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<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="iterator.concepts"></a><a class="link" href="concepts.html" title="Iterator Concepts">Iterator Concepts</a>
</h2></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="concepts.html#iterator.concepts.concepts_access">Access</a></span></dt>
<dt><span class="section"><a href="concepts/concepts_traversal.html">Traversal</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="iterator.concepts.concepts_access"></a><a class="link" href="concepts.html#iterator.concepts.concepts_access" title="Access">Access</a>
</h3></div></div></div>
<h3>
<a name="iterator.concepts.concepts_access.h0"></a>
<span class="phrase"><a name="iterator.concepts.concepts_access.readable_iterator_concept"></a></span><a class="link" href="concepts.html#iterator.concepts.concepts_access.readable_iterator_concept">Readable
Iterator Concept</a>
</h3>
<p>
A class or built-in type <code class="computeroutput"><span class="identifier">X</span></code>
models the <span class="bold"><strong>Readable Iterator</strong></span> concept for
value type <code class="computeroutput"><span class="identifier">T</span></code> if, in addition
to <code class="computeroutput"><span class="identifier">X</span></code> being Assignable and
Copy Constructible, the following expressions are valid and respect the stated
semantics. <code class="computeroutput"><span class="identifier">U</span></code> is the type
of any specified member of type <code class="computeroutput"><span class="identifier">T</span></code>.
</p>
<div class="table">
<a name="iterator.concepts.concepts_access.readable_iterator_requirements_i"></a><p class="title"><b>Table&#160;1.1.&#160;Readable Iterator Requirements (in addition to Assignable and Copy
Constructible)</b></p>
<div class="table-contents"><table class="table" summary="Readable Iterator Requirements (in addition to Assignable and Copy
Constructible)">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Return Type
</p>
</th>
<th>
<p>
Note/Precondition
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">iterator_traits</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">value_type</span></code>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="identifier">T</span></code>
</p>
</td>
<td>
<p>
Any non-reference, non cv-qualified type
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code>
</p>
</td>
<td>
<p>
Convertible to <code class="computeroutput"><span class="identifier">T</span></code>
</p>
</td>
<td>
<p>
pre: <code class="computeroutput"><span class="identifier">a</span></code> is dereferenceable.
If <code class="computeroutput"><span class="identifier">a</span> <span class="special">==</span>
<span class="identifier">b</span></code> then <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code>
is equivalent to <code class="computeroutput"><span class="special">*</span><span class="identifier">b</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">a</span><span class="special">-&gt;</span><span class="identifier">m</span></code>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="identifier">U</span><span class="special">&amp;</span></code>
</p>
</td>
<td>
<p>
pre: <code class="computeroutput"><span class="special">(*</span><span class="identifier">a</span><span class="special">).</span><span class="identifier">m</span></code>
is well-defined. Equivalent to <code class="computeroutput"><span class="special">(*</span><span class="identifier">a</span><span class="special">).</span><span class="identifier">m</span></code>.
</p>
</td>
</tr>
</tbody>
</table></div>
</div>
<br class="table-break"><h3>
<a name="iterator.concepts.concepts_access.h1"></a>
<span class="phrase"><a name="iterator.concepts.concepts_access.writable_iterator_concept"></a></span><a class="link" href="concepts.html#iterator.concepts.concepts_access.writable_iterator_concept">Writable
Iterator Concept </a>
</h3>
<p>
A class or built-in type <code class="computeroutput"><span class="identifier">X</span></code>
models the <span class="bold"><strong>Writable Iterator</strong></span> concept if,
in addition to <code class="computeroutput"><span class="identifier">X</span></code> being Copy
Constructible, the following expressions are valid and respect the stated
semantics. Writable Iterators have an associated <span class="bold"><strong>set
of value types</strong></span>.
