension</tt>=true). If the file doesn't exist, then <tt>Package.load</tt> returns <b>nil</b>. If the file exists, then its content is compiled into a chunk calling <a href="#Luan.load"><tt>Luan.load</tt></a> and passing in an empty table as the <tt>env</tt> value. This chunk is run passing in <tt>mod_uri</tt> as an argument. If the chunk returns a value other than <b>nil</b>, then that value is the value of this module. Otherwise the <tt>env</tt> that was passed in is the value of this module. | |
2357 | |
2358 <p> | |
2359 If a new value for the module successful loaded, then it is stored in <tt>Package.loaded[mod_uri]</tt>. The value is returned. | |
2360 | |
2361 | |
2362 | |
2363 | |
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2364 <h4 <%=heading_options%> ><a name="Package.loaded"><tt>Package.loaded</tt></a></h4> |
476 | 2365 |
2366 | |
2367 <p> | |
2368 A table used by <a href="#Package.load"><tt>Package.load</tt></a> to control which | |
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2369 modules are already loaded. |
476 | 2370 When you load a module <tt>mod_uri</tt> and |
2371 <tt>Package.loaded[modname]</tt> is not <b>nil</b>, | |
2372 <a href="#Package.load"><tt>Package.load</tt></a> simply returns the value stored there. | |
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2373 |
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2374 |
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2375 <p> |
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2376 This variable is only a reference to the real table; |
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2377 assignments to this variable do not change the |
476 | 2378 table used by <a href="#Package.load"><tt>Package.load</tt></a>. |
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2379 |
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2380 |
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2381 |
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2382 |
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2383 |
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2384 |
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2385 <h2>6.4 – <a name="6.4">String Manipulation</a></h2> |
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2386 |
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2387 <p> |
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2388 This library provides generic functions for string manipulation, |
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2389 such as finding and extracting substrings, and pattern matching. |
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2390 When indexing a string in Lua, the first character is at position 1 |
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2391 (not at 0, as in C). |
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2392 Indices are allowed to be negative and are interpreted as indexing backwards, |
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2393 from the end of the string. |
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2394 Thus, the last character is at position -1, and so on. |
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2395 |
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2396 |
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2397 <p> |
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2398 The string library provides all its functions inside the table |
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2399 <a name="pdf-string"><code>string</code></a>. |
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2400 It also sets a metatable for strings |
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2401 where the <code>__index</code> field points to the <code>string</code> table. |
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2402 Therefore, you can use the string functions in object-oriented style. |
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2403 For instance, <code>string.byte(s,i)</code> |
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2404 can be written as <code>s:byte(i)</code>. |
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2405 |
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2406 |
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2407 <p> |
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2408 The string library assumes one-byte character encodings. |
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2409 |
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2410 |
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2411 <p> |
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2412 <hr><h3><a name="pdf-string.byte"><code>string.byte (s [, i [, j]])</code></a></h3> |
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2413 Returns the internal numerical codes of the characters <code>s[i]</code>, |
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2414 <code>s[i+1]</code>, ..., <code>s[j]</code>. |
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2415 The default value for <code>i</code> is 1; |
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2416 the default value for <code>j</code> is <code>i</code>. |
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2417 These indices are corrected |
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2418 following the same rules of function <a href="#pdf-string.sub"><code>string.sub</code></a>. |
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2419 |
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2420 |
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2421 <p> |
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2422 Numerical codes are not necessarily portable across platforms. |
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2423 |
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2424 |
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2425 |
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2426 |
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2427 <p> |
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2428 <hr><h3><a name="pdf-string.char"><code>string.char (···)</code></a></h3> |
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2429 Receives zero or more integers. |
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2430 Returns a string with length equal to the number of arguments, |
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2431 in which each character has the internal numerical code equal |
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2432 to its corresponding argument. |
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2433 |
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2434 |
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2435 <p> |
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2436 Numerical codes are not necessarily portable across platforms. |
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2437 |
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2438 |
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2439 |
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2440 |
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2441 <p> |
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2442 <hr><h3><a name="pdf-string.dump"><code>string.dump (function [, strip])</code></a></h3> |
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2443 |
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2444 |
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2445 <p> |
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2446 Returns a string containing a binary representation |
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2447 (a <em>binary chunk</em>) |
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2448 of the given function, |
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2449 so that a later <a href="#pdf-load"><code>load</code></a> on this string returns |
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2450 a copy of the function (but with new upvalues). |
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2451 If <code>strip</code> is a true value, |
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2452 the binary representation is created without debug information |
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2453 about the function |
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2454 (local variable names, lines, etc.). |
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|
2455 |
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|
2456 |
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2457 <p> |
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2458 Functions with upvalues have only their number of upvalues saved. |
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2459 When (re)loaded, |
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2460 those upvalues receive fresh instances containing <b>nil</b>. |
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2461 (You can use the debug library to serialize |
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2462 and reload the upvalues of a function |
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2463 in a way adequate to your needs.) |
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2464 |
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2465 |
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|
2466 |
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2467 |
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2468 <p> |
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2469 <hr><h3><a name="pdf-string.find"><code>string.find (s, pattern [, init [, plain]])</code></a></h3> |
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2470 |
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|
2471 |
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2472 <p> |
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2473 Looks for the first match of |
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2474 <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. |
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2475 If it finds a match, then <code>find</code> returns the indices of <code>s</code> |
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2476 where this occurrence starts and ends; |
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2477 otherwise, it returns <b>nil</b>. |
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2478 A third, optional numerical argument <code>init</code> specifies |
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2479 where to start the search; |
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2480 its default value is 1 and can be negative. |
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2481 A value of <b>true</b> as a fourth, optional argument <code>plain</code> |
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2482 turns off the pattern matching facilities, |
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2483 so the function does a plain "find substring" operation, |
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2484 with no characters in <code>pattern</code> being considered magic. |
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2485 Note that if <code>plain</code> is given, then <code>init</code> must be given as well. |
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2486 |
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2487 |
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2488 <p> |
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2489 If the pattern has captures, |
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2490 then in a successful match |
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2491 the captured values are also returned, |
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2492 after the two indices. |
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2493 |
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2494 |
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2495 |
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2496 |
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2497 <p> |
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2498 <hr><h3><a name="pdf-string.format"><code>string.format (formatstring, ···)</code></a></h3> |
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2499 |
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2500 |
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2501 <p> |
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2502 Returns a formatted version of its variable number of arguments |
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2503 following the description given in its first argument (which must be a string). |
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2504 The format string follows the same rules as the ISO C function <code>sprintf</code>. |
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2505 The only differences are that the options/modifiers |
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2506 <code>*</code>, <code>h</code>, <code>L</code>, <code>l</code>, <code>n</code>, |
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2507 and <code>p</code> are not supported |
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2508 and that there is an extra option, <code>q</code>. |
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2509 The <code>q</code> option formats a string between double quotes, |
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2510 using escape sequences when necessary to ensure that |
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2511 it can safely be read back by the Lua interpreter. |
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2512 For instance, the call |
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2513 |
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2514 <pre> |
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2515 string.format('%q', 'a string with "quotes" and \n new line') |
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2516 </pre><p> |
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2517 may produce the string: |
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2518 |
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2519 <pre> |
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2520 "a string with \"quotes\" and \ |
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2521 new line" |
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2522 </pre> |
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2523 |
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2524 <p> |
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2525 Options |
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2526 <code>A</code> and <code>a</code> (when available), |
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2527 <code>E</code>, <code>e</code>, <code>f</code>, |
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2528 <code>G</code>, and <code>g</code> all expect a number as argument. |
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2529 Options <code>c</code>, <code>d</code>, |
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2530 <code>i</code>, <code>o</code>, <code>u</code>, <code>X</code>, and <code>x</code> |
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2531 expect an integer. |
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2532 Option <code>q</code> expects a string; |
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2533 option <code>s</code> expects a string without embedded zeros. |
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2534 If the argument to option <code>s</code> is not a string, |
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2535 it is converted to one following the same rules of <a href="#pdf-tostring"><code>tostring</code></a>. |
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2536 |
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2537 |
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2538 |
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2539 |
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2540 <p> |
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2541 <hr><h3><a name="pdf-string.gmatch"><code>string.gmatch (s, pattern)</code></a></h3> |
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2542 Returns an iterator function that, |
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2543 each time it is called, |
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2544 returns the next captures from <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) |
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2545 over the string <code>s</code>. |
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2546 If <code>pattern</code> specifies no captures, |
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2547 then the whole match is produced in each call. |
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2548 |
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2549 |
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2550 <p> |
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2551 As an example, the following loop |
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2552 will iterate over all the words from string <code>s</code>, |
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2553 printing one per line: |
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2554 |
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2555 <pre> |
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2556 s = "hello world from Lua" |
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2557 for w in string.gmatch(s, "%a+") do |
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2558 print(w) |
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2559 end |
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2560 </pre><p> |
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2561 The next example collects all pairs <code>key=value</code> from the |
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2562 given string into a table: |
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2563 |
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2564 <pre> |
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2565 t = {} |
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2566 s = "from=world, to=Lua" |
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2567 for k, v in string.gmatch(s, "(%w+)=(%w+)") do |
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2568 t[k] = v |
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2569 end |
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2570 </pre> |
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2571 |
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2572 <p> |
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2573 For this function, a caret '<code>^</code>' at the start of a pattern does not |
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2574 work as an anchor, as this would prevent the iteration. |
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2575 |
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|
2576 |
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|
2577 |
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|
2578 |
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2579 <p> |
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2580 <hr><h3><a name="pdf-string.gsub"><code>string.gsub (s, pattern, repl [, n])</code></a></h3> |
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2581 Returns a copy of <code>s</code> |
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2582 in which all (or the first <code>n</code>, if given) |
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2583 occurrences of the <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) have been |
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2584 replaced by a replacement string specified by <code>repl</code>, |
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2585 which can be a string, a table, or a function. |
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2586 <code>gsub</code> also returns, as its second value, |
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2587 the total number of matches that occurred. |
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2588 The name <code>gsub</code> comes from <em>Global SUBstitution</em>. |
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2589 |
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|
2590 |
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2591 <p> |
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2592 If <code>repl</code> is a string, then its value is used for replacement. |
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2593 The character <code>%</code> works as an escape character: |
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2594 any sequence in <code>repl</code> of the form <code>%<em>d</em></code>, |
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2595 with <em>d</em> between 1 and 9, |
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2596 stands for the value of the <em>d</em>-th captured substring. |
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2597 The sequence <code>%0</code> stands for the whole match. |
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2598 The sequence <code>%%</code> stands for a single <code>%</code>. |
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2599 |
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2600 |
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2601 <p> |
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2602 If <code>repl</code> is a table, then the table is queried for every match, |
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2603 using the first capture as the key. |
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2604 |
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2605 |
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2606 <p> |
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2607 If <code>repl</code> is a function, then this function is called every time a |
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2608 match occurs, with all captured substrings passed as arguments, |
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2609 in order. |
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2610 |
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2611 |
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2612 <p> |
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2613 In any case, |
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2614 if the pattern specifies no captures, |
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2615 then it behaves as if the whole pattern was inside a capture. |
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2616 |
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2617 |
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2618 <p> |
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2619 If the value returned by the table query or by the function call |
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2620 is a string or a number, |
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2621 then it is used as the replacement string; |
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2622 otherwise, if it is <b>false</b> or <b>nil</b>, |
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2623 then there is no replacement |
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2624 (that is, the original match is kept in the string). |
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2625 |
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2626 |
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2627 <p> |
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2628 Here are some examples: |
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|
2629 |
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2630 <pre> |
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2631 x = string.gsub("hello world", "(%w+)", "%1 %1") |
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|
2632 --> x="hello hello world world" |
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|
2633 |
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2634 x = string.gsub("hello world", "%w+", "%0 %0", 1) |
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|
2635 --> x="hello hello world" |
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|
2636 |
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|
2637 x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1") |
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|
2638 --> x="world hello Lua from" |
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|
2639 |
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|
2640 x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv) |
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2641 --> x="home = /home/roberto, user = roberto" |
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2642 |
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2643 x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s) |
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2644 return load(s)() |
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2645 end) |
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2646 --> x="4+5 = 9" |
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|
2647 |
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2648 local t = {name="lua", version="5.3"} |
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2649 x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t) |
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2650 --> x="lua-5.3.tar.gz" |
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|
2651 </pre> |
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|
2652 |
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2653 |
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|
2654 |
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|
2655 <p> |
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|
2656 <hr><h3><a name="pdf-string.len"><code>string.len (s)</code></a></h3> |
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2657 Receives a string and returns its length. |
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2658 The empty string <code>""</code> has length 0. |
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2659 Embedded zeros are counted, |
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2660 so <code>"a\000bc\000"</code> has length 5. |
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|
2661 |
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|
2662 |
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|
2663 |
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|
2664 |
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2665 <p> |
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|
2666 <hr><h3><a name="pdf-string.lower"><code>string.lower (s)</code></a></h3> |
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2667 Receives a string and returns a copy of this string with all |
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2668 uppercase letters changed to lowercase. |
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2669 All other characters are left unchanged. |
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2670 The definition of what an uppercase letter is depends on the current locale. |
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|
2671 |
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|
2672 |
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|
2673 |
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|
2674 |
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|
2675 <p> |
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|
2676 <hr><h3><a name="pdf-string.match"><code>string.match (s, pattern [, init])</code></a></h3> |
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2677 Looks for the first <em>match</em> of |
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2678 <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. |
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2679 If it finds one, then <code>match</code> returns |
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2680 the captures from the pattern; |
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2681 otherwise it returns <b>nil</b>. |
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2682 If <code>pattern</code> specifies no captures, |
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2683 then the whole match is returned. |
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2684 A third, optional numerical argument <code>init</code> specifies |
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2685 where to start the search; |
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2686 its default value is 1 and can be negative. |
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|
2687 |
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|
2688 |
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|
2689 |
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|
2690 |
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|
2691 <p> |
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|
2692 <hr><h3><a name="pdf-string.pack"><code>string.pack (fmt, v1, v2, ···)</code></a></h3> |
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|
2693 |
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|
2694 |
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|
2695 <p> |
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|
2696 Returns a binary string containing the values <code>v1</code>, <code>v2</code>, etc. |
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2697 packed (that is, serialized in binary form) |
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|
2698 according to the format string <code>fmt</code> (see <a href="#6.4.2">§6.4.2</a>). |
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|
2699 |
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|
2700 |
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|
2701 |
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|
2702 |
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|
2703 <p> |
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|
2704 <hr><h3><a name="pdf-string.packsize"><code>string.packsize (fmt)</code></a></h3> |
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|
2705 |
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|
2706 |
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|
2707 <p> |
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|
2708 Returns the size of a string resulting from <a href="#pdf-string.pack"><code>string.pack</code></a> |
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|
2709 with the given format. |
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|
2710 The format string cannot have the variable-length options |
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|
