ceph/src/boost/libs/type_traits/include/boost/type_traits/is_copy_assignable.hpp

   1 //  (C) Copyright Ion Gaztanaga 2014.
   2 //
   3 //  Use, modification and distribution are subject to the Boost Software License,
   4 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   5 //  http://www.boost.org/LICENSE_1_0.txt).
   6 //
   7 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
   8
   9 #ifndef BOOST_TT_IS_COPY_ASSIGNABLE_HPP_INCLUDED
  10 #define BOOST_TT_IS_COPY_ASSIGNABLE_HPP_INCLUDED
  11
  12 #include <boost/config.hpp>
  13 #include <boost/type_traits/detail/yes_no_type.hpp>
  14 #include <boost/type_traits/is_base_and_derived.hpp>
  15 #include <boost/noncopyable.hpp>
  16
  17 #if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS) && !defined(BOOST_NO_CXX11_DECLTYPE) \
  18    && !defined(BOOST_INTEL_CXX_VERSION) && \
  19       !(defined(BOOST_MSVC) && _MSC_VER == 1800)
  20 #define BOOST_TT_CXX11_IS_COPY_ASSIGNABLE
  21 #include <boost/type_traits/declval.hpp>
  22 #else
  23    //For compilers without decltype
  24    #include <boost/type_traits/is_const.hpp>
  25    #include <boost/type_traits/is_array.hpp>
  26    #include <boost/type_traits/add_reference.hpp>
  27    #include <boost/type_traits/remove_reference.hpp>
  28 #endif
  29
  30 namespace boost {
  31
  32 namespace detail{
  33
  34 template <bool DerivedFromNoncopyable, class T>
  35 struct is_copy_assignable_impl2 {
  36
  37 // Intel compiler has problems with SFINAE for copy constructors and deleted functions:
  38 //
  39 // error: function *function_name* cannot be referenced -- it is a deleted function
  40 // static boost::type_traits::yes_type test(T1&, decltype(T1(boost::declval<T1&>()))* = 0);
  41 //                                                        ^
  42 //
  43 // MSVC 12.0 (Visual 2013) has problems when the copy constructor has been deleted. See:
  44 // https://connect.microsoft.com/VisualStudio/feedback/details/800328/std-is-copy-constructible-is-broken
  45 #if defined(BOOST_TT_CXX11_IS_COPY_ASSIGNABLE)
  46     typedef boost::type_traits::yes_type yes_type;
  47     typedef boost::type_traits::no_type  no_type;
  48
  49     template <class U>
  50     static decltype(::boost::declval<U&>() = ::boost::declval<const U&>(), yes_type() ) test(int);
  51
  52     template <class>
  53     static no_type test(...);
  54
  55     static const bool value = sizeof(test<T>(0)) == sizeof(yes_type);
  56
  57 #else
  58     static BOOST_DEDUCED_TYPENAME boost::add_reference<T>::type produce();
  59
  60     template <class T1>
  61     static boost::type_traits::no_type test(T1&, typename T1::boost_move_no_copy_constructor_or_assign* = 0);
  62
  63     static boost::type_traits::yes_type test(...);
  64     // If you see errors like this:
  65     //
  66     //      `'T::operator=(const T&)' is private`
  67     //      `boost/type_traits/is_copy_assignable.hpp:NN:M: error: within this context`
  68     //
  69     // then you are trying to call that macro for a structure defined like that:
  70     //
  71     //      struct T {
  72     //          ...
  73     //      private:
  74     //          T & operator=(const T &);
  75     //          ...
  76     //      };
  77     //
  78     // To fix that you must modify your structure:
  79     //
  80     //      // C++03 and C++11 version
  81     //      struct T: private boost::noncopyable {
  82     //          ...
  83     //      private:
  84     //          T & operator=(const T &);
  85     //          ...
  86     //      };
  87     //
  88     //      // C++11 version
  89     //      struct T {
  90     //          ...
  91     //      private:
  92     //          T& operator=(const T &) = delete;
  93     //          ...
  94     //      };
  95     BOOST_STATIC_CONSTANT(bool, value = (
  96             sizeof(test(produce())) == sizeof(boost::type_traits::yes_type)
  97     ));
  98    #endif
  99 };
 100
 101 template <class T>
 102 struct is_copy_assignable_impl2<true, T> {
 103     BOOST_STATIC_CONSTANT(bool, value = false);
 104 };
 105
 106 template <class T>
 107 struct is_copy_assignable_impl {
 108
 109 #if !defined(BOOST_TT_CXX11_IS_COPY_ASSIGNABLE)
 110     //For compilers without decltype, at least return false on const types, arrays
 111     //types derived from boost::noncopyable and types defined as BOOST_MOVEABLE_BUT_NOT_COPYABLE
 112     typedef BOOST_DEDUCED_TYPENAME boost::remove_reference<T>::type unreferenced_t;
 113     BOOST_STATIC_CONSTANT(bool, value = (
 114         boost::detail::is_copy_assignable_impl2<
 115             boost::is_base_and_derived<boost::noncopyable, T>::value
 116             || boost::is_const<unreferenced_t>::value || boost::is_array<unreferenced_t>::value
 117             ,T
 118         >::value
 119     ));
 120     #else
 121     BOOST_STATIC_CONSTANT(bool, value = (
 122         boost::detail::is_copy_assignable_impl2<
 123             boost::is_base_and_derived<boost::noncopyable, T>::value,T
 124         >::value
 125     ));
 126     #endif
 127 };
 128
 129 } // namespace detail
 130
 131 template <class T> struct is_copy_assignable : public integral_constant<bool, ::boost::detail::is_copy_assignable_impl<T>::value>{};
 132 template <> struct is_copy_assignable<void> : public false_type{};
 133 #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
 134 template <> struct is_copy_assignable<void const> : public false_type{};
 135 template <> struct is_copy_assignable<void const volatile> : public false_type{};
 136 template <> struct is_copy_assignable<void volatile> : public false_type{};
 137 #endif
 138
 139 } // namespace boost
 140
 141 #endif // BOOST_TT_IS_COPY_ASSIGNABLE_HPP_INCLUDED