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<div class="document" id="range-utilities-for-c-0x">
<h1 class="title">Range Utilities for C++0x</h1>
<table class="docinfo" frame="void" rules="none">
<col class="docinfo-name" />
<col class="docinfo-content" />
<tbody valign="top">
<tr><th class="docinfo-name">Author:</th>
<td>Thorsten Ottosen</td></tr>
<tr><th class="docinfo-name">Contact:</th>
<td><a class="first last reference" href="mailto:thorsten.ottosen&#64;dezide.com">thorsten.ottosen&#64;dezide.com</a></td></tr>
<tr class="field"><th class="docinfo-name">Organizations:</th><td class="field-body"><a class="reference" href="http://www.dezide.com">Dezide Aps</a></td>
</tr>
<tr><th class="docinfo-name">Date:</th>
<td>2007-04-17</td></tr>
<tr class="field"><th class="docinfo-name">Number:</th><td class="field-body">WG21/N2245 and J16/07-0105 (concept-based revision of <a class="reference" href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2006/n2068.html">n2068</a>)</td>
</tr>
<tr class="field"><th class="docinfo-name">Working Group:</th><td class="field-body">Library</td>
</tr>
</tbody>
</table>
<div class="abstract topic">
<p class="topic-title first">Abstract</p>
<p>This paper provides motivation and wording for minimal 
iterator range utilities.</p>
</div>
<!-- ######################### -->
<!-- # Roles -->
<!-- ######################### -->
<div class="contents topic">
<p class="topic-title first"><a id="table-of-contents" name="table-of-contents">Table of Contents</a></p>
<ul class="simple">
<li><a class="reference" href="#introduction" id="id2" name="id2">Introduction</a></li>
<li><a class="reference" href="#wording" id="id3" name="id3">Wording</a></li>
<li><a class="reference" href="#header-iterator-synopsis" id="id4" name="id4">24.2 Header <tt class="docutils literal"><span class="pre">&lt;iterator&gt;</span></tt> synopsis</a></li>
<li><a class="reference" href="#range-utilities" id="id5" name="id5">24.3.6 Range utilities</a></li>
</ul>
</div>
<!-- section-numbering: -->
<div class="section">
<h1><a class="toc-backref" href="#id2" id="introduction" name="introduction">Introduction</a></h1>
<p>This document describes a few very handy and often
requested utility functions. They are all dependent on
the <cite>Range</cite> concept on which the new <a class="reference" href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2007/n2196.html">for-loop</a> is based.</p>
<p>Among other things, the functions make life easier for
users of built-in arrays and give users a uniform way to
calculate various iterators.</p>
<p>Basically this paper is a concept-based version of core pieces of <a class="reference" href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2006/n2068.html">n2068</a>.</p>
<!-- Each numbered section below describes a new section -->
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<!-- Comments are written in **bold** and are not part of the wording. -->
</div>
<div class="section">
<h1><a class="toc-backref" href="#id3" id="wording" name="wording">Wording</a></h1>
</div>
<div class="section">
<h1><a class="toc-backref" href="#id4" id="header-iterator-synopsis" name="header-iterator-synopsis">24.2 Header <tt class="docutils literal docutils literal"><span class="pre">&lt;iterator&gt;</span></tt> synopsis</a></h1>
<p><strong>Add the following to the synopsis</strong>:</p>
<pre class="literal-block">
template&lt;Range R&gt;
R::iterator begin( R&amp; r );

template&lt;Range R&gt;
R::iterator end( R&amp; r );

template&lt;Range R&gt;
bool empty( const R&amp; r );

template&lt;Range R&gt;
requires BidirectionalIterator&lt;R::iterator&gt;
reverse_iterator&lt;R::iterator&gt; rbegin( R&amp; r );

template&lt;Range R&gt;
requires BidirectionalIterator&lt;R::iterator&gt;
reverse_iterator&lt;R::iterator&gt; rend( R&amp; r );

template&lt;Range R&gt;
requires RandomAccessIterator&lt;R::iterator&gt;
R::iterator::difference_type size( const R&amp; r );

