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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``.
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