| .. Copyright David Abrahams 2006. Distributed under 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) |
| |
| Forward Traversal Concept |
| ......................... |
| |
| A class or built-in type ``X`` models the *Forward Traversal* |
| concept if, in addition to ``X`` meeting the requirements of Default |
| Constructible and Single Pass Iterator, the following expressions are |
| valid and respect the stated semantics. |
| |
| +--------------------------------------------------------------------------------------------------------+ |
| |Forward Traversal Iterator Requirements (in addition to Default Constructible and Single Pass Iterator) | |
| +---------------------------------------+-----------------------------------+----------------------------+ |
| |Expression |Return Type |Assertion/Note | |
| +=======================================+===================================+============================+ |
| |``X u;`` |``X&`` |note: ``u`` may have a | |
| | | |singular value. | |
| +---------------------------------------+-----------------------------------+----------------------------+ |
| |``++r`` |``X&`` |``r == s`` and ``r`` is | |
| | | |dereferenceable implies | |
| | | |``++r == ++s.`` | |
| +---------------------------------------+-----------------------------------+----------------------------+ |
| |``iterator_traits<X>::difference_type``|A signed integral type representing| | |
| | |the distance between iterators | | |
| | | | | |
| +---------------------------------------+-----------------------------------+----------------------------+ |
| |``iterator_traversal<X>::type`` |Convertible to | | |
| | |``forward_traversal_tag`` | | |
| +---------------------------------------+-----------------------------------+----------------------------+ |
