Mercurial Hosting > luan
diff website/src/manual.html.luan @ 555:e25ba7a2e816
some String documentation and fixes
author | Franklin Schmidt <fschmidt@gmail.com> |
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date | Fri, 19 Jun 2015 04:29:06 -0600 |
parents | b1256e2d19a3 |
children | d02f43598ba3 |
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--- a/website/src/manual.html.luan Thu Jun 18 03:30:18 2015 -0600 +++ b/website/src/manual.html.luan Fri Jun 19 04:29:06 2015 -0600 @@ -91,6 +91,7 @@ <li><a href="#default_lib">Default Environment</a></li> <li><a href="#luan_lib">Basic Functions</a></li> <li><a href="#package_lib">Modules</a></li> + <li><a href="#string_lib">String Manipulation</a></li> </ul> </div> @@ -2346,30 +2347,25 @@ -<h2>6.4 – <a name="6.4">String Manipulation</a></h2> +<h3 <%=heading_options%> ><a name="string_lib">String Manipulation</a></h3> + +<p> +Include this library by: + +<p><tt><pre> + local String = require "luan:String" +</pre></tt></p> <p> This library provides generic functions for string manipulation, such as finding and extracting substrings, and pattern matching. -When indexing a string in Lua, the first character is at position 1 -(not at 0, as in C). +When indexing a string in Luan, the first character is at position 1 +(not at 0, as in Java). Indices are allowed to be negative and are interpreted as indexing backwards, from the end of the string. Thus, the last character is at position -1, and so on. -<p> -The string library provides all its functions inside the table -<a name="pdf-string"><code>string</code></a>. -It also sets a metatable for strings -where the <code>__index</code> field points to the <code>string</code> table. -Therefore, you can use the string functions in object-oriented style. -For instance, <code>string.byte(s,i)</code> -can be written as <code>s:byte(i)</code>. - - -<p> -The string library assumes one-byte character encodings. <p> @@ -2387,67 +2383,46 @@ - -<p> -<hr><h3><a name="pdf-string.char"><code>string.char (···)</code></a></h3> +<h4 <%=heading_options%> ><a name="String.char"><tt>String.char (···)</tt></a></h4> + +<p> Receives zero or more integers. Returns a string with length equal to the number of arguments, in which each character has the internal numerical code equal to its corresponding argument. -<p> -Numerical codes are not necessarily portable across platforms. - - - - -<p> -<hr><h3><a name="pdf-string.dump"><code>string.dump (function [, strip])</code></a></h3> - - -<p> -Returns a string containing a binary representation -(a <em>binary chunk</em>) -of the given function, -so that a later <a href="#pdf-load"><code>load</code></a> on this string returns -a copy of the function (but with new upvalues). -If <code>strip</code> is a true value, -the binary representation is created without debug information -about the function -(local variable names, lines, etc.). - - -<p> -Functions with upvalues have only their number of upvalues saved. -When (re)loaded, -those upvalues receive fresh instances containing <b>nil</b>. -(You can use the debug library to serialize -and reload the upvalues of a function -in a way adequate to your needs.) - - - - -<p> -<hr><h3><a name="pdf-string.find"><code>string.find (s, pattern [, init [, plain]])</code></a></h3> - +<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> <p> Looks for the first match of -<code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. -If it finds a match, then <code>find</code> returns the indices of <code>s</code> +<tt>pattern</tt> (see <a href="#6.4.1">§6.4.1</a>) in the string <tt>s</tt>. +If it finds a match, then <tt>find</tt> returns the indices of <tt>s</tt> where this occurrence starts and ends; otherwise, it returns <b>nil</b>. -A third, optional numerical argument <code>init</code> specifies +A third, optional numerical argument <tt>init</tt> 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 <code>plain</code> +A value of <b>true</b> as a fourth, optional argument <tt>plain</tt> turns off the pattern matching facilities, so the function does a plain "find substring" operation, -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. - +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. <p> If the pattern has captures, @@ -2458,117 +2433,89 @@ -<p> -<hr><h3><a name="pdf-string.format"><code>string.format (formatstring, ···)</code></a></h3> +<h4 <%=heading_options%> ><a name="String.format"><tt>String.format (formatstring, ···)</tt></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 ISO C function <code>sprintf</code>. -The only differences are that the options/modifiers -<code>*</code>, <code>h</code>, <code>L</code>, <code>l</code>, <code>n</code>, -and <code>p</code> are not supported -and that there is an extra option, <code>q</code>. -The <code>q</code> option formats a string between double quotes, -using escape sequences when necessary to ensure that -it can safely be read back by the Lua interpreter. -For instance, the call - -<pre> - string.format('%q', 'a string with "quotes" and \n new line') -</pre><p> -may