ceph/src/boost/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/detail/enable_if.hpp>
  11 #include <boost/iterator/iterator_adaptor.hpp>
  12 #include <boost/iterator/iterator_categories.hpp>
  13 #include <boost/mpl/not.hpp>
  14 #include <boost/mpl/bool.hpp>
  15 #include <boost/type_traits/function_traits.hpp>
  16 #include <boost/type_traits/is_const.hpp>
  17 #include <boost/type_traits/is_class.hpp>
  18 #include <boost/type_traits/is_function.hpp>
  19 #include <boost/type_traits/is_reference.hpp>
  20 #include <boost/type_traits/remove_const.hpp>
  21 #include <boost/type_traits/remove_reference.hpp>
  22 #include <boost/utility/result_of.hpp>
  23
  24 #include <iterator>
  25
  26 #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1310))
  27 # include <boost/type_traits/is_base_and_derived.hpp>
  28 #endif
  29
  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 #ifdef BOOST_RESULT_OF_USE_TR1
  51           , result_of<const UnaryFunc(typename std::iterator_traits<Iterator>::reference)>
  52 #else
  53           , result_of<const UnaryFunc&(typename std::iterator_traits<Iterator>::reference)>
  54 #endif
  55         >::type reference;
  56
  57         // To get the default for Value: remove any reference on the
  58         // result type, but retain any constness to signal
  59         // non-writability.  Note that if we adopt Thomas' suggestion
  60         // to key non-writability *only* on the Reference argument,
  61         // we'd need to strip constness here as well.
  62         typedef typename ia_dflt_help<
  63             Value
  64           , remove_reference<reference>
  65         >::type cv_value_type;
  66
  67      public:
  68         typedef iterator_adaptor<
  69             transform_iterator<UnaryFunc, Iterator, Reference, Value>
  70           , Iterator
  71           , cv_value_type
  72           , use_default    // Leave the traversal category alone
  73           , reference
  74         > type;
  75     };
  76   }
  77
  78   template <class UnaryFunc, class Iterator, class Reference, class Value>
  79   class transform_iterator
  80     : public boost::iterators::detail::transform_iterator_base<UnaryFunc, Iterator, Reference, Value>::type
  81   {
  82     typedef typename
  83     boost::iterators::detail::transform_iterator_base<UnaryFunc, Iterator, Reference, Value>::type
  84     super_t;
  85
  86     friend class iterator_core_access;
  87
  88   public:
  89     transform_iterator() { }
  90
  91     transform_iterator(Iterator const& x, UnaryFunc f)
  92       : super_t(x), m_f(f) { }
  93
  94     explicit transform_iterator(Iterator const& x)
  95       : super_t(x)
  96     {
  97         // Pro8 is a little too aggressive about instantiating the
  98         // body of this function.
  99 #if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
 100         // don't provide this constructor if UnaryFunc is a
 101         // function pointer type, since it will be 0.  Too dangerous.
 102         BOOST_STATIC_ASSERT(is_class<UnaryFunc>::value);
 103 #endif
 104     }
 105
 106     template <
 107         class OtherUnaryFunction
 108       , class OtherIterator
 109       , class OtherReference
 110       , class OtherValue>
 111     transform_iterator(
 112          transform_iterator<OtherUnaryFunction, OtherIterator, OtherReference, OtherValue> const& t
 113        , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
 114 #if !BOOST_WORKAROUND(BOOST_MSVC, == 1310)
 115        , typename enable_if_convertible<OtherUnaryFunction, UnaryFunc>::type* = 0
 116 #endif
 117     )
 118       : super_t(t.base()), m_f(t.functor())
 119    {}
 120
 121     UnaryFunc functor() const
 122       { return m_f; }
 123
 124   private:
 125     typename super_t::reference dereference() const
 126     { return m_f(*this->base()); }
 127
 128     // Probably should be the initial base class so it can be
 129     // optimized away via EBO if it is an empty class.
 130     UnaryFunc m_f;
 131   };
 132
 133   template <class UnaryFunc, class Iterator>
 134   inline transform_iterator<UnaryFunc, Iterator>
 135   make_transform_iterator(Iterator it, UnaryFunc fun)
 136   {
 137       return transform_iterator<UnaryFunc, Iterator>(it, fun);
 138   }
 139
 140   // Version which allows explicit specification of the UnaryFunc
 141   // type.
 142   //
 143   // This generator is not provided if UnaryFunc is a function
 144   // pointer type, because it's too dangerous: the default-constructed
 145   // function pointer in the iterator be 0, leading to a runtime
 146   // crash.
 147   template <class UnaryFunc, class Iterator>
 148   inline typename iterators::enable_if<
 149       is_class<UnaryFunc>   // We should probably find a cheaper test than is_class<>
 150     , transform_iterator<UnaryFunc, Iterator>
 151   >::type
 152   make_transform_iterator(Iterator it)
 153   {
 154       return transform_iterator<UnaryFunc, Iterator>(it, UnaryFunc());
 155   }
 156
 157 #if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION ) && !defined(BOOST_NO_FUNCTION_TEMPLATE_ORDERING)
 158   template <class Return, class Argument, class Iterator>
 159   inline transform_iterator< Return (*)(Argument), Iterator, Return>
 160   make_transform_iterator(Iterator it, Return (*fun)(Argument))
 161   {
 162     return transform_iterator<Return (*)(Argument), Iterator, Return>(it, fun);
 163   }
 164 #endif
 165
 166 } // namespace iterators
 167
 168 using iterators::transform_iterator;
 169 using iterators::make_transform_iterator;
 170
 171 } // namespace boost
 172
 173 #include <boost/iterator/detail/config_undef.hpp>
 174
 175 #endif // BOOST_TRANSFORM_ITERATOR_23022003THW_HPP