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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)
- .. Version 1.3 of this document was accepted for TR1
- ::
- template <class UnaryFunction,
- class Iterator,
- class Reference = use_default,
- class Value = use_default>
- class transform_iterator
- {
- public:
- typedef /* see below */ value_type;
- typedef /* see below */ reference;
- typedef /* see below */ pointer;
- typedef iterator_traits<Iterator>::difference_type difference_type;
- typedef /* see below */ iterator_category;
- transform_iterator();
- transform_iterator(Iterator const& x, UnaryFunction f);
- template<class F2, class I2, class R2, class V2>
- transform_iterator(
- transform_iterator<F2, I2, R2, V2> const& t
- , typename enable_if_convertible<I2, Iterator>::type* = 0 // exposition only
- , typename enable_if_convertible<F2, UnaryFunction>::type* = 0 // exposition only
- );
- UnaryFunction functor() const;
- Iterator const& base() const;
- reference operator*() const;
- transform_iterator& operator++();
- transform_iterator& operator--();
- private:
- Iterator m_iterator; // exposition only
- UnaryFunction m_f; // exposition only
- };
- If ``Reference`` is ``use_default`` then the ``reference`` member of
- ``transform_iterator`` is
- ``result_of<const UnaryFunction(iterator_traits<Iterator>::reference)>::type``.
- Otherwise, ``reference`` is ``Reference``.
- If ``Value`` is ``use_default`` then the ``value_type`` member is
- ``remove_cv<remove_reference<reference> >::type``. Otherwise,
- ``value_type`` is ``Value``.
- If ``Iterator`` models Readable Lvalue Iterator and if ``Iterator``
- models Random Access Traversal Iterator, then ``iterator_category`` is
- convertible to ``random_access_iterator_tag``. Otherwise, if
- ``Iterator`` models Bidirectional Traversal Iterator, then
- ``iterator_category`` is convertible to
- ``bidirectional_iterator_tag``. Otherwise ``iterator_category`` is
- convertible to ``forward_iterator_tag``. If ``Iterator`` does not
- model Readable Lvalue Iterator then ``iterator_category`` is
- convertible to ``input_iterator_tag``.
- ``transform_iterator`` requirements
- ...................................
- The type ``UnaryFunction`` must be Assignable, Copy Constructible, and
- the expression ``f(*i)`` must be valid where ``f`` is a const object of
- type ``UnaryFunction``, ``i`` is an object of type ``Iterator``, and
- where the type of ``f(*i)`` must be
- ``result_of<const UnaryFunction(iterator_traits<Iterator>::reference)>::type``.
- The argument ``Iterator`` shall model Readable Iterator.
- ``transform_iterator`` models
- .............................
- The resulting ``transform_iterator`` models the most refined of the
- following that is also modeled by ``Iterator``.
- * Writable Lvalue Iterator if ``transform_iterator::reference`` is a non-const reference.
- * Readable Lvalue Iterator if ``transform_iterator::reference`` is a const reference.
- * Readable Iterator otherwise.
- The ``transform_iterator`` models the most refined standard traversal
- concept that is modeled by the ``Iterator`` argument.
- If ``transform_iterator`` is a model of Readable Lvalue Iterator then
- it models the following original iterator concepts depending on what
- the ``Iterator`` argument models.
- +-----------------------------------+---------------------------------------+
- | If ``Iterator`` models | then ``transform_iterator`` models |
- +===================================+=======================================+
- | Single Pass Iterator | Input Iterator |
- +-----------------------------------+---------------------------------------+
- | Forward Traversal Iterator | Forward Iterator |
- +-----------------------------------+---------------------------------------+
- | Bidirectional Traversal Iterator | Bidirectional Iterator |
- +-----------------------------------+---------------------------------------+
- | Random Access Traversal Iterator | Random Access Iterator |
- +-----------------------------------+---------------------------------------+
- If ``transform_iterator`` models Writable Lvalue Iterator then it is a
- mutable iterator (as defined in the old iterator requirements).
- ``transform_iterator<F1, X, R1, V1>`` is interoperable with
- ``transform_iterator<F2, Y, R2, V2>`` if and only if ``X`` is
- interoperable with ``Y``.
- ``transform_iterator`` operations
- .................................
- In addition to the operations required by the concepts modeled by
- ``transform_iterator``, ``transform_iterator`` provides the following
- operations.
- ``transform_iterator();``
- :Returns: An instance of ``transform_iterator`` with ``m_f``
- and ``m_iterator`` default constructed.
- ``transform_iterator(Iterator const& x, UnaryFunction f);``
- :Returns: An instance of ``transform_iterator`` with ``m_f``
- initialized to ``f`` and ``m_iterator`` initialized to ``x``.
- ::
- template<class F2, class I2, class R2, class V2>
- transform_iterator(
- transform_iterator<F2, I2, R2, V2> const& t
- , typename enable_if_convertible<I2, Iterator>::type* = 0 // exposition only
- , typename enable_if_convertible<F2, UnaryFunction>::type* = 0 // exposition only
- );
- :Returns: An instance of ``transform_iterator`` with ``m_f``
- initialized to ``t.functor()`` and ``m_iterator`` initialized to
- ``t.base()``.
- :Requires: ``OtherIterator`` is implicitly convertible to ``Iterator``.
- ``UnaryFunction functor() const;``
- :Returns: ``m_f``
- ``Iterator const& base() const;``
- :Returns: ``m_iterator``
- ``reference operator*() const;``
- :Returns: ``m_f(*m_iterator)``
- ``transform_iterator& operator++();``
- :Effects: ``++m_iterator``
- :Returns: ``*this``
- ``transform_iterator& operator--();``
- :Effects: ``--m_iterator``
- :Returns: ``*this``
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