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25 <div class="refentry">
26 <a name="boost.proto.when_Grammar,_idp207684960.impl"></a><div class="titlepage"></div>
27 <div class="refnamediv">
28 <h2><span class="refentrytitle">Struct template impl</span></h2>
29 <p>boost::proto::when<Grammar, R(A...)>::impl</p>
31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../../proto/reference.html#header.boost.proto.transform.when_hpp" title="Header <boost/proto/transform/when.hpp>">boost/proto/transform/when.hpp</a>>
35 <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">,</span> <span class="keyword">typename</span> State<span class="special">,</span> <span class="keyword">typename</span> Data<span class="special">></span>
36 <span class="keyword">struct</span> <a class="link" href="impl.html" title="Struct template impl">impl</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="../transform_impl.html" title="Struct template transform_impl">proto::transform_impl</a>< Expr, State, Data > <span class="special">{</span>
37 <span class="comment">// types</span>
38 <span class="keyword">typedef</span> <a class="link" href="../call.html" title="Struct template call">proto::call</a><span class="special"><</span><span class="identifier">R</span><span class="special">(</span><span class="identifier">A</span><span class="special">...</span><span class="special">)</span><span class="special">></span> <a name="boost.proto.when_Grammar,_idp207684960.impl.call_"></a><span class="identifier">call_</span><span class="special">;</span> <span class="comment">// For exposition only</span>
39 <span class="keyword">typedef</span> <a class="link" href="../make.html" title="Struct template make">proto::make</a><span class="special"><</span><span class="identifier">R</span><span class="special">(</span><span class="identifier">A</span><span class="special">...</span><span class="special">)</span><span class="special">></span> <a name="boost.proto.when_Grammar,_idp207684960.impl.make_"></a><span class="identifier">make_</span><span class="special">;</span> <span class="comment">// For exposition only</span>
40 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">if_</span><span class="special"><</span><a class="link" href="../is_callable.html" title="Struct template is_callable">proto::is_callable</a><span class="special"><</span><span class="identifier">R</span><span class="special">></span><span class="special">,</span><span class="identifier">call_</span><span class="special">,</span><span class="identifier">make_</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span> <a name="boost.proto.when_Grammar,_idp207684960.impl.which"></a><span class="identifier">which</span><span class="special">;</span> <span class="comment">// For exposition only</span>
41 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special"><</span><span class="identifier">which</span><span class="special">(</span><span class="identifier">Expr</span><span class="special">,</span> <span class="identifier">State</span><span class="special">,</span> <span class="identifier">Data</span><span class="special">)</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span> <a name="boost.proto.when_Grammar,_idp207684960.impl.result_type"></a><span class="identifier">result_type</span><span class="special">;</span>
43 <span class="comment">// <a class="link" href="impl.html#idp200114672-bb">public member functions</a></span>
44 <span class="identifier">result_type</span> <a class="link" href="impl.html#idp200115232-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">expr_param</span><span class="special">,</span>
45 <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">state_param</span><span class="special">,</span>
46 <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">data_param</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
47 <span class="special">}</span><span class="special">;</span></pre></div>
48 <div class="refsect1">
49 <a name="idp392243936"></a><h2>Description</h2>
50 <div class="refsect2">
51 <a name="idp392244352"></a><h3>
52 <a name="idp200114672-bb"></a><code class="computeroutput">impl</code> public member functions</h3>
53 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
54 <pre class="literallayout"><span class="identifier">result_type</span> <a name="idp200115232-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">expr_param</span> expr<span class="special">,</span>
55 <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">state_param</span> state<span class="special">,</span>
56 <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">data_param</span> data<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
58 Evaluate <code class="computeroutput">R(A...)</code> as a transform either with
59 <code class="computeroutput"><code class="computeroutput"><a class="link" href="../call.html" title="Struct template call">proto::call<></a></code></code> or with
60 <code class="computeroutput"><code class="computeroutput"><a class="link" href="../make.html" title="Struct template make">proto::make<></a></code></code> depending
61 on whether <code class="computeroutput"><code class="computeroutput"><a class="link" href="../is_callable.html" title="Struct template is_callable">proto::is_callable</a></code><R>::value</code>
62 is <code class="computeroutput">true</code> or <code class="computeroutput">false</code>.
64 <div class="variablelist"><table border="0" class="variablelist compact">
66 <col align="left" valign="top">
71 <td><p><span class="term">Parameters:</span></p></td>
72 <td><div class="variablelist"><table border="0" class="variablelist compact">
74 <col align="left" valign="top">
79 <td><p><span class="term"><code class="computeroutput">data</code></span></p></td>
80 <td><p>An arbitrary data </p></td>
83 <td><p><span class="term"><code class="computeroutput">expr</code></span></p></td>
84 <td><p>The current expression </p></td>
87 <td><p><span class="term"><code class="computeroutput">state</code></span></p></td>
88 <td><p>The current state </p></td>
94 <td><p><span class="term">Requires:</span></p></td>
96 <code class="computeroutput"><a class="link" href="../matches.html" title="Struct template matches">proto::matches</a><Expr, Grammar>::value</code>
97 is <code class="computeroutput">true</code>.
101 <td><p><span class="term">Returns:</span></p></td>
103 <code class="computeroutput">which()(expr, state, data)</code>
112 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
113 <td align="left"></td>
114 <td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p>
115 Distributed under the Boost Software License, Version 1.0. (See accompanying
116 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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