[857] | 1 | // (C) Copyright David Abrahams 2002.
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| 2 | // (C) Copyright Jeremy Siek 2002.
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| 3 | // (C) Copyright Thomas Witt 2002.
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| 4 | // Distributed under the Boost Software License, Version 1.0. (See
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| 5 | // accompanying file LICENSE_1_0.txt or copy at
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| 6 | // http://www.boost.org/LICENSE_1_0.txt)
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| 7 | #ifndef BOOST_ITERATOR_FACADE_23022003THW_HPP
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| 8 | #define BOOST_ITERATOR_FACADE_23022003THW_HPP
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| 9 |
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| 10 | #include <boost/iterator.hpp>
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| 11 | #include <boost/iterator/interoperable.hpp>
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| 12 | #include <boost/iterator/iterator_traits.hpp>
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| 13 |
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| 14 | #include <boost/iterator/detail/facade_iterator_category.hpp>
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| 15 | #include <boost/iterator/detail/enable_if.hpp>
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| 16 |
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| 17 | #include <boost/implicit_cast.hpp>
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| 18 | #include <boost/static_assert.hpp>
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| 19 |
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| 20 | #include <boost/type_traits/is_same.hpp>
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| 21 | #include <boost/type_traits/add_const.hpp>
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| 22 | #include <boost/type_traits/add_pointer.hpp>
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| 23 | #include <boost/type_traits/remove_const.hpp>
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| 24 | #include <boost/type_traits/remove_reference.hpp>
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| 25 | #include <boost/type_traits/is_convertible.hpp>
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| 26 | #include <boost/type_traits/is_pod.hpp>
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| 27 |
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| 28 | #include <boost/mpl/eval_if.hpp>
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| 29 | #include <boost/mpl/if.hpp>
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| 30 | #include <boost/mpl/or.hpp>
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| 31 | #include <boost/mpl/and.hpp>
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| 32 | #include <boost/mpl/not.hpp>
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| 33 | #include <boost/mpl/always.hpp>
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| 34 | #include <boost/mpl/apply.hpp>
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| 35 | #include <boost/mpl/identity.hpp>
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| 36 |
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| 37 | #include <boost/iterator/detail/config_def.hpp> // this goes last
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| 38 |
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| 39 | namespace boost
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| 40 | {
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| 41 | // This forward declaration is required for the friend declaration
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| 42 | // in iterator_core_access
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| 43 | template <class I, class V, class TC, class R, class D> class iterator_facade;
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| 44 |
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| 45 | namespace detail
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| 46 | {
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| 47 | // A binary metafunction class that always returns bool. VC6
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| 48 | // ICEs on mpl::always<bool>, probably because of the default
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| 49 | // parameters.
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| 50 | struct always_bool2
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| 51 | {
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| 52 | template <class T, class U>
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| 53 | struct apply
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| 54 | {
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| 55 | typedef bool type;
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| 56 | };
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| 57 | };
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| 58 |
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| 59 | //
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| 60 | // enable if for use in operator implementation.
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| 61 | //
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| 62 | template <
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| 63 | class Facade1
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| 64 | , class Facade2
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| 65 | , class Return
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| 66 | >
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| 67 | struct enable_if_interoperable
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| 68 | #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
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| 69 | {
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| 70 | typedef typename mpl::if_<
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| 71 | mpl::or_<
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| 72 | is_convertible<Facade1, Facade2>
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| 73 | , is_convertible<Facade2, Facade1>
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| 74 | >
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| 75 | , Return
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| 76 | , int[3]
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| 77 | >::type type;
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| 78 | };
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| 79 | #else
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| 80 | : ::boost::iterators::enable_if<
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| 81 | mpl::or_<
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| 82 | is_convertible<Facade1, Facade2>
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| 83 | , is_convertible<Facade2, Facade1>
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| 84 | >
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| 85 | , Return
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| 86 | >
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| 87 | {};
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| 88 | #endif
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| 89 |
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| 90 | //
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| 91 | // Generates associated types for an iterator_facade with the
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| 92 | // given parameters.
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| 93 | //
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| 94 | template <
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| 95 | class ValueParam
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| 96 | , class CategoryOrTraversal
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| 97 | , class Reference
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| 98 | , class Difference
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| 99 | >
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| 100 | struct iterator_facade_types
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| 101 | {
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| 102 | typedef typename facade_iterator_category<
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| 103 | CategoryOrTraversal, ValueParam, Reference
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| 104 | >::type iterator_category;
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| 105 |
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| 106 | typedef typename remove_const<ValueParam>::type value_type;
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| 107 |
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| 108 | typedef typename mpl::eval_if<
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| 109 | detail::iterator_writability_disabled<ValueParam,Reference>
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| 110 | , add_pointer<const value_type>
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| 111 | , add_pointer<value_type>
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| 112 | >::type pointer;
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| 113 |
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| 114 | # if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \
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| 115 | && (BOOST_WORKAROUND(_STLPORT_VERSION, BOOST_TESTED_AT(0x452)) \
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| 116 | || BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, BOOST_TESTED_AT(310))) \
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| 117 | || BOOST_WORKAROUND(BOOST_RWSTD_VER, BOOST_TESTED_AT(0x20101)) \
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| 118 | || BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, <= 310)
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| 119 |
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| 120 | // To interoperate with some broken library/compiler
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| 121 | // combinations, user-defined iterators must be derived from
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| 122 | // std::iterator. It is possible to implement a standard
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| 123 | // library for broken compilers without this limitation.
