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| <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./algorithms.html" class="navigation-link">Algorithms</a> / <a href="./iteration-algorithms.html" class="navigation-link">Iteration Algorithms</a> / <a href="./reverse-fold.html" class="navigation-link">reverse_fold</a></td> |
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| <div class="section" id="reverse-fold"> |
| <h1><a class="toc-backref" href="./iteration-algorithms.html#id1471">reverse_fold</a></h1> |
| <div class="section" id="id509"> |
| <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> |
| <pre class="literal-block"> |
| template< |
| typename Sequence |
| , typename State |
| , typename BackwardOp |
| , typename ForwardOp = <a href="./placeholders.html" class="identifier">_1</a> |
| > |
| struct <a href="./reverse-fold.html" class="identifier">reverse_fold</a> |
| { |
| typedef <em>unspecified</em> type; |
| }; |
| </pre> |
| </div> |
| <div class="section" id="id510"> |
| <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> |
| <p>Returns the result of the successive application of binary <tt class="literal"><span class="pre">BackwardOp</span></tt> to the |
| result of the previous <tt class="literal"><span class="pre">BackwardOp</span></tt> invocation (<tt class="literal"><span class="pre">State</span></tt> if it's the first call) |
| and every element in the range [<tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><Sequence>::type</span></tt>, <tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><Sequence>::type</span></tt>) in |
| reverse order. If <tt class="literal"><span class="pre">ForwardOp</span></tt> is provided, then it is applied on forward |
| traversal to form the result that is passed to the first <tt class="literal"><span class="pre">BackwardOp</span></tt> call.</p> |
| </div> |
| <div class="section" id="id511"> |
| <h3><a class="subsection-title" href="#header" name="header">Header</a></h3> |
| <pre class="literal-block"> |
| #include <<a href="../../../../boost/mpl/reverse_fold.hpp" class="header">boost/mpl/reverse_fold.hpp</a>> |
| </pre> |
| </div> |
| <div class="section" id="id512"> |
| <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> |
| </div> |
| <div class="section" id="id513"> |
| <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> |
| <table border="1" class="docutils table"> |
| <colgroup> |
| <col width="16%" /> |
| <col width="33%" /> |
| <col width="51%" /> |
| </colgroup> |
| <thead valign="bottom"> |
| <tr><th class="head">Parameter</th> |
| <th class="head">Requirement</th> |
| <th class="head">Description</th> |
| </tr> |
| </thead> |
| <tbody valign="top"> |
| <tr><td><tt class="literal"><span class="pre">Sequence</span></tt></td> |
| <td><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></td> |
| <td>A sequence to iterate.</td> |
| </tr> |
| <tr><td><tt class="literal"><span class="pre">State</span></tt></td> |
| <td>Any type</td> |
| <td>The initial state for the first <tt class="literal"><span class="pre">BackwardOp</span></tt> |
| / <tt class="literal"><span class="pre">ForwardOp</span></tt> application.</td> |
| </tr> |
| <tr><td><tt class="literal"><span class="pre">BackwardOp</span></tt></td> |
| <td>Binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td> |
| <td>The operation to be executed on backward |
| traversal.</td> |
| </tr> |
| <tr><td><tt class="literal"><span class="pre">ForwardOp</span></tt></td> |
| <td>Binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td> |
| <td>The operation to be executed on forward |
| traversal.</td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="section" id="id514"> |
| <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> |
| <p>For any <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> <tt class="literal"><span class="pre">s</span></tt>, binary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a> <tt class="literal"><span class="pre">backward_op</span></tt> and <tt class="literal"><span class="pre">forward_op</span></tt>, |
| and arbitrary type <tt class="literal"><span class="pre">state</span></tt>:</p> |
| <pre class="literal-block"> |
| typedef <a href="./reverse-fold.html" class="identifier">reverse_fold</a>< s,state,backward_op >::type t; |
