1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Class sub_range</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="../utilities.html" title="Utilities"> 9<link rel="prev" href="iterator_range.html" title="Class iterator_range"> 10<link rel="next" href="combine.html" title="Function combine"> 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="iterator_range.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../utilities.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="combine.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="range.reference.utilities.sub_range"></a><a class="link" href="sub_range.html" title="Class sub_range">Class <code class="computeroutput"><span class="identifier">sub_range</span></code></a> 28</h4></div></div></div> 29<p> 30 The <code class="computeroutput"><span class="identifier">sub_range</span></code> class inherits 31 all its functionality from the <a class="link" href="iterator_range.html" title="Class iterator_range"><code class="computeroutput"><span class="identifier">iterator_range</span></code></a> class. The <code class="computeroutput"><span class="identifier">sub_range</span></code> class is often easier to use 32 because one must specify the <a class="link" href="../../concepts/forward_range.html" title="Forward Range">Forward 33 Range</a> template argument instead of an iterator. Moreover, the <code class="computeroutput"><span class="identifier">sub_range</span></code> class can propagate constness 34 since it knows what a corresponding <code class="computeroutput"><span class="identifier">const_iterator</span></code> 35 is. 36 </p> 37<h5> 38<a name="range.reference.utilities.sub_range.h0"></a> 39 <span class="phrase"><a name="range.reference.utilities.sub_range.synopsis"></a></span><a class="link" href="sub_range.html#range.reference.utilities.sub_range.synopsis">Synopsis</a> 40 </h5> 41<p> 42</p> 43<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> 44<span class="special">{</span> 45 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange</span> <span class="special">></span> 46 <span class="keyword">class</span> <span class="identifier">sub_range</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">iterator_range</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">range_iterator</span><span class="special"><</span><span class="identifier">ForwardRange</span><span class="special">>::</span><span class="identifier">type</span> <span class="special">></span> 47 <span class="special">{</span> 48 <span class="keyword">public</span><span class="special">:</span> 49 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">range_value</span><span class="special"><</span><span class="identifier">ForwardRange</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">value_type</span><span class="special">;</span> 50 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">range_iterator</span><span class="special"><</span><span class="identifier">ForwardRange</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">iterator</span><span class="special">;</span> 51 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">range_iterator</span><span class="special"><</span><span class="keyword">const</span> <span class="identifier">ForwardRange</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">const_iterator</span><span class="special">;</span> 52 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">range_difference</span><span class="special"><</span><span class="identifier">ForwardRange</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">difference_type</span><span class="special">;</span> 53 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">range_size</span><span class="special"><</span><span class="identifier">ForwardRange</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">size_type</span><span class="special">;</span> 54 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">range_reference</span><span class="special"><</span><span class="identifier">ForwardRange</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">reference</span><span class="special">;</span> 55 <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">range_reference</span><span class="special"><</span><span class="keyword">const</span> <span class="identifier">ForwardRange</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">const_reference</span><span class="special">;</span> 56 57 <span class="keyword">public</span><span class="special">:</span> <span class="comment">// construction, assignment</span> 58 <span class="identifier">sub_range</span><span class="special">();</span> 59 60 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardTraversalIterator</span> <span class="special">></span> 61 <span class="identifier">sub_range</span><span class="special">(</span> <span class="identifier">ForwardTraversalIterator</span> <span class="identifier">Begin</span><span class="special">,</span> <span class="identifier">ForwardTraversalIterator</span> <span class="identifier">End</span> <span class="special">);</span> 62 63 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange2</span> <span class="special">></span> 64 <span class="identifier">sub_range</span><span class="special">(</span> <span class="identifier">ForwardRange2</span><span class="special">&</span> <span class="identifier">r</span> <span class="special">);</span> 65 66 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange2</span> <span class="special">></span> 67 <span