221 lines
6.4 KiB
C++
221 lines
6.4 KiB
C++
// Move, forward and identity for C++11 + swap -*- C++ -*-
|
|
|
|
// Copyright (C) 2007-2018 Free Software Foundation, Inc.
|
|
//
|
|
// This file is part of the GNU ISO C++ Library. This library is free
|
|
// software; you can redistribute it and/or modify it under the
|
|
// terms of the GNU General Public License as published by the
|
|
// Free Software Foundation; either version 3, or (at your option)
|
|
// any later version.
|
|
|
|
// This library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU General Public License for more details.
|
|
|
|
// Under Section 7 of GPL version 3, you are granted additional
|
|
// permissions described in the GCC Runtime Library Exception, version
|
|
// 3.1, as published by the Free Software Foundation.
|
|
|
|
// You should have received a copy of the GNU General Public License and
|
|
// a copy of the GCC Runtime Library Exception along with this program;
|
|
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
|
|
// <http://www.gnu.org/licenses/>.
|
|
|
|
/** @file bits/move.h
|
|
* This is an internal header file, included by other library headers.
|
|
* Do not attempt to use it directly. @headername{utility}
|
|
*/
|
|
|
|
#ifndef _MOVE_H
|
|
#define _MOVE_H 1
|
|
|
|
#include <bits/c++config.h>
|
|
#include <bits/concept_check.h>
|
|
|
|
namespace std _GLIBCXX_VISIBILITY(default)
|
|
{
|
|
_GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|
|
|
// Used, in C++03 mode too, by allocators, etc.
|
|
/**
|
|
* @brief Same as C++11 std::addressof
|
|
* @ingroup utilities
|
|
*/
|
|
template<typename _Tp>
|
|
inline _GLIBCXX_CONSTEXPR _Tp*
|
|
__addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
|
|
{ return __builtin_addressof(__r); }
|
|
|
|
#if __cplusplus >= 201103L
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace
|
|
|
|
#include <type_traits> // Brings in std::declval too.
|
|
|
|
namespace std _GLIBCXX_VISIBILITY(default)
|
|
{
|
|
_GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|
|
|
/**
|
|
* @addtogroup utilities
|
|
* @{
|
|
*/
|
|
|
|
/**
|
|
* @brief Forward an lvalue.
|
|
* @return The parameter cast to the specified type.
|
|
*
|
|
* This function is used to implement "perfect forwarding".
|
|
*/
|
|
template<typename _Tp>
|
|
constexpr _Tp&&
|
|
forward(typename std::remove_reference<_Tp>::type& __t) noexcept
|
|
{ return static_cast<_Tp&&>(__t); }
|
|
|
|
/**
|
|
* @brief Forward an rvalue.
|
|
* @return The parameter cast to the specified type.
|
|
*
|
|
* This function is used to implement "perfect forwarding".
|
|
*/
|
|
template<typename _Tp>
|
|
constexpr _Tp&&
|
|
forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
|
|
{
|
|
static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
|
|
" substituting _Tp is an lvalue reference type");
|
|
return static_cast<_Tp&&>(__t);
|
|
}
|
|
|
|
/**
|
|
* @brief Convert a value to an rvalue.
|
|
* @param __t A thing of arbitrary type.
|
|
* @return The parameter cast to an rvalue-reference to allow moving it.
|
|
*/
|
|
template<typename _Tp>
|
|
constexpr typename std::remove_reference<_Tp>::type&&
|
|
move(_Tp&& __t) noexcept
|
|
{ return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
|
|
|
|
|
|
template<typename _Tp>
|
|
struct __move_if_noexcept_cond
|
|
: public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
|
|
is_copy_constructible<_Tp>>::type { };
|
|
|
|
/**
|
|
* @brief Conditionally convert a value to an rvalue.
|
|
* @param __x A thing of arbitrary type.
|
|
* @return The parameter, possibly cast to an rvalue-reference.
