libcxx/include/__utility/move.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___UTILITY_MOVE_H
  11 #define _LIBCPP___UTILITY_MOVE_H
  12
  13 #include <__config>
  14 #include <__type_traits/conditional.h>
  15 #include <__type_traits/is_constructible.h>
  16 #include <__type_traits/is_nothrow_constructible.h>
  17 #include <__type_traits/remove_reference.h>
  18
  19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  20 #  pragma GCC system_header
  21 #endif
  22
  23 _LIBCPP_PUSH_MACROS
  24 #include <__undef_macros>
  25
  26 _LIBCPP_BEGIN_NAMESPACE_STD
  27
  28 template <class _Tp>
  29 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __libcpp_remove_reference_t<_Tp>&&
  30 move(_LIBCPP_LIFETIMEBOUND _Tp&& __t) _NOEXCEPT {
  31   using _Up _LIBCPP_NODEBUG = __libcpp_remove_reference_t<_Tp>;
  32   return static_cast<_Up&&>(__t);
  33 }
  34
  35 template <class _Tp>
  36 using __move_if_noexcept_result_t =
  37     __conditional_t<!is_nothrow_move_constructible<_Tp>::value && is_copy_constructible<_Tp>::value, const _Tp&, _Tp&&>;
  38
  39 template <class _Tp>
  40 [[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __move_if_noexcept_result_t<_Tp>
  41 move_if_noexcept(_LIBCPP_LIFETIMEBOUND _Tp& __x) _NOEXCEPT {
  42   return std::move(__x);
  43 }
  44
  45 _LIBCPP_END_NAMESPACE_STD
  46
  47 _LIBCPP_POP_MACROS
  48
  49 #endif // _LIBCPP___UTILITY_MOVE_H