1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> 7<title>The MPL Reference Manual: deref</title> 8<link rel="stylesheet" href="../style.css" type="text/css" /> 9</head> 10<body class="docframe refmanual"> 11<table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./prior.html" class="navigation-link">Prev</a> <a href="./iterator-category.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./prior.html" class="navigation-link">Back</a> <a href="./iterator-category.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./iterator-metafunctions.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> 12<td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./iterators.html" class="navigation-link">Iterators</a> / <a href="./iterator-metafunctions.html" class="navigation-link">Iterator Metafunctions</a> / <a href="./deref.html" class="navigation-link">deref</a></td> 13</tr></table><div class="header-separator"></div> 14<div class="section" id="deref"> 15<h1><a class="toc-backref" href="./iterator-metafunctions.html#id1458">deref</a></h1> 16<div class="section" id="id437"> 17<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> 18<pre class="literal-block"> 19template< 20 typename Iterator 21 > 22struct <a href="./deref.html" class="identifier">deref</a> 23{ 24 typedef <em>unspecified</em> type; 25}; 26</pre> 27</div> 28<div class="section" id="id438"> 29<h3><a class="subsection-title" href="#description" name="description">Description</a></h3> 30<p>Dereferences an iterator.</p> 31</div> 32<div class="section" id="id439"> 33<h3><a class="subsection-title" href="#header" name="header">Header</a></h3> 34<pre class="literal-block"> 35#include <<a href="../../../../boost/mpl/deref.hpp" class="header">boost/mpl/deref.hpp</a>> 36</pre> 37</div> 38<div class="section" id="id440"> 39<h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> 40<table border="1" class="docutils table"> 41<colgroup> 42<col width="19%" /> 43<col width="35%" /> 44<col width="45%" /> 45</colgroup> 46<thead valign="bottom"> 47<tr><th class="head">Parameter</th> 48<th class="head">Requirement</th> 49<th class="head">Description</th> 50</tr> 51</thead> 52<tbody valign="top"> 53<tr><td><tt class="literal"><span class="pre">Iterator</span></tt></td> 54<td><a class="reference internal" href="./forward-iterator.html">Forward Iterator</a></td> 55<td>The iterator to dereference.</td> 56</tr> 57</tbody> 58</table> 59</div> 60<div class="section" id="id441"> 61<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> 62<p>For any <a class="reference internal" href="./forward-iterator.html">Forward Iterator</a>s <tt class="literal"><span class="pre">iter</span></tt>:</p> 63<pre class="literal-block"> 64typedef <a href="./deref.html" class="identifier">deref</a><iter>::type t; 65</pre> 66<table class="docutils field-list" frame="void" rules="none"> 67<col class="field-name" /> 68<col class="field-body" /> 69<tbody valign="top"> 70<tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A type.</p> 71</td> 72</tr> 73<tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first"><tt class="literal"><span class="pre">iter</span></tt> is dereferenceable.</p> 74</td> 75</tr> 76<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first"><tt class="literal"><span class="pre">t</span></tt> is identical to the element referenced by <tt class="literal"><span class="pre">iter</span></tt>. If <tt class="literal"><span class="pre">iter</span></tt> is 77a user-defined iterator, the library-provided default implementation is 78equivalent to</p> 79<pre class="last literal-block"> 80typedef iter::type t; 81</pre> 82</td> 83</tr> 84</tbody> 85</table> 86</div> 87<div class="section" id="id442"> 88<h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> 89<p>Amortized constant time.</p> 90</div> 91<div class="section" id="id443"> 92<h3><a class="subsection-title" href="#example" name="example">Example</a></h3> 93<pre class="literal-block"> 94typedef <a href="./vector.html" class="identifier">vector</a><char,short,int,long> types; 95typedef <a href="./begin.html" class="identifier">begin</a><types>::type iter; 96 97<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< <a href="./deref.html" class="identifier">deref</a><iter>::type, char > )); 98</pre> 99</div> 100<div class="section" id="id444"> 101<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> 102<p><a class="reference internal" href="./iterators.html">Iterators</a>, <a class="reference internal" href="./begin.html">begin</a> / <a class="reference internal" href="./end.html">end</a>, <a class="reference internal" href="./next.html">next</a></p> 103<!-- Iterators/Iterator Metafunctions//iterator_category |60 --> 104</div> 105</div> 106 107<div class="footer-separator"></div> 108<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./prior.html" class="navigation-link">Prev</a> <a href="./iterator-category.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./prior.html" class="navigation-link">Back</a> <a href="./iterator-category.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./iterator-metafunctions.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> 109<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> 110Distributed under the Boost Software License, Version 1.0. (See accompanying 111file 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> 112</html> 113