[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_TRANSFORM_ITERATOR_23022003THW_HPP
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| 8 | #define BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
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| 9 |
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| 10 | #include <boost/function.hpp>
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| 11 | #include <boost/iterator.hpp>
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| 12 | #include <boost/iterator/detail/enable_if.hpp>
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| 13 | #include <boost/iterator/iterator_adaptor.hpp>
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| 14 | #include <boost/iterator/iterator_categories.hpp>
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| 15 | #include <boost/mpl/not.hpp>
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| 16 | #include <boost/mpl/bool.hpp>
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| 17 | #include <boost/type_traits/function_traits.hpp>
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| 18 | #include <boost/type_traits/is_const.hpp>
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| 19 | #include <boost/type_traits/is_class.hpp>
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| 20 | #include <boost/type_traits/is_function.hpp>
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| 21 | #include <boost/type_traits/is_reference.hpp>
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| 22 | #include <boost/type_traits/remove_const.hpp>
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| 23 | #include <boost/type_traits/remove_reference.hpp>
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| 24 |
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| 25 | #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))
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| 26 | # include <boost/type_traits/is_base_and_derived.hpp>
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| 27 |
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| 28 | #endif
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| 29 | #include <boost/iterator/detail/config_def.hpp>
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| 30 |
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| 31 |
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| 32 | namespace boost
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| 33 | {
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| 34 | template <class UnaryFunction, class Iterator, class Reference = use_default, class Value = use_default>
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| 35 | class transform_iterator;
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| 36 |
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| 37 | namespace detail
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| 38 | {
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| 39 |
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| 40 | template <class UnaryFunction>
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| 41 | struct function_object_result
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| 42 | {
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| 43 | typedef typename UnaryFunction::result_type type;
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| 44 | };
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| 45 |
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| 46 | #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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| 47 | template <class Return, class Argument>
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| 48 | struct function_object_result<Return(*)(Argument)>
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| 49 | {
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| 50 | typedef Return type;
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| 51 | };
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| 52 | #endif
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| 53 |
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| 54 | // Compute the iterator_adaptor instantiation to be used for transform_iterator
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| 55 | template <class UnaryFunction, class Iterator, class Reference, class Value>
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| 56 | struct transform_iterator_base
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| 57 | {
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| 58 | private:
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| 59 | // By default, dereferencing the iterator yields the same as
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| 60 | // the function. Do we need to adjust the way
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| 61 | // function_object_result is computed for the standard
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| 62 | // proposal (e.g. using Doug's result_of)?
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| 63 | typedef typename ia_dflt_help<
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| 64 | Reference
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| 65 | , function_object_result<UnaryFunction>
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| 66 | >::type reference;
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| 67 |
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| 68 | // To get the default for Value: remove any reference on the
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| 69 | // result type, but retain any constness to signal
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| 70 | // non-writability. Note that if we adopt Thomas' suggestion
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| 71 | // to key non-writability *only* on the Reference argument,
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| 72 | // we'd need to strip constness here as well.
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| 73 | typedef typename ia_dflt_help<
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| 74 | Value
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| 75 | , remove_reference<reference>
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| 76 | >::type cv_value_type;
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| 77 |
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| 78 | public:
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| 79 | typedef iterator_adaptor<
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| 80 | transform_iterator<UnaryFunction, Iterator, Reference, Value>
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| 81 | , Iterator
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| 82 | , cv_value_type
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| 83 | , use_default // Leave the traversal category alone
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| 84 | , reference
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| 85 | > type;
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| 86 | };
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| 87 | }
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| 88 |
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| 89 | template <class UnaryFunction, class Iterator, class Reference, class Value>
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| 90 | class transform_iterator
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| 91 | : public detail::transform_iterator_base<UnaryFunction, Iterator, Reference, Value>::type
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| 92 | {
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| 93 | typedef typename
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| 94 | detail::transform_iterator_base<UnaryFunction, Iterator, Reference, Value>::type
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| 95 | super_t;
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| 96 |
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| 97 | friend class iterator_core_access;
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| 98 |
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| 99 | public:
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| 100 | transform_iterator() { }
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| 101 |
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| 102 | transform_iterator(Iterator const& x, UnaryFunction f)
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| 103 | : super_t(x), m_f(f) { }
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| 104 |
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| 105 | explicit transform_iterator(Iterator const& x)
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| 106 | : super_t(x)
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| 107 | {
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| 108 | // Pro8 is a little too aggressive about instantiating the
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| 109 | // body of this function.
