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diff website/src/manual.html.luan @ 562:7cc9d4a53d3b
remove SimplyHTML from documentation
| author | Franklin Schmidt <fschmidt@gmail.com> |
|---|---|
| date | Wed, 24 Jun 2015 14:20:00 -0600 |
| parents | d02f43598ba3 |
| children | 22bfd8a2eaee |
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--- a/website/src/manual.html.luan Tue Jun 23 16:45:16 2015 -0600 +++ b/website/src/manual.html.luan Wed Jun 24 14:20:00 2015 -0600 @@ -3,7 +3,6 @@ local Html = require "luan:Html" local Http = require "luan:http/Http" local Shared = require "site:/Shared" -local heading_options = Shared.heading_options return function() @@ -11,8 +10,10 @@ %> <html> <head> - <% Html.simply_html_head() %> <title>Luan Reference Manual</title> + <style> + @import "/site.css"; + </style> </head> <body> @@ -21,22 +22,20 @@ <h1>Luan Reference Manual</h1> -<p> -<small> +<p small> Original copyright © 2015 Lua.org, PUC-Rio. Freely available under the terms of the <a href="http://www.lua.org/license.html">Lua license</a>. Modified for Luan. -</small> </p> <hr/> <h2>Contents</h2> -<div margin-bottom="1em"><a href="#intro">Introduction</a></div> - -<div margin-bottom="1em"> +<div contents><a href="#intro">Introduction</a></div> + +<div contents> <a href="#basic">Basic Concepts</a> <ul> <li><a href="#types">Values and Types</a></li> @@ -47,7 +46,7 @@ </ul> </div> -<div margin-bottom="1em"> +<div contents> <a href="#lang">The Language</a> <ul> <li><a href="#lex">Lexical Conventions</a></li> @@ -85,7 +84,7 @@ </ul> </div> -<div margin-bottom="1em"> +<div contents> <a href="#libs">Standard Libraries</a> <ul> <li><a href="#default_lib">Default Environment</a></li> @@ -98,7 +97,7 @@ <hr/> -<h2 <%=heading_options%> ><a name="intro">Introduction</a></h2> +<h2 heading><a name="intro">Introduction</a></h2> <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> @@ -107,14 +106,14 @@ <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> -<h2 <%=heading_options%> ><a name="basic">Basic Concepts</a></h2> +<h2 heading><a name="basic">Basic Concepts</a></h2> <p>This section describes the basic concepts of the language.</p> -<h3 <%=heading_options%> ><a name="types">Values and Types</a></h3> - -<p> -Luan is a <i>dynamically typed language</i>. +<h3 heading><a name="types">Values and Types</a></h3> + +<p> +Luan is a <em>dynamically typed language</em>. This means that variables do not have types; only values do. There are no type definitions in the language. @@ -122,41 +121,41 @@ <p> -All values in Luan are <i>first-class values</i>. +All values in Luan are <em>first-class values</em>. This means that all values can be stored in variables, passed as arguments to other functions, and returned as results. <p> There are eight basic types in Luan: -<i>nil</i>, <i>boolean</i>, <i>number</i>, -<i>string</i>, <i>binary</i>, <i>function</i>, <i>java</i>, -and <i>table</i>. -<i>Nil</i> is the type of the value <b>nil</b>, +<em>nil</em>, <em>boolean</em>, <em>number</em>, +<em>string</em>, <em>binary</em>, <em>function</em>, <em>java</em>, +and <em>table</em>. +<em>Nil</em> is the type of the value <b>nil</b>, whose main property is to be different from any other value; it usually represents the absence of a useful value. -<i>Nil</i> is implemented as the Java value <i>null</i>. -<i>Boolean</i> is the type of the values <b>false</b> and <b>true</b>. -<i>Boolean</i> is implemented as the Java class <i>Boolean</i>. -<i>Number</i> represents both +<em>Nil</em> is implemented as the Java value <em>null</em>. +<em>Boolean</em> is the type of the values <b>false</b> and <b>true</b>. +<em>Boolean</em> is implemented as the Java class <em>Boolean</em>. +<em>Number</em> represents both integer numbers and real (floating-point) numbers. -<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 +<em>Number</em> is implemented as the Java class <em>Number</em>. Any Java subclass of <em>Number</em> is allowed and this is invisible to the Luan user. Operations on numbers follow the same rules of the underlying Java implementation. -<i>String</i> is implemented as the Java class <i>String</i>. -<i>Binary</i> is implemented as the Java type <i>byte[]</i>. +<em>String</em> is implemented as the Java class <em>String</em>. +<em>Binary</em> is implemented as the Java type <em>byte[]</em>. <p> Luan can call (and manipulate) functions written in Luan and functions written in Java (see <a href="#fn_calls">Function Calls</a>). -Both are represented by the type <i>function</i>. - - -<p> -The type <i>java</i> is provided to allow arbitrary Java objects to +Both are represented by the type <em>function</em>. + + +<p> +The type <em>java</em> is provided to allow arbitrary Java objects to be stored in Luan variables. -A <i>java</i> value is a Java object that isn't one of the standard Luan types. +A <em>java</em> value is a Java object that isn't one of the standard Luan types. Java values have no predefined operations in Luan, except assignment and identity test. Java values are useful when Java access is enabled in Luan @@ -164,10 +163,10 @@ <p> -The type <i>table</i> implements associative arrays, +The type <em>table</em> implements associative arrays, that is, arrays that can be indexed not only with numbers, but with any Luan value except <b>nil</b>. -Tables can be <i>heterogeneous</i>; +Tables can be <em>heterogeneous</em>; that is, they can contain values of all types (except <b>nil</b>). Any key with value <b>nil</b> is not considered part of the table. Conversely, any key that is not part of a table has @@ -180,15 +179,15 @@ symbol tables, sets, records, graphs, trees, etc. To represent records, Luan uses the field name as an index. The language supports this representation by -providing <tt>a.name</tt> as syntactic sugar for <tt>a["name"]</tt>. +providing <code>a.name</code> as syntactic sugar for <code>a["name"]</code>. There are several convenient ways to create tables in Luan (see <a href="#constructors">Table Constructors</a>). <p> -We use the term <i>sequence</i> to denote a table where -the set of all positive numeric keys is equal to {1..<i>n</i>} -for some non-negative integer <i>n</i>, +We use the term <em>sequence</em> to denote a table where +the set of all positive numeric keys is equal to {1..<em>n</em>} +for some non-negative integer <em>n</em>, which is called the length of the sequence (see <a href="#length">The Length Operator</a>). @@ -198,98 +197,98 @@ In particular, because functions are first-class values, table fields can contain functions. -Thus tables can also carry <i>methods</i> (see <a href="#fn_def">Function Definitions</a>). +Thus tables can also carry <em>methods</em> (see <a href="#fn_def">Function Definitions</a>). <p> The indexing of tables follows the definition of raw equality in the language. -The expressions <tt>a[i]</tt> and <tt>a[j]</tt> +The expressions <code>a[i]</code> and <code>a[j]</code> denote the same table element -if and only if <tt>i</tt> and <tt>j</tt> are raw equal +if and only if <code>i</code> and <code>j</code> are raw equal (that is, equal without metamethods). In particular, floats with integral values are equal to their respective integers -(e.g., <tt>1.0 == 1</tt>). - - -<p> -Luan values are <i>objects</i>: -variables do not actually <i>contain</i> values, -only <i>references</i> to them. +(e.g., <code>1.0 == 1</code>). + + +<p> +Luan values are <em>objects</em>: +variables do not actually <em>contain</em> values, +only <em>references</em> to them. Assignment, parameter passing, and function returns always manipulate references to values; these operations do not imply any kind of copy. <p> -The library function <a href="#Luan.type"><tt>Luan.type</tt></a> returns a string describing the type +The library function <a href="#Luan.type"><code>Luan.type</code></a> returns a string describing the type of a given value. -<h3 <%=heading_options%> ><a name="env">Environments</a></h3> - -<p> -The environment of a chunk starts with only two local variables: <tt><a href="#require">require</a></tt> and <tt><a href="#java">java</a></tt>. These are functions are used to load and access libraries and other modules. All other variables must be added to the environment using <a href="http://localhost:8080/manual.html#local_stmt">local declarations</a>. +<h3 heading><a name="env">Environments</a></h3> + +<p> +The environment of a chunk starts with only two local variables: <code><a href="#require">require</a></code> and <code><a href="#java">java</a></code>. These are functions are used to load and access libraries and other modules. All other variables must be added to the environment using <a href="http://localhost:8080/manual.html#local_stmt">local declarations</a>. <p> As will be discussed in <a href="#vars">Variables</a> and <a href=#assignment">Assignment</a>, any reference to a free name -(that is, a name not bound to any declaration) <tt>var</tt> -can be syntactically translated to <tt>_ENV.var</tt> if <tt>_ENV</tt> is defined. - - -<h3 <%=heading_options%> ><a name="error">Error Handling</a></h3> +(that is, a name not bound to any declaration) <code>var</code> +can be syntactically translated to <code>_ENV.var</code> if <code>_ENV</code> is defined. + + +<h3 heading><a name="error">Error Handling</a></h3> <p> Luan code can explicitly generate an error by calling the -<a href="#Luan.error"><tt>error</tt></a> function. +<a href="#Luan.error"><code>error</code></a> function. If you need to catch errors in Luan, -you can use <a href="#Luan.pcall"><tt>pcall</tt></a> or <a href="#Luan.try"><tt>try</tt></a> -to call a given function in <i>protected mode</i>. +you can use <a href="#Luan.pcall"><code>pcall</code></a> or <a href="#Luan.try"><code>try</code></a> +to call a given function in <em>protected mode</em>. <p> Whenever there is an error, -an <i>error table</i> +an <em>error table</em> is propagated with information about the error. -See <a href="#Luan.new_error"><tt>Luan.new_error</tt></a>. - - - -<h3 <%=heading_options%> ><a name="meta">Metatables and Metamethods</a></h3> - -<p> -Every table in Luan can have a <i>metatable</i>. -This <i>metatable</i> is an ordinary Luan table +See <a href="#Luan.new_error"><code>Luan.new_error</code></a>. + + + +<h3 heading><a name="meta">Metatables and Metamethods</a></h3> + +<p> +Every table in Luan can have a <em>metatable</em>. +This <em>metatable</em> is an ordinary Luan table that defines the behavior of the original value under certain special operations. You can change several aspects of the behavior of operations over a value by setting specific fields in its metatable. For instance, when a table is the operand of an addition, -Luan checks for a function in the field "<tt>__add</tt>" of the table's metatable. +Luan checks for a function in the field "<code>__add</code>" of the table's metatable. If it finds one, Luan calls this function to perform the addition. <p> -The keys in a metatable are derived from the <i>event</i> names; -the corresponding values are called <ii>metamethods</i>. -In the previous example, the event is <tt>"add"</tt> +The keys in a metatable are derived from the <em>event</em> names; +the corresponding values are called <ii>metamethods</em>. +In the previous example, the event is <code>"add"</code> and the metamethod is the function that performs the addition. <p> You can query the metatable of any table -using the <a href="#Luan.get_metatable"><tt>get_metatable</tt></a> function. +using the <a href="#Luan.get_metatable"><code>get_metatable</code></a> function. <p> You can replace the metatable of tables -using the <a href="#Luan.set_metatable"><tt>set_metatable</tt></a> function. +using the <a href="#Luan.set_metatable"><code>set_metatable</code></a> function. <p> @@ -302,17 +301,17 @@ A detailed list of events controlled by metatables is given next. Each operation is identified by its corresponding event name. The key for each event is a string with its name prefixed by -two underscores, '<tt>__</tt>'; +two underscores, '<code>__</code>'; for instance, the key for operation "add" is the -string "<tt>__add</tt>". +string "<code>__add</code>". Note that queries for metamethods are always raw; the access to a metamethod does not invoke other metamethods. -You can emulate how Luan queries a metamethod for an object <tt>obj</tt> +You can emulate how Luan queries a metamethod for an object <code>obj</code> with the following code: -<p><tt><pre> +<pre> raw_get(get_metatable(obj) or {}, "__" .. event_name) -</pre></tt></p> +</pre> <p> Here are the events: @@ -320,12 +319,12 @@ <ul> <li><p><b>"add": </b> -the <tt>+</tt> operation. +the <code>+</code> operation. If any operand for an addition is a table, Luan will try to call a metamethod. First, Luan will check the first operand (even if it is valid). -If that operand does not define a metamethod for the "<tt>__add</tt>" event, +If that operand does not define a metamethod for the "<code>__add</code>" event, then Luan will check the second operand. If Luan can find a metamethod, it calls the metamethod with the two operands as arguments, @@ -337,49 +336,49 @@ </li> <li><p><b>"sub": </b> -the <tt>-</tt> operation. +the <code>-</code> operation. Behavior similar to the "add" operation. </li> <li><p><b>"mul": </b> -the <tt>*</tt> operation. +the <code>*</code> operation. Behavior similar to the "add" operation. </li> <li><p><b>"div": </b> -the <tt>/</tt> operation. +the <code>/</code> operation. Behavior similar to the "add" operation. </li> <li><p><b>"mod": </b> -the <tt>%</tt> operation. +the <code>%</code> operation. Behavior similar to the "add" operation. </li> <li><p><b>"pow": </b> -the <tt>^</tt> (exponentiation) operation. +the <code>^</code> (exponentiation) operation. Behavior similar to the "add" operation. </li> <li><p><b>"unm": </b> -the <tt>-</tt> (unary minus) operation. +the <code>-</code> (unary minus) operation. Behavior similar to the "add" operation. </li> <li><p><b>"concat": </b> -the <tt>..</tt> (concatenation) operation. +the <code>..</code> (concatenation) operation. Behavior similar to the "add" operation. </li> <li><p><b>"len": </b> -the <tt>#</tt> (length) operation. +the <code>#</code> (length) operation. If there is a metamethod, Luan calls it with the object as argument, @@ -392,7 +391,7 @@ </li> <li><p><b>"eq": </b> -the <tt>==</tt> (equal) operation. +the <code>==</code> (equal) operation. Behavior similar to the "add" operation, except that Luan will try a metamethod only when the values @@ -402,59 +401,59 @@ </li> <li><p><b>"lt": </b> -the <tt><</tt> (less than) operation. +the <code><</code> (less than) operation. Behavior similar to the "add" operation. The result of the call is always converted to a boolean. </li> <li><p><b>"le": </b> -the <tt><=</tt> (less equal) operation. +the <code><=</code> (less equal) operation. Unlike other operations, The less-equal operation can use two different events. -First, Luan looks for the "<tt>__le</tt>" metamethod in both operands, +First, Luan looks for the "<code>__le</code>" metamethod in both operands, like in the "lt" operation. If it cannot find such a metamethod, -then it will try the "<tt>__lt</tt>" event, -assuming that <tt>a <= b</tt> is equivalent to <tt>not (b < a)</tt>. +then it will try the "<code>__lt</code>" event, +assuming that <code>a <= b</code> is equivalent to <code>not (b < a)</code>. As with the other comparison operators, the result is always a boolean. </li> <li><p><b>"index": </b> -The indexing access <tt>table[key]</tt>. +The indexing access <code>table[key]</code>. This event happens -when <tt>key</tt> is not present in <tt>table</tt>. -The metamethod is looked up in <tt>table</tt>. +when <code>key</code> is not present in <code>table</code>. +The metamethod is looked up in <code>table</code>. <p> Despite the name, the metamethod for this event can be any type. If it is a function, -it is called with <tt>table</tt> and <tt>key</tt> as arguments. +it is called with <code>table</code> and <code>key</code> as arguments. Otherwise -the final result is the result of indexing this metamethod object with <tt>key</tt>. +the final result is the result of indexing this metamethod object with <code>key</code>. (This indexing is regular, not raw, and therefore can trigger another metamethod if the metamethod object is a table.) </li> <li><p><b>"new_index": </b> -The indexing assignment <tt>table[key] = value</tt>. +The indexing assignment <code>table[key] = value</code>. Like the index event, this event happens when -when <tt>key</tt> is not present in <tt>table</tt>. -The metamethod is looked up in <tt>table</tt>. +when <code>key</code> is not present in <code>table</code>. +The metamethod is looked up in <code>table</code>. <p> Like with indexing, the metamethod for this event can be either a function or a table. If it is a function, -it is called with <tt>table</tt>, <tt>key</tt>, and <tt>value</tt> as arguments. +it is called with <code>table</code>, <code>key</code>, and <code>value</code> as arguments. If it is a table, Luan does an indexing assignment to this table with the same key and value. (This assignment is regular, not raw, @@ -465,18 +464,18 @@ Whenever there is a "new_index" metamethod, Luan does not perform the primitive assignment. (If necessary, -the metamethod itself can call <a href="#Luan.raw_set"><tt>raw_set</tt></a> +the metamethod itself can call <a href="#Luan.raw_set"><code>raw_set</code></a> to do the assignment.) </li> <li><p><b>"call": </b> -The call operation <tt>func(args)</tt>. +The call operation <code>func(args)</code>. This event happens when Luan tries to call a table. -The metamethod is looked up in <tt>func</tt>. +The metamethod is looked up in <code>func</code>. If present, -the metamethod is called with <tt>func</tt> as its first argument, -followed by the arguments of the original call (<tt>args</tt>). +the metamethod is called with <code>func</code> as its first argument, +followed by the arguments of the original call (<code>args</code>). </li> </ul> @@ -484,7 +483,7 @@ -<h3 <%=heading_options%> ><a name="gc">Garbage Collection</a></h3> +<h3 heading><a name="gc">Garbage Collection</a></h3> <p> Luan uses Java's garbage collection. @@ -493,7 +492,7 @@ -<h2 <%=heading_options%> ><a name="lang">The Language</a></h2> +<h2 heading><a name="lang">The Language</a></h2> <p> This section describes the lexis, the syntax, and the semantics of Luan. @@ -507,8 +506,8 @@ <p> Language constructs will be explained using the usual extended BNF notation, in which -{<i>a</i>} means 0 or more <i>a</i>'s, and -[<i>a</i>] means an optional <i>a</i>. +{<em>a</em>} means 0 or more <em>a</em>'s, and +[<em>a</em>] means an optional <em>a</em>. Non-terminals are shown like non-terminal, keywords are shown like <b>kword</b>, and other terminal symbols are shown like ‘<b>=</b>’. @@ -517,17 +516,17 @@ -<h3 <%=heading_options%> ><a name="lex">Lexical Conventions</a></h3> +<h3 heading><a name="lex">Lexical Conventions</a></h3> <p> Luan ignores spaces and comments between lexical elements (tokens), except as delimiters between names and keywords. -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. - -<p> -<i>Names</i> -(also called <i>identifiers</i>) +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 ( <em>(...)</em>, <em>[...]</em>, and <em>{...}</em> ) where the end of line is treated as white space. + +<p> +<em>Names</em> +(also called <em>identifiers</em>) in Luan can be any string of letters, digits, and underscores, not beginning with a digit. @@ -535,51 +534,51 @@ <p> -The following <i>keywords</i> are reserved +The following <em>keywords</em> are reserved and cannot be used as names: -<p><tt><pre> +<pre> and break do else elseif end false for function goto if in local nil not or repeat return then true until while -</pre></tt></p> +</pre> <p> Luan is a case-sensitive language: -<tt>and</tt> is a reserved word, but <tt>And</tt> and <tt>AND</tt> +<code>and</code> is a reserved word, but <code>And</code> and <code>AND</code> are two different, valid names. <p> The following strings denote other tokens: -<p><tt><pre> +<pre> + - * / % ^ # & ~ | << >> // == ~= <= >= < > = ( ) { } [ ] :: ; : , . .. ... -</pre></tt></p> - -<p> -<i>Literal strings</i> +</pre> + +<p> +<em>Literal strings</em> can be delimited by matching single or double quotes, and can contain the following C-like escape sequences: -'<tt>\a</tt>' (bell), -'<tt>\b</tt>' (backspace), -'<tt>\f</tt>' (form feed), -'<tt>\n</tt>' (newline), -'<tt>\r</tt>' (carriage return), -'<tt>\t</tt>' (horizontal tab), -'<tt>\v</tt>' (vertical tab), -'<tt>\\</tt>' (backslash), -'<tt>\"</tt>' (quotation mark [double quote]), -and '<tt>\'</tt>' (apostrophe [single quote]). +'<code>\a</code>' (bell), +'<code>\b</code>' (backspace), +'<code>\f</code>' (form feed), +'<code>\n</code>' (newline), +'<code>\r</code>' (carriage return), +'<code>\t</code>' (horizontal tab), +'<code>\v</code>' (vertical tab), +'<code>\\</code>' (backslash), +'<code>\"</code>' (quotation mark [double quote]), +and '<code>\'</code>' (apostrophe [single quote]). A backslash followed by a real newline results in a newline in the string. -The escape sequence '<tt>\z</tt>' skips the following span +The escape sequence '<code>\z</code>' skips the following span of white-space characters, including line breaks; it is particularly useful to break and indent a long literal string @@ -590,27 +589,27 @@ <p> Luan can specify any character in a literal string by its numerical value. This can be done -with the escape sequence <tt>\x<i>XX</i></tt>, -where <i>XX</i> is a sequence of exactly two hexadecimal digits, -or with the escape sequence <tt>\<i>ddd</i></tt>, -where <i>ddd</i> is a sequence of up to three decimal digits. +with the escape sequence <code>\x<em>XX</em></code>, +where <em>XX</em> is a sequence of exactly two hexadecimal digits, +or with the escape sequence <code>\<em>ddd</em></code>, +where <em>ddd</em> is a sequence of up to three decimal digits. (Note that if a decimal escape sequence is to be followed by a digit, it must be expressed using exactly three digits.) <p> Literal strings can also be defined using a long format -enclosed by <i>long brackets</i>. -We define an <i>opening long bracket of level <i>n</i></i> as an opening -square bracket followed by <i>n</i> equal signs followed by another +enclosed by <em>long brackets</em>. +We define an <em>opening long bracket of level <em>n</em></em> as an opening +square bracket followed by <em>n</em> equal signs followed by another opening square bracket. -So, an opening long bracket of level 0 is written as <tt>[[</tt>, -an opening long bracket of level 1 is written as <tt>[=[</tt>, +So, an opening long bracket of level 0 is written as <code>[[</code>, +an opening long bracket of level 1 is written as <code>[=[</code>, and so on. -A <i>closing long bracket</i> is defined similarly; +A <em>closing long bracket</em> is defined similarly; for instance, -a closing long bracket of level 4 is written as <tt>]====]</tt>. -A <i>long literal</i> starts with an opening long bracket of any level and +a closing long bracket of level 4 is written as <code>]====]</code>. +A <em>long literal</em> starts with an opening long bracket of any level and ends at the first closing long bracket of the same level. It can contain any text except a closing bracket of the same level. Literals in this bracketed form can run for several lines, @@ -640,7 +639,7 @@ As an example the five literal strings below denote the same string: -<p><tt><pre> +<pre> a = 'alo\n123"' a = "alo\n123\"" a = '\97lo\10\04923"' @@ -649,42 +648,42 @@ a = [==[ alo 123"]==] -</pre></tt></p> - -<p> -A <i>numerical constant</i> (or <i>numeral</i>) +</pre> + +<p> +A <em>numerical constant</em> (or <em>numeral</em>) can be written with an optional fractional part and an optional decimal exponent, -marked by a letter '<tt>e</tt>' or '<tt>E</tt>'. +marked by a letter '<code>e</code>' or '<code>E</code>'. Luan also accepts hexadecimal constants, -which start with <tt>0x</tt> or <tt>0X</tt>. +which start with <code>0x</code> or <code>0X</code>. Hexadecimal constants also accept an optional fractional part plus an optional binary exponent, -marked by a letter '<tt>p</tt>' or '<tt>P</tt>'. +marked by a letter '<code>p</code>' or '<code>P</code>'. A numeric constant with a fractional dot or an exponent denotes a float; otherwise it denotes an integer. Examples of valid integer constants are -<p><tt><pre> +<pre> 3 345 0xff 0xBEBADA -</pre></tt></p> +</pre> <p> Examples of valid float constants are -<p><tt><pre> +<pre> 3.0 3.1416 314.16e-2 0.31416E1 34e1 0x0.1E 0xA23p-4 0X1.921FB54442D18P+1 -</pre></tt></p> - -<p> -A <i>comment</i> starts with a double hyphen (<tt>--</tt>) +</pre> + +<p> +A <em>comment</em> starts with a double hyphen (<code>--</code>) anywhere outside a string. -If the text immediately after <tt>--</tt> is not an opening long bracket, -the comment is a <i>short comment</i>, +If the text immediately after <code>--</code> is not an opening long bracket, +the comment is a <em>short comment</em>, which runs until the end of the line. -Otherwise, it is a <i>long comment</i>, +Otherwise, it is a <em>long comment</em>, which runs until the corresponding closing long bracket. Long comments are frequently used to disable code temporarily. @@ -692,7 +691,7 @@ -<h3 <%=heading_options%> ><a name="vars">Variables</a></h3> +<h3 heading><a name="vars">Variables</a></h3> <p> Variables are places that store values. @@ -704,15 +703,15 @@ (or a function's formal parameter, which is a particular kind of local variable): -<p><tt><pre> +<pre> var ::= Name -</pre></tt></p> +</pre> <p> Name denotes identifiers, as defined in <a href="#lex">Lexical Conventions</a>. <p> -Local variables are <i>lexically scoped</i>: +Local variables are <em>lexically scoped</em>: local variables can be freely accessed by functions defined inside their scope (see <a href="#visibility">Visibility Rules</a>). @@ -723,39 +722,39 @@ <p> Square brackets are used to index a table: -<p><tt><pre> +<pre> var ::= prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ -</pre></tt></p> +</pre> <p> The meaning of accesses to table fields can be changed via metatables. -An access to an indexed variable <tt>t[i]</tt> is equivalent to -a call <tt>gettable_event(t,i)</tt>. +An access to an indexed variable <code>t[i]</code> is equivalent to +a call <code>gettable_event(t,i)</code>. (See <a href="#meta">Metatables and Metamethods</a> for a complete description of the -<tt>gettable_event</tt> function. +<code>gettable_event</code> function. This function is not defined or callable in Luan. We use it here only for explanatory purposes.) <p> -The syntax <tt>var.Name</tt> is just syntactic sugar for -<tt>var["Name"]</tt>: - -<p><tt><pre> +The syntax <code>var.Name</code> is just syntactic sugar for +<code>var["Name"]</code>: + +<pre> var ::= prefixexp ‘<b>.</b>’ Name -</pre></tt></p> - -<p> -Global variables are not available by default. To enable global variable, you must define <tt>_ENV</tt> as a local variable whose value is a table. If <tt>_ENV</tt> is not defined, then an unrecognized variable name will produce a compile error. If <tt>_ENV</tt> is defined then an access to an unrecognized variable name will be consider a global variable. So then an acces to global variable <tt>x</tt> -is equivalent to <tt>_ENV.x</tt>. +</pre> + +<p> +Global variables are not available by default. To enable global variable, you must define <code>_ENV</code> as a local variable whose value is a table. If <code>_ENV</code> is not defined, then an unrecognized variable name will produce a compile error. If <code>_ENV</code> is defined then an access to an unrecognized variable name will be consider a global variable. So then an acces to global variable <code>x</code> +is equivalent to <code>_ENV.x</code>. Due to the way that chunks are compiled, -<tt>_ENV</tt> is never a global name (see <a href="#env">Environments</a>). - - - - - -<h3 <%=heading_options%> ><a name="stmts">Statements</a></h3> +<code>_ENV</code> is never a global name (see <a href="#env">Environments</a>). + + + + + +<h3 heading><a name="stmts">Statements</a></h3> <p> Luan supports an almost conventional set of statements, @@ -766,32 +765,32 @@ -<h4 <%=heading_options%> ><a name="blocks">Blocks</a></h4> +<h4 heading><a name="blocks">Blocks</a></h4> <p> A block is a list of statements, which are executed sequentially: -<p><tt><pre> +<pre> block ::= {stat} -</pre></tt></p> - -<p> -Luan has <i>empty statements</i> +</pre> + +<p> +Luan has <em>empty statements</em> that allow you to separate statements with semicolons, start a block with a semicolon or write two semicolons in sequence: -<p><tt><pre> +<pre> stat ::= ‘<b>;</b>’ -</pre></tt></p> +</pre> <p> A block can be explicitly delimited to produce a single statement: -<p><tt><pre> +<pre> stat ::= <b>do</b> block <b>end</b> -</pre></tt></p> +</pre> <p> Explicit blocks are useful @@ -804,16 +803,16 @@ -<h4 <%=heading_options%> ><a name="chunks">Chunks</a></h4> - -<p> -The unit of compilation of Luan is called a <i>chunk</i>. +<h4 heading><a name="chunks">Chunks</a></h4> + +<p> +The unit of compilation of Luan is called a <em>chunk</em>. Syntactically, a chunk is simply a block: -<p><tt><pre> +<pre> chunk ::= block -</pre></tt></p> +</pre> <p> Luan handles a chunk as the body of an anonymous function @@ -826,7 +825,7 @@ <p> A chunk can be stored in a file or in a string inside the host program. To execute a chunk, -Luan first <i>loads</i> it, +Luan first <em>loads</em> it, compiling the chunk's code, and then Luan executes the compiled code. @@ -834,7 +833,7 @@ -<h4 <%=heading_options%> ><a name="assignment">Assignment</a></h4> +<h4 heading><a name="assignment">Assignment</a></h4> <p> Luan allows multiple assignments. @@ -843,11 +842,11 @@ and a list of expressions on the right side. The elements in both lists are separated by commas: -<p><tt><pre> +<pre> stat ::= varlist ‘<b>=</b>’ explist varlist ::= var {‘<b>,</b>’ var} explist ::= exp {‘<b>,</b>’ exp} -</pre></tt></p> +</pre> <p> Expressions are discussed in <a href="#expressions">Expressions</a>. @@ -855,7 +854,7 @@ <p> Before the assignment, -the list of values is <i>adjusted</i> to the length of +the list of values is <em>adjusted</em> to the length of the list of variables. If there are more values than needed, the excess values are thrown away. @@ -872,64 +871,64 @@ and only then the assignments are performed. Thus the code -<p><tt><pre> +<pre> i = 3 i, a[i] = i+1, 20 -</pre></tt></p> - -<p> -sets <tt>a[3]</tt> to 20, without affecting <tt>a[4]</tt> -because the <tt>i</tt> in <tt>a[i]</tt> is evaluated (to 3) +</pre> + +<p> +sets <code>a[3]</code> to 20, without affecting <code>a[4]</code> +because the <code>i</code> in <code>a[i]</code> is evaluated (to 3) before it is assigned 4. Similarly, the line -<p><tt><pre> +<pre> x, y = y, x -</pre></tt></p> - -<p> -exchanges the values of <tt>x</tt> and <tt>y</tt>, +</pre> + +<p> +exchanges the values of <code>x</code> and <code>y</code>, and -<p><tt><pre> +<pre> x, y, z = y, z, x -</pre></tt></p> - -<p> -cyclically permutes the values of <tt>x</tt>, <tt>y</tt>, and <tt>z</tt>. +</pre> + +<p> +cyclically permutes the values of <code>x</code>, <code>y</code>, and <code>z</code>. <p> The meaning of assignments to global variables and table fields can be changed via metatables. -An assignment to an indexed variable <tt>t[i] = val</tt> is equivalent to -<tt>settable_event(t,i,val)</tt>. +An assignment to an indexed variable <code>t[i] = val</code> is equivalent to +<code>settable_event(t,i,val)</code>. (See <a href="#meta">Metatables and Metamethods</a> for a complete description of the -<tt>settable_event</tt> function. +<code>settable_event</code> function. This function is not defined or callable in Luan. We use it here only for explanatory purposes.) <p> -An assignment to a global name <tt>x = val</tt> +An assignment to a global name <code>x = val</code> is equivalent to the assignment -<tt>_ENV.x = val</tt> (see <a href="#env">Environments</a>). -Global names are only available when <tt>_ENV</tt> is defined. - - - -<h4 <%=heading_options%> ><a name="control">Control Structures</a></h4> +<code>_ENV.x = val</code> (see <a href="#env">Environments</a>). +Global names are only available when <code>_ENV</code> is defined. + + + +<h4 heading><a name="control">Control Structures</a></h4> <p> The control structures <b>if</b>, <b>while</b>, and <b>repeat</b> have the usual meaning and familiar syntax: -<p><tt><pre> +<pre> stat ::= <b>while</b> exp <b>do</b> block <b>end</b> stat ::= <b>repeat</b> block <b>until</b> exp stat ::= <b>if</b> exp <b>then</b> block {<b>elseif</b> exp <b>then</b> block} [<b>else</b> block] <b>end</b> -</pre></tt></p> +</pre> <p> Luan also has a <b>for</b> statement (see <a href="#for">For Statement</a>). @@ -956,9 +955,9 @@ skipping to the next statement after the loop: -<p><tt><pre> +<pre> stat ::= <b>break</b> -</pre></tt></p> +</pre> <p> A <b>break</b> ends the innermost enclosing loop. @@ -972,47 +971,47 @@ Functions can return more than one value, so the syntax for the <b>return</b> statement is -<p><tt><pre> +<pre> stat ::= <b>return</b> [explist] [‘<b>;</b>’] -</pre></tt></p> - - - - -<h4 <%=heading_options%> ><a name="for">For Statement</a></h4> +</pre> + + + + +<h4 heading><a name="for">For Statement</a></h4> <p> The <b>for</b> statement works over functions, -called <i>iterators</i>. +called <em>iterators</em>. On each iteration, the iterator function is called to produce a new value, stopping when this new value is <b>nil</b>. The <b>for</b> loop has the following syntax: -<p><tt><pre> +<pre> stat ::= <b>for</b> namelist <b>in</b> exp <b>do</b> block <b>end</b> namelist ::= Name {‘<b>,</b>’ Name} -</pre></tt></p> +</pre> <p> A <b>for</b> statement like -<p><tt><pre> - for <i>var_1</i>, ···, <i>var_n</i> in <i>exp</i> do <i>block</i> end -</pre></tt></p> +<pre> + for <em>var_1</em>, ···, <em>var_n</em> in <em>exp</em> do <em>block</em> end +</pre> <p> is equivalent to the code: -<p><tt><pre> +<pre> do - local <i>f</i> = <i>exp</i> + local <em>f</em> = <em>exp</em> while true do - local <i>var_1</i>, ···, <i>var_n</i> = <i>f</i>() - if <i>var_1</i> == nil then break end - <i>block</i> + local <em>var_1</em>, ···, <em>var_n</em> = <em>f</em>() + if <em>var_1</em> == nil then break end + <em>block</em> end end -</pre></tt></p> +</pre> <p> Note the following: @@ -1020,12 +1019,12 @@ <ul> <li> -<tt><i>exp</i></tt> is evaluated only once. -Its result is an <i>iterator</i> function. +<code><em>exp</em></code> is evaluated only once. +Its result is an <em>iterator</em> function. </li> <li> -<tt><i>f</i></tt> is an invisible