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| <div class="titlepage"><div><div><h4 class="title"> |
| <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> |
| </h4></div></div></div> |
| <p> |
| The <code class="computeroutput"><span class="identifier">sub_range</span></code> class inherits |
| 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 |
| because one must specify the <a class="link" href="../../concepts/forward_range.html" title="Forward Range">Forward |
| Range</a> template argument instead of an iterator. Moreover, the <code class="computeroutput"><span class="identifier">sub_range</span></code> class can propagate constness |
| since it knows what a corresponding <code class="computeroutput"><span class="identifier">const_iterator</span></code> |
| is. |
| </p> |
| <a name="range.reference.utilities.sub_range.synopsis"></a><h5> |
| <a name="id871048"></a> |
| <a class="link" href="sub_range.html#range.reference.utilities.sub_range.synopsis">Synopsis</a> |
| </h5> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> |
| <span class="special">{</span> |
| <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange</span> <span class="special">></span> |
| <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> |
| <span class="special">{</span> |
| <span class="keyword">public</span><span class="special">:</span> |
| <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> |
| <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> |
| <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">iterator_difference</span><span class="special"><</span><span class="identifier">iterator</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">difference_type</span><span class="special">;</span> |
| |
| <span class="keyword">public</span><span class="special">:</span> <span class="comment">// construction, assignment |
| </span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardTraversalIterator</span> <span class="special">></span> |
| <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> |
| |
| <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange2</span> <span class="special">></span> |
| <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> |
| |
| <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange2</span> <span class="special">></span> |
| <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> |
| |
| <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange2</span> <span class="special">></span> |
| <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> |
| |
| <span class="keyword">template</span><span class="special"><</span> <span class="keyword">class</span> <span class="identifier">ForwardRange2</span> <span class="special">></span> |
| <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> |
| |
| <span class="keyword">public</span><span class="special">:</span> <span class="comment">// Forward Range functions |
| </span> <span class="identifier">iterator</span> <span class="identifier">begin</span><span class="special">();</span> |
| <span class="identifier">const_iterator</span> <span class="identifier">begin</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> |
| <span class="identifier">iterator</span> <span class="identifier">end</span><span class="special">();</span> |
| <span class="identifier">const_iterator</span> <span class="identifier">end</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> |
| |
| <span class="keyword">public</span><span class="special">:</span> <span class="comment">// convenience |
| </span> <span class="identifier">value_type</span><span class="special">&</span> <span class="identifier">front</span><span class="special">();</span> |
| <span class="keyword">const</span> <span class="identifier">value_type</span><span class="special">&</span> <span class="identifier">front</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> |
| <span class="identifier">value_type</span><span class="special">&</span> <span class="identifier">back</span><span class="special">();</span> |
| <span class="keyword">const</span> <span class="identifier">value_type</span><span class="special">&</span> <span class="identifier">back</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> |
| <span class="comment">// for Random Access Range only: |
| </span> <span class="identifier">value_type</span><span class="special">&</span> <span class="keyword">operator</span><span class="special">[](</span> <span class="identifier">size_type</span> <span class="identifier">at</span> <span class="special">);</span> |
| <span class="keyword">const</span> <span class="identifier">value_type</span><span class="special">&</span> <span class="keyword">operator</span><span class="special">[](</span> <span class="identifier">size_type</span> <span class="identifier">at</span> <span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> |
| |
| <span class="keyword">public</span><span class="special">:</span> |
| <span class="comment">// rest of interface inherited from iterator_range |
| </span> <span class="special">};</span> |
| |
| <span class="special">}</span> <span class="comment">// namespace 'boost' |
| </span></pre> |
| <p> |
| </p> |
| <p> |
| The class should be trivial to use as seen below. Imagine that we have |
| an algorithm that searches for a sub-string in a string. The result is |
| an iterator_range, that delimits the match. We need to store the result |
| from this algorithm. Here is an example of how we can do it with and without |
| <code class="computeroutput"><span class="identifier">sub_range</span></code> |
| </p> |
| <p> |
| |
| </p> |
| <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> |
| <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> |
| <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> |
| </pre> |
| <p> |
| </p> |
| </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>) |
| </p> |
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