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| 124 | # define BOOST_ITERATOR_FACADE_NEEDS_ITERATOR_BASE 1
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| 125 |
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| 126 | typedef
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| 127 | iterator<iterator_category, value_type, Difference, pointer, Reference>
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| 128 | base;
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| 129 | # endif
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| 130 | };
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| 131 |
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| 132 | // iterators whose dereference operators reference the same value
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| 133 | // for all iterators into the same sequence (like many input
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| 134 | // iterators) need help with their postfix ++: the referenced
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| 135 | // value must be read and stored away before the increment occurs
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| 136 | // so that *a++ yields the originally referenced element and not
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| 137 | // the next one.
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| 138 | template <class Iterator>
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| 139 | class postfix_increment_proxy
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| 140 | {
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| 141 | typedef typename iterator_value<Iterator>::type value_type;
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| 142 | public:
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| 143 | explicit postfix_increment_proxy(Iterator const& x)
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| 144 | : stored_value(*x)
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| 145 | {}
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| 146 |
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| 147 | // Returning a mutable reference allows nonsense like
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| 148 | // (*r++).mutate(), but it imposes fewer assumptions about the
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| 149 | // behavior of the value_type. In particular, recall taht
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| 150 | // (*r).mutate() is legal if operator* returns by value.
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| 151 | value_type&
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| 152 | operator*() const
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| 153 | {
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| 154 | return this->stored_value;
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| 155 | }
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| 156 | private:
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| 157 | mutable value_type stored_value;
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| 158 | };
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| 159 |
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| 160 | //
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| 161 | // In general, we can't determine that such an iterator isn't
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| 162 | // writable -- we also need to store a copy of the old iterator so
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| 163 | // that it can be written into.
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| 164 | template <class Iterator>
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| 165 | class writable_postfix_increment_proxy
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| 166 | {
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| 167 | typedef typename iterator_value<Iterator>::type value_type;
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| 168 | public:
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| 169 | explicit writable_postfix_increment_proxy(Iterator const& x)
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| 170 | : stored_value(*x)
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| 171 | , stored_iterator(x)
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| 172 | {}
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| 173 |
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| 174 | // Dereferencing must return a proxy so that both *r++ = o and
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| 175 | // value_type(*r++) can work. In this case, *r is the same as
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| 176 | // *r++, and the conversion operator below is used to ensure
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| 177 | // readability.
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| 178 | writable_postfix_increment_proxy const&
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| 179 | operator*() const
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| 180 | {
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| 181 | return *this;
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| 182 | }
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| 183 |
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| 184 | // Provides readability of *r++
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| 185 | operator value_type&() const
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| 186 | {
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| 187 | return stored_value;
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| 188 | }
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| 189 |
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| 190 | // Provides writability of *r++
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| 191 | template <class T>
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| 192 | T const& operator=(T const& x) const
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| 193 | {
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| 194 | *this->stored_iterator = x;
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| 195 | return x;
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| 196 | }
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| 197 |
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| 198 | // This overload just in case only non-const objects are writable
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| 199 | template <class T>
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| 200 | T& operator=(T& x) const
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| 201 | {
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| 202 | *this->stored_iterator = x;
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| 203 | return x;
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| 204 | }
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| 205 |
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| 206 | // Provides X(r++)
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| 207 | operator Iterator const&() const
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| 208 | {
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| 209 | return stored_iterator;
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| 210 | }
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| 211 |
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| 212 | private:
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| 213 | mutable value_type stored_value;
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| 214 | Iterator stored_iterator;
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| 215 | };
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| 216 |
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| 217 | # ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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| 218 |
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| 219 | template <class Reference, class Value>
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| 220 | struct is_non_proxy_reference_impl
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| 221 | {
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| 222 | static Reference r;
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| 223 |
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| 224 | template <class R>
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| 225 | static typename mpl::if_<
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| 226 | is_convertible<
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| 227 | R const volatile*
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| 228 | , Value const volatile*
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| 229 | >
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| 230 | , char[1]
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| 231 | , char[2]
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| 232 | >::type& helper(R const&);
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| 233 |
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| 234 | BOOST_STATIC_CONSTANT(bool, value = sizeof(helper(r)) == 1);
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| 235 | };
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| 236 |
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| 237 | template <class Reference, class Value>
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| 238 | struct is_non_proxy_reference
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| 239 | : mpl::bool_<
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| 240 | is_non_proxy_reference_impl<Reference, Value>::value
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| 241 | >
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| 242 | {};
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| 243 | # else
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| 244 | template <class Reference, class Value>
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| 245 | struct is_non_proxy_reference
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| 246 | : is_convertible<
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| 247 | typename remove_reference<Reference>::type
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| 248 | const volatile*
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| 249 | , Value const volatile*
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| 250 | >
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| 251 | {};
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| 252 | # endif
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| 253 |
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| 254 | // A metafunction to choose the result type of postfix ++
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| 255 | //
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| 256 | // Because the C++98 input iterator requirements say that *r++ has
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| 257 | // type T (value_type), implementations of some standard
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| 258 | // algorithms like lexicographical_compare may use constructions
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| 259 | // like:
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| 260 | //
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| 261 | // *r++ < *s++
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| 262 | //
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| 263 | // If *r++ returns a proxy (as required if r is writable but not
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| 264 | // multipass), this sort of expression will fail unless the proxy
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| 265 | // supports the operator<. Since there are any number of such
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| 266 | // operations, we're not going to try to support them. Therefore,
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| 267 | // even if r++ returns a proxy, *r++ will only return a proxy if
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| 268 | // *r also returns a proxy.
