<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>Define a Custom Attribute Mapping for a Generator</title>
<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.0">
<link rel="home" href="../../../../index.html" title="Spirit 2.4">
<link rel="up" href="../auto.html" title="Create Components from Attributes">
<link rel="prev" href="create_parser.html" title="Define a Custom Attribute Mapping for a Parser">
<link rel="next" href="../../../support.html" title="Supporting libraries">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td>
<td align="center"><a href="../../../../../../../../index.html">Home</a></td>
<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="create_parser.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../auto.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../../../support.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="spirit.advanced.customize.auto.create_generator"></a><a class="link" href="create_generator.html" title="Define a Custom Attribute Mapping for a Generator">
Define a Custom Attribute Mapping for a Generator</a>
</h5></div></div></div>
<a name="spirit.advanced.customize.auto.create_generator.create_generator"></a><h6>
<a name="id1243584"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.create_generator">create_generator</a>
</h6>
<p>
The template <code class="computeroutput"><span class="identifier">create_generator</span></code>
is a type used as an customization point. It is invoked by the <span class="emphasis"><em>Karma</em></span>
<a class="link" href="../../../karma/reference/generate_api/create_generator.html" title="API for Automatic Generator Creation"><code class="computeroutput"><span class="identifier">create_generator</span></code></a> API function
in order to create a custom mapping of the given data type to a generator
expression. This generator expression will be returned from <a class="link" href="../../../karma/reference/generate_api/create_generator.html" title="API for Automatic Generator Creation"><code class="computeroutput"><span class="identifier">create_generator</span></code></a> whenever the
given data type is encountered.
</p>
<a name="spirit.advanced.customize.auto.create_generator.module_headers"></a><h6>
<a name="id1243633"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.module_headers">Module
Headers</a>
</h6>
<pre class="programlisting"><span class="comment">// forwards to <boost/spirit/home/karma/auto.hpp>
</span><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">spirit</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">karma_auto</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
</pre>
<p>
Also, see <a class="link" href="../../../structure/include.html" title="Include">Include Structure</a>.
</p>
<a name="spirit.advanced.customize.auto.create_generator.namespace"></a><h6>
<a name="id1243712"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.namespace">Namespace</a>
</h6>
<div class="informaltable"><table class="table">
<colgroup><col></colgroup>
<thead><tr><th>
<p>
Name
</p>
</th></tr></thead>
<tbody><tr><td>
<p>
<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">traits</span></code>
</p>
</td></tr></tbody>
</table></div>
<a name="spirit.advanced.customize.auto.create_generator.synopsis"></a><h6>
<a name="id1243790"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.synopsis">Synopsis</a>
</h6>
<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Enable</span><span class="special">></span>
<span class="keyword">struct</span> <span class="identifier">create_generator</span>
<span class="special">{</span>
<span class="keyword">typedef</span> <span class="special"><</span><span class="identifier">unspecified</span><span class="special">></span> <span class="identifier">type</span><span class="special">;</span>
<span class="keyword">static</span> <span class="identifier">type</span> <span class="keyword">const</span><span class="special">&</span> <span class="identifier">call</span><span class="special">();</span>
<span class="special">};</span>
</pre>
<a name="spirit.advanced.customize.auto.create_generator.template_parameters"></a><h6>
<a name="id1243915"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.template_parameters">Template
parameters</a>
</h6>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Parameter
</p>
</th>
<th>
<p>
Description
</p>
</th>
<th>
<p>
Default
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">T</span></code>
</p>
</td>
<td>
<p>
The type, <code class="computeroutput"><span class="identifier">T</span></code>
for which a custom mapping to a generator should be established.
</p>
</td>
<td>
<p>
none
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">Enable</span></code>
</p>
</td>
<td>
<p>
Helper template parameter usable to selectively enable or disable
certain specializations of <code class="computeroutput"><span class="identifier">create_generator</span></code>
utilizing SFINAE (i.e. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">enable_if</span></code>
or <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">disable_if</span></code>).
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="keyword">void</span></code>
</p>
</td>
</tr>
</tbody>
</table></div>
<a name="spirit.advanced.customize.auto.create_generator.notation"></a><h6>
<a name="id1244088"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.notation">Notation</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl>
<dt><span class="term"><code class="computeroutput"><span class="identifier">T</span></code></span></dt>
<dd><p>
An arbitrary type.
</p></dd>
</dl>
</div>
<a name="spirit.advanced.customize.auto.create_generator.expression_semantics"></a><h6>
<a name="id1244128"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.expression_semantics">Expression
Semantics</a>
</h6>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Semantics
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">create_generator</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span></code>
</p>
</td>
<td>
<p>
Defines the type of the generator expression returned from
<code class="computeroutput"><span class="identifier">call</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">create_generator</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">call</span><span class="special">()</span></code>
</p>
</td>
<td>
<p>
Returns a generator expression (usually this is a proto::expression)
to be used as the default generator for the given type, <code class="computeroutput"><span class="identifier">T</span></code>.
</p>
</td>
</tr>
</tbody>
</table></div>
<a name="spirit.advanced.customize.auto.create_generator.predefined_specializations"></a><h6>
<a name="id1244274"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.predefined_specializations">Predefined
Specializations</a>
</h6>
<p>
<a href="http://boost-spirit.com" target="_top">Spirit</a> predefines specializations
of this customization point for several types. All predefined mappings
are listed here: <a class="link" href="../../../karma/reference/auto.html#spirit.karma.reference.auto.additional_requirements">Additional
Attribute Requirements for Generators</a>.
</p>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
It is possible to overload the predefined mappings for the listed types
by providing your own specialization of the <code class="computeroutput"><span class="identifier">create_generator</span></code>
cutomization point for the type to modify.
</p></td></tr>
</table></div>
<a name="spirit.advanced.customize.auto.create_generator.when_to_implement"></a><h6>
<a name="id1244316"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.when_to_implement">When
to implement</a>
</h6>
<p>
The customization point <code class="computeroutput"><span class="identifier">create_generator</span></code>
needs to be implemented for a specific type whenever this type should
be usable with the API function <a class="link" href="../../../karma/reference/generate_api/create_generator.html" title="API for Automatic Generator Creation"><code class="computeroutput"><span class="identifier">create_generator</span></code></a> (which includes
using the <code class="computeroutput"><span class="identifier">karma</span><span class="special">::</span><span class="identifier">auto_</span></code> generator and the special API
functions based on the automatic creation of the matching generator type).
</p>
<a name="spirit.advanced.customize.auto.create_generator.example"></a><h6>
<a name="id1244364"></a>
<a class="link" href="create_generator.html#spirit.advanced.customize.auto.create_generator.example">Example</a>
</h6>
<p>
For an example of how to use the customization point <code class="computeroutput"><span class="identifier">create_generator</span></code>
please see here: <a class="link" href="../../../karma/reference/auto.html#spirit.karma.reference.auto.example">Example
for Using the <code class="computeroutput"><span class="identifier">karma</span><span class="special">::</span><span class="identifier">auto_</span></code> Generator</a>.
</p>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2001-2010 Joel de Guzman, Hartmut Kaiser<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="create_parser.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../auto.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../../../support.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>