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| 110 | #if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
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| 111 | // don't provide this constructor if UnaryFunction is a
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| 112 | // function pointer type, since it will be 0. Too dangerous.
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| 113 | BOOST_STATIC_ASSERT(is_class<UnaryFunction>::value);
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| 114 | #endif
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| 115 | }
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| 116 |
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| 117 | template<
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| 118 | class OtherUnaryFunction
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| 119 | , class OtherIterator
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| 120 | , class OtherReference
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| 121 | , class OtherValue>
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| 122 | transform_iterator(
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| 123 | transform_iterator<OtherUnaryFunction, OtherIterator, OtherReference, OtherValue> const& t
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| 124 | , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
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| 125 | #if !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
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| 126 | , typename enable_if_convertible<OtherUnaryFunction, UnaryFunction>::type* = 0
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| 127 | #endif
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| 128 | )
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| 129 | : super_t(t.base()), m_f(t.functor())
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| 130 | {}
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| 131 |
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| 132 | UnaryFunction functor() const
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| 133 | { return m_f; }
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| 134 |
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| 135 | private:
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| 136 | typename super_t::reference dereference() const
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| 137 | { return m_f(*this->base()); }
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| 138 |
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| 139 | // Probably should be the initial base class so it can be
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| 140 | // optimized away via EBO if it is an empty class.
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| 141 | UnaryFunction m_f;
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| 142 | };
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| 143 |
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| 144 | template <class UnaryFunction, class Iterator>
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| 145 | transform_iterator<UnaryFunction, Iterator>
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| 146 | make_transform_iterator(Iterator it, UnaryFunction fun)
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| 147 | {
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| 148 | return transform_iterator<UnaryFunction, Iterator>(it, fun);
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| 149 | }
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| 150 |
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| 151 | // Version which allows explicit specification of the UnaryFunction
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| 152 | // type.
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| 153 | //
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| 154 | // This generator is not provided if UnaryFunction is a function
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| 155 | // pointer type, because it's too dangerous: the default-constructed
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| 156 | // function pointer in the iterator be 0, leading to a runtime
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| 157 | // crash.
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| 158 | template <class UnaryFunction, class Iterator>
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| 159 | #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
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| 160 | typename mpl::if_<
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| 161 | #else
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| 162 | typename iterators::enable_if<
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| 163 | #endif
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| 164 | is_class<UnaryFunction> // We should probably find a cheaper test than is_class<>
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| 165 | , transform_iterator<UnaryFunction, Iterator>
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| 166 | #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
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| 167 | , int[3]
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| 168 | #endif
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| 169 | >::type
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| 170 | make_transform_iterator(Iterator it)
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| 171 | {
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| 172 | return transform_iterator<UnaryFunction, Iterator>(it, UnaryFunction());
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| 173 | }
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| 174 |
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| 175 | #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
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| 176 | template <class Return, class Argument, class Iterator>
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| 177 | transform_iterator< Return (*)(Argument), Iterator, Return>
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| 178 | make_transform_iterator(Iterator it, Return (*fun)(Argument))
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| 179 | {
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| 180 | return transform_iterator<Return (*)(Argument), Iterator, Return>(it, fun);
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| 181 | }
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| 182 | #endif
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| 183 |
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| 184 | } // namespace boost
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| 185 |
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| 186 | #include <boost/iterator/detail/config_undef.hpp>
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| 187 |
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| 188 | #endif // BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
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