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| 269 | template <class Iterator, class Value, class Reference, class CategoryOrTraversal>
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| 270 | struct postfix_increment_result
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| 271 | : mpl::eval_if<
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| 272 | mpl::and_<
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| 273 | // A proxy is only needed for readable iterators
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| 274 | is_convertible<Reference,Value const&>
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| 275 |
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| 276 | // No multipass iterator can have values that disappear
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| 277 | // before positions can be re-visited
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| 278 | , mpl::not_<
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| 279 | is_convertible<
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| 280 | typename iterator_category_to_traversal<CategoryOrTraversal>::type
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| 281 | , forward_traversal_tag
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| 282 | >
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| 283 | >
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| 284 | >
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| 285 | , mpl::if_<
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| 286 | is_non_proxy_reference<Reference,Value>
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| 287 | , postfix_increment_proxy<Iterator>
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| 288 | , writable_postfix_increment_proxy<Iterator>
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| 289 | >
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| 290 | , mpl::identity<Iterator>
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| 291 | >
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| 292 | {};
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| 293 |
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| 294 | // operator->() needs special support for input iterators to strictly meet the
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| 295 | // standard's requirements. If *i is not a reference type, we must still
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| 296 | // produce a (constant) lvalue to which a pointer can be formed. We do that by
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| 297 | // returning an instantiation of this special proxy class template.
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| 298 | template <class T>
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| 299 | struct operator_arrow_proxy
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| 300 | {
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| 301 | operator_arrow_proxy(T const* px) : m_value(*px) {}
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| 302 | const T* operator->() const { return &m_value; }
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| 303 | // This function is needed for MWCW and BCC, which won't call operator->
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| 304 | // again automatically per 13.3.1.2 para 8
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| 305 | operator const T*() const { return &m_value; }
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| 306 | T m_value;
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| 307 | };
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| 308 |
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| 309 | // A metafunction that gets the result type for operator->. Also
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| 310 | // has a static function make() which builds the result from a
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| 311 | // Reference
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| 312 | template <class ValueType, class Reference, class Pointer>
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| 313 | struct operator_arrow_result
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| 314 | {
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| 315 | // CWPro8.3 won't accept "operator_arrow_result::type", and we
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| 316 | // need that type below, so metafunction forwarding would be a
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| 317 | // losing proposition here.
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| 318 | typedef typename mpl::if_<
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| 319 | is_reference<Reference>
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| 320 | , Pointer
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| 321 | , operator_arrow_proxy<ValueType>
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| 322 | >::type type;
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| 323 |
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| 324 | static type make(Reference x)
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| 325 | {
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| 326 | return implicit_cast<type>(&x);
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| 327 | }
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| 328 | };
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| 329 |
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| 330 | # if BOOST_WORKAROUND(BOOST_MSVC, <= 1200)
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| 331 | // Deal with ETI
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| 332 | template<>
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| 333 | struct operator_arrow_result<int, int, int>
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| 334 | {
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| 335 | typedef int type;
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| 336 | };
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| 337 | # endif
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| 338 |
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| 339 | // A proxy return type for operator[], needed to deal with
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| 340 | // iterators that may invalidate referents upon destruction.
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| 341 | // Consider the temporary iterator in *(a + n)
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| 342 | template <class Iterator>
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| 343 | class operator_brackets_proxy
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| 344 | {
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| 345 | // Iterator is actually an iterator_facade, so we do not have to
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| 346 | // go through iterator_traits to access the traits.
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| 347 | typedef typename Iterator::reference reference;
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| 348 | typedef typename Iterator::value_type value_type;
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| 349 |
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| 350 | public:
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| 351 | operator_brackets_proxy(Iterator const& iter)
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| 352 | : m_iter(iter)
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| 353 | {}
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| 354 |
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| 355 | operator reference() const
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| 356 | {
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| 357 | return *m_iter;
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| 358 | }
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| 359 |
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| 360 | operator_brackets_proxy& operator=(value_type const& val)
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| 361 | {
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| 362 | *m_iter = val;
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| 363 | return *this;
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| 364 | }
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| 365 |
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| 366 | private:
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| 367 | Iterator m_iter;
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| 368 | };
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| 369 |
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| 370 | // A metafunction that determines whether operator[] must return a
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| 371 | // proxy, or whether it can simply return a copy of the value_type.
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| 372 | template <class ValueType, class Reference>
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| 373 | struct use_operator_brackets_proxy
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| 374 | : mpl::not_<
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| 375 | mpl::and_<
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| 376 | // Really we want an is_copy_constructible trait here,
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| 377 | // but is_POD will have to suffice in the meantime.
