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| <a name="boost.proto.result_of.unpack_expr"></a><div class="titlepage"></div> |
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| <h2><span class="refentrytitle">Struct template unpack_expr</span></h2> |
| <p>boost::proto::result_of::unpack_expr — Metafunction that computes the return type of the |
| <code class="computeroutput"><a class="link" href="../unpack_expr_id1265992.html" title="Function unpack_expr">proto::unpack_expr()</a></code> |
| function, with a domain deduced from the domains of the children. |
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| <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> |
| <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.make_expr_hpp" title="Header <boost/proto/make_expr.hpp>">boost/proto/make_expr.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Tag<span class="special">,</span> <span class="keyword">typename</span> Sequence<span class="special">,</span> <span class="keyword">typename</span> Void <span class="special">=</span> <span class="keyword">void</span><span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="unpack_expr.html" title="Struct template unpack_expr">unpack_expr</a> <span class="special">{</span> |
| <span class="comment">// types</span> |
| <span class="keyword">typedef</span> |
| <span class="keyword">typename</span> <a class="link" href="make_expr.html" title="Struct template make_expr">proto::result_of::make_expr</a><span class="special"><</span> |
| <span class="identifier">Tag</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">fusion</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at_c</span><span class="special"><</span><em class="replaceable"><code><span class="identifier">S</span></code></em><span class="special">,</span> <span class="number">0</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span><span class="special">,</span> |
| <span class="special">...</span> |
| <span class="keyword">typename</span> <span class="identifier">fusion</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at_c</span><span class="special"><</span><em class="replaceable"><code><span class="identifier">S</span></code></em><span class="special">,</span> <em class="replaceable"><code><span class="identifier">N</span></code></em><span class="special">-</span><span class="number">1</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span> |
| <span class="special">></span><span class="special">::</span><span class="identifier">type</span> |
| <a name="boost.proto.result_of.unpack_expr.type"></a><span class="identifier">type</span><span class="special">;</span> <span class="comment">// Where S is a Fusion RandomAccessSequence equivalent to Sequence, and N is the size of S.</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2304892"></a><h2>Description</h2> |
| <p> |
| Compute the return type of the |
| <code class="computeroutput"><a class="link" href="../unpack_expr_id1265992.html" title="Function unpack_expr">proto::unpack_expr()</a></code> |
| function. |
| </p> |
| <p> |
| <code class="computeroutput">Sequence</code> is a Fusion Forward Sequence. |
| </p> |
| <p> |
| In this specialization, the domain is deduced from the domains of the child types. |
| If <code class="computeroutput"><a class="link" href="../is_domain.html" title="Struct template is_domain">proto::is_domain</a><Sequence>::value</code> |
| is <code class="computeroutput">true</code>, then another specialization is selected. |
| </p> |
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| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<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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