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<title>Random Access Sequence</title>
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<div class="titlepage"><div><div><h4 class="title">
<a name="fusion.sequence.concepts.random_access_sequence"></a><a class="link" href="random_access_sequence.html" title="Random Access Sequence">Random
Access Sequence</a>
</h4></div></div></div>
<a name="fusion.sequence.concepts.random_access_sequence.description"></a><h6>
<a name="id914030"></a>
<a class="link" href="random_access_sequence.html#fusion.sequence.concepts.random_access_sequence.description">Description</a>
</h6>
<p>
A Random Access Sequence is a <a class="link" href="bidirectional_sequence.html" title="Bidirectional Sequence">Bidirectional
Sequence</a> whose iterators model <a class="link" href="../../iterator/concepts/random_access_iterator.html" title="Random Access Iterator">Random
Access Iterator</a>. It guarantees constant time access to arbitrary
sequence elements.
</p>
<a name="fusion.sequence.concepts.random_access_sequence.refinement_of"></a><h6>
<a name="id914061"></a>
<a class="link" href="random_access_sequence.html#fusion.sequence.concepts.random_access_sequence.refinement_of">Refinement
of</a>
</h6>
<p>
<a class="link" href="bidirectional_sequence.html" title="Bidirectional Sequence">Bidirectional
Sequence</a>
</p>
<div class="variablelist">
<p class="title"><b>Notation</b></p>
<dl>
<dt><span class="term"><code class="computeroutput"><span class="identifier">s</span></code></span></dt>
<dd><p>
A Random Access Sequence
</p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">S</span></code></span></dt>
<dd><p>
A Random Access Sequence type
</p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">N</span></code></span></dt>
<dd><p>
An <a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL
Integral Constant</a>
</p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">o</span></code></span></dt>
<dd><p>
An arbitrary object
</p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">e</span></code></span></dt>
<dd><p>
A Sequence element
</p></dd>
</dl>
</div>
<a name="fusion.sequence.concepts.random_access_sequence.valid_expressions"></a><h6>
<a name="id914195"></a>
<a class="link" href="random_access_sequence.html#fusion.sequence.concepts.random_access_sequence.valid_expressions">Valid
Expressions</a>
</h6>
<p>
In addition to the requirements defined in <a class="link" href="bidirectional_sequence.html" title="Bidirectional Sequence">Bidirectional
Sequence</a>, for any Random Access Sequence the following must be met:
</p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Return type
</p>
</th>
<th>
<p>
Type Requirements
</p>
</th>
<th>
<p>
Runtime Complexity
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/functions/begin.html" title="begin"><code class="computeroutput"><span class="identifier">begin</span></code></a><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
<a class="link" href="../../iterator/concepts/random_access_iterator.html" title="Random Access Iterator">Random
Access Iterator</a>
</p>
</td>
<td>
</td>
<td>
<p>
Constant
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/functions/end.html" title="end"><code class="computeroutput"><span class="identifier">end</span></code></a><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
<a class="link" href="../../iterator/concepts/random_access_iterator.html" title="Random Access Iterator">Random
Access Iterator</a>
</p>
</td>
<td>
</td>
<td>
<p>
Constant
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/functions/at.html" title="at"><code class="computeroutput"><span class="identifier">at</span></code></a><span class="special"><</span><span class="identifier">N</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
Any type
</p>
</td>
<td>
</td>
<td>
<p>
Constant
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/functions/at.html" title="at"><code class="computeroutput"><span class="identifier">at</span></code></a><span class="special"><</span><span class="identifier">N</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span>
<span class="special">=</span> <span class="identifier">o</span></code>
</p>
</td>
<td>
<p>
Any type
</p>
</td>
<td>
<p>
<code class="computeroutput"><span class="identifier">s</span></code> is mutable
and <code class="computeroutput"><span class="identifier">e</span> <span class="special">=</span>
<span class="identifier">o</span></code>, where <code class="computeroutput"><span class="identifier">e</span></code> is the first element in the
sequence, is a valid expression.
