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<div class="titlepage"><div><div><h3 class="title">
<a name="fusion.extension.iterator_facade"></a><a href="iterator_facade.html" title="Iterator Facade">Iterator Facade</a></h3></div></div></div>
<a name="fusion.extension.iterator_facade.description"></a><h4>
<a name="id647889"></a>
<a href="iterator_facade.html#fusion.extension.iterator_facade.description">Description</a>
</h4>
<p>
The <a href="iterator_facade.html" title="Iterator Facade"><tt class="computeroutput"><span class="identifier">iterator_facade</span></tt></a>
template provides an intrusive mechanism for producing a conforming Fusion
iterator.
</p>
<a name="fusion.extension.iterator_facade.synopsis"></a><h4>
<a name="id647937"></a>
<a href="iterator_facade.html#fusion.extension.iterator_facade.synopsis">Synopsis</a>
</h4>
<pre class="programlisting">
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Derived</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">TravesalTag</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">iterator_facade</span><span class="special">;</span>
</pre>
<a name="fusion.extension.iterator_facade.usage"></a><h4>
<a name="id648032"></a>
<a href="iterator_facade.html#fusion.extension.iterator_facade.usage">Usage</a>
</h4>
<p>
The user of iterator_facade derives his iterator type from a specialization
of iterator_facade and passes the derived iterator type as the first template
parameter. The second template parameter should be the traversal category
of the iterator being implemented.
</p>
<p>
The user must the implement the key expressions required by their iterator
type.
</p>
<div class="table">
<a name="id648058"></a><p class="title"><b>Table<EFBFBD>1.93.<2E>Parameters</b></p>
<table class="table" summary="Parameters">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span></tt>, <tt class="computeroutput"><span class="identifier">It</span></tt>, <tt class="computeroutput"><span class="identifier">It1</span></tt>,
<tt class="computeroutput"><span class="identifier">It2</span></tt>
</p>
</td>
<td>
<p>
A type derived from <a href="iterator_facade.html" title="Iterator Facade"><tt class="computeroutput"><span class="identifier">iterator_facade</span></tt></a>
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">N</span></tt>
</p>
</td>
<td>
<p>
An <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL
Integral Constant</a>
</p>
</td>
</tr>
</tbody>
</table>
</div>
<div class="table">
<a name="id648216"></a><p class="title"><b>Table<EFBFBD>1.94.<2E>Key Expressions</b></p>
<table class="table" summary="Key Expressions">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Result
</p>
</th>
<th>
<p>
Default
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">value_of</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">&gt;::</span><span class="identifier">type</span></tt>
</p>
</td>
<td>
<p>
The element stored at iterator position <tt class="computeroutput"><span class="identifier">It</span></tt>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">deref</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">&gt;::</span><span class="identifier">type</span></tt>
</p>
</td>
<td>
<p>
The type returned when dereferencing an iterator of type <tt class="computeroutput"><span class="identifier">It</span></tt>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">deref</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">&gt;::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></tt>
</p>
</td>
<td>
<p>
Dereferences iterator <tt class="computeroutput"><span class="identifier">it</span></tt>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">next</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">&gt;::</span><span class="identifier">type</span></tt>
</p>
</td>
<td>
<p>
The type of the next element from <tt class="computeroutput"><span class="identifier">It</span></tt>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">next</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">&gt;::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></tt>
</p>
</td>
<td>
<p>
The next iterator after <tt class="computeroutput"><span class="identifier">it</span></tt>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">prior</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">&gt;::</span><span class="identifier">type</span></tt>
</p>
</td>
<td>
<p>
The type of the next element from <tt class="computeroutput"><span class="identifier">It</span></tt>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">prior</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">&gt;::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></tt>
</p>
</td>
<td>
<p>
The next iterator after <tt class="computeroutput"><span class="identifier">it</span></tt>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">advance</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">,</span> <span class="identifier">N</span><span class="special">&gt;::</span><span class="identifier">type</span></tt>
