forked from boostorg/iterator
93 lines
3.4 KiB
HTML
93 lines
3.4 KiB
HTML
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<html>
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<!--
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-- Copyright (c) Jeremy Siek 2000
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--
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-- Permission to use, copy, modify, distribute and sell this software
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-- and its documentation for any purpose is hereby granted without fee,
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-- provided that the above copyright notice appears in all copies and
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-- that both that copyright notice and this permission notice appear
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-- in supporting documentation. I make no representations about the
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-- suitability of this software for any purpose. It is provided "as is"
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-- without express or implied warranty.
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-->
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<head>
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<title>Boost Iterator Traits</title>
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</head>
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<body>
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<h1>Boost Iterator Traits</h1>
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Header <tt><a href="../../boost/iterator_traits.hpp">boost/iterator_traits.hpp</a></tt>
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<pre>
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namespace boost {
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template <typename Iterator>
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struct iterator_traits
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{
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if (Iterator inherits from new_iterator_base) {
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typedef typename Iterator::value_type value_type;
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typedef typename Iterator::reference reference;
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typedef typename Iterator::pointer pointer;
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typedef typename Iterator::difference_type difference_type;
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typedef typename Iterator::return_category return_category;
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typedef typename Iterator::traversal_category traversal_category;
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} else {
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typedef std::iterator_traits<Iterator> OldTraits;
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typedef typename OldTraits::value_type value_type;
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typedef typename OldTraits::reference reference;
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typedef typename OldTraits::pointer pointer;
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typedef typename OldTraits::difference_type difference_type;
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typedef typename OldTraits::iterator_category Cat;
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<i>// Determine the traversal_category based on the old iterator_category</i>
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if (Cat inherits from std::random_access_iterator_tag)
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typedef boost::random_access_iterator_tag traversal_category;
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else if (Cat inherits from std::bidirectional_iterator_tag)
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typedef boost::bidirectional_iterator_tag traversal_category;
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else if (Cat inherits from std::forward_iterator_tag)
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typedef boost::forward_iterator_tag traversal_category;
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else
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typedef boost::single_pass_iterator_tag traversal_category;
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<i>// Determine the return_category based on the old iterator_category and value_type</i>
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if (Cat inherits from std::forward_iterator_tag)
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if (is-const(T))
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typedef boost::constant_lvalue_iterator_tag return_category;
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else
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typedef boost::mutable_lvalue_iterator_tag return_category;
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else if (Cat inherits from std::input_iterator_tag)
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typedef boost::readable_iterator_tag return_category;
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else if (Cat inherits from std::output_iterator_tag)
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typedef boost::writable_iterator_tag return_category;
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else
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typedef boost::error_iterator_tag return_category;
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}
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};
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template <typename T>
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struct iterator_traits<T*>
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{
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typedef T value_type;
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typedef T& reference;
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typedef T* pointer;
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typedef std::ptrdiff_t difference_type;
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if (is-const(T))
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typedef boost::constant_lvalue_iterator_tag return_category;
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else
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typedef boost::mutable_lvalue_iterator_tag return_category;
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typedef boost::random_access_iterator_tag traversal_category;
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};
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}
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</pre>
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<hr>
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<address><a href="mailto:jsiek@lsc.nd.edu">jeremy siek</a></address>
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<!-- Created: Sun Mar 18 14:06:57 EST 2001 -->
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<!-- hhmts start -->
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Last modified: Sun Mar 18 17:10:26 EST 2001
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<!-- hhmts end -->
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</body>
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</html>
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