198 lines
9.5 KiB
HTML
198 lines
9.5 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
<html>
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
|
||
<title>Concept BidirectionalIterator</title>
|
||
<link rel="stylesheet" href="../../doc/src/boostbook.css" type="text/css">
|
||
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
|
||
<link rel="home" href="index.html" title="The Boost C++ Libraries BoostBook Documentation Subset">
|
||
<link rel="up" href="concept_check.html#concepts.reference" title="Concept reference">
|
||
<link rel="prev" href="ForwardIterator.html" title="Concept ForwardIterator">
|
||
<link rel="next" href="RandomAccessIterator.html" title="Concept RandomAccessIterator">
|
||
</head>
|
||
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
|
||
<table cellpadding="2" width="100%"><tr>
|
||
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../boost.png"></td>
|
||
<td align="center"><a href="../../index.html">Home</a></td>
|
||
<td align="center"><a href="../../libs/libraries.htm">Libraries</a></td>
|
||
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
|
||
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
|
||
<td align="center"><a href="../../more/index.htm">More</a></td>
|
||
</tr></table>
|
||
<hr>
|
||
<div class="spirit-nav">
|
||
<a accesskey="p" href="ForwardIterator.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="concept_check.html#concepts.reference"><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="RandomAccessIterator.html"><img src="../../doc/src/images/next.png" alt="Next"></a>
|
||
</div>
|
||
<div class="refentry">
|
||
<a name="BidirectionalIterator"></a><div class="titlepage"></div>
|
||
<div class="refnamediv">
|
||
<h2><span class="refentrytitle">Concept BidirectionalIterator</span></h2>
|
||
<p>BidirectionalIterator</p>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.3"></a><h2>Description</h2>
|
||
<p>A bidirectional iterator is an iterator that can read through a sequence
|
||
of values. It can move in either direction through the sequence, and can
|
||
be either mutable (data pointed to by it can be changed) or not mutable.</p>
|
||
<p>An iterator represents a position in a sequence. Therefore, the
|
||
iterator can point into the sequence (returning a value when dereferenced
|
||
and being incrementable), or be off-the-end (and not dereferenceable or
|
||
incrementable).</p>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.4"></a><h2>Refinement of</h2>
|
||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><a class="link" href="ForwardIterator.html" title="Concept ForwardIterator">ForwardIterator</a></p></li></ul></div>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.5"></a><h2>Associated types</h2>
|
||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||
<li class="listitem">
|
||
<p><span class="bold"><strong>value_type</strong></span></p>
|
||
<pre class="literallayout">std::iterator_traits<Iter>::value_type</pre>
|
||
<p>The value type of the iterator</p>
|
||
</li>
|
||
<li class="listitem">
|
||
<p><span class="bold"><strong>category</strong></span></p>
|
||
<pre class="literallayout">std::iterator_traits<Iter>::iterator_category</pre>
|
||
<p>The category of the iterator</p>
|
||
</li>
|
||
</ul></div>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.6"></a><h2>Notation</h2>
|
||
<div class="variablelist"><dl class="variablelist">
|
||
<dt><span class="term">Iter</span></dt>
|
||
<dd>A type playing the role of iterator-type in the <a class="link" href="BidirectionalIterator.html" title="Concept BidirectionalIterator">BidirectionalIterator</a> concept.</dd>
|
||
<dt>
|
||
<span class="term"><code class="varname">i</code>, </span><span class="term"><code class="varname">j</code></span>
|
||
</dt>
|
||
<dd>Objects of type Iter</dd>
|
||
<dt><span class="term"><code class="varname">x</code></span></dt>
|
||
<dd>Object of type value_type</dd>
|
||
</dl></div>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.7"></a><h2>Type expressions</h2>
|
||
<div class="variablelist"><dl class="variablelist">
|
||
<dt><span class="term">Category tag</span></dt>
|
||
<dd><p><span class="type">category</span> must be
|
||
derived from <span class="type">std::bidirectional_iterator_tag</span>.