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| 378 | boost::is_POD<ValueType>
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| 379 | , iterator_writability_disabled<ValueType,Reference>
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| 380 | >
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| 381 | >
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| 382 | {};
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| 383 |
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| 384 | template <class Iterator, class Value, class Reference>
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| 385 | struct operator_brackets_result
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| 386 | {
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| 387 | typedef typename mpl::if_<
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| 388 | use_operator_brackets_proxy<Value,Reference>
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| 389 | , operator_brackets_proxy<Iterator>
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| 390 | , Value
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| 391 | >::type type;
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| 392 | };
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| 393 |
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| 394 | template <class Iterator>
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| 395 | operator_brackets_proxy<Iterator> make_operator_brackets_result(Iterator const& iter, mpl::true_)
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| 396 | {
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| 397 | return operator_brackets_proxy<Iterator>(iter);
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| 398 | }
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| 399 |
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| 400 | template <class Iterator>
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| 401 | typename Iterator::value_type make_operator_brackets_result(Iterator const& iter, mpl::false_)
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| 402 | {
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| 403 | return *iter;
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| 404 | }
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| 405 |
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| 406 | struct choose_difference_type
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| 407 | {
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| 408 | template <class I1, class I2>
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| 409 | struct apply
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| 410 | :
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| 411 | # ifdef BOOST_NO_ONE_WAY_ITERATOR_INTEROP
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| 412 | iterator_difference<I1>
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| 413 | # elif BOOST_WORKAROUND(BOOST_MSVC, == 1200)
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| 414 | mpl::if_<
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| 415 | is_convertible<I2,I1>
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| 416 | , typename I1::difference_type
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| 417 | , typename I2::difference_type
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| 418 | >
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| 419 | # else
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| 420 | mpl::eval_if<
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| 421 | is_convertible<I2,I1>
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| 422 | , iterator_difference<I1>
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| 423 | , iterator_difference<I2>
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| 424 | >
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| 425 | # endif
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| 426 | {};
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| 427 |
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| 428 | };
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| 429 | } // namespace detail
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| 430 |
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| 431 |
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| 432 | // Macros which describe the declarations of binary operators
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| 433 | # ifdef BOOST_NO_STRICT_ITERATOR_INTEROPERABILITY
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| 434 | # define BOOST_ITERATOR_FACADE_INTEROP_HEAD(prefix, op, result_type) \
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| 435 | template < \
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| 436 | class Derived1, class V1, class TC1, class R1, class D1 \
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| 437 | , class Derived2, class V2, class TC2, class R2, class D2 \
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| 438 | > \
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| 439 | prefix typename mpl::apply2<result_type,Derived1,Derived2>::type \
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| 440 | operator op( \
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| 441 | iterator_facade<Derived1, V1, TC1, R1, D1> const& lhs \
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| 442 | , iterator_facade<Derived2, V2, TC2, R2, D2> const& rhs)
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| 443 | # else
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| 444 | # define BOOST_ITERATOR_FACADE_INTEROP_HEAD(prefix, op, result_type) \
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| 445 | template < \
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| 446 | class Derived1, class V1, class TC1, class R1, class D1 \
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| 447 | , class Derived2, class V2, class TC2, class R2, class D2 \
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| 448 | > \
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| 449 | prefix typename detail::enable_if_interoperable< \
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| 450 | Derived1, Derived2 \
|
---|
| 451 | , typename mpl::apply2<result_type,Derived1,Derived2>::type \
|
---|
| 452 | >::type \
|
---|
| 453 | operator op( \
|
---|
| 454 | iterator_facade<Derived1, V1, TC1, R1, D1> const& lhs \
|
---|
| 455 | , iterator_facade<Derived2, V2, TC2, R2, D2> const& rhs)
|
---|
| 456 | # endif
|
---|
| 457 |
|
---|
| 458 | # define BOOST_ITERATOR_FACADE_PLUS_HEAD(prefix,args) \
|
---|
| 459 | template <class Derived, class V, class TC, class R, class D> \
|
---|
| 460 | prefix Derived operator+ args
|
---|
| 461 |
|
---|
| 462 | //
|
---|
| 463 | // Helper class for granting access to the iterator core interface.
|
---|
| 464 | //
|
---|
| 465 | // The simple core interface is used by iterator_facade. The core
|
---|
| 466 | // interface of a user/library defined iterator type should not be made public
|
---|
| 467 | // so that it does not clutter the public interface. Instead iterator_core_access
|
---|
| 468 | // should be made friend so that iterator_facade can access the core
|
---|
| 469 | // interface through iterator_core_access.
|
---|
| 470 | //
|
---|
| 471 | class iterator_core_access
|
---|
| 472 | {
|
---|
| 473 | # if defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS) \
|
---|
| 474 | || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
|
---|
| 475 | // Tasteless as this may seem, making all members public allows member templates
|
---|
| 476 | // to work in the absence of member template friends.
