1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>ref_unwrapped</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Chapter 1. Range 2.0"> 8<link rel="up" href="../reference.html" title="Reference"> 9<link rel="prev" href="map_values.html" title="map_values"> 10<link rel="next" href="replaced.html" title="replaced"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="map_values.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="replaced.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="range.reference.adaptors.reference.ref_unwrapped"></a><a class="link" href="ref_unwrapped.html" title="ref_unwrapped">ref_unwrapped</a> 28</h5></div></div></div> 29<div class="toc"><dl class="toc"><dt><span class="section"><a href="ref_unwrapped.html#range.reference.adaptors.reference.ref_unwrapped.ref_unwrapped_example">ref_unwrapped 30 example</a></span></dt></dl></div> 31<div class="informaltable"><table class="table"> 32<colgroup> 33<col> 34<col> 35</colgroup> 36<thead><tr> 37<th> 38 <p> 39 Syntax 40 </p> 41 </th> 42<th> 43 <p> 44 Code 45 </p> 46 </th> 47</tr></thead> 48<tbody> 49<tr> 50<td> 51 <p> 52 Pipe 53 </p> 54 </td> 55<td> 56 <p> 57 <code class="computeroutput"><span class="identifier">rng</span> <span class="special">|</span> 58 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">adaptors</span><span class="special">::</span><span class="identifier">ref_unwrapped</span></code> 59 </p> 60 </td> 61</tr> 62<tr> 63<td> 64 <p> 65 Function 66 </p> 67 </td> 68<td> 69 <p> 70 <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adaptors</span><span class="special">::</span><span class="identifier">ref_unwrap</span><span class="special">(</span><span class="identifier">rng</span><span class="special">)</span></code> 71 </p> 72 </td> 73</tr> 74</tbody> 75</table></div> 76<p> 77 This adaptor produces a range than applies <code class="computeroutput"><span class="special">.</span><span class="identifier">get</span><span class="special">()</span></code> 78 on all values in the range. It is useful for iterating ranges of <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">reference_wrapper</span></code> values or values 79 using similar semantics. 80 </p> 81<p> 82 The adaptor is C++11 (and above) only. 83 </p> 84<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 85<li class="listitem"> 86 <span class="bold"><strong>Precondition:</strong></span> The <code class="computeroutput"><span class="identifier">value_type</span></code> of the range has a 87 <code class="computeroutput"><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span></code>. 88 </li> 89<li class="listitem"> 90 <span class="bold"><strong>Postcondition:</strong></span> For all elements 91 <code class="computeroutput"><span class="identifier">x</span></code> in the returned 92 range, <code class="computeroutput"><span class="identifier">x</span></code> is the result 93 of <code class="computeroutput"><span class="identifier">y</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span></code> 94 where <code class="computeroutput"><span class="identifier">y</span></code> is the corresponding 95 element in the original range. 96 </li> 97<li class="listitem"> 98 <span class="bold"><strong>Range Category:</strong></span> <a class="link" href="../../../concepts/single_pass_range.html" title="Single Pass Range">Single 99 Pass Range</a> 100 </li> 101<li class="listitem"> 102 <span class="bold"><strong>Range Return Type:</strong></span> <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unwrap_ref_range</span><span class="special"><</span><span class="keyword">decltype</span><span class="special">(</span><span class="identifier">rng</span><span class="special">)></span></code> 103 </li> 104<li class="listitem"> 105 <span class="bold"><strong>Returned Range Category:</strong></span> The range 106 category of <code class="computeroutput"><span class="identifier">rng</span></code>. 107 </li> 108</ul></div> 109<div class="section"> 110<div class="titlepage"><div><div><h6 class="title"> 111<a name="range.reference.adaptors.reference.ref_unwrapped.ref_unwrapped_example"></a><a class="link" href="ref_unwrapped.html#range.reference.adaptors.reference.ref_unwrapped.ref_unwrapped_example" title="ref_unwrapped example">ref_unwrapped 112 example</a> 113</h6></div></div></div> 114<p> 115</p> 116<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">range</span><span class="special">/</span><span class="identifier">adaptor</span><span class="special">/</span><span class="identifier">ref_unwrapped</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 117<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 118<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">vector</span><span class="special">></span> 119 120<span class="keyword">struct</span> <span class="identifier">example</span> 121<span class="special">{</span> 122 <span class="keyword">int</span> <span class="identifier">value</span><span class="special">;</span> 123<span class="special">};</span> 124 125<span class="keyword">int</span> <span class="identifier">main</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">argc</span><span class="special">,</span> <span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">argv</span><span class="special">[])</span> 126<span class="special">{</span> 127 <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">adaptors</span><span class="special">::</span><span class="identifier">ref_unwrapped</span><span class="special">;</span> 128 129 <span class="identifier">example</span> <span class="identifier">one</span><span class="special">{</span><span class="number">1</span><span class="special">};</span> 130 <span class="identifier">example</span> <span class="identifier">two</span><span class="special">{</span><span class="number">2</span><span class="special">};</span> 131 <span class="identifier">example</span> <span class="identifier">three</span><span class="special">{</span><span class="number">3</span><span class="special">};</span> 132 133 <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">reference_wrapper</span><span class="special"><</span><span class="identifier">example</span><span class="special">></span> <span class="special">></span> <span class="identifier">input</span><span class="special">{</span><span class="identifier">one</span><span class="special">,</span> <span class="identifier">two</span><span class="special">,</span> <span class="identifier">three</span><span class="special">};</span> 134 135 <span class="keyword">for</span> <span class="special">(</span><span class="keyword">auto</span><span class="special">&&</span> <span class="identifier">entry</span> <span class="special">:</span> <span class="identifier">input</span> <span class="special">|</span> <span class="identifier">ref_unwrapped</span><span class="special">)</span> 136 <span class="special">{</span> 137 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">entry</span><span class="special">.</span><span class="identifier">value</span><span class="special">;</span> 138 <span class="special">}</span> 139 140 <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> 141<span class="special">}</span> 142</pre> 143<p> 144 </p> 145</div> 146<p> 147 This would produce the output <code class="computeroutput"><span class="number">123</span></code>. 148 </p> 149</div> 150<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 151<td align="left"></td> 152<td align="right"><div class="copyright-footer">Copyright © 2003-2010 Thorsten Ottosen, 153 Neil Groves<p> 154 Distributed under the Boost Software License, Version 1.0. (See accompanying 155 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>) 156 </p> 157</div></td> 158</tr></table> 159<hr> 160<div class="spirit-nav"> 161<a accesskey="p" href="map_values.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="replaced.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 162</div> 163</body> 164</html> 165
