<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> <title>The MPL Reference Manual: filter_view</title> <link rel="stylesheet" href="../style.css" type="text/css" /> </head> <body class="docframe refmanual"> <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./empty-sequence.html" class="navigation-link">Prev</a> <a href="./iterator-range.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./empty-sequence.html" class="navigation-link">Back</a> <a href="./iterator-range.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./views.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./sequences.html" class="navigation-link">Sequences</a> / <a href="./views.html" class="navigation-link">Views</a> / <a href="./filter-view.html" class="navigation-link">filter_view</a></td> </tr></table><div class="header-separator"></div> <div class="section" id="filter-view"> <h1><a class="toc-backref" href="./views.html#id1418">filter_view</a></h1> <div class="section" id="id126"> <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> <pre class="literal-block"> template< typename Sequence , typename Pred > struct <a href="./filter-view.html" class="identifier">filter_view</a> { // <em>unspecified</em> // <em>...</em> }; </pre> </div> <div class="section" id="id127"> <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> <p>A view into a subset of <tt class="literal"><span class="pre">Sequence</span></tt>'s elements satisfying the predicate <tt class="literal"><span class="pre">Pred</span></tt>.</p> </div> <div class="section" id="id128"> <h3><a class="subsection-title" href="#header" name="header">Header</a></h3> <pre class="literal-block"> #include <<a href="../../../../boost/mpl/filter_view.hpp" class="header">boost/mpl/filter_view.hpp</a>> </pre> </div> <div class="section" id="id129"> <h3><a class="subsection-title" href="#model-of" name="model-of">Model of</a></h3> <ul class="simple"> <li><a class="reference internal" href="./forward-sequence.html">Forward Sequence</a></li> </ul> </div> <div class="section" id="parameters"> <h3>Parameters</h3> <table border="1" class="docutils table"> <colgroup> <col width="15%" /> <col width="36%" /> <col width="48%" /> </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 wrap.</td> </tr> <tr><td><tt class="literal"><span class="pre">Pred</span></tt></td> <td>Unary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a></td> <td>A filtering predicate.</td> </tr> </tbody> </table> </div> <div class="section" id="id130"> <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> <p>Semantics of an expression is defined only where it differs from, or is not defined in <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a>.</p> <p>In the following table, <tt class="literal"><span class="pre">v</span></tt> is an instance of <tt class="literal"><span class="pre"><a href="./filter-view.html" class="identifier">filter_view</a></span></tt>, <tt class="literal"><span class="pre">s</span></tt> is an arbitrary <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a>, <tt class="literal"><span class="pre">pred</span></tt> is an unary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a>.</p> <table border="1" class="docutils table"> <colgroup> <col width="40%" /> <col width="60%" /> </colgroup> <thead valign="bottom"> <tr><th class="head">Expression</th> <th class="head">Semantics</th> </tr> </thead> <tbody valign="top"> <tr><td><pre class="first last literal-block"> <a href="./filter-view.html" class="identifier">filter_view</a><s,pred> <a href="./filter-view.html" class="identifier">filter_view</a><s,pred>::type </pre> </td> <td>A lazy <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> sequence of all the elements in the range [<tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><s>::type</span></tt>, <tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><s>::type</span></tt>) that satisfy the predicate <tt class="literal"><span class="pre">pred</span></tt>.</td> </tr> <tr><td><tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a><v>::type</span></tt></td> <td>The size of <tt class="literal"><span class="pre">v</span></tt>; <tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a><v>::value</span> <span class="pre">==</span> <span class="pre"><a href="./count-if.html" class="identifier">count_if</a><s,pred>::value</span></tt>; linear complexity; see <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a>.</td> </tr> </tbody> </table> </div> <div class="section" id="id131"> <h3><a class="subsection-title" href="#example" name="example">Example</a></h3> <p>Find the largest floating type in a sequence.</p> <pre class="literal-block"> typedef <a href="./vector.html" class="identifier">vector</a><int,float,long,float,char[50],long double,char> types; typedef <a href="./max-element.html" class="identifier">max_element</a>< <a href="./transform-view.html" class="identifier">transform_view</a>< <a href="./filter-view.html" class="identifier">filter_view</a>< types,boost::is_float<_> >, size_of<_> > >::type iter; <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< <a href="./deref.html" class="identifier">deref</a><iter::base>::type, long double > )); </pre> </div> <div class="section" id="id132"> <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> <p><a class="reference internal" href="./sequences.html">Sequences</a>, <a class="reference internal" href="./views.html">Views</a>, <a class="reference internal" href="./transform-view.html">transform_view</a>, <a class="reference internal" href="./joint-view.html">joint_view</a>, <a class="reference internal" href="./zip-view.html">zip_view</a>, <a class="reference internal" href="./iterator-range.html">iterator_range</a></p> <!-- Sequences/Views//iterator_range --> </div> </div> <div class="footer-separator"></div> <table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./empty-sequence.html" class="navigation-link">Prev</a> <a href="./iterator-range.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./empty-sequence.html" class="navigation-link">Back</a> <a href="./iterator-range.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./views.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> Distributed under the Boost Software License, Version 1.0. 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