|
---|
| 477 | public:
|
---|
| 478 | # else
|
---|
| 479 |
|
---|
| 480 | template <class I, class V, class TC, class R, class D> friend class iterator_facade;
|
---|
| 481 |
|
---|
| 482 | # define BOOST_ITERATOR_FACADE_RELATION(op) \
|
---|
| 483 | BOOST_ITERATOR_FACADE_INTEROP_HEAD(friend,op, detail::always_bool2);
|
---|
| 484 |
|
---|
| 485 | BOOST_ITERATOR_FACADE_RELATION(==)
|
---|
| 486 | BOOST_ITERATOR_FACADE_RELATION(!=)
|
---|
| 487 |
|
---|
| 488 | BOOST_ITERATOR_FACADE_RELATION(<)
|
---|
| 489 | BOOST_ITERATOR_FACADE_RELATION(>)
|
---|
| 490 | BOOST_ITERATOR_FACADE_RELATION(<=)
|
---|
| 491 | BOOST_ITERATOR_FACADE_RELATION(>=)
|
---|
| 492 | # undef BOOST_ITERATOR_FACADE_RELATION
|
---|
| 493 |
|
---|
| 494 | BOOST_ITERATOR_FACADE_INTEROP_HEAD(
|
---|
| 495 | friend, -, detail::choose_difference_type)
|
---|
| 496 | ;
|
---|
| 497 |
|
---|
| 498 | BOOST_ITERATOR_FACADE_PLUS_HEAD(
|
---|
| 499 | friend
|
---|
| 500 | , (iterator_facade<Derived, V, TC, R, D> const&
|
---|
| 501 | , typename Derived::difference_type)
|
---|
| 502 | )
|
---|
| 503 | ;
|
---|
| 504 |
|
---|
| 505 | BOOST_ITERATOR_FACADE_PLUS_HEAD(
|
---|
| 506 | friend
|
---|
| 507 | , (typename Derived::difference_type
|
---|
| 508 | , iterator_facade<Derived, V, TC, R, D> const&)
|
---|
| 509 | )
|
---|
| 510 | ;
|
---|
| 511 |
|
---|
| 512 | # endif
|
---|
| 513 |
|
---|
| 514 | template <class Facade>
|
---|
| 515 | static typename Facade::reference dereference(Facade const& f)
|
---|
| 516 | {
|
---|
| 517 | return f.dereference();
|
---|
| 518 | }
|
---|
| 519 |
|
---|
| 520 | template <class Facade>
|
---|
| 521 | static void increment(Facade& f)
|
---|
| 522 | {
|
---|
| 523 | f.increment();
|
---|
| 524 | }
|
---|
| 525 |
|
---|
| 526 | template <class Facade>
|
---|
| 527 | static void decrement(Facade& f)
|
---|
| 528 | {
|
---|
| 529 | f.decrement();
|
---|
| 530 | }
|
---|
| 531 |
|
---|
| 532 | template <class Facade1, class Facade2>
|
---|
| 533 | static bool equal(Facade1 const& f1, Facade2 const& f2, mpl::true_)
|
---|
| 534 | {
|
---|
| 535 | return f1.equal(f2);
|
---|
| 536 | }
|
---|
| 537 |
|
---|
| 538 | template <class Facade1, class Facade2>
|
---|
| 539 | static bool equal(Facade1 const& f1, Facade2 const& f2, mpl::false_)
|
---|
| 540 | {
|
---|
| 541 | return f2.equal(f1);
|
---|
| 542 | }
|
---|
| 543 |
|
---|
| 544 | template <class Facade>
|
---|
| 545 | static void advance(Facade& f, typename Facade::difference_type n)
|
---|
| 546 | {
|
---|
| 547 | f.advance(n);
|
---|
| 548 | }
|
---|
| 549 |
|
---|
| 550 | template <class Facade1, class Facade2>
|
---|
| 551 | static typename Facade1::difference_type distance_from(
|
---|
| 552 | Facade1 const& f1, Facade2 const& f2, mpl::true_)
|
---|
| 553 | {
|
---|
| 554 | return -f1.distance_to(f2);
|
---|
| 555 | }
|
---|
| 556 |
|
---|
| 557 | template <class Facade1, class Facade2>
|
---|
| 558 | static typename Facade2::difference_type distance_from(
|
---|
| 559 | Facade1 const& f1, Facade2 const& f2, mpl::false_)
|
---|
| 560 | {
|
---|
| 561 | return f2.distance_to(f1);
|
---|
| 562 | }
|
---|
| 563 |
|
---|
| 564 | //
|
---|
| 565 | // Curiously Recurring Template interface.
|
---|
| 566 | //
|
---|
| 567 | template <class I, class V, class TC, class R, class D>
|
---|
| 568 | static I& derived(iterator_facade<I,V,TC,R,D>& facade)
|
---|
| 569 | {
|
---|
| 570 | return *static_cast<I*>(&facade);
|
---|
| 571 | }
|
---|
| 572 |
|
---|
| 573 | template <class I, class V, class TC, class R, class D>
|
---|
| 574 | static I const& derived(iterator_facade<I,V,TC,R,D> const& facade)
|
---|
| 575 | {
|
---|
| 576 | return *static_cast<I const*>(&facade);
|
---|
| 577 | }
|
---|
| 578 |
|
---|
| 579 | private:
|
---|
| 580 | // objects of this class are useless
|
---|
| 581 | iterator_core_access(); //undefined
|
---|
| 582 | };
|
---|
| 583 |
|
---|
| 584 | //
|
---|
| 585 | // iterator_facade - use as a public base class for defining new
|
---|
| 586 | // standard-conforming iterators.
