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| <a name="boost.proto.fold"></a><div class="titlepage"></div> |
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| <h2><span class="refentrytitle">Struct template fold</span></h2> |
| <p>boost::proto::fold — A <a class="link" href="../../PrimitiveTransform.html" title="Concept PrimitiveTransform">PrimitiveTransform</a> that invokes the |
| <code class="computeroutput">fusion::fold<></code> algorithm to accumulate a value.</p> |
| </div> |
| <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.transform.fold_hpp" title="Header <boost/proto/transform/fold.hpp>">boost/proto/transform/fold.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Sequence<span class="special">,</span> <span class="keyword">typename</span> State0<span class="special">,</span> <span class="keyword">typename</span> Fun<span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="fold.html" title="Struct template fold">fold</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="transform.html" title="Struct template transform">proto::transform</a><span class="special"><</span> <span class="identifier">fold</span><span class="special"><</span><span class="identifier">Sequence</span><span class="special">,</span> <span class="identifier">State0</span><span class="special">,</span> <span class="identifier">Fun</span><span class="special">></span> <span class="special">></span> <span class="special">{</span> |
| <span class="comment">// member classes/structs/unions</span> |
| <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> |
| <span class="keyword">struct</span> <a class="link" href="fold/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><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="comment">// types</span> |
| <span class="keyword">typedef</span> <a class="link" href="when.html" title="Struct template when">when</a><span class="special"><</span><a class="link" href="_.html" title="Struct _">_</a><span class="special">,</span> <span class="identifier">Sequence</span><span class="special">></span> <a class="link" href="fold/impl.html#boost.proto.fold.impl.X"><span class="identifier">X</span></a><span class="special">;</span> <span class="comment">// For exposition only</span> |
| <span class="keyword">typedef</span> <a class="link" href="when.html" title="Struct template when">when</a><span class="special"><</span><a class="link" href="_.html" title="Struct _">_</a><span class="special">,</span> <span class="identifier">State0</span><span class="special">></span> <a class="link" href="fold/impl.html#boost.proto.fold.impl.Y"><span class="identifier">Y</span></a><span class="special">;</span> <span class="comment">// For exposition only</span> |
| <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">X</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 class="link" href="fold/impl.html#boost.proto.fold.impl.seq"><span class="identifier">seq</span></a><span class="special">;</span> <span class="comment">// A Fusion sequence, for exposition only</span> |
| <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">Y</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 class="link" href="fold/impl.html#boost.proto.fold.impl.state0"><span class="identifier">state0</span></a><span class="special">;</span> <span class="comment">// An initial state for the fold, for exposition only</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">unspecified</span></em></span> <a class="link" href="fold/impl.html#boost.proto.fold.impl.fun"><span class="identifier">fun</span></a><span class="special">;</span> <span class="comment">// <code class="computeroutput">fun(d)(s,e) == when<_,Fun>()(e,s,d)</code></span> |
| <span class="keyword">typedef</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">fold</span><span class="special"><</span><span class="identifier">seq</span><span class="special">,</span> <span class="identifier">state0</span><span class="special">,</span> <span class="identifier">fun</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span> <a class="link" href="fold/impl.html#boost.proto.fold.impl.result_type"><span class="identifier">result_type</span></a><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="fold/impl.html#id1293590-bb">public member functions</a></span> |
| <span class="identifier">result_type</span> <a class="link" href="fold/impl.html#id1293595-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> |
| <span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><span class="identifier">state_param</span><span class="special">,</span> |
| <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> |
| <span class="special">}</span><span class="special">;</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2430396"></a><h2>Description</h2> |
| <p> |
| For the complete description of the behavior of the <code class="computeroutput">proto::fold<></code> |
| transform, see the documentation for the nested <code class="computeroutput"> |
| <a class="link" href="fold/impl.html" title="Struct template impl">proto::fold::impl<></a> |
| </code> class template. |
| </p> |
| </div> |
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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>) |
| </p> |
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