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Table formatting tweaks for PDF/tex generation.
Some minor editing for language improvements. [SVN r20151]
This commit is contained in:
Dave Abrahams
@ -42,7 +42,9 @@ requirements that address value access sneak in at various places. The
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following table gives a summary of the current value access
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requirements in the iterator categories.
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+------------------------+-----------------------------------------------------+
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+------------------------------------------------------------------------------+
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|Value Access Requirements in Existing Iterator Categories |
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+========================+=====================================================+
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|Output Iterator |``*i = a`` |
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+------------------------+-----------------------------------------------------+
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|Input Iterator |``*i`` is convertible to ``T`` |
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@ -138,7 +140,9 @@ algorithms.
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Forward Iterator -> Forward Traversal Iterator and Readable Iterator
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``find_end, adjacent_find, search, search_n, rotate_copy, lower_bound, upper_bound, equal_range, binary_search, min_element, max_element``
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``find_end, adjacent_find, search, search_n, rotate_copy,
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lower_bound, upper_bound, equal_range, binary_search,
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min_element, max_element``
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Forward Iterator (1) -> Single Pass Iterator and Readable Iterator
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Forward Iterator (2) -> Forward Traversal Iterator and Readable Iterator
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@ -203,7 +207,7 @@ Input Iterator (2) -> Incrementable Iterator and Readable Iterator
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Design
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========
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The iterator requirements are be separated into two hierarchies. One
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The iterator requirements are to be separated into two hierarchies. One
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set of concepts handles the syntax and semantics of value access:
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- Readable Iterator
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@ -240,7 +244,7 @@ given in the following diagram.
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.. image:: oldeqnew.png
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Like the old iterator requirements, we provide tags for purposes of
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As in the existing library, we provide tags for purposes of
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dispatching. There are two hierarchies of tags, one for the access
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concepts and one for the traversal concepts. The tags are related via
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inheritance so that a tag is convertible to another tag if the concept
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@ -252,7 +256,7 @@ whether an iterator is an Lvalue Iterator by checking whether
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We provide an access mechanism for mapping iterator types to the new
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tags. Our design reuses ``iterator_traits<Iter>::iterator_category``
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as the access mechanism. To enable this, a pair of access and
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as the access mechanism. To that end, a pair of access and
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traversal tags are combined into a single type using the following
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`iterator_tag` class.
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@ -325,24 +329,28 @@ for the value type ``T`` if the following expressions are valid and
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respect the stated semantics. ``U`` is the type of any specified
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member of type ``T``.
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+-------------------------------------------------------------------------------------------------------------------+
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|Readable Iterator Requirements (in addition to CopyConstructible) |
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+--------------------------------------+----------------------------------+-----------------------------------------+
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|Expression |Return Type |Assertion/Note/Precondition/Postcondition|
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+======================================+==================================+=========================================+
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|``iterator_traits<X>::value_type`` |``T`` |Any non-reference, non-cv-qualified type |
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+--------------------------------------+----------------------------------+-----------------------------------------+
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|``iterator_traits<X>::reference`` |Convertible to | |
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| |``iterator_traits<X>::value_type``| |
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+--------------------------------------+----------------------------------+-----------------------------------------+
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|``is_readable<X>::type`` |``truetype`` | |
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+--------------------------------------+----------------------------------+-----------------------------------------+
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|``*a`` |``iterator_traits<X>::reference`` |pre: ``a`` is dereferenceable. If ``a == |
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| | |b`` then ``*a`` is equivalent to ``*b`` |
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+--------------------------------------+----------------------------------+-----------------------------------------+
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|``a->m`` |``U&`` |pre: ``(*a).m`` is well-defined. |
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| | |Equivalent to ``(*a).m`` |
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+--------------------------------------+----------------------------------+-----------------------------------------+
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+-------------------------------------------------------------------------------------------------+
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|Readable Iterator Requirements (in addition to CopyConstructible) |
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+-----------------------------------+-----------------------------------+-------------------------+
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|Expression |Return Type |Note/Precondition |
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+===================================+===================================+=========================+
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|``iterator_traits<X>::value_type`` |``T`` |Any non-reference, |
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| | |non-cv-qualified type |
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+-----------------------------------+-----------------------------------+-------------------------+
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|``iterator_traits<X>::reference`` |Convertible to | |
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| |``iterator_traits<X>::value_type`` | |
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+-----------------------------------+-----------------------------------+-------------------------+
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|``is_readable<X>::type`` |``true_type`` | |
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+-----------------------------------+-----------------------------------+-------------------------+
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|``*a`` |``iterator_traits<X>::reference`` |pre: ``a`` is |
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| | |dereferenceable. If ``a |
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| | |== b`` then ``*a`` is |
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| | |equivalent to ``*b`` |
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+-----------------------------------+-----------------------------------+-------------------------+
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|``a->m`` |``U&`` |pre: ``(*a).m`` is |
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| | |well-defined. Equivalent|
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| | |to ``(*a).m`` |
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+-----------------------------------+-----------------------------------+-------------------------+
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.. _Writable Iterator:
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@ -356,17 +364,17 @@ semantics. In addition, a model of *Writable Iterator* must include
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in its documentation the *set of value types* that it allows for
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output.