</p>
</td>
<td>
<p>
The type of an iterator advanced <tt class="computeroutput"><span class="identifier">N</span></tt>
elements from <tt class="computeroutput"><span class="identifier">It</span></tt>
</p>
</td>
<td>
<p>
Implemented in terms of <tt class="computeroutput"><span class="identifier">next</span></tt>
and <tt class="computeroutput"><span class="identifier">prior</span></tt>
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">advance</span><span class="special">&lt;</span><span class="identifier">It</span><span class="special">,</span> <span class="identifier">N</span><span class="special">&gt;::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it</span><span class="special">)</span></tt>
</p>
</td>
<td>
<p>
An iterator advanced <tt class="computeroutput"><span class="identifier">N</span></tt>
elements from <tt class="computeroutput"><span class="identifier">it</span></tt>
</p>
</td>
<td>
<p>
Implemented in terms of <tt class="computeroutput"><span class="identifier">next</span></tt>
and <tt class="computeroutput"><span class="identifier">prior</span></tt>
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">distance</span><span class="special">&lt;</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">&gt;::</span><span class="identifier">type</span></tt>
</p>
</td>
<td>
<p>
The distance between iterators of type <tt class="computeroutput"><span class="identifier">It1</span></tt>
and <tt class="computeroutput"><span class="identifier">It2</span></tt> as an <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL
Integral Constant</a>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">distance</span><span class="special">&lt;</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">&gt;::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it1</span><span class="special">,</span> <span class="identifier">it2</span><span class="special">)</span></tt>
</p>
</td>
<td>
<p>
The distance between iterator <tt class="computeroutput"><span class="identifier">it1</span></tt>
and <tt class="computeroutput"><span class="identifier">it2</span></tt>
</p>
</td>
<td>
<p>
None
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">equal_to</span><span class="special">&lt;</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">&gt;::</span><span class="identifier">type</span></tt>
</p>
</td>
<td>
<p>
The distance between iterators of type <tt class="computeroutput"><span class="identifier">It1</span></tt>
and <tt class="computeroutput"><span class="identifier">It2</span></tt>
</p>
</td>
<td>
<p>
<tt class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">same_type</span><span class="special">&lt;</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">&gt;::</span><span class="identifier">type</span></tt>
</p>
</td>
</tr>
<tr>
<td>
<p>
<tt class="computeroutput"><span class="identifier">iterator</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">equal_to</span><span class="special">&lt;</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">&gt;::</span><span class="identifier">call</span><span class="special">(</span><span class="identifier">it1</span><span class="special">,</span> <span class="identifier">it2</span><span class="special">)</span></tt>
</p>
</td>
<td>
<p>
The distance between iterators <tt class="computeroutput"><span class="identifier">it1</span></tt>
and <tt class="computeroutput"><span class="identifier">it2</span></tt>
</p>
</td>
<td>
<p>
<tt class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">same_type</span><span class="special">&lt;</span><span class="identifier">It1</span><span class="special">,</span> <span class="identifier">It2</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">()</span></tt>
</p>
</td>
</tr>
</tbody>
</table>
</div>
<a name="fusion.extension.iterator_facade.header"></a><h4>
<a name="id649776"></a>
<a href="iterator_facade.html#fusion.extension.iterator_facade.header">Header</a>
</h4>
<pre class="programlisting">
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">iterator</span><span class="special">/</span><span class="identifier">iterator_facade</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">iterator_facade</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<a name="fusion.extension.iterator_facade.example"></a><h4>
<a name="id649935"></a>
<a href="iterator_facade.html#fusion.extension.iterator_facade.example">Example</a>
</h4>
<p>
A full worked example using <a href="iterator_facade.html" title="Iterator Facade"><tt class="computeroutput"><span class="identifier">iterator_facade</span></tt></a> is provided in triple.cpp
in the extension examples.
</p>
</div>
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<td align="right"><div class="copyright-footer"><small>Copyright <20> 2001-2007 Joel de Guzman, Dan Marsden, Tobias
Schwinger<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></small></div></td>
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