produce the string: - -<pre> - "a string with \"quotes\" and \ - new line" -</pre> - -<p> -Options -<code>A</code> and <code>a</code> (when available), -<code>E</code>, <code>e</code>, <code>f</code>, -<code>G</code>, and <code>g</code> all expect a number as argument. -Options <code>c</code>, <code>d</code>, -<code>i</code>, <code>o</code>, <code>u</code>, <code>X</code>, and <code>x</code> -expect an integer. -Option <code>q</code> expects a string; -option <code>s</code> expects a string without embedded zeros. -If the argument to option <code>s</code> is not a string, -it is converted to one following the same rules of <a href="#pdf-tostring"><code>tostring</code></a>. - - - - -<p> -<hr><h3><a name="pdf-string.gmatch"><code>string.gmatch (s, pattern)</code></a></h3> +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> + +<p> Returns an iterator function that, each time it is called, -returns the next captures from <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) -over the string <code>s</code>. -If <code>pattern</code> specifies no captures, +returns the next captures from <tt>pattern</tt> (see <a href="#6.4.1">§6.4.1</a>) +over the string <tt>s</tt>. +If <tt>pattern</tt> 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 <code>s</code>, +will iterate over all the words from string <tt>s</tt>, printing one per line: -<pre> - s = "hello world from Lua" - for w in string.gmatch(s, "%a+") do - print(w) - end -</pre><p> -The next example collects all pairs <code>key=value</code> from the +<p><tt><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 given string into a table: -<pre> - t = {} - s = "from=world, to=Lua" - for k, v in string.gmatch(s, "(%w+)=(%w+)") do - t[k] = v - end -</pre> - -<p> -For this function, a caret '<code>^</code>' at the start of a pattern does not +<p><tt><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 work as an anchor, as this would prevent the iteration. - -<p> -<hr><h3><a name="pdf-string.gsub"><code>string.gsub (s, pattern, repl [, n])</code></a></h3> -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="#6.4.1">§6.4.1</a>) have been -replaced by a replacement string specified by <code>repl</code>, +<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="#6.4.1">§6.4.1</a>) have been +replaced by a replacement string specified by <tt>repl</tt>, which can be a string, a table, or a function. -<code>gsub</code> also returns, as its second value, +<tt>gsub</tt> also returns, as its second value, the total number of matches that occurred. -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. -The sequence <code>%%</code> stands for a single <code>%</code>. - - -<p> -If <code>repl</code> is a table, then the table is queried for every match, +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, using the first capture as the key. <p> -If <code>repl</code> is a function, then this function is called every time a +If <tt>repl</tt> is a function, then this function is called every time a match occurs, with all captured substrings passed as arguments, in order. @@ -2581,9 +2528,9 @@ <p> If the value returned by the table query or by the function call -is a string or a number, +is not <b>nil</b>, then it is used as the replacement string; -otherwise, if it is <b>false</b> or <b>nil</b>, +otherwise, if it is <b>nil</b>, then there is no replacement (that is, the original match is kept in the string). @@ -2591,47 +2538,33 @@ <p> Here are some examples: -<pre> - x = string.gsub("hello world", "(%w+)", "%1 %1") +<p><tt><pre> + x = String.gsub("hello world", [[(\w+)]], "$1 $1") --> x="hello hello world world" - x = string.gsub("hello world", "%w+", "%0 %0", 1) + x = String.gsub("hello world", [[\w+]], "$0 $0", 1) --> x="hello hello world" - x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1") - --> x="world hello Lua from" - - x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv) - --> x="home = /home/roberto, user = roberto" - - x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s) + x = String.gsub("hello world from Luan", [[(\w+)\s*(\w+)]], "$2 $1") + --> x="world hello Luan from" + + x = String.gsub("4+5 = $return 4+5$", [[\$(.*?)\$]], function (s) return load(s)() end) --> x="4+5 = 9" local t = {name="lua", version="5.3"} - x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t) + x = String.gsub("$name-$version.tar.gz", [[\$(\w+)]], t) --> x="lua-5.3.tar.gz" -</pre> - - - -<p> -<hr><h3><a name="pdf-string.len"><code>string.len (s)</code></a></h3> -Receives a string and returns its length. -The empty string <code>""</code> has length 0. -Embedded zeros are counted, -so <code>"a\000bc\000"</code> has length 5. - - - - -<p> -<hr><h3><a name="pdf-string.lower"><code>string.lower (s)</code></a></h3> +</pre></tt></p> + + + +<h4 <%=heading_options%> ><a name="String.lower"><tt>String.lower (s)</tt></a></h4> +<p> Receives a string and returns a copy of this string with all uppercase letters changed to lowercase. All other characters are left unchanged. -The definition of what an uppercase letter is depends on the current locale.