|
||
</p></dd>
|
||
</dl></div>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.8"></a><h2>Valid expressions</h2>
|
||
<div class="informaltable"><table class="table">
|
||
<colgroup>
|
||
<col>
|
||
<col>
|
||
<col>
|
||
<col>
|
||
<col>
|
||
<col>
|
||
</colgroup>
|
||
<thead><tr>
|
||
<th>Name</th>
|
||
<th>Expression</th>
|
||
<th>Type</th>
|
||
<th>Precondition</th>
|
||
<th>Semantics</th>
|
||
<th>Postcondition</th>
|
||
</tr></thead>
|
||
<tbody>
|
||
<tr>
|
||
<td><p>Predecrement</p></td>
|
||
<td><p>--i</p></td>
|
||
<td><p><span class="type">Iter &</span></p></td>
|
||
<td><p><code class="computeroutput">i</code> is incrementable (not
|
||
off-the-end) and some dereferenceable iterator <code class="computeroutput">j</code> exists
|
||
such that <code class="computeroutput">i == ++j</code></p></td>
|
||
<td> </td>
|
||
<td> </td>
|
||
</tr>
|
||
<tr>
|
||
<td><p>Postdecrement</p></td>
|
||
<td><p>i--</p></td>
|
||
<td><p><span class="type">Iter</span></p></td>
|
||
<td><p>Same as for predecrement</p></td>
|
||
<td><p>Equivalent to <code class="computeroutput">{Iter j = i; --i; return j;}</code></p></td>
|
||
<td><p><code class="computeroutput">i</code> is dereferenceable or
|
||
off-the-end</p></td>
|
||
</tr>
|
||
</tbody>
|
||
</table></div>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.9"></a><h2>Complexity</h2>
|
||
<p>
|
||
All iterator operations must take amortized constant time.
|
||
</p>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.10"></a><h2>Invariants</h2>
|
||
<div class="variablelist"><dl class="variablelist">
|
||
<dt><span class="term">Predecrement must return object</span></dt>
|
||
<dd><p>
|
||
<code class="computeroutput">&i = &(--i)</code>
|
||
</p></dd>
|
||
<dt><span class="term">Unique path through sequence</span></dt>
|
||
<dd><p>
|
||
<code class="computeroutput">i == j</code> implies <code class="computeroutput">--i == --j</code>
|
||
</p></dd>
|
||
<dt><span class="term">Increment and decrement are inverses</span></dt>
|
||
<dd><p>
|
||
<code class="computeroutput">++i; --i;</code> and <code class="computeroutput">--i; ++i;</code> must end up with the
|
||
value of <code class="computeroutput">i</code> unmodified, if <code class="computeroutput">i</code> both of the
|
||
operations in the pair are valid.
|
||
</p></dd>
|
||
</dl></div>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.11"></a><h2>Models</h2>
|
||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
|
||
<li class="listitem"><span class="simplelist"><span class="type">T *</span></span></li>
|
||
<li class="listitem"><span class="simplelist"><span class="type">std::list<T>::iterator</span></span></li>
|
||
</ul></div>
|
||
</div>
|
||
<div class="refsect1">
|
||
<a name="id-1.3.50.3.8.12"></a><h2>See also</h2>
|
||
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><a class="link" href="RandomAccessIterator.html" title="Concept RandomAccessIterator">RandomAccessIterator</a></p></li></ul></div>
|
||
</div>
|
||
</div>
|
||
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
|
||
<td align="left"></td>
|
||
<td align="right"><div class="copyright-footer">Copyright © 2001, 2002 Indiana University<br>Copyright © 2000, 2001 University of Notre Dame du Lac<br>Copyright © 2000 Jeremy Siek, Lie-Quan Lee, Andrew Lumsdaine<br>Copyright © 1996-1999 Silicon Graphics Computer Systems, Inc.<br>Copyright © 1994 Hewlett-Packard Company<p>Distributed under the Boost Software License, Version 1.0.
|
||
(See accompanying file <code class="filename">LICENSE_1_0.txt</code> 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>
|
||
<p>This product includes software developed at the University
|
||
of Notre Dame and the Pervasive Technology Labs at Indiana
|
||
University. For technical information contact Andrew Lumsdaine
|
||
at the Pervasive Technology Labs at Indiana University. For
|
||
administrative and license questions contact the Advanced
|
||
Research and Technology Institute at 351 West 10th Street.
|
||
Indianapolis, Indiana 46202, phone 317-278-4100, fax
|
||
317-274-5902.</p>
|
||
<p>Some concepts based on versions from the MTL draft manual
|
||
and Boost Graph and Property Map documentation, the SGI Standard
|
||
Template Library documentation and the Hewlett-Packard STL,
|
||
under the following license:
|
||
</p>
|
||
<div class="blockquote"><blockquote class="blockquote"><p>Permission to use, copy, modify, distribute and
|
||
sell this software and its documentation for any purpose is
|
||
hereby granted without fee, provided that the above copyright
|
||
notice appears in all copies and that both that copyright
|
||
notice and this permission notice appear in supporting
|
||
documentation. Silicon Graphics makes no representations
|
||
about the suitability of this software for any purpose. It is
|
||
provided "as is" without express or implied
|
||
warranty.</p></blockquote></div>
|
||
</div></td>
|
||
</tr></table>
|
||
<hr>
|
||
<div class="spirit-nav">
|
||
<a accesskey="p" href="ForwardIterator.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="concept_check.html#concepts.reference"><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="RandomAccessIterator.html"><img src="../../doc/src/images/next.png" alt="Next"></a>
|
||
</div>
|
||
</body>
|
||
</html>
|