devn00b
/
EQ2EMu


			
				
					
						
						
							123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144
							<?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: copy_if</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="./copy.html" class="navigation-link">Prev</a>&nbsp;<a href="./transform.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./copy.html" class="navigation-link">Back</a>&nbsp;<a href="./transform.html" class="navigation-link">Along</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./transformation-algorithms.html" class="navigation-link">Up</a>&nbsp;<a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</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="./algorithms.html" class="navigation-link">Algorithms</a> / <a href="./transformation-algorithms.html" class="navigation-link">Transformation Algorithms</a> / <a href="./copy-if.html" class="navigation-link">copy_if</a></td>
</tr></table><div class="header-separator"></div>
<div class="section" id="copy-if">
<h1><a class="toc-backref" href="./transformation-algorithms.html#id1487">copy_if</a></h1>
<div class="section" id="id624">
<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
<pre class="literal-block">
template&lt;
      typename Sequence
    , typename Pred
    , typename In = <em>unspecified</em>
    &gt;
struct <a href="./copy-if.html" class="identifier">copy_if</a>
{
    typedef <em>unspecified</em> type;
};
</pre>
</div>
<div class="section" id="id625">
<h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
<p>Returns a filtered copy of the original sequence containing the elements that satisfy
the predicate <tt class="literal"><span class="pre">Pred</span></tt>.</p>
<p>[<em>Note:</em> This wording applies to a no-inserter version(s) of the algorithm. See the
<cite>Expression semantics</cite> subsection for a precise specification of the algorithm's
details in all cases — <em>end note</em>]</p>
</div>
<div class="section" id="id626">
<h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
<pre class="literal-block">
#include &lt;<a href="../../../../boost/mpl/copy_if.hpp" class="header">boost/mpl/copy_if.hpp</a>&gt;
</pre>
</div>
<div class="section" id="id627">
<h3><a class="subsection-title" href="#model-of" name="model-of">Model of</a></h3>
<p><a class="reference internal" href="./reversible-algorithm.html">Reversible Algorithm</a></p>
</div>
<div class="section" id="id628">
<h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
<table border="1" class="docutils table">
<colgroup>
<col width="19%" />
<col width="40%" />
<col width="40%" />
</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 copy.</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 copying condition.</td>
</tr>
<tr><td><tt class="literal"><span class="pre">In</span></tt></td>
<td><a class="reference internal" href="./inserter.html">Inserter</a></td>
<td>An inserter.</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="id629">
<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
<p>The semantics of an expression are defined only
where they differ from, or are not defined in <a class="reference internal" href="./reversible-algorithm.html">Reversible Algorithm</a>.</p>
<p>For any <a class="reference internal" href="./forward-sequence.html">Forward Sequence</a> <tt class="literal"><span class="pre">s</span></tt>, an unary <a class="reference internal" href="./lambda-expression.html">Lambda Expression</a> <tt class="literal"><span class="pre">pred</span></tt>, and
an <a class="reference internal" href="./inserter.html">Inserter</a> <tt class="literal"><span class="pre">in</span></tt>:</p>
<pre class="literal-block">
typedef <a href="./copy-if.html" class="identifier">copy_if</a>&lt;s,pred,in&gt;::type r;
</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>&lt;pred&gt;::type p;
typedef <a href="./lambda.html" class="identifier">lambda</a>&lt;in::operation&gt;::type op;

typedef <a href="./fold.html" class="identifier">fold</a>&lt;
      s
    , in::state
    , <a href="./eval-if.html" class="identifier">eval_if</a>&lt;
          <a href="./apply-wrap.html" class="identifier">apply_wrap</a><tt class="literal"><span class="pre">1</span></tt>&lt;p,<a href="./placeholders.html" class="identifier">_2</a>&gt;
        , <a href="./apply-wrap.html" class="identifier">apply_wrap</a><tt class="literal"><span class="pre">2</span></tt>&lt;op,<a href="./placeholders.html" class="identifier">_1</a>,<a href="./placeholders.html" class="identifier">_2</a>&gt;
        , <a href="./identity.html" class="identifier">identity</a>&lt;<a href="./placeholders.html" class="identifier">_1</a>&gt;
        &gt;
    &gt;::type r;
</pre>
</td>
</tr>
</tbody>
</table>
</div>
<div class="section" id="id630">
<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>&lt;s&gt;::value</span></tt> applications of <tt class="literal"><span class="pre">pred</span></tt>, and at
most <tt class="literal"><span class="pre"><a href="./size.html" class="identifier">size</a>&lt;s&gt;::value</span></tt> applications of <tt class="literal"><span class="pre">in::operation</span></tt>.</p>
</div>
<div class="section" id="id631">
<h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
<pre class="literal-block">
typedef <a href="./copy-if.html" class="identifier">copy_if</a>&lt;
      <a href="./range-c.html" class="identifier">range_c</a>&lt;int,0,10&gt;
    , <a href="./less.html" class="identifier">less</a>&lt; <a href="./placeholders.html" class="identifier">_1</a>, <a href="./int.html" class="identifier">int_</a>&lt;5&gt; &gt;
    , <a href="./back-inserter.html" class="identifier">back_inserter</a>&lt; <a href="./vector.html" class="identifier">vector</a>&lt;&gt; &gt;
    &gt;::type result;

<a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( <a href="./size.html" class="identifier">size</a>&lt;result&gt;::value, ==, 5 );
<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./equal.html" class="identifier">equal</a>&lt;result,<a href="./range-c.html" class="identifier">range_c</a>&lt;int,0,5&gt; > ));
</pre>
</div>
<div class="section" id="id632">
<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
<p><a class="reference internal" href="./transformation-algorithms.html">Transformation Algorithms</a>, <a class="reference internal" href="./reversible-algorithm.html">Reversible Algorithm</a>, <a class="reference internal" href="./reverse-copy-if.html">reverse_copy_if</a>, <a class="reference internal" href="./copy.html">copy</a>, <a class="reference internal" href="./remove-if.html">remove_if</a>, <a class="reference internal" href="./replace-if.html">replace_if</a></p>
<!-- Algorithms/Transformation Algorithms//transform |30 -->
</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="./copy.html" class="navigation-link">Prev</a>&nbsp;<a href="./transform.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./copy.html" class="navigation-link">Back</a>&nbsp;<a href="./transform.html" class="navigation-link">Along</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./transformation-algorithms.html" class="navigation-link">Up</a>&nbsp;<a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</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. (See accompanying
file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body>
</html>