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1#ifndef BOOST_TYPE_TRAITS_DETAIL_COMPOSITE_POINTER_TYPE_HPP_INCLUDED
2#define BOOST_TYPE_TRAITS_DETAIL_COMPOSITE_POINTER_TYPE_HPP_INCLUDED
3
4//
5// Copyright 2015 Peter Dimov
6//
7// Distributed under the Boost Software License, Version 1.0.
8// See accompanying file LICENSE_1_0.txt or copy at
9// http://www.boost.org/LICENSE_1_0.txt
10//
11
12#include <boost/type_traits/copy_cv.hpp>
13#include <boost/type_traits/remove_cv.hpp>
14#include <boost/type_traits/is_same.hpp>
15#include <boost/type_traits/is_void.hpp>
16#include <boost/type_traits/is_base_of.hpp>
17#include <boost/config.hpp>
18#include <cstddef>
19
20namespace boost
21{
22
23namespace type_traits_detail
24{
25
26template<class T, class U> struct composite_pointer_type;
27
28// same type
29
30template<class T> struct composite_pointer_type<T*, T*>
31{
32 typedef T* type;
33};
34
35// nullptr_t
36
37#if !defined( BOOST_NO_CXX11_NULLPTR )
38
39#if !defined( BOOST_NO_CXX11_DECLTYPE ) && ( ( defined( __clang__ ) && !defined( _LIBCPP_VERSION ) ) || defined( __INTEL_COMPILER ) )
40
41template<class T> struct composite_pointer_type<T*, decltype(nullptr)>
42{
43 typedef T* type;
44};
45
46template<class T> struct composite_pointer_type<decltype(nullptr), T*>
47{
48 typedef T* type;
49};
50
51template<> struct composite_pointer_type<decltype(nullptr), decltype(nullptr)>
52{
53 typedef decltype(nullptr) type;
54};
55
56#else
57
58template<class T> struct composite_pointer_type<T*, std::nullptr_t>
59{
60 typedef T* type;
61};
62
63template<class T> struct composite_pointer_type<std::nullptr_t, T*>
64{
65 typedef T* type;
66};
67
68template<> struct composite_pointer_type<std::nullptr_t, std::nullptr_t>
69{
70 typedef std::nullptr_t type;
71};
72
73#endif
74
75#endif // !defined( BOOST_NO_CXX11_NULLPTR )
76
77namespace detail
78{
79
80template<class T, class U> struct has_common_pointee
81{
82private:
83
84 typedef typename boost::remove_cv<T>::type T2;
85 typedef typename boost::remove_cv<U>::type U2;
86
87public:
88
89 BOOST_STATIC_CONSTANT( bool, value =
90 (boost::is_same<T2, U2>::value)
91 || boost::is_void<T2>::value
92 || boost::is_void<U2>::value
93 || (boost::is_base_of<T2, U2>::value)
94 || (boost::is_base_of<U2, T2>::value) );
95};
96
97template<class T, class U> struct common_pointee
98{
99private:
100
101 typedef typename boost::remove_cv<T>::type T2;
102 typedef typename boost::remove_cv<U>::type U2;
103
104public:
105
106 typedef typename boost::conditional<
107
108 boost::is_same<T2, U2>::value || boost::is_void<T2>::value || boost::is_base_of<T2, U2>::value,
109 typename boost::copy_cv<T, U>::type,
110 typename boost::copy_cv<U, T>::type
111
112 >::type type;
113};
114
115template<class T, class U> struct composite_pointer_impl
116{
117private:
118
119 typedef typename boost::remove_cv<T>::type T2;
120 typedef typename boost::remove_cv<U>::type U2;
121
122public:
123
124 typedef typename boost::copy_cv<typename boost::copy_cv<typename composite_pointer_type<T2, U2>::type const, T>::type, U>::type type;
125};
126
127//Old compilers like MSVC-7.1 have problems using boost::conditional in
128//composite_pointer_type. Partially specializing on has_common_pointee<T, U>::value
129//seems to make their life easier
130template<class T, class U, bool = has_common_pointee<T, U>::value >
131struct composite_pointer_type_dispatch
132 : common_pointee<T, U>
133{};
134
135template<class T, class U>
136struct composite_pointer_type_dispatch<T, U, false>
137 : composite_pointer_impl<T, U>
138{};
139
140
141} // detail
142
143
144template<class T, class U> struct composite_pointer_type<T*, U*>
145{
146 typedef typename detail::composite_pointer_type_dispatch<T, U>::type* type;
147};
148
149} // namespace type_traits_detail
150
151} // namespace boost
152
153#endif // #ifndef BOOST_TYPE_TRAITS_DETAIL_COMPOSITE_POINTER_TYPE_HPP_INCLUDED