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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 |