2711 '<code>s</code>' or '<code>z</code>' (see <a href="#6.4.2">§6.4.2</a>). |
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|
2712 |
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|
2713 |
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|
2714 |
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|
2715 |
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|
2716 <p> |
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|
2717 <hr><h3><a name="pdf-string.rep"><code>string.rep (s, n [, sep])</code></a></h3> |
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2718 Returns a string that is the concatenation of <code>n</code> copies of |
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2719 the string <code>s</code> separated by the string <code>sep</code>. |
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2720 The default value for <code>sep</code> is the empty string |
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2721 (that is, no separator). |
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2722 Returns the empty string if <code>n</code> is not positive. |
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|
2723 |
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|
2724 |
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|
2725 |
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|
2726 |
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2727 <p> |
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2728 <hr><h3><a name="pdf-string.reverse"><code>string.reverse (s)</code></a></h3> |
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2729 Returns a string that is the string <code>s</code> reversed. |
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|
2730 |
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|
2731 |
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|
2732 |
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|
2733 |
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2734 <p> |
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|
2735 <hr><h3><a name="pdf-string.sub"><code>string.sub (s, i [, j])</code></a></h3> |
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2736 Returns the substring of <code>s</code> that |
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2737 starts at <code>i</code> and continues until <code>j</code>; |
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2738 <code>i</code> and <code>j</code> can be negative. |
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|
2739 If <code>j</code> is absent, then it is assumed to be equal to -1 |
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|
2740 (which is the same as the string length). |
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|
2741 In particular, |
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|
2742 the call <code>string.sub(s,1,j)</code> returns a prefix of <code>s</code> |
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2743 with length <code>j</code>, |
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2744 and <code>string.sub(s, -i)</code> returns a suffix of <code>s</code> |
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2745 with length <code>i</code>. |
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|
2746 |
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|
2747 |
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2748 <p> |
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2749 If, after the translation of negative indices, |
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2750 <code>i</code> is less than 1, |
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2751 it is corrected to 1. |
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2752 If <code>j</code> is greater than the string length, |
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2753 it is corrected to that length. |
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2754 If, after these corrections, |
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2755 <code>i</code> is greater than <code>j</code>, |
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2756 the function returns the empty string. |
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2757 |
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2758 |
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2759 |
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2760 |
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2761 <p> |
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2762 <hr><h3><a name="pdf-string.unpack"><code>string.unpack (fmt, s [, pos])</code></a></h3> |
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2763 |
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2764 |
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2765 <p> |
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2766 Returns the values packed in string <code>s</code> (see <a href="#pdf-string.pack"><code>string.pack</code></a>) |
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2767 according to the format string <code>fmt</code> (see <a href="#6.4.2">§6.4.2</a>). |
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2768 An optional <code>pos</code> marks where |
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2769 to start reading in <code>s</code> (default is 1). |
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2770 After the read values, |
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2771 this function also returns the index of the first unread byte in <code>s</code>. |
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2772 |
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2773 |
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2774 |
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2775 |
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2776 <p> |
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2777 <hr><h3><a name="pdf-string.upper"><code>string.upper (s)</code></a></h3> |
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2778 Receives a string and returns a copy of this string with all |
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2779 lowercase letters changed to uppercase. |
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2780 All other characters are left unchanged. |
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2781 The definition of what a lowercase letter is depends on the current locale. |
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2782 |
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|
2783 |
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|
2784 |
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|
2785 |
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2786 |
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2787 <h3>6.4.1 – <a name="6.4.1">Patterns</a></h3> |
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2788 |
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2789 <p> |
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2790 Patterns in Lua are described by regular strings, |
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|
2791 which are interpreted as patterns by the pattern-matching functions |
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2792 <a href="#pdf-string.find"><code>string.find</code></a>, |
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2793 <a href="#pdf-string.gmatch"><code>string.gmatch</code></a>, |
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2794 <a href="#pdf-string.gsub"><code>string.gsub</code></a>, |
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2795 and <a href="#pdf-string.match"><code>string.match</code></a>. |
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2796 This section describes the syntax and the meaning |
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2797 (that is, what they match) of these strings. |
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2798 |
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|
2799 |
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2800 |
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2801 <h4>Character Class:</h4><p> |
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2802 A <em>character class</em> is used to represent a set of characters. |
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2803 The following combinations are allowed in describing a character class: |
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2804 |
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|
2805 <ul> |
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|
2806 |
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2807 <li><b><em>x</em>: </b> |
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2808 (where <em>x</em> is not one of the <em>magic characters</em> |
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2809 <code>^$()%.[]*+-?</code>) |
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2810 represents the character <em>x</em> itself. |
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2811 </li> |
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|
2812 |
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2813 <li><b><code>.</code>: </b> (a dot) represents all characters.</li> |
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2814 |
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2815 <li><b><code>%a</code>: </b> represents all letters.</li> |
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|
2816 |
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2817 <li><b><code>%c</code>: </b> represents all control characters.</li> |
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2818 |
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2819 <li><b><code>%d</code>: </b> represents all digits.</li> |
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|
2820 |
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2821 <li><b><code>%g</code>: </b> represents all printable characters except space.</li> |
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2822 |
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2823 <li><b><code>%l</code>: </b> represents all lowercase letters.</li> |
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2824 |
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2825 <li><b><code>%p</code>: </b> represents all punctuation characters.</li> |
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|
2826 |
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2827 <li><b><code>%s</code>: </b> represents all space characters.</li> |
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|
2828 |
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2829 <li><b><code>%u</code>: </b> represents all uppercase letters.</li> |
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|
2830 |
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2831 <li><b><code>%w</code>: </b> represents all alphanumeric characters.</li> |
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|
2832 |
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2833 <li><b><code>%x</code>: </b> represents all hexadecimal digits.</li> |
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|
2834 |
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2835 <li><b><code>%<em>x</em></code>: </b> (where <em>x</em> is any non-alphanumeric character) |
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2836 represents the character <em>x</em>. |
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2837 This is the standard way to escape the magic characters. |
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2838 Any non-alphanumeric character |
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2839 (including all punctuations, even the non-magical) |
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2840 can be preceded by a '<code>%</code>' |
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2841 when used to represent itself in a pattern. |
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2842 </li> |
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|
2843 |
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2844 <li><b><code>[<em>set</em>]</code>: </b> |
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2845 represents the class which is the union of all |
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2846 characters in <em>set</em>. |
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2847 A range of characters can be specified by |
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2848 separating the end characters of the range, |
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2849 in ascending order, with a '<code>-</code>'. |
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2850 All classes <code>%</code><em>x</em> described above can also be used as |
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2851 components in <em>set</em>. |
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2852 All other characters in <em>set</em> represent themselves. |
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2853 For example, <code>[%w_]</code> (or <code>[_%w]</code>) |
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2854 represents all alphanumeric characters plus the underscore, |
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2855 <code>[0-7]</code> represents the octal digits, |
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2856 and <code>[0-7%l%-]</code> represents the octal digits plus |
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2857 the lowercase letters plus the '<code>-</code>' character. |
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2858 |
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2859 |
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2860 <p> |
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2861 The interaction between ranges and classes is not defined. |
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2862 Therefore, patterns like <code>[%a-z]</code> or <code>[a-%%]</code> |
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2863 have no meaning. |
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2864 </li> |
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2865 |
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2866 <li><b><code>[^<em>set</em>]</code>: </b> |
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2867 represents the complement of <em>set</em>, |
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2868 where <em>set</em> is interpreted as above. |
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|
2869 </li> |
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|
2870 |
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|
2871 </ul><p> |
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2872 For all classes represented by single letters (<code>%a</code>, <code>%c</code>, etc.), |
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2873 the corresponding uppercase letter represents the complement of the class. |
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2874 For instance, <code>%S</code> represents all non-space characters. |
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2875 |
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2876 |
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2877 <p> |
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2878 The definitions of letter, space, and other character groups |
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2879 depend on the current locale. |
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2880 In particular, the class <code>[a-z]</code> may not be equivalent to <code>%l</code>. |
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2881 |
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2882 |
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2883 |
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|
2884 |
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|
2885 |
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2886 <h4>Pattern Item:</h4><p> |
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2887 A <em>pattern item</em> can be |
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2888 |
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2889 <ul> |
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|
2890 |
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2891 <li> |
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2892 a single character class, |
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2893 which matches any single character in the class; |
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2894 </li> |
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2895 |
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2896 <li> |
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2897 a single character class followed by '<code>*</code>', |
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2898 which matches zero or more repetitions of characters in the class. |
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2899 These repetition items will always match the longest possible sequence; |
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2900 </li> |
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2901 |
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2902 <li> |
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2903 a single character class followed by '<code>+</code>', |
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2904 which matches one or more repetitions of characters in the class. |
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2905 These repetition items will always match the longest possible sequence; |
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2906 </li> |
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|
2907 |
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2908 <li> |
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2909 a single character class followed by '<code>-</code>', |
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2910 which also matches zero or more repetitions of characters in the class. |
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2911 Unlike '<code>*</code>', |
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2912 these repetition items will always match the shortest possible sequence; |
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2913 </li> |
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|
2914 |
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2915 <li> |
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2916 a single character class followed by '<code>?</code>', |
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2917 which matches zero or one occurrence of a character in the class. |
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2918 It always matches one occurrence if possible; |
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2919 </li> |
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|
2920 |
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2921 <li> |
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2922 <code>%<em>n</em></code>, for <em>n</em> between 1 and 9; |
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2923 such item matches a substring equal to the <em>n</em>-th captured string |
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2924 (see below); |
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2925 </li> |
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|
2926 |
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2927 <li> |
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2928 <code>%b<em>xy</em></code>, where <em>x</em> and <em>y</em> are two distinct characters; |
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2929 such item matches strings that start with <em>x</em>, end with <em>y</em>, |
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2930 and where the <em>x</em> and <em>y</em> are <em>balanced</em>. |
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2931 This means that, if one reads the string from left to right, |
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2932 counting <em>+1</em> for an <em>x</em> and <em>-1</em> for a <em>y</em>, |
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2933 the ending <em>y</em> is the first <em>y</em> where the count reaches 0. |
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2934 For instance, the item <code>%b()</code> matches expressions with |
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2935 balanced parentheses. |
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2936 </li> |
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|
2937 |
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2938 <li> |
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|
2939 <code>%f[<em>set</em>]</code>, a <em>frontier pattern</em>; |
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2940 such item matches an empty string at any position such that |
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2941 the next character belongs to <em>set</em> |
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2942 and the previous character does not belong to <em>set</em>. |
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2943 The set <em>set</em> is interpreted as previously described. |
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2944 The beginning and the end of the subject are handled as if |
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|
2945 they were the character '<code>\0</code>'. |
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2946 </li> |
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|
2947 |
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|
2948 </ul> |
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|
2949 |
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|
2950 |
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|
2951 |
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|
2952 |
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2953 <h4>Pattern:</h4><p> |
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2954 A <em>pattern</em> is a sequence of pattern items. |
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2955 A caret '<code>^</code>' at the beginning of a pattern anchors the match at the |
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2956 beginning of the subject string. |
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2957 A '<code>$</code>' at the end of a pattern anchors the match at the |
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2958 end of the subject string. |
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2959 At other positions, |
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|
2960 '<code>^</code>' and '<code>$</code>' have no special meaning and represent themselves. |
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|
2961 |
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|
2962 |
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|
2963 |
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|
2964 |
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|
2965 |
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2966 <h4>Captures:</h4><p> |
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2967 A pattern can contain sub-patterns enclosed in parentheses; |
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|
2968 they describe <em>captures</em>. |
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2969 When a match succeeds, the substrings of the subject string |
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2970 that match captures are stored (<em>captured</em>) for future use. |
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2971 Captures are numbered according to their left parentheses. |
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|
2972 For instance, in the pattern <code>"(a*(.)%w(%s*))"</code>, |
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|
2973 the part of the string matching <code>"a*(.)%w(%s*)"</code> is |
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2974 stored as the first capture (and therefore has number 1); |
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2975 the character matching "<code>.</code>" is captured with number 2, |
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2976 and the part matching "<code>%s*</code>" has number 3. |
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|
2977 |
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|
2978 |
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2979 <p> |
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2980 As a special case, the empty capture <code>()</code> captures |
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2981 the current string position (a number). |
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2982 For instance, if we apply the pattern <code>"()aa()"</code> on the |
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2983 string <code>"flaaap"</code>, there will be two captures: 3 and 5. |
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2984 |
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|
2985 |
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|
2986 |
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2987 |
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|
2988 |
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|
2989 |
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2990 |
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|
2991 <h3>6.4.2 – <a name="6.4.2">Format Strings for Pack and Unpack</a></h3> |
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2992 |
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2993 <p> |
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2994 The first argument to <a href="#pdf-string.pack"><code>string.pack</code></a>, |
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2995 <a href="#pdf-string.packsize"><code>string.packsize</code></a>, and <a href="#pdf-string.unpack"><code>string.unpack</code></a> |
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2996 is a format string, |
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2997 which describes the layout of the structure being created or read. |
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2998 |
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2999 |
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3000 <p> |
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3001 A format string is a sequence of conversion options. |
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3002 The conversion options are as follows: |
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3003 |
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3004 <ul> |
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3005 <li><b><code><</code>: </b>sets little endian</li> |
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3006 <li><b><code>></code>: </b>sets big endian</li> |
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3007 <li><b><code>=</code>: </b>sets native endian</li> |
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3008 <li><b><code>![<em>n</em>]</code>: </b>sets maximum alignment to <code>n</code> |
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3009 (default is native alignment)</li> |
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3010 <li><b><code>b</code>: </b>a signed byte (<code>char</code>)</li> |
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3011 <li><b><code>B</code>: </b>an unsigned byte (<code>char</code>)</li> |
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3012 <li><b><code>h</code>: </b>a signed <code>short</code> (native size)</li> |
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3013 <li><b><code>H</code>: </b>an unsigned <code>short</code> (native size)</li> |
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3014 <li><b><code>l</code>: </b>a signed <code>long</code> (native size)</li> |
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3015 <li><b><code>L</code>: </b>an unsigned <code>long</code> (native size)</li> |
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3016 <li><b><code>j</code>: </b>a <code>lua_Integer</code></li> |
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3017 <li><b><code>J</code>: </b>a <code>lua_Unsigned</code></li> |
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3018 <li><b><code>T</code>: </b>a <code>size_t</code> (native size)</li> |
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3019 <li><b><code>i[<em>n</em>]</code>: </b>a signed <code>int</code> with <code>n</code> bytes |
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3020 (default is native size)</li> |
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3021 <li><b><code>I[<em>n</em>]</code>: </b>an unsigned <code>int</code> with <code>n</code> bytes |
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3022 (default is native size)</li> |
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3023 <li><b><code>f</code>: </b>a <code>float</code> (native size)</li> |
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3024 <li><b><code>d</code>: </b>a <code>double</code> (native size)</li> |
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3025 <li><b><code>n</code>: </b>a <code>lua_Number</code></li> |
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3026 <li><b><code>c<em>n</em></code>: </b>a fixed-sized string with <code>n</code> bytes</li> |
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3027 <li><b><code>z</code>: </b>a zero-terminated string</li> |
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3028 <li><b><code>s[<em>n</em>]</code>: </b>a string preceded by its length |
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3029 coded as an unsigned integer with <code>n</code> bytes |
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3030 (default is a <code>size_t</code>)</li> |
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3031 <li><b><code>x</code>: </b>one byte of padding</li> |
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3032 <li><b><code>X<em>op</em></code>: </b>an empty item that aligns |
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3033 according to option <code>op</code> |
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3034 (which is otherwise ignored)</li> |
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3035 <li><b>'<code> </code>': </b>(empty space) ignored</li> |
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3036 </ul><p> |
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3037 (A "<code>[<em>n</em>]</code>" means an optional integral numeral.) |
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3038 Except for padding, spaces, and configurations |
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3039 (options "<code>xX <=>!</code>"), |
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3040 each option corresponds to an argument (in <a href="#pdf-string.pack"><code>string.pack</code></a>) |
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3041 or a result (in <a href="#pdf-string.unpack"><code>string.unpack</code></a>). |
