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  27 <a name="boost.proto.make_expr_idp701696352"></a><div class="titlepage"></div>
  28 <div class="refnamediv">
  29 <h2><span class="refentrytitle">Function make_expr</span></h2>
  30 <p>boost::proto::make_expr &#8212; Construct an expression of the requested tag type with a domain and with the specified
  31           arguments as children.</p>
  32 </div>
  33 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  34 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../proto/reference.html#header.boost.proto.make_expr_hpp" title="Header &lt;boost/proto/make_expr.hpp&gt;">boost/proto/make_expr.hpp</a>&gt;
  35
  36 </span>
  37 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Tag<span class="special">,</span> <span class="keyword">typename</span><span class="special">...</span> A<span class="special">&gt;</span>
  38   <span class="keyword">typename</span> <a class="link" href="result_of/make_expr.html" title="Struct template make_expr">proto::result_of::make_expr</a><span class="special">&lt;</span><span class="identifier">Tag</span><span class="special">,</span> <span class="identifier">A</span> <span class="keyword">const</span><span class="special">...</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span> <span class="keyword">const</span>
  39   <span class="identifier">make_expr</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&amp;</span><span class="special">...</span> a<span class="special">)</span><span class="special">;</span>
  40 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Tag<span class="special">,</span> <span class="keyword">typename</span> <a class="link" href="../../Domain.html" title="Concept Domain">Domain</a><span class="special">,</span> <span class="keyword">typename</span><span class="special">...</span> A<span class="special">&gt;</span>
  41   <span class="keyword">typename</span> <a class="link" href="result_of/make_expr.html" title="Struct template make_expr">proto::result_of::make_expr</a><span class="special">&lt;</span><span class="identifier">Tag</span><span class="special">,</span> <span class="identifier">Domain</span><span class="special">,</span> <span class="identifier">A</span> <span class="keyword">const</span><span class="special">...</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span> <span class="keyword">const</span>
  42   <span class="identifier">make_expr</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&amp;</span><span class="special">...</span> a<span class="special">)</span><span class="special">;</span></pre></div>
  43 <div class="refsect1">
  44 <a name="idp468132464"></a><h2>Description</h2>
  45 <p>
  46             This function template may be invoked either with or without specifying a
  47             <code class="computeroutput">Domain</code> template parameter. If no domain is specified, the domain
  48             is deduced by examining domains of the given arguments. See
  49             <code class="computeroutput"><code class="computeroutput"><a class="link" href="deduce_domain.html" title="Struct deduce_domain">proto::deduce_domain</a></code></code> for a full
  50             description of the procedure used.
  51           </p>
  52 <p>
  53             Let <code class="computeroutput"><em class="replaceable"><code>WRAP</code></em>(x)</code> be defined such that:
  54             </p>
  55 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  56 <li class="listitem"><p>
  57                   If <code class="computeroutput">x</code> is a <code class="computeroutput">boost::reference_wrapper&lt;&gt;</code>,
  58                   <code class="computeroutput"><em class="replaceable"><code>WRAP</code></em>(x)</code> is equivalent to
  59                   <code class="computeroutput"><code class="computeroutput"><a class="link" href="as_child_idp704447440.html" title="Function as_child">proto::as_child</a></code>&lt;Domain&gt;(x.get())</code>.
  60                 </p></li>
  61 <li class="listitem"><p>
  62                   Otherwise, <code class="computeroutput"><em class="replaceable"><code>WRAP</code></em>(x)</code> is equivalent to
  63                   <code class="computeroutput"><code class="computeroutput"><a class="link" href="as_expr_idp704425472.html" title="Function as_expr">proto::as_expr</a></code>&lt;Domain&gt;(x)</code>.
  64                 </p></li>
  65 </ul></div>
  66 <p>
  67           </p>
  68 <p>
  69             If <code class="computeroutput"><code class="computeroutput"><a class="link" href="wants_basic_expr.html" title="Struct template wants_basic_expr">proto::wants_basic_expr</a></code>&lt;typename Domain::proto_generator&gt;::value</code>
  70             is true, then let <code class="computeroutput"><em class="replaceable"><code>E</code></em></code> be
  71             <code class="computeroutput"><code class="computeroutput"><a class="link" href="basic_expr.html" title="Struct template basic_expr">proto::basic_expr</a></code></code>; otherwise,
  72             let <code class="computeroutput"><em class="replaceable"><code>E</code></em></code> be
  73             <code class="computeroutput"><code class="computeroutput"><a class="link" href="expr.html" title="Struct template expr">proto::expr</a></code></code>.
  74           </p>
  75 <p>
  76             Let <code class="computeroutput"><em class="replaceable"><code>MAKE</code></em>(Tag, b...)</code> be defined as
  77             <code class="computeroutput"><em class="replaceable"><code>E</code></em>&lt;Tag,
  78             <code class="computeroutput"><a class="link" href="listN.html" title="Struct template listN">proto::listN</a></code>&lt;decltype(b)...&gt; &gt;::make(b...)</code>.
  79           </p>
  80 <p>
  81             If <code class="computeroutput">Tag</code> is
  82             <code class="computeroutput"><code class="computeroutput"><a class="link" href="tag/terminal.html" title="Struct terminal">proto::tag::terminal</a></code></code>, then return
  83             <code class="computeroutput"><em class="replaceable"><code>WRAP</code></em>(a<sub>0</sub>)</code>.
  84           </p>
  85 <p>
  86             Otherwise, return
  87             <code class="computeroutput">Domain()(<em class="replaceable"><code>MAKE</code></em>(Tag, <em class="replaceable"><code>WRAP</code></em>(a)...))</code>.
  88           </p>
  89 </div>
  90 </div>
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  93 <td align="right"><div class="copyright-footer">Copyright &#169; 2008 Eric Niebler<p>
  94         Distributed under the Boost Software License, Version 1.0. (See accompanying
  95         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>)
  96       </p>
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