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| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="fusion.support.is_view"></a><a class="link" href="is_view.html" title="is_view">is_view</a> |
| </h3></div></div></div> |
| <a name="fusion.support.is_view.description"></a><h5> |
| <a name="id837119"></a> |
| <a class="link" href="is_view.html#fusion.support.is_view.description">Description</a> |
| </h5> |
| <p> |
| Metafunction that evaluates to <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span></code> |
| if a certain type <code class="computeroutput"><span class="identifier">T</span></code> is a |
| conforming Fusion <a class="link" href="../view.html" title="View">View</a>, <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">false_</span></code> |
| otherwise. A view is a specialized sequence that does not actually contain |
| data. Views hold sequences which may be other views. In general, views are |
| held by other views by value, while non-views are held by other views by |
| reference. <code class="computeroutput"><span class="identifier">is_view</span></code> may be |
| specialized to accomodate clients providing Fusion conforming views. |
| </p> |
| <a name="fusion.support.is_view.synopsis"></a><h5> |
| <a name="id837184"></a> |
| <a class="link" href="is_view.html#fusion.support.is_view.synopsis">Synopsis</a> |
| </h5> |
| <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">traits</span> |
| <span class="special">{</span> |
| <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">struct</span> <span class="identifier">is_view</span> |
| <span class="special">{</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em>unspecified</em></span> <span class="identifier">type</span><span class="special">;</span> |
| <span class="special">};</span> |
| <span class="special">}</span> |
| </pre> |
| <a name="fusion.support.is_view.parameters"></a><h5> |
| <a name="id837278"></a> |
| <a class="link" href="is_view.html#fusion.support.is_view.parameters">Parameters</a> |
| </h5> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Parameter |
| </p> |
| </th> |
| <th> |
| <p> |
| Requirement |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| </tr></thead> |
| <tbody><tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">T</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Any type |
| </p> |
| </td> |
| <td> |
| <p> |
| The type to query. |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <a name="fusion.support.is_view.expression_semantics"></a><h5> |
| <a name="id837365"></a> |
| <a class="link" href="is_view.html#fusion.support.is_view.expression_semantics">Expression Semantics</a> |
| </h5> |
| <pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">traits</span><span class="special">::</span><span class="identifier">is_view</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">c</span><span class="special">;</span> |
| </pre> |
| <p> |
| <span class="bold"><strong>Return type</strong></span>: An <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL |
| Boolean Constant</a>. |
| </p> |
| <p> |
| <span class="bold"><strong>Semantics</strong></span>: Metafunction that evaluates to |
| <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span></code> if a certain type <code class="computeroutput"><span class="identifier">T</span></code> |
| is a conforming Fusion view, <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">false_</span></code> |
| otherwise. |
| </p> |
| <a name="fusion.support.is_view.header"></a><h5> |
| <a name="id837479"></a> |
| <a class="link" href="is_view.html#fusion.support.is_view.header">Header</a> |
| </h5> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">support</span><span class="special">/</span><span class="identifier">is_view</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">is_view</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <a name="fusion.support.is_view.example"></a><h5> |
| <a name="id837587"></a> |
| <a class="link" href="is_view.html#fusion.support.is_view.example">Example</a> |
| </h5> |
| <pre class="programlisting"><span class="identifier">BOOST_MPL_ASSERT_NOT</span><span class="special">((</span> <span class="identifier">traits</span><span class="special">::</span><span class="identifier">is_view</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="special">></span> <span class="special">));</span> |
| <span class="identifier">BOOST_MPL_ASSERT_NOT</span><span class="special">((</span> <span class="identifier">traits</span><span class="special">::</span><span class="identifier">is_view</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span> <span class="special">));</span> |
| |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">_</span> |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_pointer</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <a class="link" href="../container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a><span class="special"><</span><span class="keyword">int</span><span class="special">*,</span> <span class="keyword">char</span><span class="special">,</span> <span class="keyword">long</span><span class="special">*,</span> <span class="keyword">bool</span><span class="special">,</span> <span class="keyword">double</span><span class="special">></span> <span class="identifier">vector_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <a class="link" href="../view/filter_view.html" title="filter_view"><code class="computeroutput"><span class="identifier">filter_view</span></code></a><span class="special"><</span><span class="identifier">vector_type</span><span class="special">,</span> <span class="identifier">is_pointer</span><span class="special"><</span><span class="identifier">_</span><span class="special">></span> <span class="special">></span> <span class="identifier">filter_view_type</span><span class="special">;</span> |
| <span class="identifier">BOOST_MPL_ASSERT</span><span class="special">((</span> <span class="identifier">traits</span><span class="special">::</span><span class="identifier">is_view</span><span class="special"><</span><span class="identifier">filter_view_type</span><span class="special">></span> <span class="special">));</span> |
| </pre> |
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| <td align="right"><div class="copyright-footer">Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias |
| Schwinger<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>) |
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