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54 lines
2.0 KiB
ReStructuredText
54 lines
2.0 KiB
ReStructuredText
.. |iterator-category| replace:: *iterator-category*
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.. _iterator-category:
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.. parsed-literal::
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*iterator-category*\ (C,R,V) :=
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if (C is convertible to std::input_iterator_tag
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|| C is convertible to std::output_iterator_tag
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)
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return C
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else if (C is not convertible to incrementable_traversal_tag)
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*the program is ill-formed*
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else return a type X satisfying the following two constraints:
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1. X is convertible to X1, and not to any more-derived
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type, where X1 is defined by:
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if (R is a reference type
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&& C is convertible to forward_traversal_tag)
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{
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if (C is convertible to random_access_traversal_tag)
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X1 = random_access_iterator_tag
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else if (C is convertible to bidirectional_traversal_tag)
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X1 = bidirectional_iterator_tag
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else
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X1 = forward_iterator_tag
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}
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else
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{
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if (C is convertible to single_pass_traversal_tag
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&& R is convertible to V)
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X1 = input_iterator_tag
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else
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X1 = C
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}
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2. |category-to-traversal|_\ (X) is convertible to the most
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derived traversal tag type to which X is also
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convertible, and not to any more-derived traversal tag
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type.
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.. |category-to-traversal| replace:: *category-to-traversal*
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.. _`category-to-traversal`: new-iter-concepts.html#category-to-traversal
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[Note: the intention is to allow ``iterator_category`` to be one of
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the five original category tags when convertibility to one of the
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traversal tags would add no information]
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.. Copyright David Abrahams 2004. Use, modification and distribution is
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.. subject to the Boost 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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