template&lt;Range R&gt;
R::iterator::difference_type distance( const R&amp; r );
</pre>
</div>
<div class="section">
<h1><a class="toc-backref" href="#id5" id="range-utilities" name="range-utilities">24.3.6 Range utilities</a></h1>
<p><strong>Add the following new section</strong>:</p>
<p><tt class="docutils literal"><span class="pre">template&lt;Range</span> <span class="pre">R&gt;</span>
<span class="pre">R::iterator</span> <span class="pre">begin(</span> <span class="pre">R&amp;</span> <span class="pre">r</span> <span class="pre">);</span></tt></p>
<ul class="simple">
<li><em>Returns:</em> <tt class="docutils literal"><span class="pre">Range&lt;R&gt;::begin(r)</span></tt></li>
</ul>
<p><tt class="docutils literal"><span class="pre">template&lt;Range</span> <span class="pre">R&gt;</span>
<span class="pre">R::iterator</span> <span class="pre">end(</span> <span class="pre">R&amp;</span> <span class="pre">r</span> <span class="pre">);</span></tt></p>
<ul class="simple">
<li><em>Returns:</em> <tt class="docutils literal"><span class="pre">Range&lt;R&gt;::end(r)</span></tt></li>
</ul>
<p><tt class="docutils literal"><span class="pre">template&lt;Range</span> <span class="pre">R&gt;</span>
<span class="pre">bool</span> <span class="pre">empty(</span> <span class="pre">const</span> <span class="pre">R&amp;</span> <span class="pre">r</span> <span class="pre">);</span></tt></p>
<ul class="simple">
<li><em>Returns:</em> <tt class="docutils literal"><span class="pre">begin(r)</span> <span class="pre">==</span> <span class="pre">end(r)</span></tt></li>
</ul>
<p><tt class="docutils literal"><span class="pre">template&lt;Range</span> <span class="pre">R&gt;</span>
<span class="pre">requires</span> <span class="pre">BidirectionalIterator&lt;R::iterator&gt;</span>
<span class="pre">reverse_iterator&lt;R::iterator&gt;</span> <span class="pre">rbegin(</span> <span class="pre">R&amp;</span> <span class="pre">r</span> <span class="pre">);</span></tt></p>
<ul class="simple">
<li><em>Returns:</em> <tt class="docutils literal"><span class="pre">reverse_iterator&lt;R::iterator&gt;(</span> <span class="pre">end(r)</span> <span class="pre">)</span></tt></li>
</ul>
<p><tt class="docutils literal"><span class="pre">template&lt;Range</span> <span class="pre">R&gt;</span>
<span class="pre">requires</span> <span class="pre">BidirectionalIterator&lt;R::iterator&gt;</span>
<span class="pre">reverse_iterator&lt;R::iterator&gt;</span> <span class="pre">rend(</span> <span class="pre">R&amp;</span> <span class="pre">r</span> <span class="pre">);</span></tt></p>
<ul class="simple">
<li><em>Returns:</em> <tt class="docutils literal"><span class="pre">reverse_iterator&lt;R::iterator&gt;(</span> <span class="pre">begin(r)</span> <span class="pre">)</span></tt></li>
</ul>
<p><tt class="docutils literal"><span class="pre">template&lt;Range</span> <span class="pre">R&gt;</span>
<span class="pre">requires</span> <span class="pre">RandomAccessIterator&lt;R::iterator&gt;</span>
<span class="pre">R::iterator::difference_type</span> <span class="pre">size(</span> <span class="pre">const</span> <span class="pre">R&amp;</span> <span class="pre">r</span> <span class="pre">);</span></tt></p>
<ul class="simple">
<li><em>Returns:</em> <tt class="docutils literal"><span class="pre">returns</span> <span class="pre">end(r)</span> <span class="pre">-</span> <span class="pre">begin(r)</span></tt></li>
</ul>
<p><tt class="docutils literal"><span class="pre">template&lt;Range</span> <span class="pre">R&gt;</span>
<span class="pre">R::iterator::difference_type</span> <span class="pre">distance(</span> <span class="pre">const</span> <span class="pre">R&amp;</span> <span class="pre">r</span> <span class="pre">);</span></tt></p>
<ul class="simple">
<li><em>Returns:</em> <tt class="docutils literal"><span class="pre">distance(begin(r),end(r))</span></tt></li>
</ul>
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