|
---|
| 587 | //
|
---|
| 588 | template <
|
---|
| 589 | class Derived // The derived iterator type being constructed
|
---|
| 590 | , class Value
|
---|
| 591 | , class CategoryOrTraversal
|
---|
| 592 | , class Reference = Value&
|
---|
| 593 | , class Difference = std::ptrdiff_t
|
---|
| 594 | >
|
---|
| 595 | class iterator_facade
|
---|
| 596 | # ifdef BOOST_ITERATOR_FACADE_NEEDS_ITERATOR_BASE
|
---|
| 597 | : public detail::iterator_facade_types<
|
---|
| 598 | Value, CategoryOrTraversal, Reference, Difference
|
---|
| 599 | >::base
|
---|
| 600 | # undef BOOST_ITERATOR_FACADE_NEEDS_ITERATOR_BASE
|
---|
| 601 | # endif
|
---|
| 602 | {
|
---|
| 603 | private:
|
---|
| 604 | //
|
---|
| 605 | // Curiously Recurring Template interface.
|
---|
| 606 | //
|
---|
| 607 | Derived& derived()
|
---|
| 608 | {
|
---|
| 609 | return *static_cast<Derived*>(this);
|
---|
| 610 | }
|
---|
| 611 |
|
---|
| 612 | Derived const& derived() const
|
---|
| 613 | {
|
---|
| 614 | return *static_cast<Derived const*>(this);
|
---|
| 615 | }
|
---|
| 616 |
|
---|
| 617 | typedef detail::iterator_facade_types<
|
---|
| 618 | Value, CategoryOrTraversal, Reference, Difference
|
---|
| 619 | > associated_types;
|
---|
| 620 |
|
---|
| 621 | protected:
|
---|
| 622 | // For use by derived classes
|
---|
| 623 | typedef iterator_facade<Derived,Value,Reference,Difference> iterator_facade_;
|
---|
| 624 |
|
---|
| 625 | public:
|
---|
| 626 |
|
---|
| 627 | typedef typename associated_types::value_type value_type;
|
---|
| 628 | typedef Reference reference;
|
---|
| 629 | typedef Difference difference_type;
|
---|
| 630 | typedef typename associated_types::pointer pointer;
|
---|
| 631 | typedef typename associated_types::iterator_category iterator_category;
|
---|
| 632 |
|
---|
| 633 | reference operator*() const
|
---|
| 634 | {
|
---|
| 635 | return iterator_core_access::dereference(this->derived());
|
---|
| 636 | }
|
---|
| 637 |
|
---|
| 638 | typename detail::operator_arrow_result<
|
---|
| 639 | value_type
|
---|
| 640 | , reference
|
---|
| 641 | , pointer
|
---|
| 642 | >::type
|
---|
| 643 | operator->() const
|
---|
| 644 | {
|
---|
| 645 | return detail::operator_arrow_result<
|
---|
| 646 | value_type
|
---|
| 647 | , reference
|
---|
| 648 | , pointer
|
---|
| 649 | >::make(*this->derived());
|
---|
| 650 | }
|
---|
| 651 |
|
---|
| 652 | typename detail::operator_brackets_result<Derived,Value,reference>::type
|
---|
| 653 | operator[](difference_type n) const
|
---|
| 654 | {
|
---|
| 655 | typedef detail::use_operator_brackets_proxy<Value,Reference> use_proxy;
|
---|
| 656 |
|
---|
| 657 | return detail::make_operator_brackets_result<Derived>(
|
---|
| 658 | this->derived() + n
|
---|
| 659 | , use_proxy()
|
---|
| 660 | );
|
---|
| 661 | }
|
---|
| 662 |
|
---|
| 663 | Derived& operator++()
|
---|
| 664 | {
|
---|
| 665 | iterator_core_access::increment(this->derived());
|
---|
| 666 | return this->derived();
|
---|
| 667 | }
|
---|
| 668 |
|
---|
| 669 | # if BOOST_WORKAROUND(BOOST_MSVC, == 1200)
|
---|
| 670 | typename detail::postfix_increment_result<Derived,Value,Reference,CategoryOrTraversal>::type
|
---|
| 671 | operator++(int)
|
---|
| 672 | {
|
---|
| 673 | typename detail::postfix_increment_result<Derived,Value,Reference,CategoryOrTraversal>::type
|
---|
| 674 | tmp(this->derived());
|
---|
| 675 | ++*this;
|
---|
| 676 | return tmp;
|
---|
| 677 | }
|
---|
| 678 | # endif
|
---|
| 679 |
|
---|
| 680 | Derived& operator--()
|
---|
| 681 | {
|
---|
| 682 | iterator_core_access::decrement(this->derived());
|
---|
| 683 | return this->derived();
|
---|
| 684 | }
|
---|
| 685 |
|
---|
| 686 | Derived operator--(int)
|
---|
| 687 | {
|
---|
| 688 | Derived tmp(this->derived());
|
---|
| 689 | --*this;
|
---|
| 690 | return tmp;
|
---|
| 691 | }
|
---|
| 692 |
|
---|
| 693 | Derived& operator+=(difference_type n)
|
---|
| 694 | {
|
---|
| 695 | iterator_core_access::advance(this->derived(), n);
|
---|
| 696 | return this->derived();
|
---|
| 697 | }
|
---|
| 698 |
|
---|
| 699 | Derived& operator-=(difference_type n)
|
---|
| 700 | {
|
---|
| 701 | iterator_core_access::advance(this->derived(), -n);
|
---|
| 702 | return this->derived();
|
---|
| 703 | }
|
---|
| 704 |
|
---|
| 705 | Derived operator-(difference_type x) const
|
---|
| 706 | {
|
---|
| 707 | Derived result(this->derived());
|
---|
| 708 | return result -= x;
|
---|
| 709 | }
|
---|
| 710 |
|
---|
| 711 | # if BOOST_WORKAROUND(BOOST_MSVC, <= 1200)
|
---|
| 712 | // There appears to be a bug which trashes the data of classes
|
---|
| 713 | // derived from iterator_facade when they are assigned unless we
|
---|
| 714 | // define this assignment operator. This bug is only revealed
|
---|
| 715 | // (so far) in STLPort debug mode, but it's clearly a codegen
|
---|
| 716 | // problem so we apply the workaround for all MSVC6.