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+---------------------------------------------------------------------------------------------+
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|Writable Iterator Requirements (in addition to CopyConstructible) |
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+--------------------------------------+-------------------------+----------------------------+
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|Expression |Return Type |Precondition |
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+======================================+=========================+============================+
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|``is_writable<X>::type`` |``true_type`` | |
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+--------------------------------------+-------------------------+----------------------------+
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|``*a = o`` | | pre: The type of ``o`` |
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| | | is in the set of |
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| | | value types of ``X`` |
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+--------------------------------------+-------------------------+----------------------------+
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+---------------------------------------------------------------------+
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|Writable Iterator Requirements (in addition to CopyConstructible) |
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+-------------------------+--------------+----------------------------+
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|Expression |Return Type |Precondition |
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+=========================+==============+============================+
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|``is_writable<X>::type`` |``true_type`` | |
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+-------------------------+--------------+----------------------------+
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|``*a = o`` | | pre: The type of ``o`` |
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| | | is in the set of |
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| | | value types of ``X`` |
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+-------------------------+--------------+----------------------------+
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@ -377,15 +385,16 @@ A class or built-in type ``X`` models the *Swappable Iterator* concept
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if the following expressions are valid and respect the stated
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semantics.
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+------------------------------------------------------------------------------------------------+
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|Swappable Iterator Requirements (in addition to CopyConstructible) |
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+------------------------------------+-------------+---------------------------------------------+
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|Expression |Return Type |Postcondition |
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+====================================+=============+=============================================+
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|``is_swappable<X>::type`` |``true_type``| |
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+------------------------------------+-------------+---------------------------------------------+
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|``iter_swap(a, b)`` |``void`` |post: the pointed to values are exchanged |
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+------------------------------------+-------------+---------------------------------------------+
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+---------------------------------------------------------------------+
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|Swappable Iterator Requirements (in addition to CopyConstructible) |
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+-------------------------+-------------+-----------------------------+
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|Expression |Return Type |Postcondition |
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+=========================+=============+=============================+
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|``is_swappable<X>::type``|``true_type``| |
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+-------------------------+-------------+-----------------------------+
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|``iter_swap(a, b)`` |``void`` |the pointed to values are |
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| | |exchanged |
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+-------------------------+-------------+-----------------------------+
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[*Note:* An iterator that is a model of the *Readable* and *Writable Iterator* concepts
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is also a model of *Swappable Iterator*. *--end note*]
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@ -397,16 +406,16 @@ Lvalue Iterators [lib.lvalue.iterators]
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The *Lvalue Iterator* concept adds the requirement that the
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``reference`` type be a reference to the value type of the iterator.
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+----------------------------------------------------------------------------------------------------------+
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| Lvalue Iterator Requirements |
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+------------------------------------+---------------------------------+-----------------------------------+
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|Expression |Return Type |Assertion |
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+====================================+=================================+===================================+
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|``iterator_traits<X>::reference`` |``T&`` |``T`` is *cv* |
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| | |``iterator_traits<X>::value_type`` |
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| | |where *cv* is an optional |
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| | |cv-qualification |
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+------------------------------------+---------------------------------+-----------------------------------+
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+---------------------------------------------------------------------------------+
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| Lvalue Iterator Requirements |
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+---------------------------------+-----------+-----------------------------------+
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|Expression |Return Type|Assertion |
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+=================================+===========+===================================+
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|``iterator_traits<X>::reference``|``T&`` |``T`` is *cv* |
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| | |``iterator_traits<X>::value_type`` |
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| | |where *cv* is an optional |
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| | |cv-qualification |
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+---------------------------------+-----------+-----------------------------------+
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Iterator Traversal Concepts [lib.iterator.traversal]
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@ -426,17 +435,25 @@ concept if the following expressions are valid and respect the stated
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semantics.
