2006-09-11 22:08:18 +00:00
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.. Copyright David Abrahams 2006. Distributed under the Boost
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.. Software License, Version 1.0. (See accompanying
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.. file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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2004-01-27 17:03:46 +00:00
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Forward Traversal Concept
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.........................
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A class or built-in type ``X`` models the *Forward Traversal*
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concept if, in addition to ``X`` meeting the requirements of Default
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Constructible and Single Pass Iterator, the following expressions are
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valid and respect the stated semantics.
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+--------------------------------------------------------------------------------------------------------+
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|Forward Traversal Iterator Requirements (in addition to Default Constructible and Single Pass Iterator) |
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+---------------------------------------+-----------------------------------+----------------------------+
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|Expression |Return Type |Assertion/Note |
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+=======================================+===================================+============================+
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|``X u;`` |``X&`` |note: ``u`` may have a |
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| | |singular value. |
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+---------------------------------------+-----------------------------------+----------------------------+
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|``++r`` |``X&`` |``r == s`` and ``r`` is |
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| | |dereferenceable implies |
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| | |``++r == ++s.`` |
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+---------------------------------------+-----------------------------------+----------------------------+
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|``iterator_traits<X>::difference_type``|A signed integral type representing| |
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| |the distance between iterators | |
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| | | |
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+---------------------------------------+-----------------------------------+----------------------------+
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|``iterator_traversal<X>::type`` |Convertible to | |
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| |``forward_traversal_tag`` | |
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+---------------------------------------+-----------------------------------+----------------------------+
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