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3042 |
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3043 |
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3044 <p> |
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3045 For options "<code>!<em>n</em></code>", "<code>s<em>n</em></code>", "<code>i<em>n</em></code>", and "<code>I<em>n</em></code>", |
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3046 <code>n</code> can be any integer between 1 and 16. |
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3047 All integral options check overflows; |
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3048 <a href="#pdf-string.pack"><code>string.pack</code></a> checks whether the given value fits in the given size; |
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3049 <a href="#pdf-string.unpack"><code>string.unpack</code></a> checks whether the read value fits in a Lua integer. |
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3050 |
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3051 |
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3052 <p> |
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3053 Any format string starts as if prefixed by "<code>!1=</code>", |
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3054 that is, |
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3055 with maximum alignment of 1 (no alignment) |
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3056 and native endianness. |
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3057 |
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3058 |
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3059 <p> |
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3060 Alignment works as follows: |
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3061 For each option, |
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3062 the format gets extra padding until the data starts |
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3063 at an offset that is a multiple of the minimum between the |
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3064 option size and the maximum alignment; |
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3065 this minimum must be a power of 2. |
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3066 Options "<code>c</code>" and "<code>z</code>" are not aligned; |
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3067 option "<code>s</code>" follows the alignment of its starting integer. |
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3068 |
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3069 |
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3070 <p> |
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3071 All padding is filled with zeros by <a href="#pdf-string.pack"><code>string.pack</code></a> |
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3072 (and ignored by <a href="#pdf-string.unpack"><code>string.unpack</code></a>). |
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3073 |
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3074 |
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3075 |
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3076 |
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3077 |
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3078 |
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3079 |
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3080 <h2>6.5 – <a name="6.5">UTF-8 Support</a></h2> |
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3081 |
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3082 <p> |
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3083 This library provides basic support for UTF-8 encoding. |
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3084 It provides all its functions inside the table <a name="pdf-utf8"><code>utf8</code></a>. |
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3085 This library does not provide any support for Unicode other |
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3086 than the handling of the encoding. |
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3087 Any operation that needs the meaning of a character, |
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3088 such as character classification, is outside its scope. |
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3089 |
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3090 |
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3091 <p> |
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3092 Unless stated otherwise, |
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3093 all functions that expect a byte position as a parameter |
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3094 assume that the given position is either the start of a byte sequence |
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3095 or one plus the length of the subject string. |
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3096 As in the string library, |
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3097 negative indices count from the end of the string. |
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3098 |
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3099 |
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3100 <p> |
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3101 <hr><h3><a name="pdf-utf8.char"><code>utf8.char (···)</code></a></h3> |
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3102 Receives zero or more integers, |
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3103 converts each one to its corresponding UTF-8 byte sequence |
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3104 and returns a string with the concatenation of all these sequences. |
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3105 |
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3106 |
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|
3107 |
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3108 |
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3109 <p> |
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|
3110 <hr><h3><a name="pdf-utf8.charpattern"><code>utf8.charpattern</code></a></h3> |
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3111 The pattern (a string, not a function) "<code>[\0-\x7F\xC2-\xF4][\x80-\xBF]*</code>" |
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3112 (see <a href="#6.4.1">§6.4.1</a>), |
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3113 which matches exactly one UTF-8 byte sequence, |
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3114 assuming that the subject is a valid UTF-8 string. |
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3115 |
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3116 |
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3117 |
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3118 |
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3119 <p> |
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3120 <hr><h3><a name="pdf-utf8.codes"><code>utf8.codes (s)</code></a></h3> |
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3121 |
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3122 |
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3123 <p> |
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3124 Returns values so that the construction |
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3125 |
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3126 <pre> |
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3127 for p, c in utf8.codes(s) do <em>body</em> end |
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3128 </pre><p> |
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3129 will iterate over all characters in string <code>s</code>, |
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3130 with <code>p</code> being the position (in bytes) and <code>c</code> the code point |
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3131 of each character. |
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3132 It raises an error if it meets any invalid byte sequence. |
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3133 |
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3134 |
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3135 |
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3136 |
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3137 <p> |
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3138 <hr><h3><a name="pdf-utf8.codepoint"><code>utf8.codepoint (s [, i [, j]])</code></a></h3> |
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3139 Returns the codepoints (as integers) from all characters in <code>s</code> |
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3140 that start between byte position <code>i</code> and <code>j</code> (both included). |
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3141 The default for <code>i</code> is 1 and for <code>j</code> is <code>i</code>. |
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3142 It raises an error if it meets any invalid byte sequence. |
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3143 |
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3144 |
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3145 |
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3146 |
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3147 <p> |
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3148 <hr><h3><a name="pdf-utf8.len"><code>utf8.len (s [, i [, j]])</code></a></h3> |
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3149 Returns the number of UTF-8 characters in string <code>s</code> |
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|
3150 that start between positions <code>i</code> and <code>j</code> (both inclusive). |
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3151 The default for <code>i</code> is 1 and for <code>j</code> is -1. |
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3152 If it finds any invalid byte sequence, |
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3153 returns a false value plus the position of the first invalid byte. |
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3154 |
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3155 |
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3156 |
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3157 |
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3158 <p> |
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|
3159 <hr><h3><a name="pdf-utf8.offset"><code>utf8.offset (s, n [, i])</code></a></h3> |
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3160 Returns the position (in bytes) where the encoding of the |
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3161 <code>n</code>-th character of <code>s</code> |
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3162 (counting from position <code>i</code>) starts. |
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3163 A negative <code>n</code> gets characters before position <code>i</code>. |
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3164 The default for <code>i</code> is 1 when <code>n</code> is non-negative |
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3165 and <code>#s + 1</code> otherwise, |
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3166 so that <code>utf8.offset(s, -n)</code> gets the offset of the |
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3167 <code>n</code>-th character from the end of the string. |
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3168 If the specified character is neither in the subject |
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3169 nor right after its end, |
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3170 the function returns <b>nil</b>. |
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|
3171 |
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|
3172 |
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3173 <p> |
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3174 As a special case, |
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3175 when <code>n</code> is 0 the function returns the start of the encoding |
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3176 of the character that contains the <code>i</code>-th byte of <code>s</code>. |
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|
3177 |
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|
3178 |
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3179 <p> |
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3180 This function assumes that <code>s</code> is a valid UTF-8 string. |
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|
3181 |
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|
3182 |
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|
3183 |
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|
3184 |
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diff
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|
3185 |
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|
3186 |
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|
3187 |
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3188 <h2>6.6 – <a name="6.6">Table Manipulation</a></h2> |
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|
3189 |
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|
3190 <p> |
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|
3191 This library provides generic functions for table manipulation. |
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3192 It provides all its functions inside the table <a name="pdf-table"><code>table</code></a>. |
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3193 |
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|
3194 |
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|
3195 <p> |
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3196 Remember that, whenever an operation needs the length of a table, |
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3197 the table must be a proper sequence |
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3198 or have a <code>__len</code> metamethod (see <a href="#3.4.7">§3.4.7</a>). |
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3199 All functions ignore non-numeric keys |
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3200 in the tables given as arguments. |
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|
3201 |
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|
3202 |
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|
3203 <p> |
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3204 <hr><h3><a name="pdf-table.concat"><code>table.concat (list [, sep [, i [, j]]])</code></a></h3> |
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|
3205 |
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|
3206 |
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3207 <p> |
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|
3208 Given a list where all elements are strings or numbers, |
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3209 returns the string <code>list[i]..sep..list[i+1] ··· sep..list[j]</code>. |
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|
3210 The default value for <code>sep</code> is the empty string, |
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3211 the default for <code>i</code> is 1, |
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3212 and the default for <code>j</code> is <code>#list</code>. |
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3213 If <code>i</code> is greater than <code>j</code>, returns the empty string. |
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|
3214 |
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|
3215 |
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|
3216 |
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|
3217 |
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3218 <p> |
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|
3219 <hr><h3><a name="pdf-table.insert"><code>table.insert (list, [pos,] value)</code></a></h3> |
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|
3220 |
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|
3221 |
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|
3222 <p> |
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|
3223 Inserts element <code>value</code> at position <code>pos</code> in <code>list</code>, |
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3224 shifting up the elements |
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|
3225 <code>list[pos], list[pos+1], ···, list[#list]</code>. |
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|
3226 The default value for <code>pos</code> is <code>#list+1</code>, |
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3227 so that a call <code>table.insert(t,x)</code> inserts <code>x</code> at the end |
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3228 of list <code>t</code>. |
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|
3229 |
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|
3230 |
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|
3231 |
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|
3232 |
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|
3233 <p> |
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3234 <hr><h3><a name="pdf-table.move"><code>table.move (a1, f, e, t [,a2])</code></a></h3> |
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3235 |
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|
3236 |
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3237 <p> |
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3238 Moves elements from table <code>a1</code> to table <code>a2</code>. |
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3239 This function performs the equivalent to the following |
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|
3240 multiple assignment: |
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3241 <code>a2[t],··· = a1[f],···,a1[e]</code>. |
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3242 The default for <code>a2</code> is <code>a1</code>. |
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3243 The destination range can overlap with the source range. |
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3244 Index <code>f</code> must be positive. |
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3245 |
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|
3246 |
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|
3247 |
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|
3248 |
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3249 <p> |
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3250 <hr><h3><a name="pdf-table.pack"><code>table.pack (···)</code></a></h3> |
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|
3251 |
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|
3252 |
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|
3253 <p> |
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3254 Returns a new table with all parameters stored into keys 1, 2, etc. |
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3255 and with a field "<code>n</code>" with the total number of parameters. |
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3256 Note that the resulting table may not be a sequence. |
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|
3257 |
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|
3258 |
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|
3259 |
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|
3260 |
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|
3261 <p> |
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|
3262 <hr><h3><a name="pdf-table.remove"><code>table.remove (list [, pos])</code></a></h3> |
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|
3263 |
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|
3264 |
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|
3265 <p> |
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|
3266 Removes from <code>list</code> the element at position <code>pos</code>, |
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|
3267 returning the value of the removed element. |
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|
3268 When <code>pos</code> is an integer between 1 and <code>#list</code>, |
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|
3269 it shifts down the elements |
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|
3270 <code>list[pos+1], list[pos+2], ···, list[#list]</code> |
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|
3271 and erases element <code>list[#list]</code>; |
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|
3272 The index <code>pos</code> can also be 0 when <code>#list</code> is 0, |
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|
3273 or <code>#list + 1</code>; |
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|
3274 in those cases, the function erases the element <code>list[pos]</code>. |
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|
3275 |
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|
3276 |
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|
3277 <p> |
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|
3278 The default value for <code>pos</code> is <code>#list</code>, |
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|
3279 so that a call <code>table.remove(l)</code> removes the last element |
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|
3280 of list <code>l</code>. |
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|
3281 |
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changeset
|
3282 |
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changeset
|
3283 |
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changeset
|
3284 |
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|
3285 <p> |
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|
3286 <hr><h3><a name="pdf-table.sort"><code>table.sort (list [, comp])</code></a></h3> |
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|
3287 |
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|
3288 |
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|
3289 <p> |
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|
3290 Sorts list elements in a given order, <em>in-place</em>, |
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|
3291 from <code>list[1]</code> to <code>list[#list]</code>. |
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|
3292 If <code>comp</code> is given, |
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|
3293 then it must be a function that receives two list elements |
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|
3294 and returns true when the first element must come |
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|
3295 before the second in the final order |
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|
3296 (so that <code>not comp(list[i+1],list[i])</code> will be true after the sort). |
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|
3297 If <code>comp</code> is not given, |
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3298 then the standard Lua operator <code><</code> is used instead. |
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|
3299 |
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|
3300 |
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|
3301 <p> |
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|
3302 The sort algorithm is not stable; |
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|
3303 that is, elements considered equal by the given order |
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|
3304 may have their relative positions changed by the sort. |
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|
3305 |
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|
3306 |
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changeset
|
3307 |
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changeset
|
3308 |
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|
3309 <p> |
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|
3310 <hr><h3><a name="pdf-table.unpack"><code>table.unpack (list [, i [, j]])</code></a></h3> |
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|
3311 |
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|
3312 |
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|
3313 <p> |
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|
3314 Returns the elements from the given list. |
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|
3315 This function is equivalent to |
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|
3316 |
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|
3317 <pre> |
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3318 return list[i], list[i+1], ···, list[j] |
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3319 </pre><p> |
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|
3320 By default, <code>i</code> is 1 and <code>j</code> is <code>#list</code>. |
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|
3321 |
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|
3322 |
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changeset
|
3323 |
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|
3324 |
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|
3325 |
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|
3326 |
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|
3327 |
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|
3328 <h2>6.7 – <a name="6.7">Mathematical Functions</a></h2> |
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3329 |
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|
3330 <p> |
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|
3331 This library provides basic mathematical functions. |
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|
3332 It provides all its functions and constants inside the table <a name="pdf-math"><code>math</code></a>. |
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3333 Functions with the annotation "<code>integer/float</code>" give |
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|
3334 integer results for integer arguments |
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|
3335 and float results for float (or mixed) arguments. |
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|
3336 Rounding functions |
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|
3337 (<a href="#pdf-math.ceil"><code>math.ceil</code></a>, <a href="#pdf-math.floor"><code>math.floor</code></a>, and <a href="#pdf-math.modf"><code>math.modf</code></a>) |
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|
3338 return an integer when the result fits in the range of an integer, |
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3339 or a float otherwise. |
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|
3340 |
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|
3341 |
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3342 <p> |
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|
3343 <hr><h3><a name="pdf-math.abs"><code>math.abs (x)</code></a></h3> |
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|
3344 |
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|
3345 |
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|
3346 <p> |
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|
3347 Returns the absolute value of <code>x</code>. (integer/float) |
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|
