| .. 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``. |