class="identifier">sub_range</span><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">Range2</span><span class="special">&</span> <span class="identifier">r</span> <span class="special">);</span> 68 69 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange2</span> <span class="special">></span> 70 <span class="identifier">sub_range</span><span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="identifier">ForwardRange2</span><span class="special">&</span> <span class="identifier">r</span> <span class="special">);</span> 71 72 <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange2</span> <span class="special">></span> 73 <span class="identifier">sub_range</span><span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span> <span class="keyword">const</span> <span class="identifier">ForwardRange2</span><span class="special">&</span> <span class="identifier">r</span> <span class="special">);</span> 74 75 <span class="comment">// iterator accessors</span> 76 <span class="identifier">const_iterator</span> <span class="identifier">begin</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> 77 <span class="identifier">iterator</span> <span class="identifier">begin</span><span class="special">();</span> 78 <span class="identifier">const_iterator</span> <span class="identifier">end</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> 79 <span class="identifier">iterator</span> <span class="identifier">end</span><span class="special">();</span> 80 81 <span class="identifier">reference</span> <span class="identifier">front</span><span class="special">();</span> 82 <span class="identifier">const_reference</span> <span class="identifier">front</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> 83 84 <span class="identifier">sub_range</span><span class="special">&</span> <span class="identifier">advance_begin</span><span class="special">(</span><span class="identifier">difference_type</span> <span class="identifier">n</span><span class="special">);</span> 85 <span class="identifier">sub_range</span><span class="special">&</span> <span class="identifier">advance_end</span><span class="special">(</span><span class="identifier">difference_type</span> <span class="identifier">n</span><span class="special">);</span> 86 87 <span class="comment">// If traversal >= bidirectional:</span> 88 <span class="identifier">reference</span> <span class="identifier">back</span><span class="special">();</span> 89 <span class="identifier">const_reference</span> <span class="identifier">back</span><span class="special">();</span> 90 91 <span class="comment">// If traversal >= random-access:</span> 92 <span class="identifier">reference</span> <span class="keyword">operator</span><span class="special">[](</span><span class="identifier">difference_type</span> <span class="identifier">n</span><span class="special">);</span> 93 <span class="identifier">const_reference</span> <span class="keyword">operator</span><span class="special">[](</span><span class="identifier">difference_type</span> <span class="identifier">n</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 94 95 <span class="keyword">public</span><span class="special">:</span> 96 <span class="comment">// rest of interface inherited from iterator_range</span> 97 <span class="special">};</span> 98 99<span class="special">}</span> <span class="comment">// namespace 'boost'</span> 100</pre> 101<p> 102 </p> 103<p> 104 The class should be trivial to use as seen below. Imagine that we have 105 an algorithm that searches for a sub-string in a string. The result is 106 an iterator_range, that delimits the match. We need to store the result 107 from this algorithm. Here is an example of how we can do it with and without 108 <code class="computeroutput"><span class="identifier">sub_range</span></code> 109 </p> 110<p> 111</p> 112<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">str</span><span class="special">(</span><span class="string">"hello"</span><span class="special">);</span> 113<span class="identifier">iterator_range</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">::</span><span class="identifier">iterator</span><span class="special">></span> <span class="identifier">ir</span> <span class="special">=</span> <span class="identifier">find_first</span><span class="special">(</span> <span class="identifier">str</span><span class="special">,</span> <span class="string">"ll"</span> <span class="special">);</span> 114<span class="identifier">sub_range</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">></span> <span class="identifier">sub</span> <span class="special">=</span> <span class="identifier">find_first</span><span class="special">(</span> <span class="identifier">str</span><span class="special">,</span> <span class="string">"ll"</span> <span class="special">);</span> 115</pre> 116<p> 117 </p> 118</div> 119<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 120<td align="left"></td> 121<td align="right"><div class="copyright-footer">Copyright © 2003-2010 Thorsten Ottosen, 122 Neil Groves<p> 123 Distributed under the Boost Software License, Version 1.0. (See accompanying 124 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>) 125 </p> 126</div></td> 127</tr></table> 128<hr> 129<div class="spirit-nav"> 130<a accesskey="p" href="iterator_range.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../utilities.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="combine.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> 131</div> 132</body> 133</html> 134
