Brian Silverman | 5962333 | 2018-08-04 23:36:56 -0700 | [diff] [blame^] | 1 | .. Copyright David Abrahams 2006. Distributed under the Boost |
| 2 | .. Software License, Version 1.0. (See accompanying |
| 3 | .. file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| 4 | |
| 5 | :: |
| 6 | |
| 7 | template<typename IteratorTuple> |
| 8 | class zip_iterator |
| 9 | { |
| 10 | |
| 11 | public: |
| 12 | typedef /* see below */ reference; |
| 13 | typedef reference value_type; |
| 14 | typedef value_type* pointer; |
| 15 | typedef /* see below */ difference_type; |
| 16 | typedef /* see below */ iterator_category; |
| 17 | |
| 18 | zip_iterator(); |
| 19 | zip_iterator(IteratorTuple iterator_tuple); |
| 20 | |
| 21 | template<typename OtherIteratorTuple> |
| 22 | zip_iterator( |
| 23 | const zip_iterator<OtherIteratorTuple>& other |
| 24 | , typename enable_if_convertible< |
| 25 | OtherIteratorTuple |
| 26 | , IteratorTuple>::type* = 0 // exposition only |
| 27 | ); |
| 28 | |
| 29 | const IteratorTuple& get_iterator_tuple() const; |
| 30 | |
| 31 | private: |
| 32 | IteratorTuple m_iterator_tuple; // exposition only |
| 33 | }; |
| 34 | |
| 35 | template<typename IteratorTuple> |
| 36 | zip_iterator<IteratorTuple> |
| 37 | make_zip_iterator(IteratorTuple t); |
| 38 | |
| 39 | |
| 40 | The ``reference`` member of ``zip_iterator`` is the type of the tuple |
| 41 | made of the reference types of the iterator types in the ``IteratorTuple`` |
| 42 | argument. |
| 43 | |
| 44 | The ``difference_type`` member of ``zip_iterator`` is the ``difference_type`` |
| 45 | of the first of the iterator types in the ``IteratorTuple`` argument. |
| 46 | |
| 47 | The ``iterator_category`` member of ``zip_iterator`` is convertible to the |
| 48 | minimum of the traversal categories of the iterator types in the ``IteratorTuple`` |
| 49 | argument. For example, if the ``zip_iterator`` holds only vector |
| 50 | iterators, then ``iterator_category`` is convertible to |
| 51 | ``boost::random_access_traversal_tag``. If you add a list iterator, then |
| 52 | ``iterator_category`` will be convertible to ``boost::bidirectional_traversal_tag``, |
| 53 | but no longer to ``boost::random_access_traversal_tag``. |
| 54 | |
| 55 | |
| 56 | ``zip_iterator`` requirements |
| 57 | ................................... |
| 58 | |
| 59 | All iterator types in the argument ``IteratorTuple`` shall model Readable Iterator. |
| 60 | |
| 61 | |
| 62 | ``zip_iterator`` models |
| 63 | ............................. |
| 64 | |
| 65 | The resulting ``zip_iterator`` models Readable Iterator. |
| 66 | |
| 67 | The fact that the ``zip_iterator`` models only Readable Iterator does not |
| 68 | prevent you from modifying the values that the individual iterators point |
| 69 | to. The tuple returned by the ``zip_iterator``'s ``operator*`` is a tuple |
| 70 | constructed from the reference types of the individual iterators, not |
| 71 | their value types. For example, if ``zip_it`` is a ``zip_iterator`` whose |
| 72 | first member iterator is an ``std::vector<double>::iterator``, then the |
| 73 | following line will modify the value which the first member iterator of |
| 74 | ``zip_it`` currently points to: |
| 75 | |
| 76 | :: |
| 77 | |
| 78 | zip_it->get<0>() = 42.0; |
| 79 | |
| 80 | |
| 81 | Consider the set of standard traversal concepts obtained by taking |
| 82 | the most refined standard traversal concept modeled by each individual |
| 83 | iterator type in the ``IteratorTuple`` argument.The ``zip_iterator`` |
| 84 | models the least refined standard traversal concept in this set. |
| 85 | |
| 86 | ``zip_iterator<IteratorTuple1>`` is interoperable with |
| 87 | ``zip_iterator<IteratorTuple2>`` if and only if ``IteratorTuple1`` |
| 88 | is interoperable with ``IteratorTuple2``. |
| 89 | |
| 90 | |
| 91 | |
| 92 | ``zip_iterator`` operations |
| 93 | ................................. |
| 94 | |
| 95 | In addition to the operations required by the concepts modeled by |
| 96 | ``zip_iterator``, ``zip_iterator`` provides the following |
| 97 | operations. |
| 98 | |
| 99 | |
| 100 | ``zip_iterator();`` |
| 101 | |
| 102 | :Returns: An instance of ``zip_iterator`` with ``m_iterator_tuple`` |
| 103 | default constructed. |
| 104 | |
| 105 | |
| 106 | ``zip_iterator(IteratorTuple iterator_tuple);`` |
| 107 | |
| 108 | :Returns: An instance of ``zip_iterator`` with ``m_iterator_tuple`` |
| 109 | initialized to ``iterator_tuple``. |
| 110 | |
| 111 | |
| 112 | :: |
| 113 | |
| 114 | template<typename OtherIteratorTuple> |
| 115 | zip_iterator( |
| 116 | const zip_iterator<OtherIteratorTuple>& other |
| 117 | , typename enable_if_convertible< |
| 118 | OtherIteratorTuple |
| 119 | , IteratorTuple>::type* = 0 // exposition only |
| 120 | ); |
| 121 | |
| 122 | :Returns: An instance of ``zip_iterator`` that is a copy of ``other``. |
| 123 | :Requires: ``OtherIteratorTuple`` is implicitly convertible to ``IteratorTuple``. |
| 124 | |
| 125 | |
| 126 | ``const IteratorTuple& get_iterator_tuple() const;`` |
| 127 | |
| 128 | :Returns: ``m_iterator_tuple`` |
| 129 | |
| 130 | |
| 131 | ``reference operator*() const;`` |
| 132 | |
| 133 | :Returns: A tuple consisting of the results of dereferencing all iterators in |
| 134 | ``m_iterator_tuple``. |
| 135 | |
| 136 | |
| 137 | ``zip_iterator& operator++();`` |
| 138 | |
| 139 | :Effects: Increments each iterator in ``m_iterator_tuple``. |
| 140 | :Returns: ``*this`` |
| 141 | |
| 142 | |
| 143 | ``zip_iterator& operator--();`` |
| 144 | |
| 145 | :Effects: Decrements each iterator in ``m_iterator_tuple``. |
| 146 | :Returns: ``*this`` |
| 147 | |
| 148 | :: |
| 149 | |
| 150 | template<typename IteratorTuple> |
| 151 | zip_iterator<IteratorTuple> |
| 152 | make_zip_iterator(IteratorTuple t); |
| 153 | |
| 154 | :Returns: An instance of ``zip_iterator<IteratorTuple>`` with ``m_iterator_tuple`` |
| 155 | initialized to ``t``. |