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

   1 #ifndef BOOST_TYPE_TRAITS_DETAIL_COMMON_TYPE_IMPL_HPP_INCLUDED
   2 #define BOOST_TYPE_TRAITS_DETAIL_COMMON_TYPE_IMPL_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/detail/common_arithmetic_type.hpp>
  13 #include <boost/type_traits/detail/composite_pointer_type.hpp>
  14 #include <boost/type_traits/detail/composite_member_pointer_type.hpp>
  15 #include <boost/type_traits/type_identity.hpp>
  16 #include <boost/type_traits/is_class.hpp>
  17 #include <boost/type_traits/is_union.hpp>
  18 #include <boost/type_traits/is_convertible.hpp>
  19 #include <boost/type_traits/is_pointer.hpp>
  20 #include <boost/type_traits/is_member_pointer.hpp>
  21 #include <boost/type_traits/conditional.hpp>
  22
  23 namespace boost
  24 {
  25
  26 namespace type_traits_detail
  27 {
  28
  29 // the arguments to common_type_impl have already been passed through decay<>
  30
  31 template<class T, class U> struct common_type_impl;
  32
  33 // same type
  34
  35 template<class T> struct common_type_impl<T, T>
  36 {
  37     typedef T type;
  38 };
  39
  40 // one of the operands is a class type, try conversions in both directions
  41
  42 template<class T, class U> struct ct_class
  43 {
  44     BOOST_STATIC_CONSTANT( bool, ct = boost::is_class<T>::value || boost::is_union<T>::value );
  45     BOOST_STATIC_CONSTANT( bool, cu = boost::is_class<U>::value || boost::is_union<U>::value );
  46
  47     BOOST_STATIC_CONSTANT( bool, value = ct || cu );
  48 };
  49
  50 template<class T, class U> struct common_type_impl3;
  51
  52 template<class T, class U> struct common_type_class: public boost::conditional<
  53
  54     boost::is_convertible<T, U>::value && !boost::is_convertible<U, T>::value,
  55     boost::type_identity<U>,
  56
  57     typename boost::conditional<
  58
  59         boost::is_convertible<U, T>::value && !boost::is_convertible<T, U>::value,
  60         boost::type_identity<T>,
  61
  62         common_type_impl3<T, U>
  63     >::type
  64 >::type
  65 {
  66 };
  67
  68 template<class T, class U> struct common_type_impl: public boost::conditional<
  69     ct_class<T, U>::value,
  70     common_type_class<T, U>,
  71     common_type_impl3<T, U> >::type
  72 {
  73 };
  74
  75 // pointers
  76
  77 template<class T, class U> struct common_type_impl4;
  78
  79 template<class T, class U> struct common_type_impl3: public boost::conditional<
  80     boost::is_pointer<T>::value || boost::is_pointer<U>::value,
  81     composite_pointer_type<T, U>,
  82     common_type_impl4<T, U> >::type
  83 {
  84 };
  85
  86 // pointers to members
  87
  88 template<class T, class U> struct common_type_impl5;
  89
  90 template<class T, class U> struct common_type_impl4: public boost::conditional<
  91     boost::is_member_pointer<T>::value || boost::is_member_pointer<U>::value,
  92     composite_member_pointer_type<T, U>,
  93     common_type_impl5<T, U> >::type
  94 {
  95 };
  96
  97 // arithmetic types (including class types w/ conversions to arithmetic and enums)
  98
  99 template<class T, class U> struct common_type_impl5: public common_arithmetic_type<T, U>
 100 {
 101 };
 102
 103 } // namespace type_traits_detail
 104
 105 } // namespace boost
 106
 107 #endif // #ifndef BOOST_TYPE_TRAITS_DETAIL_COMMON_TYPE_IMPL_HPP_INCLUDED