| .. |iterator-category| replace:: *iterator-category* |
| .. _iterator-category: |
| |
| .. parsed-literal:: |
| |
| *iterator-category*\ (C,R,V) := |
| if (C is convertible to std::input_iterator_tag |
| || C is convertible to std::output_iterator_tag |
| ) |
| return C |
| |
| else if (C is not convertible to incrementable_traversal_tag) |
| *the program is ill-formed* |
| |
| else return a type X satisfying the following two constraints: |
| |
| 1. X is convertible to X1, and not to any more-derived |
| type, where X1 is defined by: |
| |
| if (R is a reference type |
| && C is convertible to forward_traversal_tag) |
| { |
| if (C is convertible to random_access_traversal_tag) |
| X1 = random_access_iterator_tag |
| else if (C is convertible to bidirectional_traversal_tag) |
| X1 = bidirectional_iterator_tag |
| else |
| X1 = forward_iterator_tag |
| } |
| else |
| { |
| if (C is convertible to single_pass_traversal_tag |
| && R is convertible to V) |
| X1 = input_iterator_tag |
| else |
| X1 = C |
| } |
| |
| 2. |category-to-traversal|_\ (X) is convertible to the most |
| derived traversal tag type to which X is also |
| convertible, and not to any more-derived traversal tag |
| type. |
| |
| .. |category-to-traversal| replace:: *category-to-traversal* |
| .. _`category-to-traversal`: new-iter-concepts.html#category-to-traversal |
| |
| [Note: the intention is to allow ``iterator_category`` to be one of |
| the five original category tags when convertibility to one of the |
| traversal tags would add no information] |
| |
| .. Copyright David Abrahams 2004. Use, modification and distribution is |
| .. subject to the Boost Software License, Version 1.0. (See accompanying |
| .. file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |