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Separate access and traversal for iterator_adaptor

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[SVN r20162]
This commit is contained in:
Dave Abrahams
2003-09-22 19:55:01 +00:00
parent 50fe1b062b
commit ebb09db44e
12 changed files with 485 additions and 170 deletions
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25
doc/iterator_facade_ref.rst
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@ -3,7 +3,7 @@
template <
class Derived
, class Value
, class AccessCategory
, unsigned AccessCategory
, class TraversalCategory
, class Reference = /* see below__ \*/
, class Difference = ptrdiff_t
@ -108,12 +108,25 @@ out of the overload set when the types are not interoperable.]
``iterator_facade`` requirements
................................
Some of the constraints on template parameters to
``iterator_facade`` are expressed in terms of resulting nested
types and should be viewed in the context of their impact on
``iterator_traits<Derived>``.
The ``Derived`` template parameter must be a class derived from
``iterator_facade``.
The default for the ``Reference`` parameter is ``Value&`` if the
access category for ``iterator_facade`` is implicitly convertible to
``writable_iterator_tag``, and ``const Value&`` otherwise.
The nested ``::value_type`` type will be the same as
``remove_cv<Value>::type``, so the ``Value`` parameter must be
an (optionally ``const``\ -qualified) non-reference type.
``AccessCategory`` must be an unsigned value which uses no more
bits than the greatest value of ``iterator_access``.
The nested ``::reference`` will be the same as the ``Reference``
parameter; it must be a suitable reference type for the resulting
iterator. The default for the ``Reference`` parameter is
``Value&``.
The following table describes the other requirements on the
``Derived`` parameter. Depending on the resulting iterator's
@ -188,8 +201,8 @@ __ `operator arrow`_
object ``a`` of type ``X``, ``a->m`` is equivalent to ``(w = *a,
w.m)`` for some temporary object ``w`` of type ``X::value_type``.
The type ``X::pointer`` is ``Value*`` if the access category for
``X`` is implicitly convertible to ``writable_iterator_tag``, and
The type ``X::pointer`` is ``Value*`` if
``is_writable_iterator<X>::value`` is ``true``, and
``Value const*`` otherwise.