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+-------------------------------------------------------------------------------------------------------------------------+
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|Incrementable Iterator Requirements (in addition to Assignable, Copy Constructible) |
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+--------------------------------+---------------------------------------------+------------------------------------------+
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|Expression |Return Type |Assertion/Semantics |
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+================================+=============================================+==========================================+
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|``++r`` |``X&`` |``&r == &++r`` |
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+--------------------------------+---------------------------------------------+------------------------------------------+
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|``r++`` |``X`` |``{ X tmp = r; ++r; return tmp; }`` |
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+--------------------------------+---------------------------------------------+------------------------------------------+
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|``traversal_category<X>::type`` |Convertible to ``incrementable_iterator_tag``| |
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+--------------------------------+---------------------------------------------+------------------------------------------+
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+-------------------------------------------------------------------------------------+
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|Incrementable Iterator Requirements (in addition to Assignable, Copy Constructible) |
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| |
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+--------------------------------+-------------------------------+--------------------+
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|Expression |Return Type |Assertion/Semantics |
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+================================+===============================+====================+
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|``++r`` |``X&`` |``&r == &++r`` |
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+--------------------------------+-------------------------------+--------------------+
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|``r++`` |``X`` |:: |
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| | | |
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| | | { |
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| | | X tmp = r; |
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| | | ++r; |
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| | | return tmp; |
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| | | } |
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+--------------------------------+-------------------------------+--------------------+
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|``traversal_category<X>::type`` |Convertible to | |
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| |``incrementable_iterator_tag`` | |
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+--------------------------------+-------------------------------+--------------------+
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Single Pass Iterators [lib.single.pass.iterators]
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@ -447,23 +464,26 @@ concept if the following expressions are valid and respect the stated
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semantics.
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+--------------------------------------------------------------------------------------------------------+
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|Single Pass Iterator Requirements (in addition to Incrementable Iterator and Equality Comparable) |
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+----------------------------------+----------------------------+----------------------------------------+
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|Expression |Return Type |Assertion/Semantics/Pre-/Post-condition |
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+==================================+============================+========================================+
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|``++r`` |``X&`` |pre: ``r`` is dereferenceable; post: |
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| | |``r`` is dereferenceable or ``r`` is |
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| | |past-the-end |
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+----------------------------------+----------------------------+----------------------------------------+
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|``a == b`` |convertible to ``bool`` |``==`` is an equivalence relation over |
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| | |its domain |
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+----------------------------------+----------------------------+----------------------------------------+
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|``a != b`` |convertible to ``bool`` |``!(a == b)`` |
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+----------------------------------+----------------------------+----------------------------------------+
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|``traversal_category<X>::type`` |Convertible to | |
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| |``single_pass_iterator_tag``| |
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+----------------------------------+----------------------------+----------------------------------------+
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+------------------------------------------------------------------------------------------+
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|Single Pass Iterator Requirements (in addition to Incrementable Iterator and Equality |
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|Comparable) |
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+--------------------------------+-----------------------------+---------------------------+
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|Expression |Return Type |Assertion/Semantics / |
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| | |Pre-/Post-condition |
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+================================+=============================+===========================+
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|``++r`` |``X&`` |pre: ``r`` is |
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| | |dereferenceable; post: |
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| | |``r`` is dereferenceable or|
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| | |``r`` is past-the-end |
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+--------------------------------+-----------------------------+---------------------------+
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|``a == b`` |convertible to ``bool`` |``==`` is an equivalence |
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| | |relation over its domain |
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+--------------------------------+-----------------------------+---------------------------+
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|``a != b`` |convertible to ``bool`` |``!(a == b)`` |
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+--------------------------------+-----------------------------+---------------------------+
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|``traversal_category<X>::type`` |Convertible to | |
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| |``single_pass_iterator_tag`` | |
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+--------------------------------+-----------------------------+---------------------------+
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Forward Traversal Iterators [lib.forward.traversal.iterators]
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@ -473,24 +493,28 @@ A class or built-in type ``X`` models the *Forward Traversal Iterator*
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concept if the following expressions are valid and respect the stated
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semantics.
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+------------------------------------------------------------------------------------------------------+
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|Forward Traversal Iterator Requirements (in addition to Single Pass Iterator) |
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+---------------------------------------+-------------------------------------+------------------------+
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|Expression |Return Type |Assertion/Note |
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+=======================================+=====================================+========================+
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|``X u;`` |``X&`` |``note: u may have a |
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| | |singular value.`` |
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+---------------------------------------+-------------------------------------+------------------------+
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|``++r`` |``X&`` |``r == s`` and ``r`` is |
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| | |dereferenceable implies |
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| | |``++r == ++s.`` |
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+---------------------------------------+-------------------------------------+------------------------+
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|``iterator_traits<X>::difference_type``|A signed integral type representing | |
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| |the distance between iterators | |
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+---------------------------------------+-------------------------------------+------------------------+
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|``traversal_category<X>::type`` |Convertible to | |
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| |``forward_traversal_iterator_tag`` | |
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+---------------------------------------+-------------------------------------+------------------------+
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+-------------------------------------------------------------------------------------------+
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|Forward Traversal Iterator Requirements (in addition to Single Pass Iterator) |
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+---------------------------------------+-----------------------------------+---------------+
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|Expression |Return Type |Assertion/Note |
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+=======================================+===================================+===============+
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|``X u;`` |``X&`` |note: ``u`` may|
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| | |have a singular|
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| | |value. |
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+---------------------------------------+-----------------------------------+---------------+
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|``++r`` |``X&`` |``r == s`` and |
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| | |``r`` is |
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| | |dereferenceable|
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| | |implies ``++r |
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| | |== ++s.`` |
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+---------------------------------------+-----------------------------------+---------------+
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|``iterator_traits<X>::difference_type``|A signed integral type representing| |
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| |the distance between iterators | |
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| | | |
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+---------------------------------------+-----------------------------------+---------------+
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|``traversal_category<X>::type`` |Convertible to | |
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| |``forward_traversal_iterator_tag`` | |
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+---------------------------------------+-----------------------------------+---------------+
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Bidirectional Traversal Iterators [lib.bidirectional.traversal.iterators]
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@ -500,25 +524,34 @@ A class or built-in type ``X`` models the *Bidirectional Traversal
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Iterator* concept if the following expressions are valid and respect
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the stated semantics.
|
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|
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+----------------------------------------------------------------------------------------------------------------+
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|Bidirectional Traversal Iterator Requirements (in addition to Forward Traversal Iterator) |
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+-------------------------------+----------------------------------------+---------------------------------------+
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|Expression |Return Type |Assertion/Semantics/Pre-/Post-condition|
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+===============================+========================================+=======================================+
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|``--r`` |``X&`` |pre: there exists ``s`` such that ``r |
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| | |== ++s``. post: ``s`` is |
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| | |dereferenceable. ``--(++r) == r``. |
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| | |``--r == --s`` implies ``r == s``. ``&r|
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| | |== &--r``. |
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+-------------------------------+----------------------------------------+---------------------------------------+
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|``r--`` |convertible to ``const X&`` |``{ X tmp = r; --r; return tmp; }`` |
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| | | |
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| | | |
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+-------------------------------+----------------------------------------+---------------------------------------+
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|``traversal_category<X>::type``|Convertible to | |
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| |``bidirectional_traversal_iterator_tag``| |
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| | | |
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+-------------------------------+----------------------------------------+---------------------------------------+
|
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+--------------------------------------------------------------------------------------------------------+
|
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|Bidirectional Traversal Iterator Requirements (in addition to Forward Traversal Iterator) |
|
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+------------------------------------+---------------------------------------------+---------------------+
|
||||
|Expression |Return Type |Assertion/Semantics /|
|
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| | |Pre-/Post-condition |
|
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+====================================+=============================================+=====================+
|
||||
|``--r`` |``X&`` |pre: there exists |
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| | |``s`` such that ``r |
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| | |== ++s``. post: |
|
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| | |``s`` is |
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| | |dereferenceable. |
|
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| | |``--(++r) == r``. |
|
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| | |``--r == --s`` |
|
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| | |implies ``r == |
|
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| | |s``. ``&r == &--r``. |
|
||||
+------------------------------------+---------------------------------------------+---------------------+
|
||||
|``r--`` |convertible to ``const X&`` |:: |
|
||||
| | | |
|
||||
| | | { |
|
||||
| | | X tmp = r; |
|
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| | | --r; |
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| | | return tmp; |
|
||||
| | | } |
|
||||
+------------------------------------+---------------------------------------------+---------------------+
|
||||
|``traversal_category<X>::type`` |Convertible to | |
|
||||
| |``bidirectional_traversal_iterator_tag`` | |
|
||||
| | | |
|
||||
+------------------------------------+---------------------------------------------+---------------------+
|
||||
|
||||
|
||||
Random Access Traversal Iterators [lib.random.access.traversal.iterators]
|
||||
@ -530,56 +563,60 @@ the stated semantics. In the table below, ``Distance`` is
|
||||
``iterator_traits<X>::difference_type`` and ``n`` represents a
|
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constant object of type ``Distance``.