3348 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3349 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3350 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3351 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3352 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3353 <hr><h3><a name="pdf-math.acos"><code>math.acos (x)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3354 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3355 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3356 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3357 Returns the arc cosine of <code>x</code> (in radians). |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3358 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3359 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3360 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3361 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3362 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3363 <hr><h3><a name="pdf-math.asin"><code>math.asin (x)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3364 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3365 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3366 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3367 Returns the arc sine of <code>x</code> (in radians). |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3368 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3369 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3370 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3371 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3372 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3373 <hr><h3><a name="pdf-math.atan"><code>math.atan (y [, x])</code></a></h3> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3374 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3375 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3376 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3377 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3378 Returns the arc tangent of <code>y/x</code> (in radians), |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3379 but uses the signs of both parameters to find the |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3380 quadrant of the result. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3381 (It also handles correctly the case of <code>x</code> being zero.) |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3382 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3383 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3384 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3385 The default value for <code>x</code> is 1, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3386 so that the call <code>math.atan(y)</code> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3387 returns the arc tangent of <code>y</code>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3388 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3389 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3390 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3391 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3392 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3393 <hr><h3><a name="pdf-math.ceil"><code>math.ceil (x)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3394 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3395 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3396 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3397 Returns the smallest integral value larger than or equal to <code>x</code>. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3398 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3399 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3400 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3401 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3402 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3403 <hr><h3><a name="pdf-math.cos"><code>math.cos (x)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3404 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3405 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3406 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3407 Returns the cosine of <code>x</code> (assumed to be in radians). |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3408 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3409 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3410 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3411 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3412 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3413 <hr><h3><a name="pdf-math.deg"><code>math.deg (x)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3414 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3415 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3416 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3417 Converts the angle <code>x</code> from radians to degrees. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3418 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3419 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3420 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3421 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3422 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3423 <hr><h3><a name="pdf-math.exp"><code>math.exp (x)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3424 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3425 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3426 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3427 Returns the value <em>e<sup>x</sup></em> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3428 (where <code>e</code> is the base of natural logarithms). |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3429 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3430 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3431 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3432 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3433 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3434 <hr><h3><a name="pdf-math.floor"><code>math.floor (x)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3435 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3436 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3437 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3438 Returns the largest integral value smaller than or equal to <code>x</code>. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3439 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3440 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3441 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3442 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3443 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3444 <hr><h3><a name="pdf-math.fmod"><code>math.fmod (x, y)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3445 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3446 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3447 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3448 Returns the remainder of the division of <code>x</code> by <code>y</code> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3449 that rounds the quotient towards zero. (integer/float) |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3450 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3451 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3452 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3453 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3454 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3455 <hr><h3><a name="pdf-math.huge"><code>math.huge</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3456 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3457 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3458 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3459 The float value <code>HUGE_VAL</code>, |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3460 a value larger than any other numerical value. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3461 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3462 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3463 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3464 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3465 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3466 <hr><h3><a name="pdf-math.log"><code>math.log (x [, base])</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3467 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3468 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3469 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3470 Returns the logarithm of <code>x</code> in the given base. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3471 The default for <code>base</code> is <em>e</em> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3472 (so that the function returns the natural logarithm of <code>x</code>). |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3473 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3474 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3475 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3476 |
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changeset
|
3477 <p> |
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|
3478 <hr><h3><a name="pdf-math.max"><code>math.max (x, ···)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3479 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3480 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3481 <p> |
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parents:
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|
3482 Returns the argument with the maximum value, |
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parents:
diff
changeset
|
3483 according to the Lua operator <code><</code>. (integer/float) |
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|
3484 |
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diff
changeset
|
3485 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3486 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3487 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3488 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3489 <hr><h3><a name="pdf-math.maxinteger"><code>math.maxinteger</code></a></h3> |
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parents:
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|
3490 An integer with the maximum value for an integer. |
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parents:
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|
3491 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3492 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3493 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3494 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3495 <p> |
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|
3496 <hr><h3><a name="pdf-math.min"><code>math.min (x, ···)</code></a></h3> |
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|
3497 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3498 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3499 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3500 Returns the argument with the minimum value, |
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parents:
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|
3501 according to the Lua operator <code><</code>. (integer/float) |
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|
3502 |
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|
3503 |
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|
3504 |
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|
3505 |
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|
3506 <p> |
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|
3507 <hr><h3><a name="pdf-math.mininteger"><code>math.mininteger</code></a></h3> |
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|
3508 An integer with the minimum value for an integer. |
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|
3509 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3510 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3511 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3512 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3513 <p> |
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|
3514 <hr><h3><a name="pdf-math.modf"><code>math.modf (x)</code></a></h3> |
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|
3515 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3516 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3517 <p> |
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|
3518 Returns the integral part of <code>x</code> and the fractional part of <code>x</code>. |
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|
3519 Its second result is always a float. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3520 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3521 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3522 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3523 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3524 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3525 <hr><h3><a name="pdf-math.pi"><code>math.pi</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3526 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3527 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3528 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3529 The value of <em>π</em>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3530 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3531 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3532 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3533 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
3534 <p> |
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|
3535 <hr><h3><a name="pdf-math.rad"><code>math.rad (x)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3536 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3537 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3538 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3539 Converts the angle <code>x</code> from degrees to radians. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3540 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3541 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3542 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3543 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
3544 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3545 <hr><h3><a name="pdf-math.random"><code>math.random ([m [, n]])</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3546 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3547 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
3548 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3549 When called without arguments, |
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parents:
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|
3550 returns a pseudo-random float with uniform distribution |
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parents:
diff
changeset
|
3551 in the range <em>[0,1)</em>. |
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parents:
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|
3552 When called with two integers <code>m</code> and <code>n</code>, |
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parents:
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|
3553 <code>math.random</code> returns a pseudo-random integer |
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parents:
diff
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|
3554 with uniform distribution in the range <em>[m, n]</em>. |
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parents:
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|
3555 (The value <em>m-n</em> cannot be negative and must fit in a Lua integer.) |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3556 The call <code>math.random(n)</code> is equivalent to <code>math.random(1,n)</code>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3557 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3558 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3559 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3560 This function is an interface to the underling |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3561 pseudo-random generator function provided by C. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3562 No guarantees can be given for its statistical properties. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3563 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3564 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3565 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3566 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3567 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3568 <hr><h3><a name="pdf-math.randomseed"><code>math.randomseed (x)</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3569 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3570 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3571 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3572 Sets <code>x</code> as the "seed" |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3573 for the pseudo-random generator: |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3574 equal seeds produce equal sequences of numbers. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3575 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3576 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3577 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3578 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3579 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3580 <hr><h3><a name="pdf-math.sin"><code>math.sin (x)</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3581 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3582 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3583 <p> |
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parents:
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changeset
|
3584 Returns the sine of <code>x</code> (assumed to be in radians). |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3585 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3586 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3587 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3588 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3589 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3590 <hr><h3><a name="pdf-math.sqrt"><code>math.sqrt (x)</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
3591 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3592 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3593 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3594 Returns the square root of <code>x</code>. |
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parents:
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changeset
|
3595 (You can also use the expression <code>x^0.5</code> to compute this value.) |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3596 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3597 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3598 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3599 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3600 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3601 <hr><h3><a name="pdf-math.tan"><code>math.tan (x)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3602 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3603 |
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3604 <p> |
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3605 Returns the tangent of <code>x</code> (assumed to be in radians). |
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3606 |
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3607 |
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3608 |
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3609 |
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3610 <p> |
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3611 <hr><h3><a name="pdf-math.tointeger"><code>math.tointeger (x)</code></a></h3> |
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|
3612 |
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|
3613 |
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3614 <p> |
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3615 If the value <code>x</code> is convertible to an integer, |
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|
3616 returns that integer. |
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3617 Otherwise, returns <b>nil</b>. |
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|
3618 |
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|
3619 |
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|
3620 |
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|
3621 |
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3622 <p> |
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3623 <hr><h3><a name="pdf-math.type"><code>math.type (x)</code></a></h3> |
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3624 |
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3625 |
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3626 <p> |
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3627 Returns "<code>integer</code>" if <code>x</code> is an integer, |
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3628 "<code>float</code>" if it is a float, |
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3629 or <b>nil</b> if <code>x</code> is not a number. |
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|
3630 |
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3631 |
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3632 |
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3633 |
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3634 <p> |
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3635 <hr><h3><a name="pdf-math.ult"><code>math.ult (m, n)</code></a></h3> |
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|
3636 |
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|
3637 |
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3638 <p> |
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3639 Returns a boolean, |
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|
3640 true if integer <code>m</code> is below integer <code>n</code> when |
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3641 they are compared as unsigned integers. |
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|
3642 |
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|
3643 |
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|
3644 |
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|
3645 |
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|
3646 |
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|
3647 |
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|
3648 |
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|
3649 <h2>6.8 – <a name="6.8">Input and Output Facilities</a></h2> |
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3650 |
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3651 <p> |
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3652 The I/O library provides two different styles for file manipulation. |
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3653 The first one uses implicit file handles; |
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3654 that is, there are operations to set a default input file and a |
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3655 default output file, |
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3656 and all input/output operations are over these default files. |
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3657 The second style uses explicit file handles. |
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|
3658 |
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3659 |
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3660 <p> |
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3661 When using implicit file handles, |
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|
3662 all operations are supplied by table <a name="pdf-io"><code>io</code></a>. |
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3663 When using explicit file handles, |
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|
3664 the operation <a href="#pdf-io.open"><code>io.open</code></a> returns a file handle |
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3665 and then all operations are supplied as methods of the file handle. |
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|
3666 |
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|
3667 |
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|
3668 <p> |
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|
3669 The table <code>io</code> also provides |
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|
3670 three predefined file handles with their usual meanings from C: |
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|
3671 <a name="pdf-io.stdin"><code>io.stdin</code></a>, <a name="pdf-io.stdout"><code>io.stdout</code></a>, and <a name="pdf-io.stderr"><code>io.stderr</code></a>. |
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|
3672 The I/O library never closes these files. |
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|
3673 |
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|
3674 |
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|
3675 <p> |
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|
3676 Unless otherwise stated, |
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|
3677 all I/O functions return <b>nil</b> on failure |
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|
3678 (plus an error message as a second result and |
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3679 a system-dependent error code as a third result) |
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3680 and some value different from <b>nil</b> on success. |
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|
3681 On non-POSIX systems, |
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|
3682 the computation of the error message and error code |
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|
3683 in case of errors |
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|
3684 may be not thread safe, |
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|
3685 because they rely on the global C variable <code>errno</code>. |
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|
3686 |
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|
3687 |
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|
3688 <p> |
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|
3689 <hr><h3><a name="pdf-io.close"><code>io.close ([file])</code></a></h3> |
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|
3690 |
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changeset
|
3691 |
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|
3692 <p> |
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|
3693 Equivalent to <code>file:close()</code>. |
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|
3694 Without a <code>file</code>, closes the default output file. |
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|
3695 |
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|
3696 |
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|
3697 |
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|
3698 |
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3699 <p> |
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|
3700 <hr><h3><a name="pdf-io.flush"><code>io.flush ()</code></a></h3> |
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|
3701 |
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|
3702 |
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3703 <p> |
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|
3704 Equivalent to <code>io.output():flush()</code>. |
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|
3705 |
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|
3706 |
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3707 |
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3708 |
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3709 <p> |
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|
3710 <hr><h3><a name="pdf-io.input"><code>io.input ([file])</code></a></h3> |
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3711 |
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3712 |
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3713 <p> |
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|
3714 When called with a file name, it opens the named file (in text mode), |
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|
3715 and sets its handle as the default input file. |
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|
3716 When called with a file handle, |
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|
3717 it simply sets this file handle as the default input file. |
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3718 When called without parameters, |
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|
3719 it returns the current default input file. |
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|
3720 |
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3721 |
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3722 <p> |
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3723 In case of errors this function raises the error, |
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3724 instead of returning an error code. |
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3725 |
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3726 |
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3727 |
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3728 |
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3729 <p> |
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|
3730 <hr><h3><a name="pdf-io.lines"><code>io.lines ([filename ···])</code></a></h3> |
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|
3731 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3732 |
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diff
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|
3733 <p> |
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diff
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|
3734 Opens the given file name in read mode |
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|
3735 and returns an iterator function that |
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parents:
diff
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|
3736 works like <code>file:lines(···)</code> over the opened file. |
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parents:
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|
3737 When the iterator function detects the end of file, |
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diff
changeset
|
3738 it returns no values (to finish the loop) and automatically closes the file. |
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|
3739 |
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|
3740 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3741 <p> |
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diff
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|
3742 The call <code>io.lines()</code> (with no file name) is equivalent |
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parents:
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changeset
|
3743 to <code>io.input():lines("*l")</code>; |
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parents:
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|
3744 that is, it iterates over the lines of the default input file. |
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parents:
diff
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|
3745 In this case it does not close the file when the loop ends. |
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parents:
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|
3746 |
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diff
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|
3747 |
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|
3748 <p> |
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|
3749 In case of errors this function raises the error, |
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|
3750 instead of returning an error code. |
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|
3751 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3752 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3753 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3754 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3755 <p> |
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|
3756 <hr><h3><a name="pdf-io.open"><code>io.open (filename [, mode])</code></a></h3> |
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|
3757 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3758 |
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|
3759 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3760 This function opens a file, |
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parents:
diff
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|
3761 in the mode specified in the string <code>mode</code>. |
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3762 It returns a new file handle, |
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diff
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3763 or, in case of errors, <b>nil</b> plus an error message. |
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|
3764 |
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diff
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|
3765 |
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|
3766 <p> |
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|
3767 The <code>mode</code> string can be any of the following: |
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|
3768 |
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|
3769 <ul> |
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|
3770 <li><b>"<code>r</code>": </b> read mode (the default);</li> |
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|
3771 <li><b>"<code>w</code>": </b> write mode;</li> |
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|
3772 <li><b>"<code>a</code>": </b> append mode;</li> |
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|
3773 <li><b>"<code>r+</code>": </b> update mode, all previous data is preserved;</li> |
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|
3774 <li><b>"<code>w+</code>": </b> update mode, all previous data is erased;</li> |
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|