|
|
*
|
|
* Same as std::move unless the type's move constructor could throw and the
|
|
* type is copyable, in which case an lvalue-reference is returned instead.
|
|
*/
|
|
template<typename _Tp>
|
|
constexpr typename
|
|
conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
|
|
move_if_noexcept(_Tp& __x) noexcept
|
|
{ return std::move(__x); }
|
|
|
|
// declval, from type_traits.
|
|
|
|
#if __cplusplus > 201402L
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 2296. std::addressof should be constexpr
|
|
# define __cpp_lib_addressof_constexpr 201603
|
|
#endif
|
|
/**
|
|
* @brief Returns the actual address of the object or function
|
|
* referenced by r, even in the presence of an overloaded
|
|
* operator&.
|
|
* @param __r Reference to an object or function.
|
|
* @return The actual address.
|
|
*/
|
|
template<typename _Tp>
|
|
inline _GLIBCXX17_CONSTEXPR _Tp*
|
|
addressof(_Tp& __r) noexcept
|
|
{ return std::__addressof(__r); }
|
|
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 2598. addressof works on temporaries
|
|
template<typename _Tp>
|
|
const _Tp* addressof(const _Tp&&) = delete;
|
|
|
|
// C++11 version of std::exchange for internal use.
|
|
template <typename _Tp, typename _Up = _Tp>
|
|
inline _Tp
|
|
__exchange(_Tp& __obj, _Up&& __new_val)
|
|
{
|
|
_Tp __old_val = std::move(__obj);
|
|
__obj = std::forward<_Up>(__new_val);
|
|
return __old_val;
|
|
}
|
|
|
|
/// @} group utilities
|
|
|
|
#define _GLIBCXX_MOVE(__val) std::move(__val)
|
|
#define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
|
|
#else
|
|
#define _GLIBCXX_MOVE(__val) (__val)
|
|
#define _GLIBCXX_FORWARD(_Tp, __val) (__val)
|
|
#endif
|
|
|
|
/**
|
|
* @addtogroup utilities
|
|
* @{
|
|
*/
|
|
|
|
/**
|
|
* @brief Swaps two values.
|
|
* @param __a A thing of arbitrary type.
|
|
* @param __b Another thing of arbitrary type.
|
|
* @return Nothing.
|
|
*/
|
|
template<typename _Tp>
|
|
inline
|
|
#if __cplusplus >= 201103L
|
|
typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>,
|
|
is_move_constructible<_Tp>,
|
|
is_move_assignable<_Tp>>::value>::type
|
|
swap(_Tp& __a, _Tp& __b)
|
|
noexcept(__and_<is_nothrow_move_constructible<_Tp>,
|
|
is_nothrow_move_assignable<_Tp>>::value)
|
|
#else
|
|
void
|
|
swap(_Tp& __a, _Tp& __b)
|
|
#endif
|
|
{
|
|
// concept requirements
|
|
__glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
|
|
|
|
_Tp __tmp = _GLIBCXX_MOVE(__a);
|
|
__a = _GLIBCXX_MOVE(__b);
|
|
__b = _GLIBCXX_MOVE(__tmp);
|
|
}
|
|
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// DR 809. std::swap should be overloaded for array types.
|
|
/// Swap the contents of two arrays.
|
|
template<typename _Tp, size_t _Nm>
|
|
inline
|
|
#if __cplusplus >= 201103L
|
|
typename enable_if<__is_swappable<_Tp>::value>::type
|
|
swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
|
|
noexcept(__is_nothrow_swappable<_Tp>::value)
|
|
#else
|
|
void
|
|
swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
|
|
#endif
|
|
{
|
|
for (size_t __n = 0; __n < _Nm; ++__n)
|
|
swap(__a[__n], __b[__n]);
|
|
}
|
|
|
|
/// @} group utilities
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace
|
|
|
|
#endif /* _MOVE_H */
|