variable. +<code><em>f</em></code> is an invisible variable. The name is here for explanatory purposes only. </li> @@ -1034,7 +1033,7 @@ </li> <li> -The loop variables <tt><i>var_i</i></tt> are local to the loop; +The loop variables <code><em>var_i</em></code> are local to the loop; you cannot use their values after the <b>for</b> ends. If you need these values, then assign them to other variables before breaking or exiting the loop. @@ -1045,15 +1044,15 @@ -<h4 <%=heading_options%> ><a name="fn_stmt">Function Calls as Statements</a></h4> +<h4 heading><a name="fn_stmt">Function Calls as Statements</a></h4> <p> To allow possible side-effects, function calls can be executed as statements: -<p><tt><pre> +<pre> stat ::= functioncall -</pre></tt></p> +</pre> <p> In this case, all returned values are thrown away. @@ -1061,15 +1060,15 @@ -<h4 <%=heading_options%> ><a name="local_stmt">Local Declarations</a></h4> +<h4 heading><a name="local_stmt">Local Declarations</a></h4> <p> Local variables can be declared anywhere inside a block. The declaration can include an initial assignment: -<p><tt><pre> +<pre> stat ::= <b>local</b> namelist [‘<b>=</b>’ explist] -</pre></tt></p> +</pre> <p> If present, an initial assignment has the same semantics @@ -1086,36 +1085,36 @@ The visibility rules for local variables are explained in <a href="#visibility">Visibility Rules</a>. -<h4 <%=heading_options%> ><a name="template_stmt">Template Statements</a></h4> +<h4 heading><a name="template_stmt">Template Statements</a></h4> <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> -<p><tt><pre><%=Html.encode[[ +<pre><%=Html.encode[[ local name = "Bob" %> Hello <%= name %>! Bye <%= name %>. <% -]]%></pre></tt></p> +]]%></pre> <p>is equivalent to the code:</p> -<p><tt><pre><%=Html.encode[[ +<pre><%=Html.encode[[ local name = "Bob" require("luan:Io").stdout.write( %> Hello <%= name %>! Bye <%= name %>. <% ) -]]%></pre></tt></p> - - - -<h3 <%=heading_options%> ><a name="expressions">Expressions</a></h3> +]]%></pre> + + + +<h3 heading><a name="expressions">Expressions</a></h3> <p> The basic expressions in Luan are the following: -<p><tt><pre> +<pre> exp ::= prefixexp exp ::= <b>nil</b> | <b>false</b> | <b>true</b> exp ::= Numeral @@ -1126,7 +1125,7 @@ exp ::= exp binop exp exp ::= unop exp prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ -</pre></tt></p> +</pre> <p> Numerals and literal strings are explained in <a href="#lex">Lexical Conventions</a>; @@ -1135,7 +1134,7 @@ function calls are explained in <a href="#fn_calls">Function Calls</a>; table constructors are explained in <a href="#constructors">Table Constructors</a>. Vararg expressions, -denoted by three dots ('<tt>...</tt>'), can only be used when +denoted by three dots ('<code>...</code>'), can only be used when directly inside a vararg function; they are explained in <a href="#fn_def">Function Definitions</a>. @@ -1167,7 +1166,7 @@ <p> Here are some examples: -<p><tt><pre> +<pre> f() -- adjusted to 0 results g(f(), x) -- f() is adjusted to 1 result g(x, f()) -- g gets x plus all results from f() @@ -1184,31 +1183,31 @@ {f()} -- creates a list with all results from f() {...} -- creates a list with all vararg parameters {f(), nil} -- f() is adjusted to 1 result -</pre></tt></p> +</pre> <p> Any expression enclosed in parentheses always results in only one value. Thus, -<tt>(f(x,y,z))</tt> is always a single value, -even if <tt>f</tt> returns several values. -(The value of <tt>(f(x,y,z))</tt> is the first value returned by <tt>f</tt> -or <b>nil</b> if <tt>f</tt> does not return any values.) - - - -<h4 <%=heading_options%> ><a name="arithmetic">Arithmetic Operators</a></h4> +<code>(f(x,y,z))</code> is always a single value, +even if <code>f</code> returns several values. +(The value of <code>(f(x,y,z))</code> is the first value returned by <code>f</code> +or <b>nil</b> if <code>f</code> does not return any values.) + + + +<h4 heading><a name="arithmetic">Arithmetic Operators</a></h4> <p> Luan supports the following arithmetic operators: <ul> -<li><b><tt>+</tt>: </b>addition</li> -<li><b><tt>-</tt>: </b>subtraction</li> -<li><b><tt>*</tt>: </b>multiplication</li> -<li><b><tt>/</tt>: </b>division</li> -<li><b><tt>%</tt>: </b>modulo</li> -<li><b><tt>^</tt>: </b>exponentiation</li> -<li><b><tt>-</tt>: </b>unary minus</li> +<li><b><code>+</code>: </b>addition</li> +<li><b><code>-</code>: </b>subtraction</li> +<li><b><code>*</code>: </b>multiplication</li> +<li><b><code>/</code>: </b>division</li> +<li><b><code>%</code>: </b>modulo</li> +<li><b><code>^</code>: </b>exponentiation</li> +<li><b><code>-</code>: </b>unary minus</li> </ul> <p> @@ -1221,7 +1220,7 @@ -<h4 <%=heading_options%> ><a name="conversions">Coercions and Conversions</a></h4> +<h4 heading><a name="conversions">Coercions and Conversions</a></h4> <p> Luan generally avoids automatic conversions. @@ -1233,24 +1232,24 @@ -<h4 <%=heading_options%> ><a name="relational">Relational Operators</a></h4> +<h4 heading><a name="relational">Relational Operators</a></h4> <p> Luan supports the following relational operators: <ul> -<li><b><tt>==</tt>: </b>equality</li> -<li><b><tt>~=</tt>: </b>inequality</li> -<li><b><tt><</tt>: </b>less than</li> -<li><b><tt>></tt>: </b>greater than</li> -<li><b><tt><=</tt>: </b>less or equal</li> -<li><b><tt>>=</tt>: </b>greater or equal</li> +<li><b><code>==</code>: </b>equality</li> +<li><b><code>~=</code>: </b>inequality</li> +<li><b><code><</code>: </b>less than</li> +<li><b><code>></code>: </b>greater than</li> +<li><b><code><=</code>: </b>less or equal</li> +<li><b><code>>=</code>: </b>greater or equal</li> </ul><p> These operators always result in <b>false</b> or <b>true</b>. <p> -Equality (<tt>==</tt>) first compares the type of its operands. +Equality (<code>==</code>) first compares the type of its operands. If the types are different, then the result is <b>false</b>. Otherwise, the values of the operands are compared. Strings, numbers, and binary values are compared in the obvious way (by value). @@ -1268,18 +1267,18 @@ by using the "eq" metamethod (see <a href="#meta">Metatables and Metamethods</a>). <p> -Java values 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. +Java values 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)"><code>equals</code></a> method. <p> Equality comparisons do not convert strings to numbers or vice versa. -Thus, <tt>"0"==0</tt> evaluates to <b>false</b>, -and <tt>t[0]</tt> and <tt>t["0"]</tt> denote different +Thus, <code>"0"==0</code> evaluates to <b>false</b>, +and <code>t[0]</code> and <code>t["0"]</code> denote different entries in a table. <p> -The operator <tt>~=</tt> is exactly the negation of equality (<tt>==</tt>). +The operator <code>~=</code> is exactly the negation of equality (<code>==</code>). <p> @@ -1292,14 +1291,14 @@ then their values are compared according to the current locale. Otherwise, Luan tries to call the "lt" or the "le" metamethod (see <a href="#meta">Metatables and Metamethods</a>). -A comparison <tt>a > b</tt> is translated to <tt>b < a</tt> -and <tt>a >= b</tt> is translated to <tt>b <= a</tt>. - - - - - -<h4 <%=heading_options%> ><a name="logical_ops">Logical Operators</a></h4> +A comparison <code>a > b</code> is translated to <code>b < a</code> +and <code>a >= b</code> is translated to <code>b <= a</code>. + + + + + +<h4 heading><a name="logical_ops">Logical Operators</a></h4> <p> The logical operators in Luan are @@ -1322,7 +1321,7 @@ the second operand is evaluated only if necessary. Here are some examples: -<p><tt><pre> +<pre> 10 or 20 --> 10 10 or error() --> 10 nil or "a" --> "a" @@ -1331,39 +1330,39 @@ false and nil --> false false or nil --> nil 10 and 20 --> 20 -</pre></tt></p> +</pre> <p> (In this manual, -<tt>--></tt> indicates the result of the preceding expression.) - - - -<h4 <%=heading_options%> ><a name="concatenation">Concatenation</a></h4> +<code>--></code> indicates the result of the preceding expression.) + + + +<h4 heading><a name="concatenation">Concatenation</a></h4> <p> The string concatenation operator in Luan is -denoted by two dots ('<tt>..</tt>'). +denoted by two dots ('<code>..</code>'). All operands are converted to strings. -<h4 <%=heading_options%> ><a name="length">The Length Operator</a></h4> - -<p> -The length operator is denoted by the unary prefix operator <tt>#</tt>. +<h4 heading><a name="length">The Length Operator</a></h4> + +<p> +The length operator is denoted by the unary prefix operator <code>#</code>. The length of a string is its number of characters. The length of a binary is its number of bytes. <p> A program can modify the behavior of the length operator for -any table through the <tt>__len</tt> metamethod (see <a href="#meta">Metatables and Metamethods</a>). - - -<p> -Unless a <tt>__len</tt> metamethod is given, -the length of a table <tt>t</tt> is defined +any table through the <code>__len</code> metamethod (see <a href="#meta">Metatables and Metamethods</a>). + + +<p> +Unless a <code>__len</code> metamethod is given, +the length of a table <code>t</code> is defined as the number of elements in <em>sequence</em>, that is, the size of the set of its positive numeric keys is equal to <em>{1..n}</em> @@ -1371,24 +1370,24 @@ In that case, <em>n</em> is its length. Note that a table like -<p><tt><pre> +<pre> {10, 20, nil, 40} -</pre></tt></p> - -<p> -has a length of <tt>2</tt>, because that is the last key in sequence. - - - - - -<h4 <%=heading_options%> ><a name="precedence">Precedence</a></h4> +</pre> + +<p> +has a length of <code>2</code>, because that is the last key in sequence. + + + + + +<h4 heading><a name="precedence">Precedence</a></h4> <p> Operator precedence in Luan follows the table below, from lower to higher priority: -<p><tt><pre> +<pre> or and < > <= >= ~= == @@ -1397,12 +1396,12 @@ * / % unary operators (not # -) ^ -</pre></tt></p> +</pre> <p> As usual, you can use parentheses to change the precedences of an expression. -The concatenation ('<tt>..</tt>') and exponentiation ('<tt>^</tt>') +The concatenation ('<code>..