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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``
|
