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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)
::
template<typename IteratorTuple>
class zip_iterator
{
public:
typedef /* see below */ reference;
typedef reference value_type;
typedef value_type* pointer;
typedef /* see below */ difference_type;
typedef /* see below */ iterator_category;
zip_iterator();
zip_iterator(IteratorTuple iterator_tuple);
template<typename OtherIteratorTuple>
zip_iterator(
const zip_iterator<OtherIteratorTuple>& other
, typename enable_if_convertible<
OtherIteratorTuple
, IteratorTuple>::type* = 0 // exposition only
);
const IteratorTuple& get_iterator_tuple() const;
private:
IteratorTuple m_iterator_tuple; // exposition only
};
template<typename IteratorTuple>
zip_iterator<IteratorTuple>
make_zip_iterator(IteratorTuple t);
The ``reference`` member of ``zip_iterator`` is the type of the tuple
made of the reference types of the iterator types in the ``IteratorTuple``
argument.
The ``difference_type`` member of ``zip_iterator`` is the ``difference_type``
of the first of the iterator types in the ``IteratorTuple`` argument.
The ``iterator_category`` member of ``zip_iterator`` is convertible to the
minimum of the traversal categories of the iterator types in the ``IteratorTuple``
argument. For example, if the ``zip_iterator`` holds only vector
iterators, then ``iterator_category`` is convertible to
``boost::random_access_traversal_tag``. If you add a list iterator, then
``iterator_category`` will be convertible to ``boost::bidirectional_traversal_tag``,
but no longer to ``boost::random_access_traversal_tag``.
``zip_iterator`` requirements
...................................
All iterator types in the argument ``IteratorTuple`` shall model Readable Iterator.
``zip_iterator`` models
.............................
The resulting ``zip_iterator`` models Readable Iterator.
The fact that the ``zip_iterator`` models only Readable Iterator does not
prevent you from modifying the values that the individual iterators point
to. The tuple returned by the ``zip_iterator``'s ``operator*`` is a tuple
constructed from the reference types of the individual iterators, not
their value types. For example, if ``zip_it`` is a ``zip_iterator`` whose
first member iterator is an ``std::vector<double>::iterator``, then the
following line will modify the value which the first member iterator of
``zip_it`` currently points to:
::
zip_it->get<0>() = 42.0;
Consider the set of standard traversal concepts obtained by taking
the most refined standard traversal concept modeled by each individual
iterator type in the ``IteratorTuple`` argument.The ``zip_iterator``
models the least refined standard traversal concept in this set.
``zip_iterator<IteratorTuple1>`` is interoperable with
``zip_iterator<IteratorTuple2>`` if and only if ``IteratorTuple1``
is interoperable with ``IteratorTuple2``.
``zip_iterator`` operations
.................................
In addition to the operations required by the concepts modeled by
``zip_iterator``, ``zip_iterator`` provides the following
operations.
``zip_iterator();``
:Returns: An instance of ``zip_iterator`` with ``m_iterator_tuple``
default constructed.
``zip_iterator(IteratorTuple iterator_tuple);``
:Returns: An instance of ``zip_iterator`` with ``m_iterator_tuple``
initialized to ``iterator_tuple``.
::
template<typename OtherIteratorTuple>
zip_iterator(
const zip_iterator<OtherIteratorTuple>& other
, typename enable_if_convertible<
OtherIteratorTuple
, IteratorTuple>::type* = 0 // exposition only
);
:Returns: An instance of ``zip_iterator`` that is a copy of ``other``.
:Requires: ``OtherIteratorTuple`` is implicitly convertible to ``IteratorTuple``.
``const IteratorTuple& get_iterator_tuple() const;``
:Returns: ``m_iterator_tuple``
``reference operator*() const;``
:Returns: A tuple consisting of the results of dereferencing all iterators in
``m_iterator_tuple``.
``zip_iterator& operator++();``
:Effects: Increments each iterator in ``m_iterator_tuple``.
:Returns: ``*this``
``zip_iterator& operator--();``
:Effects: Decrements each iterator in ``m_iterator_tuple``.
:Returns: ``*this``
::
template<typename IteratorTuple>
zip_iterator<IteratorTuple>
make_zip_iterator(IteratorTuple t);
:Returns: An instance of ``zip_iterator<IteratorTuple>`` with ``m_iterator_tuple``
initialized to ``t``.
|