| </pre> |
| <table class="docutils field-list" frame="void" rules="none"> |
| <col class="field-name" /> |
| <col class="field-body" /> |
| <tbody valign="top"> |
| <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type</p> |
| </td> |
| </tr> |
| <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> |
| <pre class="last literal-block"> |
| typedef <a href="./lambda.html" class="identifier">lambda</a><backward_op>::type op; |
| typedef <a href="./reverse-iter-fold.html" class="identifier">reverse_iter_fold</a>< |
| s |
| , state |
| , apply_wrap2< op, <a href="./placeholders.html" class="identifier">_1</a>, <a href="./deref.html" class="identifier">deref</a><<a href="./placeholders.html" class="identifier">_2</a>> > |
| >::type t; |
| </pre> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --> |
| <pre class="literal-block"> |
| typedef <a href="./reverse-fold.html" class="identifier">reverse_fold</a>< s,state,backward_op,forward_op >::type t; |
| </pre> |
| <table class="docutils field-list" frame="void" rules="none"> |
| <col class="field-name" /> |
| <col class="field-body" /> |
| <tbody valign="top"> |
| <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type.</p> |
| </td> |
| </tr> |
| <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> |
| <pre class="last literal-block"> |
| typedef <a href="./reverse-fold.html" class="identifier">reverse_fold</a>< |
| Sequence |
| , <a href="./fold.html" class="identifier">fold</a><s,state,forward_op>::type |
| , backward_op |
| >::type t; |
| </pre> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="section" id="id515"> |
| <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> |
| <p>Linear. Exactly <tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a><s>::value</span></tt> applications of <tt class="literal"><span class="pre">backward_op</span></tt> and <tt class="literal"><span class="pre">forward_op</span></tt>.</p> |
| </div> |
| <div class="section" id="id516"> |
| <h3><a class="subsection-title" href="#example" name="example">Example</a></h3> |
| <p>Remove non-negative elements from a sequence <a class="footnote-reference" href="#reverse-fold-note" id="id517">[2]</a>.</p> |
| <pre class="literal-block"> |
| typedef <a href="./list-c.html" class="identifier">list_c</a><int,5,-1,0,-7,-2,0,-5,4> numbers; |
| typedef <a href="./list-c.html" class="identifier">list_c</a><int,-1,-7,-2,-5> negatives; |
| typedef <a href="./reverse-fold.html" class="identifier">reverse_fold</a>< |
| numbers |
| , <a href="./list-c.html" class="identifier">list_c</a><int> |
| , <a href="./if.html" class="identifier">if_</a>< <a href="./less.html" class="identifier">less</a>< <a href="./placeholders.html" class="identifier">_2</a>,<a href="./int.html" class="identifier">int_</a><0> >, <a href="./push-front.html" class="identifier">push_front</a><<a href="./placeholders.html" class="identifier">_1</a>,<a href="./placeholders.html" class="identifier">_2</a>,>, <a href="./placeholders.html" class="identifier">_1</a> > |
| >::type result; |
| |
| <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./equal.html" class="identifier">equal</a>< negatives,result > )); |
| </pre> |
| <table class="docutils footnote" frame="void" id="reverse-fold-note" rules="none"> |
| <colgroup><col class="label" /><col /></colgroup> |
| <tbody valign="top"> |
| <tr><td class="label"><a class="fn-backref" href="#id517">[2]</a></td><td>See <tt class="literal"><span class="pre"><a href="./remove-if.html" class="identifier">remove_if</a></span></tt> for a more compact way to do this.</td></tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="section" id="id518"> |
| <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> |
| <p><a class="reference internal" href="./algorithms.html">Algorithms</a>, <a class="reference internal" href="./fold.html">fold</a>, <a class="reference internal" href="./reverse-iter-fold.html">reverse_iter_fold</a>, <a class="reference internal" href="./iter-fold.html">iter_fold</a></p> |
| <!-- Algorithms/Iteration Algorithms//reverse_iter_fold --> |
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| Distributed under the Boost Software License, Version 1.0. (See accompanying |
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