3775 <li><b>"<code>a+</code>": </b> append update mode, previous data is preserved, |
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|
3776 writing is only allowed at the end of file.</li> |
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|
3777 </ul><p> |
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parents:
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|
3778 The <code>mode</code> string can also have a '<code>b</code>' at the end, |
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parents:
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|
3779 which is needed in some systems to open the file in binary mode. |
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parents:
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|
3780 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3781 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3782 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3783 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3784 <p> |
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|
3785 <hr><h3><a name="pdf-io.output"><code>io.output ([file])</code></a></h3> |
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|
3786 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3787 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3788 <p> |
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diff
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|
3789 Similar to <a href="#pdf-io.input"><code>io.input</code></a>, but operates over the default output file. |
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|
3790 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3791 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3792 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3793 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3794 <p> |
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|
3795 <hr><h3><a name="pdf-io.popen"><code>io.popen (prog [, mode])</code></a></h3> |
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|
3796 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3797 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3798 <p> |
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diff
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|
3799 This function is system dependent and is not available |
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|
3800 on all platforms. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3801 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3802 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3803 <p> |
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|
3804 Starts program <code>prog</code> in a separated process and returns |
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diff
changeset
|
3805 a file handle that you can use to read data from this program |
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parents:
diff
changeset
|
3806 (if <code>mode</code> is <code>"r"</code>, the default) |
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add manual.html as copy of Lua 5.3 Reference Manual
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changeset
|
3807 or to write data to this program |
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parents:
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changeset
|
3808 (if <code>mode</code> is <code>"w"</code>). |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
3809 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3810 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3811 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3812 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3813 <p> |
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|
3814 <hr><h3><a name="pdf-io.read"><code>io.read (···)</code></a></h3> |
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|
3815 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3816 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3817 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3818 Equivalent to <code>io.input():read(···)</code>. |
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changeset
|
3819 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3820 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3821 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3822 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3823 <p> |
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|
3824 <hr><h3><a name="pdf-io.tmpfile"><code>io.tmpfile ()</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
3825 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3826 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
3827 <p> |
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changeset
|
3828 Returns a handle for a temporary file. |
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diff
changeset
|
3829 This file is opened in update mode |
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changeset
|
3830 and it is automatically removed when the program ends. |
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parents:
diff
changeset
|
3831 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3832 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3833 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3834 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3835 <p> |
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parents:
diff
changeset
|
3836 <hr><h3><a name="pdf-io.type"><code>io.type (obj)</code></a></h3> |
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parents:
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changeset
|
3837 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3838 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
3839 <p> |
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diff
changeset
|
3840 Checks whether <code>obj</code> is a valid file handle. |
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changeset
|
3841 Returns the string <code>"file"</code> if <code>obj</code> is an open file handle, |
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parents:
diff
changeset
|
3842 <code>"closed file"</code> if <code>obj</code> is a closed file handle, |
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parents:
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changeset
|
3843 or <b>nil</b> if <code>obj</code> is not a file handle. |
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parents:
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changeset
|
3844 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3845 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3846 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3847 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3848 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
3849 <hr><h3><a name="pdf-io.write"><code>io.write (···)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3850 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3851 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3852 <p> |
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parents:
diff
changeset
|
3853 Equivalent to <code>io.output():write(···)</code>. |
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changeset
|
3854 |
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parents:
diff
changeset
|
3855 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3856 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3857 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3858 <p> |
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parents:
diff
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|
3859 <hr><h3><a name="pdf-file:close"><code>file:close ()</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3860 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3861 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3862 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3863 Closes <code>file</code>. |
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parents:
diff
changeset
|
3864 Note that files are automatically closed when |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3865 their handles are garbage collected, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3866 but that takes an unpredictable amount of time to happen. |
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parents:
diff
changeset
|
3867 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3868 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3869 <p> |
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parents:
diff
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|
3870 When closing a file handle created with <a href="#pdf-io.popen"><code>io.popen</code></a>, |
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parents:
diff
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|
3871 <a href="#pdf-file:close"><code>file:close</code></a> returns the same values |
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parents:
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|
3872 returned by <a href="#pdf-os.execute"><code>os.execute</code></a>. |
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|
3873 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3874 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3875 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3876 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3877 <p> |
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parents:
diff
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|
3878 <hr><h3><a name="pdf-file:flush"><code>file:flush ()</code></a></h3> |
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parents:
diff
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|
3879 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3880 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3881 <p> |
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diff
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|
3882 Saves any written data to <code>file</code>. |
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parents:
diff
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|
3883 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3884 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3885 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3886 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3887 <p> |
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|
3888 <hr><h3><a name="pdf-file:lines"><code>file:lines (···)</code></a></h3> |
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|
3889 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3890 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3891 <p> |
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diff
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|
3892 Returns an iterator function that, |
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parents:
diff
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|
3893 each time it is called, |
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parents:
diff
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|
3894 reads the file according to the given formats. |
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parents:
diff
changeset
|
3895 When no format is given, |
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parents:
diff
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|
3896 uses "<code>l</code>" as a default. |
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diff
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|
3897 As an example, the construction |
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parents:
diff
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|
3898 |
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diff
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|
3899 <pre> |
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diff
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|
3900 for c in file:lines(1) do <em>body</em> end |
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|
3901 </pre><p> |
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parents:
diff
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|
3902 will iterate over all characters of the file, |
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parents:
diff
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|
3903 starting at the current position. |
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parents:
diff
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|
3904 Unlike <a href="#pdf-io.lines"><code>io.lines</code></a>, this function does not close the file |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3905 when the loop ends. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3906 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3907 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3908 <p> |
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|
3909 In case of errors this function raises the error, |
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diff
changeset
|
3910 instead of returning an error code. |
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parents:
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|
3911 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3912 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3913 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3914 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3915 <p> |
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|
3916 <hr><h3><a name="pdf-file:read"><code>file:read (···)</code></a></h3> |
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|
3917 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3918 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3919 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3920 Reads the file <code>file</code>, |
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parents:
diff
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|
3921 according to the given formats, which specify what to read. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3922 For each format, |
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parents:
diff
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|
3923 the function returns a string or a number with the characters read, |
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parents:
diff
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|
3924 or <b>nil</b> if it cannot read data with the specified format. |
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parents:
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|
3925 (In this latter case, |
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parents:
diff
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|
3926 the function does not read subsequent formats.) |
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parents:
diff
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|
3927 When called without formats, |
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parents:
diff
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|
3928 it uses a default format that reads the next line |
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diff
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|
3929 (see below). |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3930 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3931 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3932 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3933 The available formats are |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3934 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3935 <ul> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3936 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3937 <li><b>"<code>n</code>": </b> |
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parents:
diff
changeset
|
3938 reads a numeral and returns it as a float or an integer, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3939 following the lexical conventions of Lua. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3940 (The numeral may have leading spaces and a sign.) |
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parents:
diff
changeset
|
3941 This format always reads the longest input sequence that |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3942 is a valid prefix for a number; |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3943 if that prefix does not form a valid number |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3944 (e.g., an empty string, "<code>0x</code>", or "<code>3.4e-</code>"), |
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parents:
diff
changeset
|
3945 it is discarded and the function returns <b>nil</b>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3946 </li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3947 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3948 <li><b>"<code>i</code>": </b> |
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parents:
diff
changeset
|
3949 reads an integral number and returns it as an integer. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3950 </li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3951 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3952 <li><b>"<code>a</code>": </b> |
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parents:
diff
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|
3953 reads the whole file, starting at the current position. |
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parents:
diff
changeset
|
3954 On end of file, it returns the empty string. |
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parents:
diff
changeset
|
3955 </li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3956 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3957 <li><b>"<code>l</code>": </b> |
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parents:
diff
changeset
|
3958 reads the next line skipping the end of line, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3959 returning <b>nil</b> on end of file. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3960 This is the default format. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3961 </li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3962 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3963 <li><b>"<code>L</code>": </b> |
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parents:
diff
changeset
|
3964 reads the next line keeping the end-of-line character (if present), |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3965 returning <b>nil</b> on end of file. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3966 </li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3967 |
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parents:
diff
changeset
|
3968 <li><b><em>number</em>: </b> |
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parents:
diff
changeset
|
3969 reads a string with up to this number of bytes, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3970 returning <b>nil</b> on end of file. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3971 If <code>number</code> is zero, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3972 it reads nothing and returns an empty string, |
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parents:
diff
changeset
|
3973 or <b>nil</b> on end of file. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3974 </li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3975 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3976 </ul><p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3977 The formats "<code>l</code>" and "<code>L</code>" should be used only for text files. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3978 |
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diff
changeset
|
3979 |
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diff
changeset
|
3980 |
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diff
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|
3981 |
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|
3982 <p> |
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|
3983 <hr><h3><a name="pdf-file:seek"><code>file:seek ([whence [, offset]])</code></a></h3> |
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|
3984 |
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diff
changeset
|
3985 |
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|
3986 <p> |
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|
3987 Sets and gets the file position, |
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|
3988 measured from the beginning of the file, |
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|
3989 to the position given by <code>offset</code> plus a base |
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|
3990 specified by the string <code>whence</code>, as follows: |
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|
3991 |
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|
3992 <ul> |
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|
3993 <li><b>"<code>set</code>": </b> base is position 0 (beginning of the file);</li> |
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|
3994 <li><b>"<code>cur</code>": </b> base is current position;</li> |
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|
3995 <li><b>"<code>end</code>": </b> base is end of file;</li> |
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|
3996 </ul><p> |
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|
3997 In case of success, <code>seek</code> returns the final file position, |
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|
3998 measured in bytes from the beginning of the file. |
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|
3999 If <code>seek</code> fails, it returns <b>nil</b>, |
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|
4000 plus a string describing the error. |
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|
4001 |
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|
4002 |
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|
4003 <p> |
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|
4004 The default value for <code>whence</code> is <code>"cur"</code>, |
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|
4005 and for <code>offset</code> is 0. |
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|
4006 Therefore, the call <code>file:seek()</code> returns the current |
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|
4007 file position, without changing it; |
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4008 the call <code>file:seek("set")</code> sets the position to the |
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|
4009 beginning of the file (and returns 0); |
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|
4010 and the call <code>file:seek("end")</code> sets the position to the |
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|
4011 end of the file, and returns its size. |
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|
4012 |
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|
4013 |
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diff
changeset
|
4014 |
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changeset
|
4015 |
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|
4016 <p> |
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|
4017 <hr><h3><a name="pdf-file:setvbuf"><code>file:setvbuf (mode [, size])</code></a></h3> |
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|
4018 |
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|
4019 |
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|
4020 <p> |
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|
4021 Sets the buffering mode for an output file. |
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4022 There are three available modes: |
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|
4023 |
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|
4024 <ul> |
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|
4025 |
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|
4026 <li><b>"<code>no</code>": </b> |
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|
4027 no buffering; the result of any output operation appears immediately. |
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|
4028 </li> |
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diff
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|
4029 |
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|
4030 <li><b>"<code>full</code>": </b> |
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|
4031 full buffering; output operation is performed only |
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|
4032 when the buffer is full or when |
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diff
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|
4033 you explicitly <code>flush</code> the file (see <a href="#pdf-io.flush"><code>io.flush</code></a>). |
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|
4034 </li> |
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|
4035 |
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|
4036 <li><b>"<code>line</code>": </b> |
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|
4037 line buffering; output is buffered until a newline is output |
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|
4038 or there is any input from some special files |
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|
4039 (such as a terminal device). |
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|
4040 </li> |
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|
4041 |
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|
4042 </ul><p> |
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|
4043 For the last two cases, <code>size</code> |
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|
4044 specifies the size of the buffer, in bytes. |
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|
4045 The default is an appropriate size. |
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|
4046 |
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|
4047 |
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diff
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|
4048 |
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diff
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|
4049 |
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|
4050 <p> |
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|
4051 <hr><h3><a name="pdf-file:write"><code>file:write (···)</code></a></h3> |
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|
4052 |
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diff
changeset
|
4053 |
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diff
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|
4054 <p> |
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diff
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|
4055 Writes the value of each of its arguments to <code>file</code>. |
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|
4056 The arguments must be strings or numbers. |
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|
4057 |
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diff
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|
4058 |
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|
4059 <p> |
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|
4060 In case of success, this function returns <code>file</code>. |
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diff
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|
4061 Otherwise it returns <b>nil</b> plus a string describing the error. |
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diff
changeset
|
4062 |
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diff
changeset
|
4063 |
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diff
changeset
|
4064 |
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diff
changeset
|
4065 |
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diff
changeset
|
4066 |
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diff
changeset
|
4067 |
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diff
changeset
|
4068 |
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|
4069 <h2>6.9 – <a name="6.9">Operating System Facilities</a></h2> |
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|
4070 |
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changeset
|
4071 <p> |
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|
4072 This library is implemented through table <a name="pdf-os"><code>os</code></a>. |
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|
4073 |
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diff
changeset
|
4074 |
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|
4075 <p> |
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|
4076 <hr><h3><a name="pdf-os.clock"><code>os.clock ()</code></a></h3> |
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|
4077 |
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diff
changeset
|
4078 |
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|
4079 <p> |
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|
4080 Returns an approximation of the amount in seconds of CPU time |
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|
4081 used by the program. |
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diff
changeset
|
4082 |
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diff
changeset
|
4083 |
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diff
changeset
|
4084 |
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diff
changeset
|
4085 |
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|
4086 <p> |
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|
4087 <hr><h3><a name="pdf-os.date"><code>os.date ([format [, time]])</code></a></h3> |
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|
4088 |
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changeset
|
4089 |
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changeset
|
4090 <p> |
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|
4091 Returns a string or a table containing date and time, |
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|
4092 formatted according to the given string <code>format</code>. |
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|
4093 |
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diff
changeset
|
4094 |
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|
4095 <p> |
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|
4096 If the <code>time</code> argument is present, |
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changeset
|
4097 this is the time to be formatted |
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|
4098 (see the <a href="#pdf-os.time"><code>os.time</code></a> function for a description of this value). |
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changeset
|
4099 Otherwise, <code>date</code> formats the current time. |
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changeset
|
4100 |
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diff
changeset
|
4101 |
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|
