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<title>Associative Sequence</title>
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<div class="titlepage"><div><div><h4 class="title">
<a name="fusion.sequence.concepts.associative_sequence"></a><a class="link" href="associative_sequence.html" title="Associative Sequence">Associative
Sequence</a>
</h4></div></div></div>
<a name="fusion.sequence.concepts.associative_sequence.description"></a><h6>
<a name="id915409"></a>
<a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.description">Description</a>
</h6>
<p>
An Associative Sequence allows efficient retrieval of elements based on
keys. Like associative sequences in <a href="http://www.boost.org/libs/mpl/index.html" target="_top">MPL</a>,
and unlike associative containers in <a href="http://en.wikipedia.org/wiki/Standard_Template_Library" target="_top">STL</a>,
Fusion associative sequences have no implied ordering relation. Instead,
type identity is used to impose an equivalence relation on keys.
</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>
An Associative Sequence
</p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">S</span></code></span></dt>
<dd><p>
An Associative Sequence type
</p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">K</span></code></span></dt>
<dd><p>
An arbitrary <span class="emphasis"><em>key</em></span> type
</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.associative_sequence.valid_expressions"></a><h6>
<a name="id915548"></a>
<a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.valid_expressions">Valid
Expressions</a>
</h6>
<p>
For any Associative Sequence the following expressions must be valid:
</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/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">has_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
<a href="http://www.boost.org/libs/mpl/doc/refmanual/integral-constant.html" target="_top">MPL
Boolean Constant</a>. Convertible to bool.
</p>
</td>
<td>
</td>
<td>
<p>
Constant
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">K</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_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">K</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.associative_sequence.result_type_expressions"></a><h6>
<a name="id915844"></a>
<a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_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/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">has_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span>
<span class="identifier">K</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_key.html" title="at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span>
<span class="identifier">K</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_key.html" title="value_at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">K</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_key.html" title="at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">K</span><span class="special">></span></code> returns the actual type returned by
<code class="computeroutput"><a class="link" href="../intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">K</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_key.html" title="at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">S</span><span class="special">,</span> <span class="identifier">K</span><span class="special">></span></code>.The element at <code class="computeroutput"><span class="identifier">K</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_key.html" title="value_at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at_key</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.associative_sequence.expression_semantics"></a><h6>
<a name="id916252"></a>
<a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.expression_semantics">Expression
Semantics</a>
</h6>
<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/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">has_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
A boolean Integral Constant <code class="computeroutput"><span class="identifier">c</span></code>
such that <code class="computeroutput"><span class="identifier">c</span><span class="special">::</span><span class="identifier">value</span> <span class="special">==</span>
<span class="keyword">true</span></code> if and only if there
is one or more elements with the key <code class="computeroutput"><span class="identifier">k</span></code>
in <code class="computeroutput"><span class="identifier">s</span></code>; see <a class="link" href="../intrinsic/functions/has_key.html" title="has_key"><code class="computeroutput"><span class="identifier">has_key</span></code></a>.
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><a class="link" href="../intrinsic/functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">K</span><span class="special">>(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
The element associated with the key <code class="computeroutput"><span class="identifier">K</span></code>
in the sequence <code class="computeroutput"><span class="identifier">s</span></code>;
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.associative_sequence.models"></a><h6>
<a name="id916477"></a>
<a class="link" href="associative_sequence.html#fusion.sequence.concepts.associative_sequence.models">Models</a>
</h6>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
<a class="link" href="../../container/set.html" title="set"><code class="computeroutput"><span class="identifier">set</span></code></a>
</li>
<li class="listitem">
<a class="link" href="../../container/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a>
</li>
<li class="listitem">
<a class="link" href="../../view/filter_view.html" title="filter_view"><code class="computeroutput"><span class="identifier">filter_view</span></code></a>
(where adapted sequence is an <a class="link" href="associative_sequence.html" title="Associative Sequence">Associative
Sequence</a> and a <a class="link" href="forward_sequence.html" title="Forward Sequence">Forward
Sequence</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 iterators are <a class="link" href="../../iterator/concepts/associative_iterator.html" title="Associative Iterator">Associative
Iterator</a>s)
</li>
<li class="listitem">
<a class="link" href="../../view/joint_view.html" title="joint_view"><code class="computeroutput"><span class="identifier">joint_view</span></code></a>
(where adapted sequences are <a class="link" href="associative_sequence.html" title="Associative Sequence">Associative
Sequence</a>s and <a class="link" href="forward_sequence.html" title="Forward Sequence">Forward
Sequence</a>s)
</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>
(where adapted sequence is an <a class="link" href="associative_sequence.html" title="Associative Sequence">Associative
Sequence</a> and a <a class="link" href="bidirectional_sequence.html" title="Bidirectional Sequence">Bidirectional
Sequence</a>)
</li>
</ul></div>
</div>
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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>)
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