</p>
<div class="table">
<a name="iterator.concepts.concepts_access.writable_iterator_requirements_i"></a><p class="title"><b>Table&#160;1.2.&#160;Writable Iterator Requirements (in addition to Copy Constructible)</b></p>
<div class="table-contents"><table class="table" summary="Writable Iterator Requirements (in addition to Copy Constructible)">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Return Type
</p>
</th>
<th>
<p>
Precondition
</p>
</th>
</tr></thead>
<tbody><tr>
<td>
<p>
<code class="computeroutput"><span class="special">*</span><span class="identifier">a</span>
<span class="special">=</span> <span class="identifier">o</span></code>
</p>
</td>
<td>
</td>
<td>
<p>
pre: The type of <code class="computeroutput"><span class="identifier">o</span></code>
is in the set of value types of <code class="computeroutput"><span class="identifier">X</span></code>
</p>
</td>
</tr></tbody>
</table></div>
</div>
<br class="table-break"><h3>
<a name="iterator.concepts.concepts_access.h2"></a>
<span class="phrase"><a name="iterator.concepts.concepts_access.swappable_iterator_concept"></a></span><a class="link" href="concepts.html#iterator.concepts.concepts_access.swappable_iterator_concept">Swappable
Iterator Concept</a>
</h3>
<p>
A class or built-in type <code class="computeroutput"><span class="identifier">X</span></code>
models the <span class="bold"><strong>Swappable Iterator</strong></span> concept if,
in addition to <code class="computeroutput"><span class="identifier">X</span></code> being Copy
Constructible, the following expressions are valid and respect the stated
semantics.
</p>
<div class="table">
<a name="iterator.concepts.concepts_access.swappable_iterator_requirements_"></a><p class="title"><b>Table&#160;1.3.&#160;Swappable Iterator Requirements (in addition to Copy Constructible)</b></p>
<div class="table-contents"><table class="table" summary="Swappable Iterator Requirements (in addition to Copy Constructible)">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Return Type
</p>
</th>
<th>
<p>
Postcondition
</p>
</th>
</tr></thead>
<tbody><tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">iter_swap</span><span class="special">(</span><span class="identifier">a</span><span class="special">,</span>
<span class="identifier">b</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="keyword">void</span></code>
</p>
</td>
<td>
<p>
the pointed to values are exchanged
</p>
</td>
</tr></tbody>
</table></div>
</div>
<br class="table-break"><div class="sidebar">
<div class="titlepage"><div><div><p class="title"><b></b></p></div></div></div>
<p>
<span class="bold"><strong>Note:</strong></span> An iterator that is a model of the
<span class="bold"><strong>Readable</strong></span> and <span class="bold"><strong>Writable
Iterator</strong></span> concepts is also a model of <span class="bold"><strong>Swappable
Iterator</strong></span>. <span class="bold"><strong>--end note</strong></span>
</p>
</div>
<h3>
<a name="iterator.concepts.concepts_access.h3"></a>
<span class="phrase"><a name="iterator.concepts.concepts_access.lvalue_iterator_concept"></a></span><a class="link" href="concepts.html#iterator.concepts.concepts_access.lvalue_iterator_concept">Lvalue
Iterator Concept</a>
</h3>
<p>
The <span class="bold"><strong>Lvalue Iterator</strong></span> concept adds the requirement
that the return type of <code class="computeroutput"><span class="keyword">operator</span><span class="special">*</span></code> type be a reference to the value type of
the iterator.
</p>
<div class="table">
<a name="iterator.concepts.concepts_access.lvalue_iterator_requirements"></a><p class="title"><b>Table&#160;1.4.&#160;Lvalue Iterator Requirements</b></p>
<div class="table-contents"><table class="table" summary="Lvalue Iterator Requirements">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Return Type
</p>
</th>
<th>
<p>
Note/Assertion
</p>
</th>
</tr></thead>
<tbody><tr>
<td>
<p>
<code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="identifier">T</span><span class="special">&amp;</span></code>
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="identifier">T</span></code> is <span class="bold"><strong>cv</strong></span> <code class="computeroutput"><span class="identifier">iterator_traits</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;::</span><span class="identifier">value_type</span></code>
where <span class="bold"><strong>cv</strong></span> is an optional cv-qualification.
pre: <code class="computeroutput"><span class="identifier">a</span></code> is dereferenceable.
If <code class="computeroutput"><span class="identifier">a</span> <span class="special">==</span>
<span class="identifier">b</span></code> then <code class="computeroutput"><span class="special">*</span><span class="identifier">a</span></code>
is equivalent to <code class="computeroutput"><span class="special">*</span><span class="identifier">b</span></code>.
</p>
</td>
</tr></tbody>
</table></div>
</div>
<br class="table-break">
</div>
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<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 &#169; 2003, 2005 David Abrahams Jeremy Siek Thomas
Witt<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at &lt;ulink url="http://www.boost.org/LICENSE_1_0.txt"&gt;
http://www.boost.org/LICENSE_1_0.txt &lt;/ulink&gt;)
</p>
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