ceph/src/boost/libs/iterator/include/boost/iterator/transform_iterator.hpp

   1 // (C) Copyright David Abrahams 2002.
   2 // (C) Copyright Jeremy Siek    2002.
   3 // (C) Copyright Thomas Witt    2002.
   4 // Distributed under the Boost Software License, Version 1.0. (See
   5 // accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7 #ifndef BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
   8 #define BOOST_TRANSFORM_ITERATOR_23022003THW_HPP
   9
  10 #include <boost/iterator.hpp>
  11 #include <boost/iterator/detail/enable_if.hpp>
  12 #include <boost/iterator/iterator_adaptor.hpp>
  13 #include <boost/iterator/iterator_categories.hpp>
  14 #include <boost/mpl/not.hpp>
  15 #include <boost/mpl/bool.hpp>
  16 #include <boost/type_traits/function_traits.hpp>
  17 #include <boost/type_traits/is_const.hpp>
  18 #include <boost/type_traits/is_class.hpp>
  19 #include <boost/type_traits/is_function.hpp>
  20 #include <boost/type_traits/is_reference.hpp>
  21 #include <boost/type_traits/remove_const.hpp>
  22 #include <boost/type_traits/remove_reference.hpp>
  23 #include <boost/utility/result_of.hpp>
  24
  25
  26 #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))
  27 # include <boost/type_traits/is_base_and_derived.hpp>
  28
  29 #endif
  30 #include <boost/iterator/detail/config_def.hpp>
  31
  32
  33 namespace boost {
  34 namespace iterators {
  35
  36   template <class UnaryFunction, class Iterator, class Reference = use_default, class Value = use_default>
  37   class transform_iterator;
  38
  39   namespace detail
  40   {
  41     // Compute the iterator_adaptor instantiation to be used for transform_iterator
  42     template <class UnaryFunc, class Iterator, class Reference, class Value>
  43     struct transform_iterator_base
  44     {
  45      private:
  46         // By default, dereferencing the iterator yields the same as
  47         // the function.
  48         typedef typename ia_dflt_help<
  49             Reference
  50           , result_of<const UnaryFunc(typename std::iterator_traits<Iterator>::reference)>
  51         >::type reference;
  52
  53         // To get the default for Value: remove any reference on the
  54         // result type, but retain any constness to signal
  55         // non-writability.  Note that if we adopt Thomas' suggestion
  56         // to key non-writability *only* on the Reference argument,
  57         // we'd need to strip constness here as well.
  58         typedef typename ia_dflt_help<
  59             Value
  60           , remove_reference<reference>
  61         >::type cv_value_type;
  62
  63      public:
  64         typedef iterator_adaptor<
  65             transform_iterator<UnaryFunc, Iterator, Reference, Value>
  66           , Iterator
  67           , cv_value_type
  68           , use_default    // Leave the traversal category alone
  69           , reference
  70         > type;
  71     };
  72   }
  73
  74   template <class UnaryFunc, class Iterator, class Reference, class Value>
  75   class transform_iterator
  76     : public boost::iterators::detail::transform_iterator_base<UnaryFunc, Iterator, Reference, Value>::type
  77   {
  78     typedef typename
  79     boost::iterators::detail::transform_iterator_base<UnaryFunc, Iterator, Reference, Value>::type
  80     super_t;
  81
  82     friend class iterator_core_access;
  83
  84   public:
  85     transform_iterator() { }
  86
  87     transform_iterator(Iterator const& x, UnaryFunc f)
  88       : super_t(x), m_f(f) { }
  89
  90     explicit transform_iterator(Iterator const& x)
  91       : super_t(x)
  92     {
  93         // Pro8 is a little too aggressive about instantiating the
  94         // body of this function.
  95 #if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
  96         // don't provide this constructor if UnaryFunc is a
  97         // function pointer type, since it will be 0.  Too dangerous.
  98         BOOST_STATIC_ASSERT(is_class<UnaryFunc>::value);
  99 #endif
 100     }
 101
 102     template <
 103         class OtherUnaryFunction
 104       , class OtherIterator
 105       , class OtherReference
 106       , class OtherValue>
 107     transform_iterator(
 108          transform_iterator<OtherUnaryFunction, OtherIterator, OtherReference, OtherValue> const& t
 109        , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
 110 #if !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
 111        , typename enable_if_convertible<OtherUnaryFunction, UnaryFunc>::type* = 0
 112 #endif
 113     )
 114       : super_t(t.base()), m_f(t.functor())
 115    {}
 116
 117     UnaryFunc functor() const
 118       { return m_f; }
 119
 120   private:
 121     typename super_t::reference dereference() const
 122     { return m_f(*this->base()); }
 123
 124     // Probably should be the initial base class so it can be
 125     // optimized away via EBO if it is an empty class.
 126     UnaryFunc m_f;
 127   };
 128
 129   template <class UnaryFunc, class Iterator>
 130   inline transform_iterator<UnaryFunc, Iterator>
 131   make_transform_iterator(Iterator it, UnaryFunc fun)
 132   {
 133       return transform_iterator<UnaryFunc, Iterator>(it, fun);
 134   }
 135
 136   // Version which allows explicit specification of the UnaryFunc
 137   // type.
 138   //
 139   // This generator is not provided if UnaryFunc is a function
 140   // pointer type, because it's too dangerous: the default-constructed
 141   // function pointer in the iterator be 0, leading to a runtime
 142   // crash.
 143   template <class UnaryFunc, class Iterator>
 144   inline typename iterators::enable_if<
 145       is_class<UnaryFunc>   // We should probably find a cheaper test than is_class<>
 146     , transform_iterator<UnaryFunc, Iterator>
 147   >::type
 148   make_transform_iterator(Iterator it)
 149   {
 150       return transform_iterator<UnaryFunc, Iterator>(it, UnaryFunc());
 151   }
 152
 153 #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
 154   template <class Return, class Argument, class Iterator>
 155   inline transform_iterator< Return (*)(Argument), Iterator, Return>
 156   make_transform_iterator(Iterator it, Return (*fun)(Argument))
 157   {
 158     return transform_iterator<Return (*)(Argument), Iterator, Return>(it, fun);
 159   }
 160 #endif
 161
 162 } // namespace iterators
 163
 164 using iterators::transform_iterator;
 165 using iterators::make_transform_iterator;
 166
 167 } // namespace boost
 168
 169 #include <boost/iterator/detail/config_undef.hpp>
 170
 171 #endif // BOOST_TRANSFORM_ITERATOR_23022003THW_HPP