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| <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 |
| 3.1: Implement a Range Adaptor without arguments</a> |
| </h5></div></div></div> |
| <p> |
| To implement a Range Adaptor without arguments (e.g. reversed) you need |
| to: |
| </p> |
| <div class="orderedlist"><ol class="orderedlist" type="1"> |
| <li class="listitem"> |
| Provide a range for your return type, for example: |
| <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> |
| <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> |
| |
| <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">R</span> <span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">reverse_range</span> <span class="special">:</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">iterator_range</span><span class="special"><</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">reverse_iterator</span><span class="special"><</span> |
| <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="special">{</span> |
| <span class="keyword">private</span><span class="special">:</span> |
| <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">iterator_range</span><span class="special"><</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">reverse_iterator</span><span class="special"><</span> |
| <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> |
| |
| <span class="keyword">public</span><span class="special">:</span> |
| <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">reverse_iterator</span><span class="special"><</span> |
| <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> |
| |
| <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> |
| <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> |
| <span class="special">{</span> <span class="special">}</span> |
| <span class="special">};</span> |
| </pre> |
| </li> |
| <li class="listitem"> |
| Provide a tag to uniquely identify your adaptor in the <code class="computeroutput"><span class="keyword">operator</span><span class="special">|</span></code> |
| function overload set |
| <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">detail</span> <span class="special">{</span> |
| <span class="keyword">struct</span> <span class="identifier">reverse_forwarder</span> <span class="special">{};</span> |
| <span class="special">}</span> |
| </pre> |
| </li> |
| <li class="listitem"> |
| Implement <code class="computeroutput"><span class="keyword">operator</span><span class="special">|</span></code> |
| |
| <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> |
| <span class="keyword">inline</span> <span class="identifier">reverse_range</span><span class="special"><</span><span class="identifier">BidirectionalRng</span><span class="special">></span> |
| <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> |
| <span class="special">{</span> |
| <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> |
| <span class="special">}</span> |
| |
| <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">BidirectionalRng</span> <span class="special">></span> |
| <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> |
| <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> |
| <span class="special">{</span> |
| <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> |
| <span class="special">}</span> |
| </pre> |
| </li> |
| </ol></div> |
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| <td align="right"><div class="copyright-footer">Copyright © 2003 -2010 Thorsten Ottosen, Neil Groves<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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>) |
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