</code>') and exponentiation ('<code>^</code>') operators are right associative. All other binary operators are left associative. @@ -1410,7 +1409,7 @@ -<h4 <%=heading_options%> ><a name="constructors">Table Constructors</a></h4> +<h4 heading><a name="constructors">Table Constructors</a></h4> <p> Table constructors are expressions that create tables. @@ -1419,32 +1418,32 @@ or to create a table and initialize some of its fields. The general syntax for constructors is -<p><tt><pre> +<pre> tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ fieldlist ::= field {fieldsep field} [fieldsep] field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ -</pre></tt></p> - -<p> -Each field of the form <tt>[exp1] = exp2</tt> adds to the new table an entry -with key <tt>exp1</tt> and value <tt>exp2</tt>. -A field of the form <tt>name = exp</tt> is equivalent to -<tt>["name"] = exp</tt>. -Finally, fields of the form <tt>exp</tt> are equivalent to -<tt>[i] = exp</tt>, where <tt>i</tt> are consecutive integers +</pre> + +<p> +Each field of the form <code>[exp1] = exp2</code> adds to the new table an entry +with key <code>exp1</code> and value <code>exp2</code>. +A field of the form <code>name = exp</code> is equivalent to +<code>["name"] = exp</code>. +Finally, fields of the form <code>exp</code> are equivalent to +<code>[i] = exp</code>, where <code>i</code> are consecutive integers starting with 1. Fields in the other formats do not affect this counting. For example, -<p><tt><pre> +<pre> a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 } -</pre></tt></p> +</pre> <p> is equivalent to -<p><tt><pre> +<pre> do local t = {} t[f(1)] = g @@ -1456,7 +1455,7 @@ t[4] = 45 -- 4th exp a = t end -</pre></tt></p> +</pre> <p> The order of the assignments in a constructor is undefined. @@ -1464,7 +1463,7 @@ <p> -If the last field in the list has the form <tt>exp</tt> +If the last field in the list has the form <code>exp</code> and the expression is a function call or a vararg expression, then all values returned by this expression enter the list consecutively (see <a href="#fn_calls">Function Calls</a>). @@ -1478,19 +1477,19 @@ -<h4 <%=heading_options%> ><a name="fn_calls">Function Calls</a></h4> +<h4 heading><a name="fn_calls">Function Calls</a></h4> <p> A function call in Luan has the following syntax: -<p><tt><pre> +<pre> functioncall ::= prefixexp args -</pre></tt></p> +</pre> <p> In a function call, first prefixexp and args are evaluated. -If the value of prefixexp has type <i>function</i>, +If the value of prefixexp has type <em>function</em>, then this function is called with the given arguments. Otherwise, the prefixexp "call" metamethod is called, @@ -1502,28 +1501,28 @@ <p> Arguments have the following syntax: -<p><tt><pre> +<pre> args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ args ::= tableconstructor args ::= LiteralString -</pre></tt></p> +</pre> <p> All argument expressions are evaluated before the call. -A call of the form <tt>f{<i>fields</i>}</tt> is -syntactic sugar for <tt>f({<i>fields</i>})</tt>; +A call of the form <code>f{<em>fields</em>}</code> is +syntactic sugar for <code>f({<em>fields</em>})</code>; that is, the argument list is a single new table. -A call of the form <tt>f'<i>string</i>'</tt> -(or <tt>f"<i>string</i>"</tt> or <tt>f[[<i>string</i>]]</tt>) -is syntactic sugar for <tt>f('<i>string</i>')</tt>; +A call of the form <code>f'<em>string</em>'</code> +(or <code>f"<em>string</em>"</code> or <code>f[[<em>string</em>]]</code>) +is syntactic sugar for <code>f('<em>string</em>')</code>; that is, the argument list is a single literal string. <p> -A call of the form <tt>return <i>functioncall</i></tt> is called -a <i>tail call</i>. -Luan implements <i>proper tail calls</i> -(or <i>proper tail recursion</i>): +A call of the form <code>return <em>functioncall</em></code> is called +a <em>tail call</em>. +Luan implements <em>proper tail calls</em> +(or <em>proper tail recursion</em>): in a tail call, the called function reuses the stack entry of the calling function. Therefore, there is no limit on the number of nested tail calls that @@ -1536,98 +1535,98 @@ the returns of the called function. So, none of the following examples are tail calls: -<p><tt><pre> +<pre> return (f(x)) -- results adjusted to 1 return 2 * f(x) return x, f(x) -- additional results f(x); return -- results discarded return x or f(x) -- results adjusted to 1 -</pre></tt></p> - - - - -<h4 <%=heading_options%> ><a name="fn_def">Function Definitions</a></h4> +</pre> + + + + +<h4 heading><a name="fn_def">Function Definitions</a></h4> <p> The syntax for function definition is -<p><tt><pre> +<pre> functiondef ::= <b>function</b> funcbody funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> -</pre></tt></p> +</pre> <p> The following syntactic sugar simplifies function definitions: -<p><tt><pre> +<pre> stat ::= <b>function</b> funcname funcbody stat ::= <b>local</b> <b>function</b> Name funcbody funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] -</pre></tt></p> +</pre> <p> The statement -<p><tt><pre> - function f () <i>body</i> end -</pre></tt></p> +<pre> + function f () <em>body</em> end +</pre> <p> translates to -<p><tt><pre> - f = function () <i>body</i> end -</pre></tt></p> +<pre> + f = function () <em>body</em> end +</pre> <p> The statement -<p><tt><pre> - function t.a.b.c.f () <i>body</i> end -</pre></tt></p> +<pre> + function t.a.b.c.f () <em>body</em> end +</pre> <p> translates to -<p><tt><pre> - t.a.b.c.f = function () <i>body</i> end -</pre></tt></p> +<pre> + t.a.b.c.f = function () <em>body</em> end +</pre> <p> The statement -<p><tt><pre> - local function f () <i>body</i> end -</pre></tt></p> +<pre> + local function f () <em>body</em> end +</pre> <p> translates to -<p><tt><pre> +<pre> local f; f = function () <em>body</em> end -</pre></tt></p> +</pre> <p> not to -<p><tt><pre> +<pre> local f = function () <em>body</em> end -</pre></tt></p> +</pre> <p> (This only makes a difference when the body of the function -contains references to <tt>f</tt>.) +contains references to <code>f</code>.) <p> A function definition is an executable expression, -whose value has type <i>function</i>. +whose value has type <em>function</em>. When Luan precompiles a chunk, all its function bodies are precompiled too. Then, whenever Luan executes the function definition, -the function is <i>instantiated</i> (or <i>closed</i>). -This function instance (or <i>closure</i>) +the function is <em>instantiated</em> (or <em>closed</em>). +This function instance (or <em>closure</em>) is the final value of the expression. @@ -1635,20 +1634,20 @@ Parameters act as local variables that are initialized with the argument values: -<p><tt><pre> +<pre> parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ -</pre></tt></p> +</pre> <p> When a function is called, the list of arguments is adjusted to the length of the list of parameters, -unless the function is a <i>vararg function</i>, -which is indicated by three dots ('<tt>...</tt>') +unless the function is a <em>vararg function</em>, +which is indicated by three dots ('<code>...</code>') at the end of its parameter list. A vararg function does not adjust its argument list; instead, it collects all extra arguments and supplies them -to the function through a <i>vararg expression</i>, +to the function through a <em>vararg expression</em>, which is also written as three dots. The value of this expression is a list of all actual extra arguments, similar to a function with multiple results. @@ -1663,17 +1662,17 @@ <p> As an example, consider the following definitions: -<p><tt><pre> +<pre> function f(a, b) end function g(a, b, ...) end function r() return 1,2,3 end -</pre></tt></p> +</pre> <p> Then, we have the following mapping from arguments to parameters and to the vararg expression: -<p><tt><pre> +<pre> CALL PARAMETERS f(3) a=3, b=nil @@ -1686,7 +1685,7 @@ g(3, 4) a=3, b=4, ... --> (nothing) g(3, 4, 5, 8) a=3, b=4, ... --> 5 8 g(5, r()) a=5, b=1, ... --> 2 3 -</pre></tt></p> +</pre> <p> Results are returned using the <b>return</b> statement (see <a href="#control">Control Structures</a>). @@ -1695,27 +1694,27 @@ then the function returns with no results. -<h4 <%=heading_options%> ><a name="template_expr">Template Expressions</a></h4> +<h4 heading><a name="template_expr">Template Expressions</a></h4> <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> -<p><tt><pre><%=Html.encode[[ +<pre><%=Html.encode[[ local name = "Bob" write( %>Hello <%= name %>!<% ) -]]%></pre></tt></p> +]]%></pre> <p>This is equivalent to the code:</p> -<p><tt><pre> +<pre> local name = "Bob" write( "Hello ", name, "!" ) -</pre></tt></p> +</pre> <p>The strings in template expressions may be multiple lines.</p> -<h3 <%=heading_options%> ><a name="visibility">Visibility Rules</a></h3> +<h3 heading><a name="visibility">Visibility Rules</a></h3> <p> Luan is a lexically scoped language. @@ -1724,7 +1723,7 @@ of the innermost block that includes the declaration. Consider the following example: -<p><tt><pre> +<pre> x = 10 -- global variable do -- new block local x = x -- new 'x', with value 10 @@ -1737,12 +1736,12 @@ print(x) --> 11 end print(x) --> 10 (the global one) -</pre></tt></p> - -<p> -Notice that, in a declaration like <tt>local x = x</tt>, -the new <tt>x</tt> being declared is not in scope yet, -and so the second <tt>x</tt> refers to the outside variable. +</pre> + +<p> +Notice that, in a declaration like <code>local x = x</code>, +the new <code>x</code> being declared is not in scope yet, +and so the second <code>x</code> refers to the outside variable. <p> @@ -1750,7 +1749,7 @@ local variables can be freely accessed by functions defined inside their scope. A local variable used by an inner function is called -an <i>upvalue</i>, or <i>external local variable</i>, +an <em>upvalue</em>, or <em>external local variable</em>, inside the inner function. @@ -1759,155 +1758,155 @@ defines new local variables. Consider the following example: -<p><tt><pre> +<pre> a = {} local x = 20 for i=1,10 do local y = 0 a[i] = function () y=y+1; return x+y end end -</pre></tt></p> +</pre> <p> The loop creates ten closures (that is, ten instances of the anonymous function). -Each of these closures uses a different <tt>y</tt> variable, -while all of them share the same <tt>x</tt>. - - - - - -<h2 <%=heading_options%> ><a name="libs">Standard Libraries</a></h2> +Each of these closures uses a different <code>y</code> variable, +while all of them share the same <code>x</code>. + + + + + +<h2 heading><a name="libs">Standard Libraries</a></h2> <p> The standard Luan libraries provide useful functions that are implemented both in Java and in Luan itself. How each function is implemented shouldn't matter to the user. Some of these functions provide essential services to the language -(e.g., <a href="#Luan.type"><tt>type</tt></a> and <a href="#Luan.get_metatable"><tt>get_metatable</tt></a>); +(e.g., <a href="#Luan.type"><code>type</code></a> and <a href="#Luan.get_metatable"><code>get_metatable</code></a>); others provide access to "outside" services (e.g., I/O). -<h3 <%=heading_options%> ><a name="default_lib">Default Environment</a></h3> +<h3 heading><a name="default_lib">Default Environment</a></h3> <p> These are provided by default as local variables for any Luan code as described in <a href="#env">Environments</a>. -<h4 <%=heading_options%> ><a name="require"><tt>java ()</tt></a></h4> +<h4 heading><a name="require"><code>java ()</code></a></h4> <p> 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. -<h4 <%=heading_options%> ><a name="require"><tt>require (mod_uri)</tt></a></h4> +<h4 heading><a name="require"><code>require (mod_uri)</code></a></h4> <p> Example use: -<p><tt><pre> +<pre> local Table = require "luan:Table" -</pre></tt></p> +</pre> <p> Could be defined as: -<p><tt><pre> +<pre> local function require(mod_name) return <a href="#Package.load">Package.load</a>(mod_name) or <a href="#Luan.error">Luan.error</a>("module '"..mod_name.."' not found") end -</pre></tt></p> - - -<h3 <%=heading_options%> ><a name="luan_lib">Basic Functions</a></h3> +</pre> + + +<h3 heading><a name="luan_lib">Basic Functions</a></h3> <p> Include this library by: -<p><tt><pre> +<pre> local Luan = require "luan:Luan" -</pre></tt></p> +</pre> <p> The basic library provides basic functions to Luan that don't depend on other libaries. -<h4 <%=heading_options%> ><a name="Luan.assert"><tt>Luan.assert (v [, message])</tt></a></h4> +<h4 heading><a name="Luan.assert"><code>Luan.assert (v [, message])</code></a></h4> <p> Could be defined as: -<p><tt><pre> +<pre> function Luan.assert(v,message) return v or <a href="#Luan.error">Luan.error</a>(message or "assertion failed!") end -</pre></tt></p> - - -<h4 <%=heading_options%> ><a name="Luan.assert_binary"><tt>Luan.assert_binary (v)</tt></a></h4> +</pre> + + +<h4 heading><a name="Luan.assert_binary"><code>Luan.assert_binary (v)</code></a></h4> <p> Could be defined as: -<p><tt><pre> +<pre> function Luan.assert_binary(v) local v_type = Luan.type(v) return v_type == "binary" and v or <a href="#Luan.error">Luan.error</a>("bad argument #1 (binary