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removed constraints on reference from Readable Iterator

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[SVN r21641]
This commit is contained in:
Jeremy Siek
2004-01-12 19:54:57 +00:00
parent db9d88ad7b
commit 21381f3fa7
3 changed files with 38 additions and 47 deletions
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34
doc/new-iter-concepts.rst
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@@ -368,26 +368,18 @@ type ``T``.
|``iterator_traits<X>::value_type`` |``T`` |Any non-reference, |
| | |non-cv-qualified type |
+-----------------------------------+------------------------+-------------------------+
|``iterator_traits<X>::reference`` |``R``, Convertible to | |
| |``T`` | |
+-----------------------------------+------------------------+-------------------------+
|``*a`` |Convertible to ``R``, |pre: ``a`` is |
| |Convertible to ``T`` |dereferenceable. If ``a |
|``*a`` | Convertible to ``T`` |pre: ``a`` is |
| | |dereferenceable. If ``a |
| | |== b`` then ``*a`` is |
| | |equivalent to ``*b`` |
+-----------------------------------+------------------------+-------------------------+
|``static_cast<T>( |``T`` |equivalent to |
|static_cast<R>(*a) )`` | |``static_cast<T>(*a)`` |
| | |equivalent to ``*b``. |
+-----------------------------------+------------------------+-------------------------+
|``a->m`` |``U&`` |pre: ``(*a).m`` is |
| | |well-defined. Equivalent|
| | |to ``(*a).m`` |
+-----------------------------------+------------------------+-------------------------+
.. TR1: the originally-proposed requirement that typeof(*a) == R
was too restrictive. Now we just require that it's
convertible to R and that accessing a T through that conversion
is equivalent to accessing a T directly.
.. We won't say anything about iterator_traits<X>::reference until
the DR is resolved.
.. _Writable Iterator:
@@ -432,21 +424,27 @@ expressions are valid and respect the stated semantics.
Lvalue Iterators [lib.lvalue.iterators]
---------------------------------------
The *Lvalue Iterator* concept adds the requirement that the
``reference`` type be a reference to the value type of the iterator.
The *Lvalue Iterator* concept adds the requirement that the return
type of ``operator*`` type be a reference to the value type of the
iterator.
+---------------------------------------------------------------------------------+
| Lvalue Iterator Requirements |
+---------------------------------+-----------+-----------------------------------+
|Expression |Return Type|Assertion |
|Expression |Return Type|Note/Assertion |
+=================================+===========+===================================+
|``iterator_traits<X>::reference``|``T&`` |``T`` is *cv* |
|``*a`` | ``T&`` |``T`` is *cv* |
| | |``iterator_traits<X>::value_type`` |
| | |where *cv* is an optional |
| | |cv-qualification |
| | |cv-qualification. |
| | |pre: ``a`` is |
| | |dereferenceable. If ``a |
| | |== b`` then ``*a`` is |
| | |equivalent to ``*b``. |
+---------------------------------+-----------+-----------------------------------+
Iterator Traversal Concepts [lib.iterator.traversal]
++++++++++++++++++++++++++++++++++++++++++++++++++++