|
---|
| 717 | iterator_facade& operator=(iterator_facade const&)
|
---|
| 718 | {
|
---|
| 719 | return *this;
|
---|
| 720 | }
|
---|
| 721 | # endif
|
---|
| 722 | };
|
---|
| 723 |
|
---|
| 724 | # if !BOOST_WORKAROUND(BOOST_MSVC, == 1200)
|
---|
| 725 | template <class I, class V, class TC, class R, class D>
|
---|
| 726 | typename detail::postfix_increment_result<I,V,R,TC>::type
|
---|
| 727 | operator++(
|
---|
| 728 | iterator_facade<I,V,TC,R,D>& i
|
---|
| 729 | , int
|
---|
| 730 | )
|
---|
| 731 | {
|
---|
| 732 | typename detail::postfix_increment_result<I,V,R,TC>::type
|
---|
| 733 | tmp(*static_cast<I*>(&i));
|
---|
| 734 |
|
---|
| 735 | ++i;
|
---|
| 736 |
|
---|
| 737 | return tmp;
|
---|
| 738 | }
|
---|
| 739 | # endif
|
---|
| 740 |
|
---|
| 741 |
|
---|
| 742 | //
|
---|
| 743 | // Comparison operator implementation. The library supplied operators
|
---|
| 744 | // enables the user to provide fully interoperable constant/mutable
|
---|
| 745 | // iterator types. I.e. the library provides all operators
|
---|
| 746 | // for all mutable/constant iterator combinations.
|
---|
| 747 | //
|
---|
| 748 | // Note though that this kind of interoperability for constant/mutable
|
---|
| 749 | // iterators is not required by the standard for container iterators.
|
---|
| 750 | // All the standard asks for is a conversion mutable -> constant.
|
---|
| 751 | // Most standard library implementations nowadays provide fully interoperable
|
---|
| 752 | // iterator implementations, but there are still heavily used implementations
|
---|
| 753 | // that do not provide them. (Actually it's even worse, they do not provide
|
---|
| 754 | // them for only a few iterators.)
|
---|
| 755 | //
|
---|
| 756 | // ?? Maybe a BOOST_ITERATOR_NO_FULL_INTEROPERABILITY macro should
|
---|
| 757 | // enable the user to turn off mixed type operators
|
---|
| 758 | //
|
---|
| 759 | // The library takes care to provide only the right operator overloads.
|
---|
| 760 | // I.e.
|
---|
| 761 | //
|
---|
| 762 | // bool operator==(Iterator, Iterator);
|
---|
| 763 | // bool operator==(ConstIterator, Iterator);
|
---|
| 764 | // bool operator==(Iterator, ConstIterator);
|
---|
| 765 | // bool operator==(ConstIterator, ConstIterator);
|
---|
| 766 | //
|
---|
| 767 | // ...
|
---|
| 768 | //
|
---|
| 769 | // In order to do so it uses c++ idioms that are not yet widely supported
|
---|
| 770 | // by current compiler releases. The library is designed to degrade gracefully
|
---|
| 771 | // in the face of compiler deficiencies. In general compiler
|
---|
| 772 | // deficiencies result in less strict error checking and more obscure
|
---|
| 773 | // error messages, functionality is not affected.
|
---|
| 774 | //
|
---|
| 775 | // For full operation compiler support for "Substitution Failure Is Not An Error"
|
---|
| 776 | // (aka. enable_if) and boost::is_convertible is required.
|
---|
| 777 | //
|
---|
| 778 | // The following problems occur if support is lacking.
|
---|
| 779 | //
|
---|
| 780 | // Pseudo code
|
---|
| 781 | //
|
---|
| 782 | // ---------------
|
---|
| 783 | // AdaptorA<Iterator1> a1;
|
---|
| 784 | // AdaptorA<Iterator2> a2;
|
---|
| 785 | //
|
---|
| 786 | // // This will result in a no such overload error in full operation
|
---|
| 787 | // // If enable_if or is_convertible is not supported
|
---|
| 788 | // // The instantiation will fail with an error hopefully indicating that
|
---|
| 789 | // // there is no operator== for Iterator1, Iterator2
|
---|
| 790 | // // The same will happen if no enable_if is used to remove
|
---|
| 791 | // // false overloads from the templated conversion constructor
|
---|
| 792 | // // of AdaptorA.