expected, got "..v_type..")") end -</pre></tt></p> - - -<h4 <%=heading_options%> ><a name="Luan.assert_boolean"><tt>Luan.assert_boolean (v)</tt></a></h4> - -<p> -Like <a href="#Luan.assert_binary"><tt>assert_binary</tt></a> but for type <tt>boolean</tt>. - - -<h4 <%=heading_options%> ><a name="Luan.assert_integer"><tt>Luan.assert_integer (v)</tt></a></h4> - -<p> -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. - - -<h4 <%=heading_options%> ><a name="Luan.assert_long"><tt>Luan.assert_long (v)</tt></a></h4> - -<p> -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. - - -<h4 <%=heading_options%> ><a name="Luan.assert_number"><tt>Luan.assert_number (v)</tt></a></h4> - -<p> -Like <a href="#Luan.assert_binary"><tt>assert_binary</tt></a> but for type <tt>number</tt>. - - -<h4 <%=heading_options%> ><a name="Luan.assert_string"><tt>Luan.assert_string (v)</tt></a></h4> - -<p> -Like <a href="#Luan.assert_binary"><tt>assert_binary</tt></a> but for type <tt>string</tt>. - - -<h4 <%=heading_options%> ><a name="Luan.assert_table"><tt>Luan.assert_table (v)</tt></a></h4> - -<p> -Like <a href="#Luan.assert_binary"><tt>assert_binary</tt></a> but for type <tt>table</tt>. - - -<h4 <%=heading_options%> ><a name="Luan.do_file"><tt>Luan.do_file ([uri])</tt></a></h4> +</pre> + + +<h4 heading><a name="Luan.assert_boolean"><code>Luan.assert_boolean (v)</code></a></h4> + +<p> +Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>boolean</code>. + + +<h4 heading><a name="Luan.assert_integer"><code>Luan.assert_integer (v)</code></a></h4> + +<p> +Asserts that <code>v</code> 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. + + +<h4 heading><a name="Luan.assert_long"><code>Luan.assert_long (v)</code></a></h4> + +<p> +Asserts that <code>v</code> 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. + + +<h4 heading><a name="Luan.assert_number"><code>Luan.assert_number (v)</code></a></h4> + +<p> +Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>number</code>. + + +<h4 heading><a name="Luan.assert_string"><code>Luan.assert_string (v)</code></a></h4> + +<p> +Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>string</code>. + + +<h4 heading><a name="Luan.assert_table"><code>Luan.assert_table (v)</code></a></h4> + +<p> +Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>table</code>. + + +<h4 heading><a name="Luan.do_file"><code>Luan.do_file ([uri])</code></a></h4> <p> Could be defined as: -<p><tt><pre> +<pre> function Luan.do_file(uri) return <a href="#Luan.load_file">Luan.load_file</a>(uri)() end -</pre></tt></p> - - - -<h4 <%=heading_options%> ><a name="Luan.error"><tt>Luan.error (message)</tt></a></h4> +</pre> + + + +<h4 heading><a name="Luan.error"><code>Luan.error (message)</code></a></h4> <p> Throws an error containing the message. @@ -1915,43 +1914,43 @@ <p> Could be defined as: -<p><tt><pre> +<pre> function Luan.error(message) <a href="#Luan.new_error">Luan.new_error</a>(message).throw() end -</pre></tt></p> - - - -<h4 <%=heading_options%> ><a name="Luan.get_metatable"><tt>Luan.get_metatable (table)</tt></a></h4> - -<p> -If <tt>table</tt> does not have a metatable, returns <b>nil</b>. +</pre> + + + +<h4 heading><a name="Luan.get_metatable"><code>Luan.get_metatable (table)</code></a></h4> + +<p> +If <code>table</code> does not have a metatable, returns <b>nil</b>. Otherwise, -if the table's metatable has a <tt>"__metatable"</tt> field, +if the table's metatable has a <code>"__metatable"</code> field, returns the associated value. Otherwise, returns the metatable of the given table. -<h4 <%=heading_options%> ><a name="Luan.ipairs"><tt>Luan.ipairs (t)</tt></a></h4> +<h4 heading><a name="Luan.ipairs"><code>Luan.ipairs (t)</code></a></h4> <p> Returns an iterator function so that the construction -<p><tt><pre> - for i,v in ipairs(t) do <i>body</i> end -</pre></tt></p> +<pre> + for i,v in ipairs(t) do <em>body</em> end +</pre> <p> will iterate over the key–value pairs -(<tt>1,t[1]</tt>), (<tt>2,t[2]</tt>), ..., +(<code>1,t[1]</code>), (<code>2,t[2]</code>), ..., up to the first nil value. <p> Could be defined as: -<p><tt><pre> +<pre> function Luan.ipairs(t) local i = 0 return function() @@ -1961,70 +1960,70 @@ end end end -</pre></tt></p> - - - -<h4 <%=heading_options%> ><a name="Luan.load"><tt>Luan.load (text, source_name [env, [, allow_expression]])</tt></a></h4> +</pre> + + + +<h4 heading><a name="Luan.load"><code>Luan.load (text, source_name [env, [, allow_expression]])</code></a></h4> <p> Loads a chunk. <p> -The <tt>text</tt> is compiled. +The <code>text</code> is compiled. If there are no syntactic errors, returns the compiled chunk as a function; otherwise, throws an error. <p> -The <tt>source_name</tt> parameter is a string saying where the text came from. It is used to produce error messages. - -<p> -If the <tt>env</tt> parameter is supplied, it becomes the <tt>_ENV</tt> of the chunk. - -<p> -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. - - -<h4 <%=heading_options%> ><a name="Luan.load_file"><tt>Luan.load_file (file_uri [, add_extension])</tt></a></h4> - -<p> -Similar to <a href="#Luan.load"><tt>load</tt></a>, -but gets the chunk from file <tt>file_uri</tt> +The <code>source_name</code> parameter is a string saying where the text came from. It is used to produce error messages. + +<p> +If the <code>env</code> parameter is supplied, it becomes the <code>_ENV</code> of the chunk. + +<p> +If the <code>allow_expression</code> parameter is <code>true</code> then the entire text can be nothing more than an expression in which case the chunk returns the value of this expression. + + +<h4 heading><a name="Luan.load_file"><code>Luan.load_file (file_uri [, add_extension])</code></a></h4> + +<p> +Similar to <a href="#Luan.load"><code>load</code></a>, +but gets the chunk from file <code>file_uri</code> or from the standard input, if no file uri is given. <p> Could be defined as: -<p><tt><pre> +<pre> function Luan.load_file(file_uri,add_extension) file_uri = file_uri or "stdin:" local f = Io.uri(file_uri,add_extension) f.exists() or <a href="#Luan.error">Luan.error</a>("file '"..file_uri.."' not found") return <a href="#Luan.load">Luan.load</a>( f.read_text(), file_uri ) end -</pre></tt></p> - - -<h4 <%=heading_options%> ><a name="Luan.new_error"><tt>Luan.new_error (message)</tt></a></h4> - -<p> -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. +</pre> + + +<h4 heading><a name="Luan.new_error"><code>Luan.new_error (message)</code></a></h4> + +<p> +Creates a new error table containing the message assigned to "<code>message</code>". The error table also contains a <code>throw</code> function which throws the error. The table also contains a list of stack trace elements where each stack trace element is a table containing "<code>source</code>", "<code>line</code>", and possible "<code>call_to</code>". The table also has a metatable containing "<code>__to_string</code>" to render the error. <p> To print the current stack trace, you could do: -<p><tt><pre> +<pre> Io.print( Luan.new_error "stack" ) -</pre></tt></p> - - -<h4 <%=heading_options%> ><a name="Luan.pairs"><tt>Luan.pairs (t)</tt></a></h4> - -<p> -If <tt>t</tt> has a metamethod <tt>__pairs</tt>, -calls it with <tt>t</tt> as argument and returns the +</pre> + + +<h4 heading><a name="Luan.pairs"><code>Luan.pairs (t)</code></a></h4> + +<p> +If <code>t</code> has a metamethod <code>__pairs</code>, +calls it with <code>t</code> as argument and returns the result from the call. @@ -2033,28 +2032,28 @@ returns a function so that the construction -<p><tt><pre> - for k,v in pairs(t) do <i>body</i> end -</pre></tt></p> - -<p> -will iterate over all key–value pairs of table <tt>t</tt>. - - - -<h4 <%=heading_options%> ><a name="Luan.pcall"><tt>Luan.pcall (f [, arg1, ···])</tt></a></h4> - -<p> -Calls function <tt>f</tt> with -the given arguments in <i>protected mode</i>. -This means that any error inside <tt>f</tt> is not propagated; -instead, <tt>pcall</tt> catches the error +<pre> + for k,v in pairs(t) do <em>body</em> end +</pre> + +<p> +will iterate over all key–value pairs of table <code>t</code>. + + + +<h4 heading><a name="Luan.pcall"><code>Luan.pcall (f [, arg1, ···])</code></a></h4> + +<p> +Calls function <code>f</code> with +the given arguments in <em>protected mode</em>. +This means that any error inside <code>f</code> is not propagated; +instead, <code>pcall</code> catches the error and returns a status code. Its first result is the status code (a boolean), which is true if the call succeeds without errors. -In such case, <tt>pcall</tt> also returns all results from the call, +In such case, <code>pcall</code> also returns all results from the call, after this first result. -In case of any error, <tt>pcall</tt> returns <b>false</b> plus the error. +In case of any error, <code>pcall</code> returns <b>false</b> plus the error. @@ -2072,7 +2071,7 @@ -<h4 <%=heading_options%> ><a name="Luan.range"><tt>Luan.range (start, stop [, step])</tt></a></h4> +<h4 heading><a name="Luan.range"><code>Luan.range (start, stop [, step])</code></a></h4> <p> 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. @@ -2080,19 +2079,19 @@ <p> Example use: -<p><tt><pre> +<pre> for i in range(1,10) do Io.print("count up:",i) end for i in range(10,0,-1) do Io.print("count down:",i) end -</pre></tt></p> +</pre> <p> Could be defined as: -<p><tt><pre> +<pre> function Luan.range(start, stop, step) step = step or 1 step == 0 and <a href="#Luan.error">Luan.error</a> "bad argument #3 (step may not be zero)" @@ -2105,83 +2104,83 @@ end end end -</pre></tt></p> - - - -<h4 <%=heading_options%> ><a name="Luan.raw_equal"><tt>Luan.raw_equal (v1, v2)</tt></a></h4> - -<p> -Checks whether <tt>v1</tt> is equal to <tt>v2</tt>, +</pre> + + + +<h4 heading><a name="Luan.raw_equal"><code>Luan.raw_equal (v1, v2)</code></a></h4> + +<p> +Checks whether <code>v1</code> is equal to <code>v2</code>, without invoking any metamethod. Returns a boolean. -<h4 <%=heading_options%> ><a name="Luan.raw_get"><tt>Luan.raw_get (table, index)</tt></a></h4> - -<p> -Gets the real value of <tt>table[index]</tt>, +<h4 heading><a name="Luan.raw_get"><code>Luan.raw_get (table, index)</code></a></h4> + +<p> +Gets the real value of <code>table[index]</code>, without invoking any metamethod. -<tt>table</tt> must be a table; -<tt>index</tt> may be any value. - - - -<h4 <%=heading_options%> ><a name="Luan.raw_len"><tt>Luan.raw_len (v)</tt></a></h4> - -<p> -Returns the length of the object <tt>v</tt>, +<code>table</code> must be a table; +<code>index</code> may be any value. + + + +<h4 heading><a name="Luan.raw_len"><code>Luan.raw_len (v)</code></a></h4> + +<p> +Returns the length of the object <code>v</code>, which must be a table or a string, without invoking any metamethod. Returns an integer. -<h4 <%=heading_options%> ><a name="Luan.raw_set"><tt>Luan.raw_set (table, index, value)</tt></a></h4> - -<p> -Sets the real value of <tt>table[index]</tt> to <tt>value</tt>, +<h4 heading><a name="Luan.raw_set"><code>Luan.raw_set (table, index, value)</code></a></h4> + +<p> +Sets the real value of <code>table[index]</code> to <code>value</code>, without invoking any metamethod. -<tt>table</tt> must be a table, -<tt>index</tt> any value different from <b>nil</b>, -and <tt>value</tt> any Lua value. - - -<h4 <%=heading_options%> ><a name="Luan.set_metatable"><tt>Luan.set_metatable (table, metatable)</tt></a></h4> +<code>table</code> must be a table, +<code>index</code> any value different from <b>nil</b>, +and <code>value</code> any Lua value. + + +<h4 heading><a name="Luan.set_metatable"><code>Luan.set_metatable (table, metatable)</code></a></h4> <p> Sets the metatable for the given table. -If <tt>metatable</tt> is <b>nil</b>, +If <code>metatable</code> is <b>nil</b>, removes the metatable of the given table. -If the original metatable has a <tt>"__metatable"</tt> field, +If the original metatable has a <code>"__metatable"</code> field, raises an error. -<h4 <%=heading_options%> ><a name="Luan.to_string"><tt>Luan.to_string (v)</tt></a></h4> +<h4 heading><a name="Luan.to_string"><code>Luan.to_string (v)</code></a></h4> <p> Receives a value of any type and converts it to a string in a human-readable format. <p> -If the metatable of <tt>v</tt> has a <tt>"__to_string"</tt> field, -then <tt>to_string</tt> calls the corresponding value -with <tt>v</tt> as argument, +If the metatable of <code>v</code> has a <code>"__to_string"</code> field, +then <code>to_string</code> calls the corresponding value +with <code>v</code> as argument, and uses the result of the call as its result. -<h4 <%=heading_options%> ><a name="Luan.try"><tt>Luan.try (t)</tt></a></h4> - -<p> -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. +<h4 heading><a name="Luan.try"><code>Luan.try (t)</code></a></h4> + +<p> +Implements try-catch as found in other languages where each block is in table <code>t</code>. <code>t[1]</code> is the "try" block. The <code>t.catch</code> and <code>t.finally</code> blocks are optional. Returns the result of the "try" block or the "catch" block. <p> Example use: -<p><tt><pre> +<pre> try { function() a_dangerous_fn() @@ -2193,12 +2192,12 @@ -- clean up end; } -</pre></tt></p> +</pre> <p> Could be defined as: -<p><tt><pre> +<pre> function Luan.try(t) local r = { <a href="#Luan.pcall">Luan.pcall</a>(t[1]) } if r[1] then @@ -2212,115 +2211,115 @@ t.finally and t.finally() return Table.unpack(r) end -</pre></tt></p> - - -<h4 <%=heading_options%> ><a name="Luan.type"><tt>Luan.type (v)</tt></a></h4> +</pre> + + +<h4 heading><a name="Luan.type"><code>Luan.type (v)</code></a></h4> <p> Returns the type of its only argument, coded as a string. The possible results of this function are -"<tt>nil</tt>" (a string, not the value <b>nil</b>), -"<tt>number</tt>", -"<tt>string</tt>", -"<tt>binary</tt>", -"<tt>boolean</tt>", -"<tt>table</tt>", -"<tt>function</tt>", -and "<tt>java</tt>". - - -<h4 <%=heading_options%> ><a name="Luan.values"><tt>Luan.values (···)</tt></a></h4> +"<code>nil</code>" (a string, not the value <b>nil</b>), +"<code>number</code>", +"<code>string</code>", +"<code>binary</code>", +"<code>boolean</code>", +"<code>table</code>", +"<code>function</code>", +and "<code>java</code>". + + +<h4 heading><a name="Luan.values"><code>Luan.values (···)</code></a></h4> <p> Returns a function so that the construction -<p><tt><pre> - for v in Luan.values(···) do <i>body</i> end -</pre></tt></p> - -<p> -will iterate over all values of <tt>···</tt>. - - - -<h4 <%=heading_options%> ><a name="Luan.VERSION"><tt>Luan.VERSION</tt></a></h4> +<pre> + for v in Luan.values(···) do <em>body</em> end +</pre> + +<p> +will iterate over all values of <code>···</code>. + + + +<h4 heading><a name="Luan.VERSION"><code>Luan.VERSION</code></a></h4> <p> A global variable (not a function) that holds a string containing the current interpreter version. -The current value of this variable is "<tt><%=Luan.VERSION%></tt>". - - - - - - -<h3 <%=heading_options%> ><a name="package_lib">Modules</a></h3> +The current value of this variable is "<code><%=Luan.VERSION%></code>". + + + + + + +<h3 heading><a name="package_lib">Modules</a></h3> <p> Include this library by: -<p><tt><pre> +<pre> local Package = require "luan:Package" -</pre></tt></p> +</pre> <p> The package library provides basic facilities for loading modules in Luan. -<h4 <%=heading_options%> ><a name="Package.load"><tt>Package.load (mod_uri)</tt></a></h4> +<h4 heading><a name="Package.load"><code>Package.load (mod_uri)</code></a></h4> <p> Loads the given module. -The function starts by looking into the <a href="#Package.loaded"><tt>Package.loaded</tt></a> table -to determine whether <tt>mod_uri</tt> is already loaded. -If it is, then <tt>Package.load</tt> returns the value stored -at <tt>Package.loaded[mod_uri]</tt>. +The function starts by looking into the <a href="#Package.loaded"><code>Package.loaded</code></a> table +to determine whether <code>mod_uri</code> is already loaded. +If it is, then <code>Package.load</code> returns the value stored +at <code>Package.loaded[mod_uri]</code>. Otherwise, it tries to load a new value for the module. <p> -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. - -<p> -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. - -<p> -If a new value for the module successful loaded, then it is stored in <tt>Package.loaded[mod_uri]</tt>. The value is returned. - - - - -<h4 <%=heading_options%> ><a name="Package.loaded"><tt>Package.loaded</tt></a></h4> - - -<p> -A table used by <a href="#Package.load"><tt>Package.load</tt></a> to control which +To load a new value, <code>Package.load</code> first checks if <code>mod_uri</code> starts with "<b>java:</b>". If yes, then this is a Java class which is loaded by special Java code. + +<p> +If <code>mod_uri</code> is not a Java class, then <code>Package.load</code> tries to read the text of the file referred to by <code>mod_uri</code> (using <code>add_extension</code>=true). If the file doesn't exist, then <code>Package.load</code> returns <b>nil</b>. If the file exists, then its content is compiled into a chunk calling <a href="#Luan.load"><code>Luan.load</code></a> and passing in an empty table as the <code>env</code> value. This chunk is run passing in <code>mod_uri</code> 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 <code>env</code> that was passed in is the value of this module. + +<p> +If a new value for the module successful loaded, then it is stored in <code>Package.loaded[mod_uri]</code>. The value is returned. + + + + +<h4 heading><a name="Package.loaded"><code>Package.loaded</code></a></h4> + + +<p> +A table used by <a href="#Package.load"><code>Package.load</code></a> to control which modules are already loaded. -When you load a module <tt>mod_uri</tt> and -<tt>Package.loaded[mod_uri]</tt> is not <b>nil</b>, -<a href="#Package.load"><tt>Package.load</tt></a> simply returns the value stored there. +When you load a module <code>mod_uri</code> and +<code>Package.loaded[mod_uri]</code> is not <b>nil</b>, +<a href="#Package.load"><code>Package.load</code></a> simply returns the value stored there. <p> This variable is only a reference to the real table; assignments to this variable do not change the -table used by <a href="#Package.load"><tt>Package.load</tt></a>. - - - - - - -<h3 <%=heading_options%> ><a name="string_lib">String Manipulation</a></h3> +table used by <a href="#Package.load"><code>Package.load</code></a>. + + + + + + +<h3 heading><a name="string_lib">String Manipulation</a></h3> <p> Include this library by: -<p><tt><pre> +<pre> local String = require "luan:String" -</pre></tt></p> +</pre> <p> This library provides generic functions for string manipulation, @@ -2333,7 +2332,7 @@ -<h4 <%=heading_options%> ><a name="String.char"><tt>String.char (···)</tt></a></h4> +<h4 heading><a name="String.char"><code>String.char (···)</code></a></h4> <p> Receives zero or more integers. @@ -2342,37 +2341,37 @@ to its corresponding argument. -<h4 <%=heading_options%> ><a name="String.concat"><tt>String.concat (···)</tt></a></h4> - -<p> -Concatenates the <a href="#Luan.to_string"><tt>to_string</tt></a> value of all arguments. - - - -<h4 <%=heading_options%> ><a name="String.encode"><tt>String.encode (s)</tt></a></h4> - -<p> -Encodes argument <tt>s</tt> into a string that can be placed in quotes so as to return the original value of the string. - - - - -<h4 <%=heading_options%> ><a name="String.find"><tt>String.find (s, pattern [, init [, plain]])</tt></a></h4> +<h4 heading><a name="String.concat"><code>String.concat (···)</code></a></h4> + +<p> +Concatenates the <a href="#Luan.to_string"><code>to_string</code></a> value of all arguments. + + + +<h4 heading><a name="String.encode"><code>String.encode (s)</code></a></h4> + +<p> +Encodes argument <code>s</code> into a string that can be placed in quotes so as to return the original value of the string. + + + + +<h4 heading><a name="String.find"><code>String.find (s, pattern [, init [, plain]])</code></a></h4> <p> Looks for the first match of -<tt>pattern</tt> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) in the string <tt>s</tt>. -If it finds a match, then <tt>find</tt> returns the indices of <tt>s</tt> +<code>pattern</code> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) in the string <code>s</code>. +If it finds a match, then <code>find</code> returns the indices of <code>s</code> where this occurrence starts and ends; otherwise, it returns <b>nil</b>. -A third, optional numerical argument <tt>init</tt> specifies +A third, optional numerical argument <code>init</code> specifies where to start the search; its default value is 1 and can be negative. -A value of <b>true</b> as a fourth, optional argument <tt>plain</tt> +A value of <b>true</b> as a fourth, optional argument <code>plain</code> turns off the pattern matching facilities, so the function does a plain "find substring" operation, -with no characters in <tt>pattern</tt> being considered magic. -Note that if <tt>plain</tt> is given, then <tt>init</tt> must be given as well. +with no characters in <code>pattern</code> being considered magic. +Note that if <code>plain</code> is given, then <code>init</code> must be given as well. <p> If the pattern has captures, @@ -2383,89 +2382,89 @@ -<h4 <%=heading_options%> ><a name="String.format"><tt>String.format (formatstring, ···)</tt></a></h4> +<h4 heading><a name="String.format"><code>String.format (formatstring, ···)</code></a></h4> <p> Returns a formatted version of its variable number of arguments following the description given in its first argument (which must be a string). -The format string follows the same rules as the Java function <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#format(java.lang.String,%20java.lang.Object...)"><tt>String.format</tt></a> because Luan calls this internally. - -<p> -Note that Java's <tt>String.format</tt> is too stupid to convert between ints and floats, so you must provide the right kind of number. - - - -<h4 <%=heading_options%> ><a name="String.gmatch"><tt>String.gmatch (s, pattern)</tt></a></h4> +The format string follows the same rules as the Java function <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#format(java.lang.String,%20java.lang.Object...)"