4102 <p> |
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|
4103 If <code>format</code> starts with '<code>!</code>', |
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4104 then the date is formatted in Coordinated Universal Time. |
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4105 After this optional character, |
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4106 if <code>format</code> is the string "<code>*t</code>", |
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4107 then <code>date</code> returns a table with the following fields: |
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4108 <code>year</code> (four digits), <code>month</code> (1–12), <code>day</code> (1–31), |
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4109 <code>hour</code> (0–23), <code>min</code> (0–59), <code>sec</code> (0–61), |
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4110 <code>wday</code> (weekday, Sunday is 1), |
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4111 <code>yday</code> (day of the year), |
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4112 and <code>isdst</code> (daylight saving flag, a boolean). |
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4113 This last field may be absent |
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4114 if the information is not available. |
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4115 |
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4116 |
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4117 <p> |
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4118 If <code>format</code> is not "<code>*t</code>", |
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4119 then <code>date</code> returns the date as a string, |
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4120 formatted according to the same rules as the ISO C function <code>strftime</code>. |
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4121 |
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4122 |
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4123 <p> |
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4124 When called without arguments, |
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4125 <code>date</code> returns a reasonable date and time representation that depends on |
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4126 the host system and on the current locale |
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4127 (that is, <code>os.date()</code> is equivalent to <code>os.date("%c")</code>). |
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4128 |
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4129 |
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4130 <p> |
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4131 On non-POSIX systems, |
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4132 this function may be not thread safe |
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4133 because of its reliance on C function <code>gmtime</code> and C function <code>localtime</code>. |
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4134 |
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4135 |
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|
4136 |
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|
4137 |
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4138 <p> |
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4139 <hr><h3><a name="pdf-os.difftime"><code>os.difftime (t2, t1)</code></a></h3> |
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4140 |
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|
4141 |
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4142 <p> |
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4143 Returns the difference, in seconds, |
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|
4144 from time <code>t1</code> to time <code>t2</code> |
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|
4145 (where the times are values returned by <a href="#pdf-os.time"><code>os.time</code></a>). |
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4146 In POSIX, Windows, and some other systems, |
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4147 this value is exactly <code>t2</code><em>-</em><code>t1</code>. |
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|
4148 |
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|
4149 |
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|
4150 |
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|
4151 |
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|
4152 <p> |
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4153 <hr><h3><a name="pdf-os.execute"><code>os.execute ([command])</code></a></h3> |
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|
4154 |
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|
4155 |
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|
4156 <p> |
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4157 This function is equivalent to the ISO C function <code>system</code>. |
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4158 It passes <code>command</code> to be executed by an operating system shell. |
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4159 Its first result is <b>true</b> |
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4160 if the command terminated successfully, |
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4161 or <b>nil</b> otherwise. |
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4162 After this first result |
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4163 the function returns a string plus a number, |
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|
4164 as follows: |
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|
4165 |
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|
4166 <ul> |
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|
4167 |
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|
4168 <li><b>"<code>exit</code>": </b> |
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|
4169 the command terminated normally; |
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|
4170 the following number is the exit status of the command. |
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|
4171 </li> |
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|
4172 |
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4173 <li><b>"<code>signal</code>": </b> |
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4174 the command was terminated by a signal; |
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|
4175 the following number is the signal that terminated the command. |
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|
4176 </li> |
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|
4177 |
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|
4178 </ul> |
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|
4179 |
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|
4180 <p> |
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|
4181 When called without a <code>command</code>, |
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4182 <code>os.execute</code> returns a boolean that is true if a shell is available. |
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|
4183 |
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|
4184 |
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|
4185 |
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|
4186 |
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|
4187 <p> |
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|
4188 <hr><h3><a name="pdf-os.exit"><code>os.exit ([code [, close]])</code></a></h3> |
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|
4189 |
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|
4190 |
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|
4191 <p> |
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|
4192 Calls the ISO C function <code>exit</code> to terminate the host program. |
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|
4193 If <code>code</code> is <b>true</b>, |
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|
4194 the returned status is <code>EXIT_SUCCESS</code>; |
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|
4195 if <code>code</code> is <b>false</b>, |
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|
4196 the returned status is <code>EXIT_FAILURE</code>; |
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|
4197 if <code>code</code> is a number, |
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|
4198 the returned status is this number. |
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4199 The default value for <code>code</code> is <b>true</b>. |
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|
4200 |
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|
4201 |
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|
4202 <p> |
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|
4203 If the optional second argument <code>close</code> is true, |
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|
4204 closes the Lua state before exiting. |
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|
4205 |
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|
4206 |
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|
4207 |
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changeset
|
4208 |
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4209 <p> |
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|
4210 <hr><h3><a name="pdf-os.getenv"><code>os.getenv (varname)</code></a></h3> |
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|
4211 |
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|
4212 |
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|
4213 <p> |
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|
4214 Returns the value of the process environment variable <code>varname</code>, |
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|
4215 or <b>nil</b> if the variable is not defined. |
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|
4216 |
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|
4217 |
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changeset
|
4218 |
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|
4219 |
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|
4220 <p> |
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|
4221 <hr><h3><a name="pdf-os.remove"><code>os.remove (filename)</code></a></h3> |
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|
4222 |
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changeset
|
4223 |
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|
4224 <p> |
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4225 Deletes the file (or empty directory, on POSIX systems) |
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4226 with the given name. |
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parents:
diff
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|
4227 If this function fails, it returns <b>nil</b>, |
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diff
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|
4228 plus a string describing the error and the error code. |
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diff
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|
4229 |
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diff
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|
4230 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
4231 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
4232 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
4233 <p> |
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|
4234 <hr><h3><a name="pdf-os.rename"><code>os.rename (oldname, newname)</code></a></h3> |
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|
4235 |
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diff
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|
4236 |
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diff
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|
4237 <p> |
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diff
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|
4238 Renames file or directory named <code>oldname</code> to <code>newname</code>. |
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|
4239 If this function fails, it returns <b>nil</b>, |
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parents:
diff
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|
4240 plus a string describing the error and the error code. |
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diff
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|
4241 |
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diff
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|
4242 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
4243 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
4244 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
4245 <p> |
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|
4246 <hr><h3><a name="pdf-os.setlocale"><code>os.setlocale (locale [, category])</code></a></h3> |
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|
4247 |
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diff
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|
4248 |
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diff
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|
4249 <p> |
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|
4250 Sets the current locale of the program. |
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|
4251 <code>locale</code> is a system-dependent string specifying a locale; |
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|
4252 <code>category</code> is an optional string describing which category to change: |
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|
4253 <code>"all"</code>, <code>"collate"</code>, <code>"ctype"</code>, |
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|
4254 <code>"monetary"</code>, <code>"numeric"</code>, or <code>"time"</code>; |
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|
4255 the default category is <code>"all"</code>. |
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|
4256 The function returns the name of the new locale, |
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|
4257 or <b>nil</b> if the request cannot be honored. |
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|
4258 |
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diff
changeset
|
4259 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4260 <p> |
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diff
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|
4261 If <code>locale</code> is the empty string, |
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parents:
diff
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|
4262 the current locale is set to an implementation-defined native locale. |
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diff
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|
4263 If <code>locale</code> is the string "<code>C</code>", |
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parents:
diff
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|
4264 the current locale is set to the standard C locale. |
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diff
changeset
|
4265 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4266 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4267 <p> |
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diff
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|
4268 When called with <b>nil</b> as the first argument, |
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diff
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|
4269 this function only returns the name of the current locale |
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|
4270 for the given category. |
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parents:
diff
changeset
|
4271 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4272 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4273 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4274 This function may be not thread safe |
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diff
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|
4275 because of its reliance on C function <code>setlocale</code>. |
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diff
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|
4276 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4277 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4278 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4279 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4280 <p> |
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|
4281 <hr><h3><a name="pdf-os.time"><code>os.time ([table])</code></a></h3> |
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|
4282 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4283 |
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diff
changeset
|
4284 <p> |
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diff
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|
4285 Returns the current time when called without arguments, |
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diff
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|
4286 or a time representing the date and time specified by the given table. |
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diff
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|
4287 This table must have fields <code>year</code>, <code>month</code>, and <code>day</code>, |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
4288 and may have fields |
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diff
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|
4289 <code>hour</code> (default is 12), |
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parents:
diff
changeset
|
4290 <code>min</code> (default is 0), |
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parents:
diff
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|
4291 <code>sec</code> (default is 0), |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
4292 and <code>isdst</code> (default is <b>nil</b>). |
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diff
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|
4293 For a description of these fields, see the <a href="#pdf-os.date"><code>os.date</code></a> function. |
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diff
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|
4294 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4295 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4296 <p> |
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diff
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|
4297 The returned value is a number, whose meaning depends on your system. |
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parents:
diff
changeset
|
4298 In POSIX, Windows, and some other systems, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4299 this number counts the number |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4300 of seconds since some given start time (the "epoch"). |
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parents:
diff
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|
4301 In other systems, the meaning is not specified, |
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diff
changeset
|
4302 and the number returned by <code>time</code> can be used only as an argument to |
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parents:
diff
changeset
|
4303 <a href="#pdf-os.date"><code>os.date</code></a> and <a href="#pdf-os.difftime"><code>os.difftime</code></a>. |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
4304 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4305 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4306 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4307 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4308 <p> |
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diff
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|
4309 <hr><h3><a name="pdf-os.tmpname"><code>os.tmpname ()</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4310 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4311 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4312 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4313 Returns a string with a file name that can |
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diff
changeset
|
4314 be used for a temporary file. |
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parents:
diff
changeset
|
4315 The file must be explicitly opened before its use |
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diff
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|
4316 and explicitly removed when no longer needed. |
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diff
changeset
|
4317 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4318 |
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diff
changeset
|
4319 <p> |
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diff
changeset
|
4320 On POSIX systems, |
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parents:
diff
changeset
|
4321 this function also creates a file with that name, |
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diff
changeset
|
4322 to avoid security risks. |
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parents:
diff
changeset
|
4323 (Someone else might create the file with wrong permissions |
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diff
changeset
|
4324 in the time between getting the name and creating the file.) |
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diff
changeset
|
4325 You still have to open the file to use it |
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diff
changeset
|
4326 and to remove it (even if you do not use it). |
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diff
changeset
|
4327 |
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diff
changeset
|
4328 |
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diff
changeset
|
4329 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4330 When possible, |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4331 you may prefer to use <a href="#pdf-io.tmpfile"><code>io.tmpfile</code></a>, |
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diff
changeset
|
4332 which automatically removes the file when the program ends. |
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diff
changeset
|
4333 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4334 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4335 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4336 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4337 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4338 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4339 |
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diff
changeset
|
4340 <h2>6.10 – <a name="6.10">The Debug Library</a></h2> |
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changeset
|
4341 |
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diff
changeset
|
4342 <p> |
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diff
changeset
|
4343 This library provides |
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changeset
|
4344 the functionality of the debug interface (<a href="#4.9">§4.9</a>) to Lua programs. |
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changeset
|
4345 You should exert care when using this library. |
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diff
changeset
|
4346 Several of its functions |
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diff
changeset
|
4347 violate basic assumptions about Lua code |
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diff
changeset
|
4348 (e.g., that variables local to a function |
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diff
changeset
|
4349 cannot be accessed from outside; |
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diff
changeset
|
4350 that userdata metatables cannot be changed by Lua code; |
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4351 that Lua programs do not crash) |
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4352 and therefore can compromise otherwise secure code. |
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4353 Moreover, some functions in this library may be slow. |
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4354 |
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|
4355 |
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|
4356 <p> |
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4357 All functions in this library are provided |
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4358 inside the <a name="pdf-debug"><code>debug</code></a> table. |
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4359 All functions that operate over a thread |
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4360 have an optional first argument which is the |
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4361 thread to operate over. |
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4362 The default is always the current thread. |
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|
4363 |
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|
4364 |
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|
4365 <p> |
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4366 <hr><h3><a name="pdf-debug.debug"><code>debug.debug ()</code></a></h3> |
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|
4367 |
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|
4368 |
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|
4369 <p> |
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4370 Enters an interactive mode with the user, |
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4371 running each string that the user enters. |
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4372 Using simple commands and other debug facilities, |
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4373 the user can inspect global and local variables, |
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4374 change their values, evaluate expressions, and so on. |
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4375 A line containing only the word <code>cont</code> finishes this function, |
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4376 so that the caller continues its execution. |
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|
4377 |
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|
4378 |
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|
4379 <p> |
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4380 Note that commands for <code>debug.debug</code> are not lexically nested |
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4381 within any function and so have no direct access to local variables. |
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|
4382 |
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|
4383 |
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|
4384 |
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|
4385 |
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|
4386 <p> |
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|
4387 <hr><h3><a name="pdf-debug.gethook"><code>debug.gethook ([thread])</code></a></h3> |
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|
4388 |
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|
4389 |
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|
4390 <p> |
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4391 Returns the current hook settings of the thread, as three values: |
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|
4392 the current hook function, the current hook mask, |
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|
4393 and the current hook count |
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|
4394 (as set by the <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> function). |
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|
4395 |
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|
4396 |
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|
4397 |
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|
4398 |
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|
4399 <p> |
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|
4400 <hr><h3><a name="pdf-debug.getinfo"><code>debug.getinfo ([thread,] f [, what])</code></a></h3> |
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|
4401 |
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|
4402 |
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|
4403 <p> |
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|
4404 Returns a table with information about a function. |
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|
4405 You can give the function directly |
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|
4406 or you can give a number as the value of <code>f</code>, |
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4407 which means the function running at level <code>f</code> of the call stack |
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|
4408 of the given thread: |
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|
4409 level 0 is the current function (<code>getinfo</code> itself); |
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|
4410 level 1 is the function that called <code>getinfo</code> |
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|
4411 (except for tail calls, which do not count on the stack); |
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|
4412 and so on. |
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|
4413 If <code>f</code> is a number larger than the number of active functions, |
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|
4414 then <code>getinfo</code> returns <b>nil</b>. |
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|
4415 |
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|
4416 |
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|
4417 <p> |
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|
4418 The returned table can contain all the fields returned by <a href="#lua_getinfo"><code>lua_getinfo</code></a>, |
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|
4419 with the string <code>what</code> describing which fields to fill in. |
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|
4420 The default for <code>what</code> is to get all information available, |
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|
4421 except the table of valid lines. |
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|
4422 If present, |
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|
4423 the option '<code>f</code>' |
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|
4424 adds a field named <code>func</code> with the function itself. |
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|
4425 If present, |
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|
4426 the option '<code>L</code>' |
