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7 <title>The MPL Reference Manual: iterator_category
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14 <div class=
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15 <h1><a class=
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"./iterator-metafunctions.html#id1459">iterator_category
</a></h1>
16 <div class=
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17 <h3><a class=
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</a></h3>
18 <pre class=
"literal-block">
22 struct
<a href=
"./iterator-category.html" class=
"identifier">iterator_category
</a>
24 typedef typename Iterator::category type;
28 <div class=
"section" id=
"id446">
29 <h3><a class=
"subsection-title" href=
"#description" name=
"description">Description
</a></h3>
30 <p>Returns one of the following iterator category tags:
</p>
32 <li><tt class=
"literal"><span class=
"pre">forward_iterator_tag
</span></tt></li>
33 <li><tt class=
"literal"><span class=
"pre">bidirectional_iterator_tag
</span></tt></li>
34 <li><tt class=
"literal"><span class=
"pre">random_access_iterator_tag
</span></tt></li>
37 <div class=
"section" id=
"id447">
38 <h3><a class=
"subsection-title" href=
"#header" name=
"header">Header
</a></h3>
39 <pre class=
"literal-block">
40 #include
<<a href=
"../../../../boost/mpl/iterator_category.hpp" class=
"header">boost/mpl/iterator_category.hpp
</a>>
41 #include
<<a href=
"../../../../boost/mpl/iterator_tags.hpp" class=
"header">boost/mpl/iterator_tags.hpp
</a>>
44 <div class=
"section" id=
"id448">
45 <h3><a class=
"subsection-title" href=
"#parameters" name=
"parameters">Parameters
</a></h3>
46 <table border=
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52 <thead valign=
"bottom">
53 <tr><th class=
"head">Parameter
</th>
54 <th class=
"head">Requirement
</th>
55 <th class=
"head">Description
</th>
59 <tr><td><tt class=
"literal"><span class=
"pre">Iterator
</span></tt></td>
60 <td><a class=
"reference internal" href=
"./forward-iterator.html">Forward Iterator
</a></td>
61 <td>The iterator to obtain a category for.
</td>
66 <div class=
"section" id=
"id449">
67 <h3><a class=
"subsection-title" href=
"#expression-semantics" name=
"expression-semantics">Expression semantics
</a></h3>
68 <p>For any
<a class=
"reference internal" href=
"./forward-iterator.html">Forward Iterator
</a>s
<tt class=
"literal"><span class=
"pre">iter
</span></tt>:
</p>
69 <pre class=
"literal-block">
70 typedef
<a href=
"./iterator-category.html" class=
"identifier">iterator_category
</a><iter
>::type tag;
72 <table class=
"docutils field-list" frame=
"void" rules=
"none">
73 <col class=
"field-name" />
74 <col class=
"field-body" />
76 <tr class=
"field"><th class=
"field-name">Return type:
</th><td class=
"field-body"><p class=
"first"><a class=
"reference internal" href=
"./integral-constant.html">Integral Constant
</a>.
</p>
79 <tr class=
"field"><th class=
"field-name">Semantics:
</th><td class=
"field-body"><p class=
"first"><tt class=
"literal"><span class=
"pre">tag
</span></tt> is
<tt class=
"literal"><span class=
"pre">forward_iterator_tag
</span></tt> if
<tt class=
"literal"><span class=
"pre">iter
</span></tt> is a model of
<a class=
"reference internal" href=
"./forward-iterator.html">Forward Iterator
</a>,
80 <tt class=
"literal"><span class=
"pre">bidirectional_iterator_tag
</span></tt> if
<tt class=
"literal"><span class=
"pre">iter
</span></tt> is a model of
<a class=
"reference internal" href=
"./bidirectional-iterator.html">Bidirectional Iterator
</a>,
81 or
<tt class=
"literal"><span class=
"pre">random_access_iterator_tag
</span></tt> if
<tt class=
"literal"><span class=
"pre">iter
</span></tt> is a model of
<a class=
"reference internal" href=
"./random-access-iterator.html">Random Access Iterator
</a>;
</p>
84 <tr class=
"field"><th class=
"field-name">Postcondition:
</th><td class=
"field-body"><dl class=
"first last docutils">
85 <dt><tt class=
"literal"><span class=
"pre">forward_iterator_tag::value
</span> <span class=
"pre"><</span> <span class=
"pre">bidirectional_iterator_tag::value
</span></tt>,
</dt>
86 <dd><p class=
"first last"><tt class=
"literal"><span class=
"pre">bidirectional_iterator_tag::value
</span> <span class=
"pre"><</span> <span class=
"pre">random_access_iterator_tag::value
</span></tt>.
</p>
94 <div class=
"section" id=
"id450">
95 <h3><a class=
"subsection-title" href=
"#complexity" name=
"complexity">Complexity
</a></h3>
96 <p>Amortized constant time.
</p>
98 <div class=
"section" id=
"id451">
99 <h3><a class=
"subsection-title" href=
"#example" name=
"example">Example
</a></h3>
100 <pre class=
"literal-block">
101 template
< typename Tag, typename Iterator
>
102 struct algorithm_impl
104 //
<em>O(n)
</em> implementation
107 template
< typename Iterator
>
108 struct algorithm_impl
<random_access_iterator_tag,Iterator
>
110 //
<em>O(
1)
</em> implementation
113 template
< typename Iterator
>
116 <a href=
"./iterator-category.html" class=
"identifier">iterator_category
</a><Iterator
>::type
123 <div class=
"section" id=
"id452">
124 <h3><a class=
"subsection-title" href=
"#see-also" name=
"see-also">See also
</a></h3>
125 <p><a class=
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"./iterators.html">Iterators
</a>,
<a class=
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</a> /
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</a>,
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131 <td><div class=
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2001-
2009 Aleksey Gurtovoy and David Abrahams
</div>
132 Distributed under the Boost Software License, Version
1.0. (See accompanying
133 file LICENSE_1_0.txt or copy at
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