><code>String.format</code></a> because Luan calls this internally. + +<p> +Note that Java's <code>String.format</code> is too stupid to convert between ints and floats, so you must provide the right kind of number. + + + +<h4 heading><a name="String.gmatch"><code>String.gmatch (s, pattern)</code></a></h4> <p> Returns an iterator function that, each time it is called, -returns the next captures from <tt>pattern</tt> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) -over the string <tt>s</tt>. -If <tt>pattern</tt> specifies no captures, +returns the next captures from <code>pattern</code> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) +over the string <code>s</code>. +If <code>pattern</code> specifies no captures, then the whole match is produced in each call. <p> As an example, the following loop -will iterate over all the words from string <tt>s</tt>, +will iterate over all the words from string <code>s</code>, printing one per line: -<p><tt><pre> +<pre> local s = "hello world from Lua" for w in String.gmatch(s, [[\w+]]) do print(w) end -</pre></tt></p> - -<p> -The next example collects all pairs <tt>key=value</tt> from the +</pre> + +<p> +The next example collects all pairs <code>key=value</code> from the given string into a table: -<p><tt><pre> +<pre> local t = {} local s = "from=world, to=Lua" for k, v in String.gmatch(s, [[(\w+)=(\w+)]]) do t[k] = v end -</pre></tt></p> - -<p> -For this function, a caret '<tt>^</tt>' at the start of a pattern does not +</pre> + +<p> +For this function, a caret '<code>^</code>' at the start of a pattern does not work as an anchor, as this would prevent the iteration. -<h4 <%=heading_options%> ><a name="String.gsub"><tt>String.gsub (s, pattern, repl [, n])</tt></a></h4> - -<p> -Returns a copy of <tt>s</tt> -in which all (or the first <tt>n</tt>, if given) -occurrences of the <tt>pattern</tt> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) have been -replaced by a replacement string specified by <tt>repl</tt>, +<h4 heading><a name="String.gsub"><code>String.gsub (s, pattern, repl [, n])</code></a></h4> + +<p> +Returns a copy of <code>s</code> +in which all (or the first <code>n</code>, if given) +occurrences of the <code>pattern</code> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) have been +replaced by a replacement string specified by <code>repl</code>, which can be a string, a table, or a function. -<tt>gsub</tt> also returns, as its second value, +<code>gsub</code> also returns, as its second value, the total number of matches that occurred. -The name <tt>gsub</tt> comes from <i>Global SUBstitution</i>. - - -<p> -If <tt>repl</tt> is a string, then its value is used for replacement. -The character <tt>\</tt> works as an escape character. -Any sequence in <tt>repl</tt> of the form <tt>$<i>d</i></tt>, -with <i>d</i> between 1 and 9, -stands for the value of the <i>d</i>-th captured substring. -The sequence <tt>$0</tt> stands for the whole match. - - -<p> -If <tt>repl</tt> is a table, then the table is queried for every match, +The name <code>gsub</code> comes from <em>Global SUBstitution</em>. + + +<p> +If <code>repl</code> is a string, then its value is used for replacement. +The character <code>\</code> works as an escape character. +Any sequence in <code>repl</code> of the form <code>$<em>d</em></code>, +with <em>d</em> between 1 and 9, +stands for the value of the <em>d</em>-th captured substring. +The sequence <code>$0</code> stands for the whole match. + + +<p> +If <code>repl</code> is a table, then the table is queried for every match, using the first capture as the key. <p> -If <tt>repl</tt> is a function, then this function is called every time a +If <code>repl</code> is a function, then this function is called every time a match occurs, with all captured substrings passed as arguments, in order. @@ -2488,7 +2487,7 @@ <p> Here are some examples: -<p><tt><pre> +<pre> x = String.gsub("hello world", [[(\w+)]], "$1 $1") --> x="hello hello world world" @@ -2506,16 +2505,16 @@ local t = {name="lua", version="5.3"} x = String.gsub("$name-$version.tar.gz", [[\$(\w+)]], t) --> x="lua-5.3.tar.gz" -</pre></tt></p> - - - -<h4 <%=heading_options%> ><a name="String.literal"><tt>String.literal (s)</tt></a></h4> -<p> -Returns a string which matches the literal string <tt>s</tt> in a regular expression. This function is simply the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#quote(java.lang.String)"><tt>Pattern.quote</tt></a>. - - -<h4 <%=heading_options%> ><a name="String.lower"><tt>String.lower (s)</tt></a></h4> +</pre> + + + +<h4 heading><a name="String.literal"><code>String.literal (s)</code></a></h4> +<p> +Returns a string which matches the literal string <code>s</code> in a regular expression. This function is simply the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#quote(java.lang.String)"><code>Pattern.quote</code></a>. + + +<h4 heading><a name="String.lower"><code>String.lower (s)</code></a></h4> <p> Receives a string and returns a copy of this string with all uppercase letters changed to lowercase. @@ -2524,127 +2523,127 @@ -<h4 <%=heading_options%> ><a name="String.match"><tt>String.match (s, pattern [, init])</tt></a></h4> - -<p> -Looks for the first <i>match</i> of -<tt>pattern</tt> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) in the string <tt>s</tt>. -If it finds one, then <tt>match</tt> returns +<h4 heading><a name="String.match"><code>String.match (s, pattern [, init])</code></a></h4> + +<p> +Looks for the first <em>match</em> of +<code>pattern</code> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) in the string <code>s</code>. +If it finds one, then <code>match</code> returns the captures from the pattern; otherwise it returns <b>nil</b>. -If <tt>pattern</tt> specifies no captures, +If <code>pattern</code> specifies no captures, then the whole match is returned. -A third, optional numerical argument <tt>init</tt> specifies +A third, optional numerical argument <code>init</code> specifies where to start the search; its default value is 1 and can be negative. -<h4 <%=heading_options%> ><a name="String.matches"><tt>String.matches (s, pattern)</tt></a></h4> -<p> -Returns a boolean indicating whether the entire string <tt>s</tt> matches <tt>pattern</tt>. - - - -<h4 <%=heading_options%> ><a name="String.rep"><tt>String.rep (s, n [, sep])</tt></a></h4> -<p> -Returns a string that is the concatenation of <tt>n</tt> copies of -the string <tt>s</tt> separated by the string <tt>sep</tt>. -The default value for <tt>sep</tt> is the empty string +<h4 heading><a name="String.matches"><code>String.matches (s, pattern)</code></a></h4> +<p> +Returns a boolean indicating whether the entire string <code>s</code> matches <code>pattern</code>. + + + +<h4 heading><a name="String.rep"><code>String.rep (s, n [, sep])</code></a></h4> +<p> +Returns a string that is the concatenation of <code>n</code> copies of +the string <code>s</code> separated by the string <code>sep</code>. +The default value for <code>sep</code> is the empty string (that is, no separator). -Returns the empty string if <tt>n</tt> is not positive. - - - - -<h4 <%=heading_options%> ><a name="String.reverse"><tt>String.reverse (s)</tt></a></h4> -<p> -Returns a string that is the string <tt>s</tt> reversed. - - - - -<h4 <%=heading_options%> ><a name="String.sub"><tt>String.sub (s, i [, j])</tt></a></h4> - -<p> -Returns the substring of <tt>s</tt> that -starts at <tt>i</tt> and continues until <tt>j</tt>; -<tt>i</tt> and <tt>j</tt> can be negative. -If <tt>j</tt> is absent, then it is assumed to be equal to -1 +Returns the empty string if <code>n</code> is not positive. + + + + +<h4 heading><a name="String.reverse"><code>String.reverse (s)</code></a></h4> +<p> +Returns a string that is the string <code>s</code> reversed. + + + + +<h4 heading><a name="String.sub"><code>String.sub (s, i [, j])</code></a></h4> + +<p> +Returns the substring of <code>s</code> that +starts at <code>i</code> and continues until <code>j</code>; +<code>i</code> and <code>j</code> can be negative. +If <code>j</code> is absent, then it is assumed to be equal to -1 (which is the same as the string length). In particular, -the call <tt>string.sub(s,1,j)</tt> returns a prefix of <tt>s</tt> -with length <tt>j</tt>, -and <tt>string.sub(s, -i)</tt> returns a suffix of <tt>s</tt> -with length <tt>i</tt>. +the call <code>string.sub(s,1,j)</code> returns a prefix of <code>s</code> +with length <code>j</code>, +and <code>string.sub(s, -i)</code> returns a suffix of <code>s</code> +with length <code>i</code>. <p> If, after the translation of negative indices, -<tt>i</tt> is less than 1, +<code>i</code> is less than 1, it is corrected to 1. -If <tt>j</tt> is greater than the string length, +If <code>j</code> is greater than the string length, it is corrected to that length. If, after these corrections, -<tt>i</tt> is greater than <tt>j</tt>, +<code>i</code> is greater than <code>j</code>, the function returns the empty string. -<h4 <%=heading_options%> ><a name="String.to_binary"><tt>String.to_binary (s)</tt></a></h4> - -<p> -Converts a string to a binary by calling the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes()"><tt>String.getBytes</tt></a>. - - - -<h4 <%=heading_options%> ><a name="String.to_number"><tt>String.to_number (s [, base])</tt></a></h4> - -<p> -When called with no <tt>base</tt>, -<tt>to_number</tt> tries to convert its argument to a number. +<h4 heading><a name="String.to_binary"><code>String.to_binary (s)</code></a></h4> + +<p> +Converts a string to a binary by calling the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes()"><code>String.getBytes</code></a>. + + + +<h4 heading><a name="String.to_number"><code>String.to_number (s [, base])</code></a></h4> + +<p> +When called with no <code>base</code>, +<code>to_number</code> tries to convert its argument to a number. If the argument is a string convertible to a number, -then <tt>to_number</tt> returns this number; +then <code>to_number</code> returns this number; otherwise, it returns <b>nil</b>. The conversion of strings can result in integers or floats. <p> -When called with <tt>base</tt>, -then <tt>s</tt> must be a string to be interpreted as +When called with <code>base</code>, +then <code>s</code> must be a string to be interpreted as an integer numeral in that base. -In bases above 10, the letter '<tt>A</tt>' (in either upper or lower case) -represents 10, '<tt>B</tt>' represents 11, and so forth, -with '<tt>Z</tt>' representing 35. -If the string <tt>s</tt> is not a valid numeral in the given base, +In bases above 10, the letter '<code>A</code>' (in either upper or lower case) +represents 10, '<code>B</code>' represents 11, and so forth, +with '<code>Z</code>' representing 35. +If the string <code>s</code> is not a valid numeral in the given base, the function returns <b>nil</b>. -<h4 <%=heading_options%> ><a name="String.trim"><tt>String.trim (s)</tt></a></h4> - -<p> -Removes the leading and trailing whitespace by calling the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#trim()"><tt>String.trim</tt></a>. - - - - -<h4 <%=heading_options%> ><a name="String.unicode"><tt>String.unicode (s [, i [, j]])</tt></a></h4> - -<p> -Returns the internal numerical codes of the characters <tt>s[i]</tt>, -<tt>s[i+1]</tt>, ..., <tt>s[j]</tt>. -The default value for <tt>i</tt> is 1; -the default value for <tt>j</tt> is <tt>i</tt>. +<h4 heading><a name="String.trim"><code>String.trim (s)</code></a></h4> + +<p> +Removes the leading and trailing whitespace by calling the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#trim()"><code>String.trim</code></a>. + + + + +<h4 heading><a name="String.unicode"><code>String.unicode (s [, i [, j]])</code></a></h4> + +<p> +Returns the internal numerical codes of the characters <code>s[i]</code>, +<code>s[i+1]</code>, ..., <code>s[j]</code>. +The default value for <code>i</code> is 1; +the default value for <code>j</code> is <code>i</code>. These indices are corrected -following the same rules of function <a href="#String.sub"><tt>String.sub</tt></a>. - - - - - -<h4 <%=heading_options%> ><a name="String.upper"><tt>String.upper (s)</tt></a></h4> +following the same rules of function <a href="#String.sub"><code>String.sub</code></a>. + + + + + +<h4 heading><a name="String.upper"><code>String.upper (s)</code></a></h4> <p> Receives a string and returns a copy of this string with all lowercase letters changed to uppercase. @@ -4597,7 +4596,6 @@ </div> -<% Html.simply_html_body_bottom() %> </body> </html> <%