ceph/src/boost/libs/icl/include/boost/icl/type_traits/difference_type_of.hpp

   1 /*-----------------------------------------------------------------------------+
   2 Copyright (c) 2008-2009: Joachim Faulhaber
   3 +------------------------------------------------------------------------------+
   4    Distributed under the Boost Software License, Version 1.0.
   5       (See accompanying file LICENCE.txt or copy at
   6            http://www.boost.org/LICENSE_1_0.txt)
   7 +-----------------------------------------------------------------------------*/
   8 #ifndef BOOST_ICL_TYPE_TRAITS_DIFFERENCE_TYPE_OF_HPP_JOFA_080911
   9 #define BOOST_ICL_TYPE_TRAITS_DIFFERENCE_TYPE_OF_HPP_JOFA_080911
  10
  11 #include <boost/config.hpp> // For macro BOOST_STATIC_CONSTANT
  12 #include <boost/type_traits/is_pointer.hpp>
  13 #include <boost/mpl/has_xxx.hpp>
  14 #include <boost/mpl/or.hpp>
  15 #include <boost/mpl/and.hpp>
  16 #include <boost/mpl/not.hpp>
  17 #include <boost/icl/type_traits/no_type.hpp>
  18 #include <boost/icl/type_traits/is_numeric.hpp>
  19 #include <boost/icl/type_traits/rep_type_of.hpp>
  20
  21 namespace boost{ namespace icl
  22 {
  23     namespace detail
  24     {
  25         BOOST_MPL_HAS_XXX_TRAIT_DEF(difference_type)
  26     }
  27
  28     //--------------------------------------------------------------------------
  29     template <class Type>
  30     struct has_difference_type
  31       : mpl::bool_<detail::has_difference_type<Type>::value>
  32     {};
  33
  34     //--------------------------------------------------------------------------
  35     template<class Type> // type_of(T-T)==T
  36     struct is_subtraction_closed
  37     {
  38         typedef is_subtraction_closed type;
  39         BOOST_STATIC_CONSTANT(bool,
  40             value = (mpl::or_< is_numeric<Type>
  41                              , mpl::and_< has_rep_type<Type>
  42                                         , mpl::not_<has_difference_type<Type> >
  43                                         >
  44                              >::value)
  45             );
  46     };
  47
  48     //--------------------------------------------------------------------------
  49     template<class Type>
  50     struct has_difference
  51     {
  52         typedef has_difference type;
  53         BOOST_STATIC_CONSTANT(bool,
  54             value = (mpl::or_< is_subtraction_closed<Type>
  55                              , is_pointer<Type>
  56                              , has_difference_type<Type> >::value)
  57             );
  58     };
  59
  60     //--------------------------------------------------------------------------
  61     template <class Type, bool has_difference, bool has_diff_type>
  62     struct get_difference_type;
  63
  64     template <class Type>
  65     struct get_difference_type<Type, false, false>
  66     {
  67         typedef no_type type;
  68     };
  69
  70     template <class Type>
  71     struct get_difference_type<Type*, true, false>
  72     {
  73         typedef std::ptrdiff_t type;
  74     };
  75
  76     template <class Type>
  77     struct get_difference_type<Type, true, false>
  78     {
  79         typedef Type type;
  80     };
  81
  82     template <class Type>
  83     struct get_difference_type<Type, true, true>
  84     {
  85         typedef typename Type::difference_type type;
  86     };
  87
  88     //--------------------------------------------------------------------------
  89     template<class Type>
  90     struct difference_type_of
  91     {
  92         typedef typename
  93             get_difference_type< Type
  94                                , has_difference<Type>::value
  95                                , has_difference_type<Type>::value
  96                                >::type type;
  97     };
  98
  99 }} // namespace boost icl
 100
 101 #endif
 102
 103