</p>
</td>
<td>
<p>
Constant
</p>
</td>
</tr>
</tbody>
</table></div>
<a name="fusion.sequence.concepts.random_access_sequence.result_type_expressions"></a><h6>
<a name="id914680"></a>
<a class="link" href="random_access_sequence.html#fusion.sequence.concepts.random_access_sequence.result_type_expressions">Result
Type Expressions</a>
</h6>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Compile Time Complexity
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/begin.html" title="begin"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">begin</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">>::</span><span class="identifier">type</span></code>
</p>
</td>
<td>
<p>
Amortized constant time
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/end.html" title="end"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">end</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">>::</span><span class="identifier">type</span></code>
</p>
</td>
<td>
<p>
Amortized constant time
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/at.html" title="at"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span>
<span class="identifier">N</span><span class="special">>::</span><span class="identifier">type</span></code>
</p>
</td>
<td>
<p>
Amortized constant time
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/value_at.html" title="value_at"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span>
<span class="identifier">N</span><span class="special">>::</span><span class="identifier">type</span></code>
</p>
</td>
<td>
<p>
Amortized constant time
</p>
</td>
</tr>
</tbody>
</table></div>
<div class="sidebar">
<p class="title"><b></b></p>
<p>
<span class="inlinemediaobject"><img src="../../../images/note.png" alt="note"></span> <code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/at.html" title="at"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">N</span><span class="special">></span></code> returns the actual type returned by
<code class="computeroutput"><a class="link" href="../intrinsic/functions/at.html" title="at"><code class="computeroutput"><span class="identifier">at</span></code></a><span class="special"><</span><span class="identifier">N</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code>. In
most cases, this is a reference. Hence, there is no way to know the exact
element type using <code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/at.html" title="at"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">N</span><span class="special">></span></code>.The element at <code class="computeroutput"><span class="identifier">N</span></code>
may actually be a reference to begin with. For this purpose, you can use
<code class="computeroutput"><a class="link" href="../intrinsic/metafunctions/value_at.html" title="value_at"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">N</span><span class="special">></span></code>.
</p>
</div>
<a name="fusion.sequence.concepts.random_access_sequence.expression_semantics"></a><h6>
<a name="id915133"></a>
<a class="link" href="random_access_sequence.html#fusion.sequence.concepts.random_access_sequence.expression_semantics">Expression
Semantics</a>
</h6>
<p>
The semantics of an expression are defined only where they differ from,
or are not defined in <a class="link" href="bidirectional_sequence.html" title="Bidirectional Sequence">Bidirectional
Sequence</a>.
</p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Semantics
</p>
</th>
</tr></thead>
<tbody><tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/functions/at.html" title="at"><code class="computeroutput"><span class="identifier">at</span></code></a><span class="special"><</span><span class="identifier">N</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
The Nth element from the beginning of the sequence; see <a class="link" href="../intrinsic/functions/at.html" title="at"><code class="computeroutput"><span class="identifier">at</span></code></a>.
</p>
</td>
</tr></tbody>
</table></div>
<a name="fusion.sequence.concepts.random_access_sequence.models"></a><h6>
<a name="id915247"></a>
<a class="link" href="random_access_sequence.html#fusion.sequence.concepts.random_access_sequence.models">Models</a>
</h6>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a class="link" href="../../adapted/std__pair.html" title="std::pair"><code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code></a>
</li>
<li class="listitem">
<a class="link" href="../../adapted/boost__array.html" title="boost::array"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span></code></a>
</li>
<li class="listitem">
<a class="link" href="../../container/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a>
</li>
<li class="listitem">
<a class="link" href="../../view/reverse_view.html" title="reverse_view"><code class="computeroutput"><span class="identifier">reverse_view</span></code></a>
</li>
<li class="listitem">
<a class="link" href="../../view/iterator_range.html" title="iterator_range"><code class="computeroutput"><span class="identifier">iterator_range</span></code></a>
(where adapted sequence is a Random Access Sequence)
</li>
<li class="listitem">
<a class="link" href="../../view/transform_view.html" title="transform_view"><code class="computeroutput"><span class="identifier">transform_view</span></code></a>
(where adapted sequence is a Random Access Sequence)
</li>
<li class="listitem">
<a class="link" href="../../view/zip_view.html" title="zip_view"><code class="computeroutput"><span class="identifier">zip_view</span></code></a>
(where adapted sequences are models of Random Access Sequence)
</li>
</ul></div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="right"><div class="copyright-footer">Copyright © 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>
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