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| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string"></a><a class="link" href="extract_c_string.html" title="Get a C-style String from a String Type">Get |
| a C-style String from a String Type</a> |
| </h5></div></div></div> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.extract_c_string"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.extract_c_string-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.extract_c_string">extract_c_string</a> |
| </h6> |
| <p> |
| <code class="computeroutput"><span class="identifier">extract_c_string</span></code> returns |
| a pointer to an array of elements of a const character type. It is invoked |
| through a static method <code class="computeroutput"><span class="identifier">call</span></code>. |
| This customization point is responsible for handling it's own garbage |
| collecting; the lifetime of the returned C-string must be no shorter |
| than the lifetime of the string instance passed to the <code class="computeroutput"><span class="identifier">call</span></code> method. |
| </p> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.module_headers"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.module_headers-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.module_headers">Module |
| Headers</a> |
| </h6> |
| <pre class="programlisting"><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">home</span><span class="special">/</span><span class="identifier">support</span><span class="special">/</span><span class="identifier">string_traits</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> |
| <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> |
| This header file does not need to be included directly by any user |
| program as it is normally included by other Spirit header files relying |
| on its content. |
| </p></td></tr> |
| </table></div> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.namespace"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.namespace-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.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.string_traits.extract_c_string.synopsis"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.synopsis-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.synopsis">Synopsis</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">String</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">extract_c_string</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">char_type</span><span class="special">;</span> |
| |
| <span class="keyword">static</span> <span class="identifier">char_type</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">call</span> <span class="special">(</span><span class="identifier">String</span> <span class="keyword">const</span><span class="special">&);</span> |
| <span class="special">};</span> |
| </pre> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.template_parameters"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.template_parameters-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.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">String</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| A string type. |
| </p> |
| </td> |
| <td> |
| <p> |
| none |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <div class="variablelist"> |
| <p class="title"><b>Notation</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> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">Char</span></code></span></dt> |
| <dd><p> |
| A character type. |
| </p></dd> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">Traits</span></code></span></dt> |
| <dd><p> |
| A character traits type. |
| </p></dd> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">Allocator</span></code></span></dt> |
| <dd><p> |
| A standard allocator type. |
| </p></dd> |
| <dt><span class="term"><code class="computeroutput"><span class="identifier">str</span></code></span></dt> |
| <dd><p> |
| A string instance. |
| </p></dd> |
| </dl> |
| </div> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.expression_semantics"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.expression_semantics-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.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">extract_c_string</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">char_type</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| The return type of <code class="computeroutput"><span class="identifier">call</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">extract_c_string</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">str</span><span class="special">)</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Extract a c-string of type <code class="computeroutput"><span class="identifier">char_type</span></code> |
| from <code class="computeroutput"><span class="identifier">str</span></code>. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.predefined_specializations"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.predefined_specializations-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.predefined_specializations">Predefined |
| Specializations</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Type |
| </p> |
| </th> |
| <th> |
| <p> |
| Semantics |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">T</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">call</span></code> takes |
| a parameter of type <code class="computeroutput"><span class="identifier">T</span> |
| <span class="keyword">const</span><span class="special">*</span></code>, |
| and returns it without modification. An overload of <code class="computeroutput"><span class="identifier">call</span></code> takes a parameter of |
| type <code class="computeroutput"><span class="identifier">T</span><span class="special">*</span></code> |
| and casts it to <code class="computeroutput"><span class="identifier">T</span> |
| <span class="keyword">const</span><span class="special">*</span></code>, |
| returning the result. <code class="computeroutput"><span class="identifier">char_type</span></code> |
| is <code class="computeroutput"><span class="identifier">char_type_of</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">T</span> <span class="keyword">const</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">call</span></code> takes |
| a parameter <code class="computeroutput"><span class="identifier">str</span></code> |
| of type <code class="computeroutput"><span class="identifier">T</span> <span class="keyword">const</span></code> and returns <code class="computeroutput"><span class="identifier">extract_c_string</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">str</span><span class="special">)</span></code>. |
| <code class="computeroutput"><span class="identifier">char_type</span></code> is |
| <code class="computeroutput"><span class="identifier">char_type_of</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">T</span><span class="special">&</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">call</span></code> takes |
| a parameter <code class="computeroutput"><span class="identifier">str</span></code> |
| of type <code class="computeroutput"><span class="identifier">T</span><span class="special">&</span></code> |
| and returns <code class="computeroutput"><span class="identifier">extract_c_string</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">str</span><span class="special">)</span></code>. <code class="computeroutput"><span class="identifier">char_type</span></code> |
| is <code class="computeroutput"><span class="identifier">char_type_of</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">call</span></code> takes |
| a parameter <code class="computeroutput"><span class="identifier">str</span></code> |
| of type <code class="computeroutput"><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&</span></code> |
| and returns <code class="computeroutput"><span class="identifier">extract_c_string</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">str</span><span class="special">)</span></code>. <code class="computeroutput"><span class="identifier">char_type</span></code> |
| is <code class="computeroutput"><span class="identifier">char_type_of</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span></code>. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">basic_string</span><span class="special"><</span><span class="identifier">Char</span><span class="special">,</span> |
| <span class="identifier">Traits</span><span class="special">,</span> |
| <span class="identifier">Allocator</span><span class="special">></span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">call</span></code> takes |
| a parameter <code class="computeroutput"><span class="identifier">str</span></code> |
| and returns <code class="computeroutput"><span class="identifier">str</span><span class="special">.</span><span class="identifier">c_str</span><span class="special">()</span></code>. <code class="computeroutput"><span class="identifier">char_type</span></code> |
| is <code class="computeroutput"><span class="identifier">Char</span></code>. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.when_to_implement"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.when_to_implement-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.when_to_implement">When |
| to implement</a> |
| </h6> |
| <p> |
| This customization point needs to be implemented whenever <a class="link" href="../is_string.html" title="Determine if a Type Should be Treated as a String (Qi and Karma)"><code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">is_string</span></code></a> is implemented. |
| </p> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.related_attribute_customization_points"></a><h6> |
| <a name="spirit.advanced.customize.string_traits.extract_c_string.related_attribute_customization_points-heading"></a> |
| <a class="link" href="extract_c_string.html#spirit.advanced.customize.string_traits.extract_c_string.related_attribute_customization_points">Related |
| Attribute Customization Points</a> |
| </h6> |
| <p> |
| If this customization point is implemented, the following other customization |
| points need to be implemented as well. |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Name |
| </p> |
| </th> |
| <th> |
| <p> |
| When to implement |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="is_char.html" title="Determine if a Type is a Character"><code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">is_char</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| For string types whose underlying character type is not <code class="computeroutput"><span class="keyword">char</span></code> or <code class="computeroutput"><span class="keyword">wchar_t</span></code>, |
| <code class="computeroutput"><span class="identifier">is_char</span></code> must |
| be implemented. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="../is_string.html" title="Determine if a Type Should be Treated as a String (Qi and Karma)"><code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">is_string</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Whenever <code class="computeroutput"><span class="identifier">extract_c_string</span></code> |
| is implemented. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <a class="link" href="char_type_of.html" title="Determine the Character Type of a String"><code class="computeroutput"><span class="identifier">traits</span><span class="special">::</span><span class="identifier">char_type_of</span></code></a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Whenever <code class="computeroutput"><span class="identifier">extract_c_string</span></code> |
| is implemented. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </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 © 2001-2011 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> |
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| <div class="spirit-nav"> |
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