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- .. 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)
- Interoperable Iterator Concept
- ..............................
- A class or built-in type ``X`` that models Single Pass Iterator is
- *interoperable with* a class or built-in type ``Y`` that also models
- Single Pass Iterator if the following expressions are valid and
- respect the stated semantics. In the tables below, ``x`` is an object
- of type ``X``, ``y`` is an object of type ``Y``, ``Distance`` is
- ``iterator_traits<Y>::difference_type``, and ``n`` represents a
- constant object of type ``Distance``.
- +-----------+-----------------------+---------------------------------------------------+
- |Expression |Return Type |Assertion/Precondition/Postcondition |
- +===========+=======================+===================================================+
- |``y = x`` |``Y`` |post: ``y == x`` |
- +-----------+-----------------------+---------------------------------------------------+
- |``Y(x)`` |``Y`` |post: ``Y(x) == x`` |
- +-----------+-----------------------+---------------------------------------------------+
- |``x == y`` |convertible to ``bool``|``==`` is an equivalence relation over its domain. |
- +-----------+-----------------------+---------------------------------------------------+
- |``y == x`` |convertible to ``bool``|``==`` is an equivalence relation over its domain. |
- +-----------+-----------------------+---------------------------------------------------+
- |``x != y`` |convertible to ``bool``|``bool(a==b) != bool(a!=b)`` over its domain. |
- +-----------+-----------------------+---------------------------------------------------+
- |``y != x`` |convertible to ``bool``|``bool(a==b) != bool(a!=b)`` over its domain. |
- +-----------+-----------------------+---------------------------------------------------+
- If ``X`` and ``Y`` both model Random Access Traversal Iterator then
- the following additional requirements must be met.
- +-----------+-----------------------+---------------------+--------------------------------------+
- |Expression |Return Type |Operational Semantics|Assertion/ Precondition |
- +===========+=======================+=====================+======================================+
- |``x < y`` |convertible to ``bool``|``y - x > 0`` |``<`` is a total ordering relation |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``y < x`` |convertible to ``bool``|``x - y > 0`` |``<`` is a total ordering relation |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``x > y`` |convertible to ``bool``|``y < x`` |``>`` is a total ordering relation |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``y > x`` |convertible to ``bool``|``x < y`` |``>`` is a total ordering relation |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``x >= y`` |convertible to ``bool``|``!(x < y)`` | |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``y >= x`` |convertible to ``bool``|``!(y < x)`` | |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``x <= y`` |convertible to ``bool``|``!(x > y)`` | |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``y <= x`` |convertible to ``bool``|``!(y > x)`` | |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``y - x`` |``Distance`` |``distance(Y(x),y)`` |pre: there exists a value ``n`` of |
- | | | |``Distance`` such that ``x + n == y``.|
- | | | |``y == x + (y - x)``. |
- +-----------+-----------------------+---------------------+--------------------------------------+
- |``x - y`` |``Distance`` |``distance(y,Y(x))`` |pre: there exists a value ``n`` of |
- | | | |``Distance`` such that ``y + n == x``.|
- | | | |``x == y + (x - y)``. |
- +-----------+-----------------------+---------------------+--------------------------------------+
|
