1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Method 3.1: Implement a Range Adaptor without arguments</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="../method_3.html" title="Method 3: provide range adaptor implementations"> 9<link rel="prev" href="../method_3.html" title="Method 3: provide range adaptor implementations"> 10<link rel="next" href="method_3_2.html" title="Method 3.2: Implement a Range Adaptor with arguments"> 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="../method_3.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../method_3.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="method_3_2.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.extending.method_3.method_3_1"></a><a class="link" href="method_3_1.html" title="Method 3.1: Implement a Range Adaptor without arguments">Method 28 3.1: Implement a Range Adaptor without arguments</a> 29</h5></div></div></div> 30<p> 31 To implement a Range Adaptor without arguments (e.g. reversed) you need 32 to: 33 </p> 34<div class="orderedlist"><ol class="orderedlist" type="1"> 35<li class="listitem"> 36 Provide a range for your return type, for example: 37<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">iterator_range</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 38<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">iterator</span><span class="special">/</span><span class="identifier">reverse_iterator</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 39 40<span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">R</span> <span class="special">></span> 41<span class="keyword">struct</span> <span class="identifier">reverse_range</span> <span class="special">:</span> 42 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">iterator_range</span><span class="special"><</span> 43 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">reverse_iterator</span><span class="special"><</span> 44 <span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_iterator</span><span class="special"><</span><span class="identifier">R</span><span class="special">>::</span><span class="identifier">type</span><span class="special">></span> <span class="special">></span> 45<span class="special">{</span> 46<span class="keyword">private</span><span class="special">:</span> 47 <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">iterator_range</span><span class="special"><</span> 48 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">reverse_iterator</span><span class="special"><</span> 49 <span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_iterator</span><span class="special"><</span><span class="identifier">R</span><span class="special">>::</span><span class="identifier">type</span><span class="special">></span> <span class="special">></span> <span class="identifier">base</span><span class="special">;</span> 50 51<span class="keyword">public</span><span class="special">:</span> 52 <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">reverse_iterator</span><span class="special"><</span> 53 <span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">range_iterator</span><span class="special"><</span><span class="identifier">R</span><span class="special">>::</span><span class="identifier">type</span> <span class="special">></span> <span class="identifier">iterator</span><span class="special">;</span> 54 55 <span class="identifier">reverse_range</span><span class="special">(</span><span class="identifier">R</span><span class="special">&</span> <span class="identifier">r</span><span class="special">)</span> 56 <span class="special">:</span> <span class="identifier">base</span><span class="special">(</span><span class="identifier">iterator</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">end</span><span class="special">(</span><span class="identifier">r</span><span class="special">)),</span> <span class="identifier">iterator</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">begin</span><span class="special">(</span><span class="identifier">r</span><span class="special">)))</span> 57 <span class="special">{</span> <span class="special">}</span> 58<span class="special">};</span> 59</pre> 60 </li> 61<li class="listitem"> 62 Provide a tag to uniquely identify your adaptor in the <code class="computeroutput"><span class="keyword">operator</span><span class="special">|</span></code> 63 function overload set 64<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">detail</span> <span class="special">{</span> 65 <span class="keyword">struct</span> <span class="identifier">reverse_forwarder</span> <span class="special">{};</span> 66<span class="special">}</span> 67</pre> 68 </li> 69<li class="listitem"> 70 Implement <code class="computeroutput"><span class="keyword">operator</span><span class="special">|</span></code> 71<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">BidirectionalRng</span> <span class="special">></span> 72<span class="keyword">inline</span> <span class="identifier">reverse_range</span><span class="special"><</span><span class="identifier">BidirectionalRng</span><span class="special">></span> 73<span class="keyword">operator</span><span class="special">|(</span> <span class="identifier">BidirectionalRng</span><span class="special">&</span> <span class="identifier">r</span><span class="special">,</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">reverse_forwarder</span> <span class="special">)</span> 74<span class="special">{</span> 75 <span class="keyword">return</span> <span class="identifier">reverse_range</span><span class="special"><</span><span class="identifier">BidirectionalRng</span><span class="special">>(</span> <span class="identifier">r</span> <span class="special">);</span> 76<span class="special">}</span> 77 78<span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">BidirectionalRng</span> <span class="special">></span> 79<span class="keyword">inline</span> <span class="identifier">reverse_range</span><span class="special"><</span><span class="keyword">const</span> <span class="identifier">BidirectionalRng</span><span class="special">></span> 80<span class="keyword">operator</span><span class="special">|(</span> <span class="keyword">const</span> <span class="identifier">BidirectionalRng</span><span class="special">&</span> <span class="identifier">r</span><span class="special">,</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">reverse_forwarder</span> <span class="special">)</span> 81<span class="special">{</span> 82 <span class="keyword">return</span> <span class="identifier">reverse_range</span><span class="special"><</span><span class="keyword">const</span> <span class="identifier">BidirectionalRng</span><span class="special">>(</span> <span class="identifier">r</span> <span class="special">);</span> 83<span class="special">}</span> 84</pre> 85 </li> 86<li class="listitem"> 87 Declare the adaptor itself (it is a variable of the tag type). 88<pre class="programlisting"><span class="keyword">namespace</span> 89<span class="special">{</span> 90 <span class="keyword">const</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">reverse_forwarder</span> <span class="identifier">reversed</span> <span class="special">=</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">reverse_forwarder</span><span class="special">();</span> 91<span class="special">}</span> 92</pre> 93 </li> 94</ol></div> 95</div> 96<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 97<td align="left"></td> 98<td align="right"><div class="copyright-footer">Copyright © 2003-2010 Thorsten Ottosen, 99 Neil Groves<p> 100 Distributed under the Boost Software License, Version 1.0. (See accompanying 101 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>) 102 </p> 103</div></td> 104</tr></table> 105<hr> 106<div class="spirit-nav"> 107<a accesskey="p" href="../method_3.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../method_3.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="method_3_2.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 108</div> 109</body> 110</html> 111