|
||||
|
||||
+------------------------------------------------------------------------------------------------------------------------------+
|
||||
|Random Access Traversal Iterator Requirements (in addition to Bidirectional Traversal Iterator) |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
| Expression |Return Type | Operational Semantics| Assertion/Precondition |
|
||||
+================================+========================================+======================+=============================+
|
||||
|``r += n`` |``X&`` |:: | |
|
||||
| | | | |
|
||||
| | | { | |
|
||||
| | | Distance m = n; | |
|
||||
| | | if (m >= 0) | |
|
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| | | while (m--) | |
|
||||
| | | ++r; | |
|
||||
| | | else | |
|
||||
| | | while (m++) | |
|
||||
| | | --r; | |
|
||||
| | | return r; | |
|
||||
| | | } | |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
| ``a + n``, ``n + a`` |``X`` |``{ X tmp = a; return | |
|
||||
| | |tmp += n; }`` | |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``r -= n`` |``X&`` |``return r += -n`` | |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``a - n`` |``X`` |``{ X tmp = a; return | |
|
||||
| | |tmp -= n; }`` | |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``b - a`` |``Distance`` |``a < b ? |pre: there exists a value |
|
||||
| | |distance(a,b) : |``n`` of ``Distance`` such |
|
||||
| | |-distance(b,a)`` |that ``a + n == b``. ``b == |
|
||||
| | | |a + (b - a)``. |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``a[n]`` |convertible to T |``*(a + n)`` |pre: a is a `readable |
|
||||
| | | |iterator`_ |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``a[n] = v`` |convertible to T |``*(a + n) = v`` |pre: a is a `writable |
|
||||
| | | |iterator`_ |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``a < b`` |convertible to ``bool`` |``b - a > 0`` |``<`` is a total ordering |
|
||||
| | | |relation |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``a > b`` |convertible to ``bool`` |``b < a`` |``>`` is a total ordering |
|
||||
| | | |relation |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``a >= b`` |convertible to ``bool`` |``!(a < b)`` | |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``a <= b`` |convertible to ``bool`` |``!(a > b)`` | |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
|``traversal_category<X>::type`` |Convertible to | | |
|
||||
| |``random_access_traversal_iterator_tag``| | |
|
||||
+--------------------------------+----------------------------------------+----------------------+-----------------------------+
|
||||
+----------------------------------------------------------------------------------------------------------------------------------------------+
|
||||
|Random Access Traversal Iterator Requirements (in addition to Bidirectional Traversal Iterator) |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|Expression |Return Type |Operational Semantics |Assertion/ |
|
||||
| | | |Precondition |
|
||||
+===========================================+=================================================+=========================+======================+
|
||||
|``r += n`` |``X&`` |:: | |
|
||||
| | | | |
|
||||
| | | { | |
|
||||
| | | Distance m = n; | |
|
||||
| | | if (m >= 0) | |
|
||||
| | | while (m--) | |
|
||||
| | | ++r; | |
|
||||
| | | else | |
|
||||
| | | while (m++) | |
|
||||
| | | --r; | |
|
||||
| | | return r; | |
|
||||
| | | } | |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``a + n``, ``n + a`` |``X`` |``{ X tmp = a; return tmp| |
|
||||
| | |+= n; }`` | |
|
||||
| | | | |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``r -= n`` |``X&`` |``return r += -n`` | |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``a - n`` |``X`` |``{ X tmp = a; return tmp| |
|
||||
| | |-= n; }`` | |
|
||||
| | | | |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``b - a`` |``Distance`` |``a < b ? distance(a,b) |pre: there exists a |
|
||||
| | |: -distance(b,a)`` |value ``n`` of |
|
||||
| | | |``Distance`` such that|
|
||||
| | | |``a + n == b``. ``b |
|
||||
| | | |== a + (b - a)``. |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``a[n]`` |convertible to T |``*(a + n)`` |pre: a is a `readable |
|
||||
| | | |iterator`_ |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``a[n] = v`` |convertible to T |``*(a + n) = v`` |pre: a is a `writable |
|
||||
| | | |iterator`_ |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``a < b`` |convertible to ``bool`` |``b - a > 0`` |``<`` is a total |
|
||||
| | | |ordering relation |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``a > b`` |convertible to ``bool`` |``b < a`` |``>`` is a total |
|
||||
| | | |ordering relation |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``a >= b`` |convertible to ``bool`` |``!(a < b)`` | |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``a <= b`` |convertible to ``bool`` |``!(a > b)`` | |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|``traversal_category<X>::type`` |Convertible to | | |
|
||||
| |``random_access_traversal_iterator_tag`` | | |
|
||||
+-------------------------------------------+-------------------------------------------------+-------------------------+----------------------+
|
||||
|
||||
|
||||
|
||||
|
||||
Reference in New Issue
Block a user