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< title > Counting Iterator< / title >
< meta name = "author" content = "David Abrahams, Jeremy Siek, Thomas Witt" / >
< meta name = "organization" content = "Boost Consulting, Indiana University Open Systems Lab, University of Hanover Institute for Transport Railway Operation and Construction" / >
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< h1 class = "title" > Counting Iterator< / h1 >
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< tr > < th class = "docinfo-name" > Author:< / th >
< td > David Abrahams, Jeremy Siek, Thomas Witt< / td > < / tr >
< tr > < th class = "docinfo-name" > Contact:< / th >
< td > < a class = "first reference" href = "mailto:dave@boost-consulting.com" > dave@ boost-consulting.com< / a > , < a class = "reference" href = "mailto:jsiek@osl.iu.edu" > jsiek@ osl.iu.edu< / a > , < a class = "last reference" href = "mailto:witt@ive.uni-hannover.de" > witt@ ive.uni-hannover.de< / a > < / td > < / tr >
< tr > < th class = "docinfo-name" > Organization:< / th >
< td > < a class = "first reference" href = "http://www.boost-consulting.com" > Boost Consulting< / a > , Indiana University < a class = "reference" href = "http://www.osl.iu.edu" > Open Systems
Lab< / a > , University of Hanover < a class = "last reference" href = "http://www.ive.uni-hannover.de" > Institute for Transport
Railway Operation and Construction< / a > < / td > < / tr >
< tr > < th class = "docinfo-name" > Date:< / th >
2003-09-22 15:10:34 +00:00
< td > 2003-09-14< / td > < / tr >
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< tr > < th class = "docinfo-name" > Copyright:< / th >
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< td > Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. All rights reserved< / td > < / tr >
2003-08-05 19:48:41 +00:00
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< tr class = "field" > < th class = "field-name" > abstract:< / th > < td class = "field-body" > < / td >
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< p > The counting iterator adaptor implements dereference by returning a
reference to the base object. The other operations are implemented by
the base < tt class = "literal" > < span class = "pre" > m_iterator< / span > < / tt > , as per the inheritance from
< tt class = "literal" > < span class = "pre" > iterator_adaptor< / span > < / tt > .< / p >
< div class = "contents topic" id = "table-of-contents" >
< p class = "topic-title" > < a name = "table-of-contents" > Table of Contents< / a > < / p >
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< li > < a class = "reference" href = "#counting-iterator-requirements" id = "id1" name = "id1" > < tt class = "literal" > < span class = "pre" > counting_iterator< / span > < / tt > requirements< / a > < / li >
< li > < a class = "reference" href = "#counting-iterator-operations" id = "id2" name = "id2" > < tt class = "literal" > < span class = "pre" > counting_iterator< / span > < / tt > operations< / a > < / li >
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< pre class = "literal-block" >
template < class Incrementable, class Category = use_default, class Difference = use_default>
class counting_iterator
: public iterator_adaptor<
counting_iterator< Incrementable, Category, Difference>
, Incrementable
, Incrementable
, /* see details for category */
, Incrementable const&
, Incrementable const*
, /* distance = Difference or a signed integral type */>
{
friend class iterator_core_access;
public:
counting_iterator();
counting_iterator(counting_iterator const& rhs);
counting_iterator(Incrementable x);
private:
typename counting_iterator::reference dereference() const
{
return this-> base_reference();
}
};
< / pre >
< dl >
< dt > [< em > Note:< / em > implementers are encouraged to provide an implementation of< / dt >
< dd > < tt class = "literal" > < span class = "pre" > distance_to< / span > < / tt > and a < tt class = "literal" > < span class = "pre" > difference_type< / span > < / tt > that avoids overflows in
the cases when the < tt class = "literal" > < span class = "pre" > Incrementable< / span > < / tt > type is a numeric type.]< / dd >
< / dl >
< div class = "section" id = "counting-iterator-requirements" >
< h1 > < a class = "toc-backref" href = "#id1" name = "counting-iterator-requirements" > < tt class = "literal" > < span class = "pre" > counting_iterator< / span > < / tt > requirements< / a > < / h1 >
< p > The < tt class = "literal" > < span class = "pre" > Incrementable< / span > < / tt > type must be Default Constructible, Copy
Constructible, and Assignable. The default distance is
an implementation defined signed integegral type.< / p >
< p > The resulting < tt class = "literal" > < span class = "pre" > counting_iterator< / span > < / tt > models Readable Lvalue Iterator.< / p >
< p > Furthermore, if you wish to create a counting iterator that is a Forward
Traversal Iterator, then the following expressions must be valid:< / p >
< pre class = "literal-block" >
Incrementable i, j;
++i // pre-increment
i == j // operator equal
< / pre >
< p > If you wish to create a counting iterator that is a
Bidirectional Traversal Iterator, then pre-decrement is also required:< / p >
< pre class = "literal-block" >
--i
< / pre >
< p > If you wish to create a counting iterator that is a Random Access
Traversal Iterator, then these additional expressions are also
required:< / p >
< pre class = "literal-block" >
counting_iterator::difference_type n;
i += n
n = i - j
i < j
< / pre >
< / div >
< div class = "section" id = "counting-iterator-operations" >
< h1 > < a class = "toc-backref" href = "#id2" name = "counting-iterator-operations" > < tt class = "literal" > < span class = "pre" > counting_iterator< / span > < / tt > operations< / a > < / h1 >
< p > < tt class = "literal" > < span class = "pre" > counting_iterator();< / span > < / tt > < / p >
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< tr class = "field" > < th class = "field-name" > Returns:< / th > < td class = "field-body" > A default constructed instance of < tt class = "literal" > < span class = "pre" > counting_iterator< / span > < / tt > .< / td >
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< p > < tt class = "literal" > < span class = "pre" > counting_iterator(counting_iterator< / span > < span class = "pre" > const& < / span > < span class = "pre" > rhs);< / span > < / tt > < / p >
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< tr class = "field" > < th class = "field-name" > Returns:< / th > < td class = "field-body" > An instance of < tt class = "literal" > < span class = "pre" > counting_iterator< / span > < / tt > that is a copy of < tt class = "literal" > < span class = "pre" > rhs< / span > < / tt > .< / td >
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< p > < tt class = "literal" > < span class = "pre" > counting_iterator(Incrementable< / span > < span class = "pre" > x);< / span > < / tt > < / p >
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< tr class = "field" > < th class = "field-name" > Returns:< / th > < td class = "field-body" > An instance of < tt class = "literal" > < span class = "pre" > counting_iterator< / span > < / tt > with its base
object copy constructed from < tt class = "literal" > < span class = "pre" > x< / span > < / tt > .< / td >
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