|
---|
| 793 | //
|
---|
| 794 | // a1 == a2;
|
---|
| 795 | // ----------------
|
---|
| 796 | //
|
---|
| 797 | // AdaptorA<Iterator> a;
|
---|
| 798 | // AdaptorB<Iterator> b;
|
---|
| 799 | //
|
---|
| 800 | // // This will result in a no such overload error in full operation
|
---|
| 801 | // // If enable_if is not supported the static assert used
|
---|
| 802 | // // in the operator implementation will fail.
|
---|
| 803 | // // This will accidently work if is_convertible is not supported.
|
---|
| 804 | //
|
---|
| 805 | // a == b;
|
---|
| 806 | // ----------------
|
---|
| 807 | //
|
---|
| 808 |
|
---|
| 809 | # ifdef BOOST_NO_ONE_WAY_ITERATOR_INTEROP
|
---|
| 810 | # define BOOST_ITERATOR_CONVERTIBLE(a,b) mpl::true_()
|
---|
| 811 | # else
|
---|
| 812 | # define BOOST_ITERATOR_CONVERTIBLE(a,b) is_convertible<a,b>()
|
---|
| 813 | # endif
|
---|
| 814 |
|
---|
| 815 | # define BOOST_ITERATOR_FACADE_INTEROP(op, result_type, return_prefix, base_op) \
|
---|
| 816 | BOOST_ITERATOR_FACADE_INTEROP_HEAD(inline, op, result_type) \
|
---|
| 817 | { \
|
---|
| 818 | /* For those compilers that do not support enable_if */ \
|
---|
| 819 | BOOST_STATIC_ASSERT(( \
|
---|
| 820 | is_interoperable< Derived1, Derived2 >::value \
|
---|
| 821 | )); \
|
---|
| 822 | return_prefix iterator_core_access::base_op( \
|
---|
| 823 | *static_cast<Derived1 const*>(&lhs) \
|
---|
| 824 | , *static_cast<Derived2 const*>(&rhs) \
|
---|
| 825 | , BOOST_ITERATOR_CONVERTIBLE(Derived2,Derived1) \
|
---|
| 826 | ); \
|
---|
| 827 | }
|
---|
| 828 |
|
---|
| 829 | # define BOOST_ITERATOR_FACADE_RELATION(op, return_prefix, base_op) \
|
---|
| 830 | BOOST_ITERATOR_FACADE_INTEROP( \
|
---|
| 831 | op \
|
---|
| 832 | , detail::always_bool2 \
|
---|
| 833 | , return_prefix \
|
---|
| 834 | , base_op \
|
---|
| 835 | )
|
---|
| 836 |
|
---|
| 837 | BOOST_ITERATOR_FACADE_RELATION(==, return, equal)
|
---|
| 838 | BOOST_ITERATOR_FACADE_RELATION(!=, return !, equal)
|
---|
| 839 |
|
---|
| 840 | BOOST_ITERATOR_FACADE_RELATION(<, return 0 >, distance_from)
|
---|
| 841 | BOOST_ITERATOR_FACADE_RELATION(>, return 0 <, distance_from)
|
---|
| 842 | BOOST_ITERATOR_FACADE_RELATION(<=, return 0 >=, distance_from)
|
---|
| 843 | BOOST_ITERATOR_FACADE_RELATION(>=, return 0 <=, distance_from)
|
---|
| 844 | # undef BOOST_ITERATOR_FACADE_RELATION
|
---|
| 845 |
|
---|
| 846 | // operator- requires an additional part in the static assertion
|
---|
| 847 | BOOST_ITERATOR_FACADE_INTEROP(
|
---|
| 848 | -
|
---|
| 849 | , detail::choose_difference_type
|
---|
| 850 | , return
|
---|
| 851 | , distance_from
|
---|
| 852 | )
|
---|
| 853 | # undef BOOST_ITERATOR_FACADE_INTEROP
|
---|
| 854 | # undef BOOST_ITERATOR_FACADE_INTEROP_HEAD
|
---|
| 855 |
|
---|
| 856 | # define BOOST_ITERATOR_FACADE_PLUS(args) \
|
---|
| 857 | BOOST_ITERATOR_FACADE_PLUS_HEAD(inline, args) \
|
---|
| 858 | { \
|
---|
| 859 | Derived tmp(static_cast<Derived const&>(i)); \
|
---|
| 860 | return tmp += n; \
|
---|
| 861 | }
|
---|
| 862 |
|
---|
| 863 | BOOST_ITERATOR_FACADE_PLUS((
|
---|
| 864 | iterator_facade<Derived, V, TC, R, D> const& i
|
---|
| 865 | , typename Derived::difference_type n
|
---|
| 866 | ))
|
---|
| 867 |
|
---|
| 868 | BOOST_ITERATOR_FACADE_PLUS((
|
---|
| 869 | typename Derived::difference_type n
|
---|
| 870 | , iterator_facade<Derived, V, TC, R, D> const& i
|
---|
| 871 | ))
|
---|
| 872 | # undef BOOST_ITERATOR_FACADE_PLUS
|
---|
| 873 | # undef BOOST_ITERATOR_FACADE_PLUS_HEAD
|
---|
| 874 |
|
---|
| 875 | } // namespace boost
|
---|
| 876 |
|
---|
| 877 | #include <boost/iterator/detail/config_undef.hpp>
|
---|
| 878 |
|
---|
| 879 | #endif // BOOST_ITERATOR_FACADE_23022003THW_HPP
|
---|