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84 lines
5.9 KiB
HTML
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<link rel="home" href="../../index.html" title="Chapter 1. Range 2.0">
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</div>
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<div class="section" title="Utilities">
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<div class="titlepage"><div><div><h3 class="title">
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<a name="range.reference.utilities"></a><a class="link" href="utilities.html" title="Utilities"> Utilities</a>
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</h3></div></div></div>
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<div class="toc"><dl>
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<dt><span class="section"><a href="utilities/iterator_range.html"> Class <code class="computeroutput"><span class="identifier">iterator_range</span></code></a></span></dt>
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<dt><span class="section"><a href="utilities/sub_range.html"> Class <code class="computeroutput"><span class="identifier">sub_range</span></code></a></span></dt>
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<dt><span class="section"><a href="utilities/join.html"> Function join</a></span></dt>
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</dl></div>
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<p>
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Having an abstraction that encapsulates a pair of iterators is very useful.
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The standard library uses <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code>
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in some circumstances, but that class is cumbersome to use because we need
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to specify two template arguments, and for all range algorithm purposes we
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must enforce the two template arguments to be the same. Moreover, <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special"><</span><span class="identifier">iterator</span><span class="special">,</span><span class="identifier">iterator</span><span class="special">></span></code> is hardly self-documenting whereas more
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domain specific class names are. Therefore these two classes are provided:
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</p>
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<div class="itemizedlist"><ul class="itemizedlist" type="disc">
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<li class="listitem">
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Class <code class="computeroutput"><span class="identifier">iterator_range</span></code>
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</li>
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<li class="listitem">
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Class <code class="computeroutput"><span class="identifier">sub_range</span></code>
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</li>
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<li class="listitem">
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Function <code class="computeroutput"><span class="identifier">join</span></code>
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</li>
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</ul></div>
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<p>
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The <code class="computeroutput"><span class="identifier">iterator_range</span></code> class
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is templated on an <a href="../../../../../../libs/iterator/doc/new-iter-concepts.html#forward-traversal-iterators-lib-forward-traversal-iterators" target="_top">Forward
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Traversal Iterator</a> and should be used whenever fairly general code
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is needed. The <code class="computeroutput"><span class="identifier">sub_range</span></code>
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class is templated on an <a class="link" href="../concepts/forward_range.html" title="Forward Range">Forward
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Range</a> and it is less general, but a bit easier to use since its template
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argument is easier to specify. The biggest difference is, however, that a
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<code class="computeroutput"><span class="identifier">sub_range</span></code> can propagate constness
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because it knows what a corresponding <code class="computeroutput"><span class="identifier">const_iterator</span></code>
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is.
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</p>
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<p>
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Both classes can be used as ranges since they implement the <a class="link" href="extending.html" title="Extending the library">minimal
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interface</a> required for this to work automatically.
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</p>
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</div>
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<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="left"></td>
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<td align="right"><div class="copyright-footer">Copyright © 2003 -2010 Thorsten Ottosen, Neil Groves<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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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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</p>
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</div></td>
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