libcxx/include/__concepts/constructible.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___CONCEPTS_CONSTRUCTIBLE_H
  10 #define _LIBCPP___CONCEPTS_CONSTRUCTIBLE_H
  11
  12 #include <__concepts/convertible_to.h>
  13 #include <__concepts/destructible.h>
  14 #include <__config>
  15 #include <type_traits>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_BEGIN_NAMESPACE_STD
  22
  23 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
  24
  25 // [concept.constructible]
  26 template<class _Tp, class... _Args>
  27 concept constructible_from =
  28     destructible<_Tp> && is_constructible_v<_Tp, _Args...>;
  29
  30 // [concept.default.init]
  31
  32 template<class _Tp>
  33 concept __default_initializable = requires { ::new _Tp; };
  34
  35 template<class _Tp>
  36 concept default_initializable = constructible_from<_Tp> &&
  37     requires { _Tp{}; } && __default_initializable<_Tp>;
  38
  39 // [concept.moveconstructible]
  40 template<class _Tp>
  41 concept move_constructible =
  42   constructible_from<_Tp, _Tp> && convertible_to<_Tp, _Tp>;
  43
  44 // [concept.copyconstructible]
  45 template<class _Tp>
  46 concept copy_constructible =
  47   move_constructible<_Tp> &&
  48   constructible_from<_Tp, _Tp&> && convertible_to<_Tp&, _Tp> &&
  49   constructible_from<_Tp, const _Tp&> && convertible_to<const _Tp&, _Tp> &&
  50   constructible_from<_Tp, const _Tp> && convertible_to<const _Tp, _Tp>;
  51
  52 #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
  53
  54 _LIBCPP_END_NAMESPACE_STD
  55
  56 #endif // _LIBCPP___CONCEPTS_CONSTRUCTIBLE_H