Mercurial > hg > nginx-site
view xml/en/docs/http/ngx_http_map_module.xml @ 733:7f8e85a50845
Renamed OX X to Mac OS X for uniformity.
author | Sergey Budnevitch <sb@waeme.net> |
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date | Tue, 16 Oct 2012 12:55:23 +0000 |
parents | 81ec181c084e |
children | 95c3c3bbf1ce |
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<?xml version="1.0"?> <!-- Copyright (C) Igor Sysoev Copyright (C) Nginx, Inc. --> <!DOCTYPE module SYSTEM "../../../../dtd/module.dtd"> <module name="Module ngx_http_map_module" link="/en/docs/http/ngx_http_map_module.html" lang="en" rev="2"> <section id="summary"> <para> The <literal>ngx_http_map_module</literal> module creates variables whose values depend on values of other variables. </para> </section> <section id="example" name="Example Configuration"> <para> <example> map $http_host $name { hostnames; default 0; example.com 1; *.example.com 1; example.org 2; *.example.org 2; .example.net 3; wap.* 4; } map $http_user_agent $mobile { default 0; "~Opera Mini" 1; } </example> </para> </section> <section id="directives" name="Directives"> <directive name="map"> <syntax block="yes"> <value>string</value> <value>$variable</value></syntax> <default/> <context>http</context> <para> Creates a new variable whose value depends on values of one or more of the source variables specified in the first parameter. <note> Before version 0.9.0 only a single variable could be specified in the first parameter. </note> </para> <para> <note> Since variables are evaluated only when used, the mere existence of even a large number of declared “<literal>map</literal>” variables does not incur any extra costs for request processing. </note> </para> <para> Parameters inside the <literal>map</literal> block specify a mapping between source and resulting values. </para> <para> Source values are specified as strings or regular expressions (0.9.6). </para> <para> A regular expression should either start from the “<literal>~</literal>” symbol for a case-sensitive matching, or from the “<literal>~*</literal>” symbols (1.0.4) for case-insensitive matching. A regular expression can contain named and positional captures that can later be used in other directives along with the resulting variable. </para> <para> If a source value matches one of the names of special parameters described below, it should be prefixed with the “<literal>\</literal>” symbol. </para> <para> The resulting value can be a string or another variable (0.9.0). </para> <para> The directive also supports three special parameters: <list type="tag"> <tag-name><literal>default</literal> <value>value</value></tag-name> <tag-desc> sets the resulting value if the source value matches none of the specified variants. When <literal>default</literal> is not specified, the default resulting value will be an empty string. </tag-desc> <tag-name><literal>hostnames</literal></tag-name> <tag-desc> allows to specify hostnames with a prefix or suffix mask, as source values, for example, <example> *.example.com 1; example.* 1; </example> The following two records <example> example.com 1; *.example.com 1; </example> can be combined: <example> .example.com 1; </example> This parameter should be specified before the list of values. </tag-desc> <tag-name><literal>include</literal> <value>file</value></tag-name> <tag-desc> includes a file with values. There can be several inclusions. </tag-desc> </list> </para> <para> If the source value matches more than one of the specified variants, e.g. both mask and regular expression match, the first matching variant will be chosen, in the following order of precedence: <list type="enum"> <listitem> string value without a mask </listitem> <listitem> longest string value with a prefix mask, e.g. “<literal>*.example.com</literal>” </listitem> <listitem> longest string value with a suffix mask, e.g. “<literal>mail.*</literal>” </listitem> <listitem> first matching regular expression (in order of appearance in a configuration file) </listitem> <listitem> default value </listitem> </list> </para> </directive> <directive name="map_hash_bucket_size"> <syntax><value>size</value></syntax> <default>32|64|128</default> <context>http</context> <para> Sets the bucket size for the <link id="map"/> variables hash tables. Default value depends on the size of the processor’s cache line. Details of setting up hash tables are provided in a separate <link doc="../hash.xml">document</link>. </para> </directive> <directive name="map_hash_max_size"> <syntax><value>size</value></syntax> <default>2048</default> <context>http</context> <para> Sets the maximum <value>size</value> of the <link id="map"/> variables hash tables. Details of setting up hash tables are provided in a separate <link doc="../hash.xml">document</link>. </para> </directive> </section> </module>