Brian Silverman | 5962333 | 2018-08-04 23:36:56 -0700 | [diff] [blame^] | 1 | .. 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 | .. Version 1.4 of this ReStructuredText document corresponds to |
| 6 | n1530_, the paper accepted by the LWG for TR1. |
| 7 | |
| 8 | .. Copyright David Abrahams, Jeremy Siek, and Thomas Witt 2003. |
| 9 | |
| 10 | .. parsed-literal:: |
| 11 | |
| 12 | template < |
| 13 | class Derived |
| 14 | , class Base |
| 15 | , class Value = use_default |
| 16 | , class CategoryOrTraversal = use_default |
| 17 | , class Reference = use_default |
| 18 | , class Difference = use_default |
| 19 | > |
| 20 | class iterator_adaptor |
| 21 | : public iterator_facade<Derived, *V'*, *C'*, *R'*, *D'*> // see details__ |
| 22 | { |
| 23 | friend class iterator_core_access; |
| 24 | public: |
| 25 | iterator_adaptor(); |
| 26 | explicit iterator_adaptor(Base const& iter); |
| 27 | typedef Base base_type; |
| 28 | Base const& base() const; |
| 29 | protected: |
| 30 | typedef iterator_adaptor iterator_adaptor\_; |
| 31 | Base const& base_reference() const; |
| 32 | Base& base_reference(); |
| 33 | private: // Core iterator interface for iterator_facade. |
| 34 | typename iterator_adaptor::reference dereference() const; |
| 35 | |
| 36 | template < |
| 37 | class OtherDerived, class OtherIterator, class V, class C, class R, class D |
| 38 | > |
| 39 | bool equal(iterator_adaptor<OtherDerived, OtherIterator, V, C, R, D> const& x) const; |
| 40 | |
| 41 | void advance(typename iterator_adaptor::difference_type n); |
| 42 | void increment(); |
| 43 | void decrement(); |
| 44 | |
| 45 | template < |
| 46 | class OtherDerived, class OtherIterator, class V, class C, class R, class D |
| 47 | > |
| 48 | typename iterator_adaptor::difference_type distance_to( |
| 49 | iterator_adaptor<OtherDerived, OtherIterator, V, C, R, D> const& y) const; |
| 50 | |
| 51 | private: |
| 52 | Base m_iterator; // exposition only |
| 53 | }; |
| 54 | |
| 55 | __ base_parameters_ |
| 56 | |
| 57 | .. _requirements: |
| 58 | |
| 59 | ``iterator_adaptor`` requirements |
| 60 | --------------------------------- |
| 61 | |
| 62 | ``static_cast<Derived*>(iterator_adaptor*)`` shall be well-formed. |
| 63 | The ``Base`` argument shall be Assignable and Copy Constructible. |
| 64 | |
| 65 | |
| 66 | .. _base_parameters: |
| 67 | |
| 68 | ``iterator_adaptor`` base class parameters |
| 69 | ------------------------------------------ |
| 70 | |
| 71 | The *V'*, *C'*, *R'*, and *D'* parameters of the ``iterator_facade`` |
| 72 | used as a base class in the summary of ``iterator_adaptor`` |
| 73 | above are defined as follows: |
| 74 | |
| 75 | .. parsed-literal:: |
| 76 | |
| 77 | *V'* = if (Value is use_default) |
| 78 | return iterator_traits<Base>::value_type |
| 79 | else |
| 80 | return Value |
| 81 | |
| 82 | *C'* = if (CategoryOrTraversal is use_default) |
| 83 | return iterator_traversal<Base>::type |
| 84 | else |
| 85 | return CategoryOrTraversal |
| 86 | |
| 87 | *R'* = if (Reference is use_default) |
| 88 | if (Value is use_default) |
| 89 | return iterator_traits<Base>::reference |
| 90 | else |
| 91 | return Value& |
| 92 | else |
| 93 | return Reference |
| 94 | |
| 95 | *D'* = if (Difference is use_default) |
| 96 | return iterator_traits<Base>::difference_type |
| 97 | else |
| 98 | return Difference |
| 99 | |
| 100 | .. ``iterator_adaptor`` models |
| 101 | --------------------------- |
| 102 | |
| 103 | In order for ``Derived`` to model the iterator concepts corresponding |
| 104 | to ``iterator_traits<Derived>::iterator_category``, the expressions |
| 105 | involving ``m_iterator`` in the specifications of those private member |
| 106 | functions of ``iterator_adaptor`` that may be called by |
| 107 | ``iterator_facade<Derived, V, C, R, D>`` in evaluating any valid |
| 108 | expression involving ``Derived`` in those concepts' requirements. |
| 109 | |
| 110 | .. The above is confusing and needs a rewrite. -JGS |
| 111 | .. That's why it's removed. We're embracing inheritance, remember? |
| 112 | |
| 113 | ``iterator_adaptor`` public operations |
| 114 | -------------------------------------- |
| 115 | |
| 116 | ``iterator_adaptor();`` |
| 117 | |
| 118 | :Requires: The ``Base`` type must be Default Constructible. |
| 119 | :Returns: An instance of ``iterator_adaptor`` with |
| 120 | ``m_iterator`` default constructed. |
| 121 | |
| 122 | |
| 123 | ``explicit iterator_adaptor(Base const& iter);`` |
| 124 | |
| 125 | :Returns: An instance of ``iterator_adaptor`` with |
| 126 | ``m_iterator`` copy constructed from ``iter``. |
| 127 | |
| 128 | ``Base const& base() const;`` |
| 129 | |
| 130 | :Returns: ``m_iterator`` |
| 131 | |
| 132 | ``iterator_adaptor`` protected member functions |
| 133 | ----------------------------------------------- |
| 134 | |
| 135 | ``Base const& base_reference() const;`` |
| 136 | |
| 137 | :Returns: A const reference to ``m_iterator``. |
| 138 | |
| 139 | |
| 140 | ``Base& base_reference();`` |
| 141 | |
| 142 | :Returns: A non-const reference to ``m_iterator``. |
| 143 | |
| 144 | |
| 145 | ``iterator_adaptor`` private member functions |
| 146 | --------------------------------------------- |
| 147 | |
| 148 | ``typename iterator_adaptor::reference dereference() const;`` |
| 149 | |
| 150 | :Returns: ``*m_iterator`` |
| 151 | |
| 152 | :: |
| 153 | |
| 154 | template < |
| 155 | class OtherDerived, class OtherIterator, class V, class C, class R, class D |
| 156 | > |
| 157 | bool equal(iterator_adaptor<OtherDerived, OtherIterator, V, C, R, D> const& x) const; |
| 158 | |
| 159 | :Returns: ``m_iterator == x.base()`` |
| 160 | |
| 161 | |
| 162 | ``void advance(typename iterator_adaptor::difference_type n);`` |
| 163 | |
| 164 | :Effects: ``m_iterator += n;`` |
| 165 | |
| 166 | ``void increment();`` |
| 167 | |
| 168 | :Effects: ``++m_iterator;`` |
| 169 | |
| 170 | ``void decrement();`` |
| 171 | |
| 172 | :Effects: ``--m_iterator;`` |
| 173 | |
| 174 | :: |
| 175 | |
| 176 | template < |
| 177 | class OtherDerived, class OtherIterator, class V, class C, class R, class D |
| 178 | > |
| 179 | typename iterator_adaptor::difference_type distance_to( |
| 180 | iterator_adaptor<OtherDerived, OtherIterator, V, C, R, D> const& y) const; |
| 181 | |
| 182 | :Returns: ``y.base() - m_iterator`` |