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|
4427 adds a field named <code>activelines</code> with the table of |
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|
4428 valid lines. |
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|
4429 |
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|
4430 |
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|
4431 <p> |
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|
4432 For instance, the expression <code>debug.getinfo(1,"n").name</code> returns |
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|
4433 a table with a name for the current function, |
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|
4434 if a reasonable name can be found, |
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diff
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|
4435 and the expression <code>debug.getinfo(print)</code> |
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|
4436 returns a table with all available information |
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|
4437 about the <a href="#pdf-print"><code>print</code></a> function. |
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|
4438 |
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|
4439 |
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|
4440 |
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|
4441 |
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|
4442 <p> |
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|
4443 <hr><h3><a name="pdf-debug.getlocal"><code>debug.getlocal ([thread,] f, local)</code></a></h3> |
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|
4444 |
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|
4445 |
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|
4446 <p> |
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|
4447 This function returns the name and the value of the local variable |
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|
4448 with index <code>local</code> of the function at level <code>f</code> of the stack. |
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|
4449 This function accesses not only explicit local variables, |
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|
4450 but also parameters, temporaries, etc. |
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|
4451 |
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|
4452 |
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|
4453 <p> |
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|
4454 The first parameter or local variable has index 1, and so on, |
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|
4455 following the order that they are declared in the code, |
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|
4456 counting only the variables that are active |
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|
4457 in the current scope of the function. |
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|
4458 Negative indices refer to vararg parameters; |
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|
4459 -1 is the first vararg parameter. |
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|
4460 The function returns <b>nil</b> if there is no variable with the given index, |
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|
4461 and raises an error when called with a level out of range. |
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|
4462 (You can call <a href="#pdf-debug.getinfo"><code>debug.getinfo</code></a> to check whether the level is valid.) |
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|
4463 |
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|
4464 |
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|
4465 <p> |
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|
4466 Variable names starting with '<code>(</code>' (open parenthesis) |
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|
4467 represent variables with no known names |
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|
4468 (internal variables such as loop control variables, |
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|
4469 and variables from chunks saved without debug information). |
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|
4470 |
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changeset
|
4471 |
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|
4472 <p> |
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|
4473 The parameter <code>f</code> may also be a function. |
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4474 In that case, <code>getlocal</code> returns only the name of function parameters. |
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4475 |
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|
4476 |
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diff
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|
4477 |
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|
4478 |
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|
4479 <p> |
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4480 <hr><h3><a name="pdf-debug.getmetatable"><code>debug.getmetatable (value)</code></a></h3> |
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|
4481 |
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|
4482 |
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|
4483 <p> |
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4484 Returns the metatable of the given <code>value</code> |
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4485 or <b>nil</b> if it does not have a metatable. |
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|
4486 |
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|
4487 |
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|
4488 |
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|
4489 |
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4490 <p> |
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|
4491 <hr><h3><a name="pdf-debug.getregistry"><code>debug.getregistry ()</code></a></h3> |
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4492 |
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|
4493 |
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4494 <p> |
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4495 Returns the registry table (see <a href="#4.5">§4.5</a>). |
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|
4496 |
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|
4497 |
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4498 |
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4499 |
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4500 <p> |
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4501 <hr><h3><a name="pdf-debug.getupvalue"><code>debug.getupvalue (f, up)</code></a></h3> |
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4502 |
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4503 |
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4504 <p> |
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4505 This function returns the name and the value of the upvalue |
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4506 with index <code>up</code> of the function <code>f</code>. |
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4507 The function returns <b>nil</b> if there is no upvalue with the given index. |
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|
4508 |
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|
4509 |
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4510 <p> |
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4511 Variable names starting with '<code>(</code>' (open parenthesis) |
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4512 represent variables with no known names |
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4513 (variables from chunks saved without debug information). |
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|
4514 |
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|
4515 |
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|
4516 |
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|
4517 |
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4518 <p> |
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4519 <hr><h3><a name="pdf-debug.getuservalue"><code>debug.getuservalue (u)</code></a></h3> |
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|
4520 |
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|
4521 |
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|
4522 <p> |
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4523 Returns the Lua value associated to <code>u</code>. |
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4524 If <code>u</code> is not a userdata, |
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4525 returns <b>nil</b>. |
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|
4526 |
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|
4527 |
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|
4528 |
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|
4529 |
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|
4530 <p> |
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|
4531 <hr><h3><a name="pdf-debug.sethook"><code>debug.sethook ([thread,] hook, mask [, count])</code></a></h3> |
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|
4532 |
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|
4533 |
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|
4534 <p> |
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|
4535 Sets the given function as a hook. |
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|
4536 The string <code>mask</code> and the number <code>count</code> describe |
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|
4537 when the hook will be called. |
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|
4538 The string mask may have any combination of the following characters, |
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|
4539 with the given meaning: |
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|
4540 |
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|
4541 <ul> |
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|
4542 <li><b>'<code>c</code>': </b> the hook is called every time Lua calls a function;</li> |
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|
4543 <li><b>'<code>r</code>': </b> the hook is called every time Lua returns from a function;</li> |
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|
4544 <li><b>'<code>l</code>': </b> the hook is called every time Lua enters a new line of code.</li> |
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|
4545 </ul><p> |
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|
4546 Moreover, |
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|
4547 with a <code>count</code> different from zero, |
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|
4548 the hook is called also after every <code>count</code> instructions. |
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|
4549 |
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|
4550 |
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|
4551 <p> |
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|
4552 When called without arguments, |
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|
4553 <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> turns off the hook. |
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|
4554 |
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|
4555 |
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|
4556 <p> |
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|
4557 When the hook is called, its first parameter is a string |
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|
4558 describing the event that has triggered its call: |
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|
4559 <code>"call"</code> (or <code>"tail call"</code>), |
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|
4560 <code>"return"</code>, |
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|
4561 <code>"line"</code>, and <code>"count"</code>. |
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|
4562 For line events, |
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|
4563 the hook also gets the new line number as its second parameter. |
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|
4564 Inside a hook, |
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|
4565 you can call <code>getinfo</code> with level 2 to get more information about |
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|
4566 the running function |
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|
4567 (level 0 is the <code>getinfo</code> function, |
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|
4568 and level 1 is the hook function). |
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|
4569 |
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changeset
|
4570 |
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|
4571 |
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|
4572 |
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|
4573 <p> |
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|
4574 <hr><h3><a name="pdf-debug.setlocal"><code>debug.setlocal ([thread,] level, local, value)</code></a></h3> |
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|
4575 |
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|
4576 |
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|
4577 <p> |
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|
4578 This function assigns the value <code>value</code> to the local variable |
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|
4579 with index <code>local</code> of the function at level <code>level</code> of the stack. |
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4580 The function returns <b>nil</b> if there is no local |
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|
4581 variable with the given index, |
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|
4582 and raises an error when called with a <code>level</code> out of range. |
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|
4583 (You can call <code>getinfo</code> to check whether the level is valid.) |
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|
4584 Otherwise, it returns the name of the local variable. |
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|
4585 |
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|
4586 |
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|
4587 <p> |
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|
4588 See <a href="#pdf-debug.getlocal"><code>debug.getlocal</code></a> for more information about |
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|
4589 variable indices and names. |
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|
4590 |
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changeset
|
4591 |
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changeset
|
4592 |
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changeset
|
4593 |
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4594 <p> |
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|
4595 <hr><h3><a name="pdf-debug.setmetatable"><code>debug.setmetatable (value, table)</code></a></h3> |
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4596 |
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|
4597 |
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4598 <p> |
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4599 Sets the metatable for the given <code>value</code> to the given <code>table</code> |
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4600 (which can be <b>nil</b>). |
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4601 Returns <code>value</code>. |
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4602 |
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4603 |
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4604 |
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4605 |
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4606 <p> |
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4607 <hr><h3><a name="pdf-debug.setupvalue"><code>debug.setupvalue (f, up, value)</code></a></h3> |
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4608 |
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4609 |
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4610 <p> |
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4611 This function assigns the value <code>value</code> to the upvalue |
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4612 with index <code>up</code> of the function <code>f</code>. |
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4613 The function returns <b>nil</b> if there is no upvalue |
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4614 with the given index. |
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4615 Otherwise, it returns the name of the upvalue. |
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4616 |
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4617 |
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4618 |
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4619 |
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4620 <p> |
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4621 <hr><h3><a name="pdf-debug.setuservalue"><code>debug.setuservalue (udata, value)</code></a></h3> |
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4622 |
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4623 |
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4624 <p> |
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4625 Sets the given <code>value</code> as |
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4626 the Lua value associated to the given <code>udata</code>. |
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4627 <code>udata</code> must be a full userdata. |
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4628 |
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4629 |
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4630 <p> |
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4631 Returns <code>udata</code>. |
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|
4632 |
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|
4633 |
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|
4634 |
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|
4635 |
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4636 <p> |
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4637 <hr><h3><a name="pdf-debug.traceback"><code>debug.traceback ([thread,] [message [, level]])</code></a></h3> |
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4638 |
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|
4639 |
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4640 <p> |
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|
4641 If <code>message</code> is present but is neither a string nor <b>nil</b>, |
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|
4642 this function returns <code>message</code> without further processing. |
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4643 Otherwise, |
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4644 it returns a string with a traceback of the call stack. |
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4645 The optional <code>message</code> string is appended |
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4646 at the beginning of the traceback. |
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4647 An optional <code>level</code> number tells at which level |
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|
4648 to start the traceback |
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|
4649 (default is 1, the function calling <code>traceback</code>). |
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|
4650 |
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|
4651 |
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|
4652 |
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|
4653 |
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|
4654 <p> |
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4655 <hr><h3><a name="pdf-debug.upvalueid"><code>debug.upvalueid (f, n)</code></a></h3> |
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|
4656 |
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|
4657 |
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|
4658 <p> |
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4659 Returns a unique identifier (as a light userdata) |
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|
4660 for the upvalue numbered <code>n</code> |
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|
4661 from the given function. |
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|
4662 |
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|
4663 |
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|
4664 <p> |
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|
4665 These unique identifiers allow a program to check whether different |
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|
4666 closures share upvalues. |
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|
4667 Lua closures that share an upvalue |
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|
4668 (that is, that access a same external local variable) |
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|
4669 will return identical ids for those upvalue indices. |
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|
4670 |
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|
4671 |
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diff
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|
4672 |
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|
4673 |
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|
4674 <p> |
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|
4675 <hr><h3><a name="pdf-debug.upvaluejoin"><code>debug.upvaluejoin (f1, n1, f2, n2)</code></a></h3> |
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|
4676 |
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|
4677 |
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|
4678 <p> |
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|
4679 Make the <code>n1</code>-th upvalue of the Lua closure <code>f1</code> |
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|
4680 refer to the <code>n2</code>-th upvalue of the Lua closure <code>f2</code>. |
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|
4681 |
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|
4682 |
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|
4683 |
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|
4684 |
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changeset
|
4685 |
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changeset
|
4686 |
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|
4687 |
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|
4688 <h1>7 – <a name="7">Lua Standalone</a></h1> |
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|
4689 |
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|
4690 <p> |
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|
4691 Although Lua has been designed as an extension language, |
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|
4692 to be embedded in a host C program, |
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|
4693 it is also frequently used as a standalone language. |
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|
4694 An interpreter for Lua as a standalone language, |
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4695 called simply <code>lua</code>, |
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|
4696 is provided with the standard distribution. |
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|
4697 The standalone interpreter includes |
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4698 all standard libraries, including the debug library. |
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|
4699 Its usage is: |
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|
4700 |
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|
4701 <pre> |
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|
4702 lua [options] [script [args]] |
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|
4703 </pre><p> |
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|
4704 The options are: |
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|
4705 |
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changeset
|
4706 <ul> |
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|
4707 <li><b><code>-e <em>stat</em></code>: </b> executes string <em>stat</em>;</li> |
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|
4708 <li><b><code>-l <em>mod</em></code>: </b> "requires" <em>mod</em>;</li> |
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4709 <li><b><code>-i</code>: </b> enters interactive mode after running <em>script</em>;</li> |
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4710 <li><b><code>-v</code>: </b> prints version information;</li> |
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4711 <li><b><code>-E</code>: </b> ignores environment variables;</li> |
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4712 <li><b><code>--</code>: </b> stops handling options;</li> |
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4713 <li><b><code>-</code>: </b> executes <code>stdin</code> as a file and stops handling options.</li> |
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|
4714 </ul><p> |
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|
4715 After handling its options, <code>lua</code> runs the given <em>script</em>. |
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4716 When called without arguments, |
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4717 <code>lua</code> behaves as <code>lua -v -i</code> |
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4718 when the standard input (<code>stdin</code>) is a terminal, |
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4719 and as <code>lua -</code> otherwise. |
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|
4720 |
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|
4721 |
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|
4722 <p> |
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|
4723 When called without option <code>-E</code>, |
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4724 the interpreter checks for an environment variable <a name="pdf-LUA_INIT_5_3"><code>LUA_INIT_5_3</code></a> |
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|
4725 (or <a name="pdf-LUA_INIT"><code>LUA_INIT</code></a> if the versioned name is not defined) |
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4726 before running any argument. |
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|
4727 If the variable content has the format <code>@<em>filename</em></code>, |
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|
4728 then <code>lua</code> executes the file. |
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|
4729 Otherwise, <code>lua</code> executes the string itself. |
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4730 |
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|
4731 |
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|
4732 <p> |
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|
4733 When called with option <code>-E</code>, |
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|
4734 besides ignoring <code>LUA_INIT</code>, |
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|
4735 Lua also ignores |
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4736 the values of <code>LUA_PATH</code> and <code>LUA_CPATH</code>, |
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4737 setting the values of |
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4738 <a href="#pdf-package.path"><code>package.path</code></a> and <a href="#pdf-package.cpath"><code>package.cpath</code></a> |
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4739 with the default paths defined in <code>luaconf.h</code>. |
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4740 |
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|
4741 |
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4742 <p> |
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4743 All options are handled in order, except <code>-i</code> and <code>-E</code>. |
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4744 For instance, an invocation like |
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|
4745 |
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4746 <pre> |
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4747 $ lua -e'a=1' -e 'print(a)' script.lua |
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4748 </pre><p> |
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|
4749 will first set <code>a</code> to 1, then print the value of <code>a</code>, |
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4750 and finally run the file <code>script.lua</code> with no arguments. |
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4751 (Here <code>$</code> is the shell prompt. Your prompt may be different.) |
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4752 |
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|
4753 |
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|
4754 <p> |
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|
4755 Before running any code, |
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|
4756 <code>lua</code> collects all command-line arguments |
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4757 in a global table called <code>arg</code>. |
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4758 The script name goes to index 0, |
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4759 the first argument after the script name goes to index 1, |
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|
4760 and so on. |
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|
4761 Any arguments before the script name |
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|
4762 (that is, the interpreter name plus its options) |
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4763 go to negative indices. |
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|
4764 For instance, in the call |
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|
4765 |
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|
4766 <pre> |
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|
4767 $ lua -la b.lua t1 t2 |
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4768 </pre><p> |
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|
4769 the table is like this: |
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|
4770 |
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|
4771 <pre> |
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|
4772 arg = { [-2] = "lua", [-1] = "-la", |
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4773 [0] = "b.lua", |
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4774 [1] = "t1", [2] = "t2" } |
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4775 </pre><p> |
