ceph/src/boost/libs/type_traits/include/boost/type_traits/detail/composite_pointer_type.hpp

   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
  20 namespace boost
  21 {
  22
  23 namespace type_traits_detail
  24 {
  25
  26 template<class T, class U> struct composite_pointer_type;
  27
  28 // same type
  29
  30 template<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
  41 template<class T> struct composite_pointer_type<T*, decltype(nullptr)>
  42 {
  43     typedef T* type;
  44 };
  45
  46 template<class T> struct composite_pointer_type<decltype(nullptr), T*>
  47 {
  48     typedef T* type;
  49 };
  50
  51 template<> struct composite_pointer_type<decltype(nullptr), decltype(nullptr)>
  52 {
  53     typedef decltype(nullptr) type;
  54 };
  55
  56 #else
  57
  58 template<class T> struct composite_pointer_type<T*, std::nullptr_t>
  59 {
  60     typedef T* type;
  61 };
  62
  63 template<class T> struct composite_pointer_type<std::nullptr_t, T*>
  64 {
  65     typedef T* type;
  66 };
  67
  68 template<> 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
  77 namespace detail
  78 {
  79
  80 template<class T, class U> struct has_common_pointee
  81 {
  82 private:
  83
  84     typedef typename boost::remove_cv<T>::type T2;
  85     typedef typename boost::remove_cv<U>::type U2;
  86
  87 public:
  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
  97 template<class T, class U> struct common_pointee
  98 {
  99 private:
 100
 101     typedef typename boost::remove_cv<T>::type T2;
 102     typedef typename boost::remove_cv<U>::type U2;
 103
 104 public:
 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
 115 template<class T, class U> struct composite_pointer_impl
 116 {
 117 private:
 118
 119     typedef typename boost::remove_cv<T>::type T2;
 120     typedef typename boost::remove_cv<U>::type U2;
 121
 122 public:
 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
 130 template<class T, class U, bool = has_common_pointee<T, U>::value >
 131 struct composite_pointer_type_dispatch
 132    : common_pointee<T, U>
 133 {};
 134
 135 template<class T, class U>
 136 struct composite_pointer_type_dispatch<T, U, false>
 137    : composite_pointer_impl<T, U>
 138 {};
 139
 140
 141 } // detail
 142
 143
 144 template<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