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|
4776 If there is no script in the call, |
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|
4777 the interpreter name goes to index 0, |
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|
4778 followed by the other arguments. |
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|
4779 For instance, the call |
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|
4780 |
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|
4781 <pre> |
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|
4782 $ lua -e "print(arg[1])" |
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|
4783 </pre><p> |
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|
4784 will print "<code>-e</code>". |
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|
4785 If there is a script, |
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|
4786 the script is called with parameters |
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|
4787 <code>arg[1]</code>, ···, <code>arg[#arg]</code>. |
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4788 (Like all chunks in Lua, |
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|
4789 the script is compiled as a vararg function.) |
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|
4790 |
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|
4791 |
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|
4792 <p> |
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|
4793 In interactive mode, |
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|
4794 Lua repeatedly prompts and waits for a line. |
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4795 After reading a line, |
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|
4796 Lua first try to interpret the line as an expression. |
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|
4797 If it succeeds, it prints its value. |
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|
4798 Otherwise, it interprets the line as a statement. |
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|
4799 If you write an incomplete statement, |
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|
4800 the interpreter waits for its completion |
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|
4801 by issuing a different prompt. |
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|
4802 |
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|
4803 |
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|
4804 <p> |
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|
4805 In case of unprotected errors in the script, |
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|
4806 the interpreter reports the error to the standard error stream. |
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|
4807 If the error object is not a string but |
429
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|
4808 has a metamethod <code>__to_string</code>, |
371
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4809 the interpreter calls this metamethod to produce the final message. |
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|
4810 Otherwise, the interpreter converts the error object to a string |
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4811 and adds a stack traceback to it. |
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|
4812 |
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|
4813 |
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|
4814 <p> |
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|
4815 When finishing normally, |
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4816 the interpreter closes its main Lua state |
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|
4817 (see <a href="#lua_close"><code>lua_close</code></a>). |
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|
4818 The script can avoid this step by |
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|
4819 calling <a href="#pdf-os.exit"><code>os.exit</code></a> to terminate. |
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4820 |
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|
4821 |
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|
4822 <p> |
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|
4823 To allow the use of Lua as a |
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|
4824 script interpreter in Unix systems, |
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|
4825 the standalone interpreter skips |
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|
4826 the first line of a chunk if it starts with <code>#</code>. |
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|
4827 Therefore, Lua scripts can be made into executable programs |
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|
4828 by using <code>chmod +x</code> and the <code>#!</code> form, |
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|
4829 as in |
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|
4830 |
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|
4831 <pre> |
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|
4832 #!/usr/local/bin/lua |
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|
4833 </pre><p> |
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|
4834 (Of course, |
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|
4835 the location of the Lua interpreter may be different in your machine. |
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|
4836 If <code>lua</code> is in your <code>PATH</code>, |
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|
4837 then |
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|
4838 |
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|
4839 <pre> |
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|
4840 #!/usr/bin/env lua |
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|
4841 </pre><p> |
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|
4842 is a more portable solution.) |
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|
4843 |
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|
4844 |
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|
4845 |
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|
4846 <h1>8 – <a name="8">Incompatibilities with the Previous Version</a></h1> |
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4847 |
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|
4848 <p> |
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|
4849 Here we list the incompatibilities that you may find when moving a program |
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4850 from Lua 5.2 to Lua 5.3. |
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|
4851 You can avoid some incompatibilities by compiling Lua with |
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|
4852 appropriate options (see file <code>luaconf.h</code>). |
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4853 However, |
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4854 all these compatibility options will be removed in the future. |
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|
4855 |
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|
4856 |
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4857 <p> |
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|
4858 Lua versions can always change the C API in ways that |
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4859 do not imply source-code changes in a program, |
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4860 such as the numeric values for constants |
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4861 or the implementation of functions as macros. |
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4862 Therefore, |
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|
4863 you should not assume that binaries are compatible between |
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4864 different Lua versions. |
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4865 Always recompile clients of the Lua API when |
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4866 using a new version. |
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|
4867 |
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|
4868 |
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4869 <p> |
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4870 Similarly, Lua versions can always change the internal representation |
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4871 of precompiled chunks; |
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4872 precompiled chunks are not compatible between different Lua versions. |
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4873 |
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|
4874 |
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|
4875 <p> |
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|
4876 The standard paths in the official distribution may |
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4877 change between versions. |
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|
4878 |
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|
4879 |
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|
4880 |
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|
4881 <h2>8.1 – <a name="8.1">Changes in the Language</a></h2> |
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4882 <ul> |
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|
4883 |
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4884 <li> |
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4885 The main difference between Lua 5.2 and Lua 5.3 is the |
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4886 introduction of an integer subtype for numbers. |
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|
4887 Although this change should not affect "normal" computations, |
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|
4888 some computations |
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4889 (mainly those that involve some kind of overflow) |
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4890 can give different results. |
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|
4891 |
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|
4892 |
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|
4893 <p> |
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|
4894 You can fix these differences by forcing a number to be a float |
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|
4895 (in Lua 5.2 all numbers were float), |
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|
4896 in particular writing constants with an ending <code>.0</code> |
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|
4897 or using <code>x = x + 0.0</code> to convert a variable. |
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|
4898 (This recommendation is only for a quick fix |
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|
4899 for an occasional incompatibility; |
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|
4900 it is not a general guideline for good programming. |
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4901 For good programming, |
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|
4902 use floats where you need floats |
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|
4903 and integers where you need integers.) |
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|
4904 </li> |
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|
4905 |
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|
4906 <li> |
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|
4907 The conversion of a float to a string now adds a <code>.0</code> suffix |
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|
4908 to the result if it looks like an integer. |
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|
4909 (For instance, the float 2.0 will be printed as <code>2.0</code>, |
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|
4910 not as <code>2</code>.) |
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|
4911 You should always use an explicit format |
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|
4912 when you need a specific format for numbers. |
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|
4913 |
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|
4914 |
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|
4915 <p> |
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|
4916 (Formally this is not an incompatibility, |
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|
4917 because Lua does not specify how numbers are formatted as strings, |
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|
4918 but some programs assumed a specific format.) |
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|
4919 </li> |
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|
4920 |
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|
4921 <li> |
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|
4922 The generational mode for the garbage collector was removed. |
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|
4923 (It was an experimental feature in Lua 5.2.) |
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|
4924 </li> |
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|
4925 |
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|
4926 </ul> |
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|
4927 |
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|
4928 |
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|
4929 |
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|
4930 |
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|
4931 <h2>8.2 – <a name="8.2">Changes in the Libraries</a></h2> |
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|
4932 <ul> |
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|
4933 |
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|
4934 <li> |
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|
4935 The <code>bit32</code> library has been deprecated. |
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|
4936 It is easy to require a compatible external library or, |
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|
4937 better yet, to replace its functions with appropriate bitwise operations. |
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|
4938 (Keep in mind that <code>bit32</code> operates on 32-bit integers, |
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|
4939 while the bitwise operators in standard Lua operate on 64-bit integers.) |
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|
4940 </li> |
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|
4941 |
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|
4942 <li> |
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|
4943 The Table library now respects metamethods |
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|
4944 for setting and getting elements. |
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|
4945 </li> |
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|
4946 |
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|
4947 <li> |
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|
4948 The <a href="#pdf-ipairs"><code>ipairs</code></a> iterator now respects metamethods and |
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|
4949 its <code>__ipairs</code> metamethod has been deprecated. |
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|
4950 </li> |
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|
4951 |
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|
4952 <li> |
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|
4953 Option names in <a href="#pdf-io.read"><code>io.read</code></a> do not have a starting '<code>*</code>' anymore. |
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4954 For compatibility, Lua will continue to ignore this character. |
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|
4955 </li> |
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|
4956 |
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|
4957 <li> |
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4958 The following functions were deprecated in the mathematical library: |
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|
4959 <code>atan2</code>, <code>cosh</code>, <code>sinh</code>, <code>tanh</code>, <code>pow</code>, |
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4960 <code>frexp</code>, and <code>ldexp</code>. |
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|
4961 You can replace <code>math.pow(x,y)</code> with <code>x^y</code>; |
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|
4962 you can replace <code>math.atan2</code> with <code>math.atan</code>, |
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|
4963 which now accepts one or two parameters; |
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|
4964 you can replace <code>math.ldexp(x,exp)</code> with <code>x * 2.0^exp</code>. |
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|
4965 For the other operations, |
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|
4966 you can either use an external library or |
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|
4967 implement them in Lua. |
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4968 </li> |
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|
4969 |
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|
4970 <li> |
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4971 The searcher for C loaders used by <a href="#pdf-require"><code>require</code></a> |
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4972 changed the way it handles versioned names. |
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4973 Now, the version should come after the module name |
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4974 (as is usual in most other tools). |
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4975 For compatibility, that searcher still tries the old format |
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4976 if it cannot find an open function according to the new style. |
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4977 (Lua 5.2 already worked that way, |
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4978 but it did not document the change.) |
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4979 </li> |
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|
4980 |
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4981 </ul> |
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4982 |
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4983 |
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4984 |
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4985 |
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4986 <h2>8.3 – <a name="8.3">Changes in the API</a></h2> |
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4987 |
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4988 |
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4989 <ul> |
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4990 |
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4991 <li> |
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4992 Continuation functions now receive as parameters what they needed |
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4993 to get through <code>lua_getctx</code>, |
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4994 so <code>lua_getctx</code> has been removed. |
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4995 Adapt your code accordingly. |
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|
4996 </li> |
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|
4997 |
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|
4998 <li> |
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4999 Function <a href="#lua_dump"><code>lua_dump</code></a> has an extra parameter, <code>strip</code>. |
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5000 Use 0 as the value of this parameter to get the old behavior. |
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|
5001 </li> |
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|
5002 |
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|
5003 <li> |
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|
5004 Functions to inject/project unsigned integers |
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5005 (<code>lua_pushunsigned</code>, <code>lua_tounsigned</code>, <code>lua_tounsignedx</code>, |
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|
5006 <code>luaL_checkunsigned</code>, <code>luaL_optunsigned</code>) |
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|
5007 were deprecated. |
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|
5008 Use their signed equivalents with a type cast. |
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|
5009 </li> |
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|
5010 |
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|
5011 <li> |
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|
5012 Macros to project non-default integer types |
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|
5013 (<code>luaL_checkint</code>, <code>luaL_optint</code>, <code>luaL_checklong</code>, <code>luaL_optlong</code>) |
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5014 were deprecated. |
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|
5015 Use their equivalent over <a href="#lua_Integer"><code>lua_Integer</code></a> with a type cast |
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|
5016 (or, when possible, use <a href="#lua_Integer"><code>lua_Integer</code></a> in your code). |
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|
5017 </li> |
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|
5018 |
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|
5019 </ul> |
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|
5020 |
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|
5021 |
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|
5022 |
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|
5023 |
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5024 <h1>9 – <a name="9">The Complete Syntax of Lua</a></h1> |
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5025 |
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|
5026 <p> |
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5027 Here is the complete syntax of Lua in extended BNF. |
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5028 As usual in extended BNF, |
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5029 {A} means 0 or more As, |
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5030 and [A] means an optional A. |
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|
5031 (For operator precedences, see <a href="#3.4.8">§3.4.8</a>; |
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5032 for a description of the terminals |
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|
5033 Name, Numeral, |
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|
5034 and LiteralString, see <a href="#3.1">§3.1</a>.) |
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|
5035 |
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|
5036 |
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|
5037 |
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|
5038 |
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|
5039 <pre> |
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|
5040 |
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|
5041 chunk ::= block |
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|
5042 |
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|
5043 block ::= {stat} [retstat] |
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|
5044 |
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|
5045 stat ::= ‘<b>;</b>’ | |
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|
5046 varlist ‘<b>=</b>’ explist | |
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5047 functioncall | |
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|
5048 label | |
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|
5049 <b>break</b> | |
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|
5050 <b>goto</b> Name | |
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|
5051 <b>do</b> block <b>end</b> | |
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|
5052 <b>while</b> exp <b>do</b> block <b>end</b> | |
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|
5053 <b>repeat</b> block <b>until</b> exp | |
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|
5054 <b>if</b> exp <b>then</b> block {<b>elseif</b> exp <b>then</b> block} [<b>else</b> block] <b>end</b> | |
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|
5055 <b>for</b> Name ‘<b>=</b>’ exp ‘<b>,</b>’ exp [‘<b>,</b>’ exp] <b>do</b> block <b>end</b> | |
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|
5056 <b>for</b> namelist <b>in</b> explist <b>do</b> block <b>end</b> | |
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5057 <b>function</b> funcname funcbody | |
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5058 <b>local</b> <b>function</b> Name funcbody | |
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5059 <b>local</b> namelist [‘<b>=</b>’ explist] |
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|
5060 |
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|
5061 retstat ::= <b>return</b> [explist] [‘<b>;</b>’] |
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|
5062 |
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|
5063 label ::= ‘<b>::</b>’ Name ‘<b>::</b>’ |
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|
5064 |
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|
5065 funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] |
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|
5066 |
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|
5067 varlist ::= var {‘<b>,</b>’ var} |
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|
5068 |
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|
5069 var ::= Name | prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ | prefixexp ‘<b>.</b>’ Name |
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|
5070 |
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5071 namelist ::= Name {‘<b>,</b>’ Name} |
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5072 |
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5073 explist ::= exp {‘<b>,</b>’ exp} |
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5074 |
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|
5075 exp ::= <b>nil</b> | <b>false</b> | <b>true</b> | Numeral | LiteralString | ‘<b>...</b>’ | functiondef | |
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5076 prefixexp | tableconstructor | exp binop exp | unop exp |
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5077 |
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5078 prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ |
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5079 |
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5080 functioncall ::= prefixexp args | prefixexp ‘<b>:</b>’ Name args |
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5081 |
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5082 args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ | tableconstructor | LiteralString |
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5083 |
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5084 functiondef ::= <b>function</b> funcbody |
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5085 |
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|
5086 funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> |
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5087 |
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5088 parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ |
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5089 |
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5090 tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ |
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5091 |
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5092 fieldlist ::= field {fieldsep field} [fieldsep] |
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5093 |
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5094 field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp |
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5095 |
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5096 fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ |
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5097 |
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5098 binop ::= ‘<b>+</b>’ | ‘<b>-</b>’ | ‘<b>*</b>’ | ‘<b>/</b>’ | ‘<b>//</b>’ | ‘<b>^</b>’ | ‘<b>%</b>’ | |
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5099 ‘<b>&</b>’ | ‘<b>~</b>’ | ‘<b>|</b>’ | ‘<b>>></b>’ | ‘<b><<</b>’ | ‘<b>..</b>’ | |
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5100 ‘<b><</b>’ | ‘<b><=</b>’ | ‘<b>></b>’ | ‘<b>>=</b>’ | ‘<b>==</b>’ | ‘<b>~=</b>’ | |
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5101 <b>and</b> | <b>or</b> |
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5102 |
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5103 unop ::= ‘<b>-</b>’ | <b>not</b> | ‘<b>#</b>’ | ‘<b>~</b>’ |
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5104 |
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5105 </pre> |
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5106 |
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5107 <p> |
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5108 |
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5109 |
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5110 |
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5111 |
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5112 |
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5113 |
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5114 |
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5115 |
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5116 <HR> |
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5117 <SMALL CLASS="footer"> |
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5118 Last update: |
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5119 Fri Jan 16 00:58:20 BRST 2015 |
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5120 </SMALL> |
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5121 <!-- |
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5122 Last change: minor edit |
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5123 --> |
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5124 |
372 | 5125 </div> |
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5126 |
391
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5127 <% Html.simply_html_body_bottom() %> |
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5128 </body> |
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5129 </html> |
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5130 <% |
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5131 end |