/
compressed_pair.h
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/
compressed_pair.h
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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___MEMORY_COMPRESSED_PAIR_H
#define _LIBCPP___MEMORY_COMPRESSED_PAIR_H
#include <__config>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <tuple> // needed in c++03 for some constructors
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
// Tag used to default initialize one or both of the pair's elements.
struct __default_init_tag {};
struct __value_init_tag {};
template <class _Tp, int _Idx,
bool _CanBeEmptyBase =
is_empty<_Tp>::value && !__libcpp_is_final<_Tp>::value>
struct __compressed_pair_elem {
typedef _Tp _ParamT;
typedef _Tp& reference;
typedef const _Tp& const_reference;
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
__compressed_pair_elem(__default_init_tag) {}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
__compressed_pair_elem(__value_init_tag) : __value_() {}
template <class _Up, class = typename enable_if<
!is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
>::type>
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR explicit
__compressed_pair_elem(_Up&& __u)
: __value_(_VSTD::forward<_Up>(__u))
{
}
#ifndef _LIBCPP_CXX03_LANG
template <class... _Args, size_t... _Indexes>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
__compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args,
__tuple_indices<_Indexes...>)
: __value_(_VSTD::forward<_Args>(_VSTD::get<_Indexes>(__args))...) {}
#endif
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 reference __get() _NOEXCEPT { return __value_; }
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR const_reference __get() const _NOEXCEPT { return __value_; }
private:
_Tp __value_;
};
template <class _Tp, int _Idx>
struct __compressed_pair_elem<_Tp, _Idx, true> : private _Tp {
typedef _Tp _ParamT;
typedef _Tp& reference;
typedef const _Tp& const_reference;
typedef _Tp __value_type;
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR __compressed_pair_elem() = default;
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
__compressed_pair_elem(__default_init_tag) {}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
__compressed_pair_elem(__value_init_tag) : __value_type() {}
template <class _Up, class = typename enable_if<
!is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
>::type>
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR explicit
__compressed_pair_elem(_Up&& __u)
: __value_type(_VSTD::forward<_Up>(__u))
{}
#ifndef _LIBCPP_CXX03_LANG
template <class... _Args, size_t... _Indexes>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
__compressed_pair_elem(piecewise_construct_t, tuple<_Args...> __args,
__tuple_indices<_Indexes...>)
: __value_type(_VSTD::forward<_Args>(_VSTD::get<_Indexes>(__args))...) {}
#endif
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 reference __get() _NOEXCEPT { return *this; }
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR const_reference __get() const _NOEXCEPT { return *this; }
};
template <class _T1, class _T2>
class __compressed_pair : private __compressed_pair_elem<_T1, 0>,
private __compressed_pair_elem<_T2, 1> {
public:
// NOTE: This static assert should never fire because __compressed_pair
// is *almost never* used in a scenario where it's possible for T1 == T2.
// (The exception is std::function where it is possible that the function
// object and the allocator have the same type).
static_assert((!is_same<_T1, _T2>::value),
"__compressed_pair cannot be instantiated when T1 and T2 are the same type; "
"The current implementation is NOT ABI-compatible with the previous "
"implementation for this configuration");
typedef _LIBCPP_NODEBUG __compressed_pair_elem<_T1, 0> _Base1;
typedef _LIBCPP_NODEBUG __compressed_pair_elem<_T2, 1> _Base2;
template <bool _Dummy = true,
class = typename enable_if<
__dependent_type<is_default_constructible<_T1>, _Dummy>::value &&
__dependent_type<is_default_constructible<_T2>, _Dummy>::value
>::type
>
_LIBCPP_INLINE_VISIBILITY
_LIBCPP_CONSTEXPR __compressed_pair() : _Base1(__value_init_tag()), _Base2(__value_init_tag()) {}
template <class _U1, class _U2>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
__compressed_pair(_U1&& __t1, _U2&& __t2)
: _Base1(_VSTD::forward<_U1>(__t1)), _Base2(_VSTD::forward<_U2>(__t2)) {}
#ifndef _LIBCPP_CXX03_LANG
template <class... _Args1, class... _Args2>
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
__compressed_pair(piecewise_construct_t __pc, tuple<_Args1...> __first_args,
tuple<_Args2...> __second_args)
: _Base1(__pc, _VSTD::move(__first_args),
typename __make_tuple_indices<sizeof...(_Args1)>::type()),
_Base2(__pc, _VSTD::move(__second_args),
typename __make_tuple_indices<sizeof...(_Args2)>::type()) {}
#endif
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 typename _Base1::reference first() _NOEXCEPT {
return static_cast<_Base1&>(*this).__get();
}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename _Base1::const_reference first() const _NOEXCEPT {
return static_cast<_Base1 const&>(*this).__get();
}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 typename _Base2::reference second() _NOEXCEPT {
return static_cast<_Base2&>(*this).__get();
}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR typename _Base2::const_reference second() const _NOEXCEPT {
return static_cast<_Base2 const&>(*this).__get();
}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
static _Base1* __get_first_base(__compressed_pair* __pair) _NOEXCEPT {
return static_cast<_Base1*>(__pair);
}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
static _Base2* __get_second_base(__compressed_pair* __pair) _NOEXCEPT {
return static_cast<_Base2*>(__pair);
}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 void swap(__compressed_pair& __x)
_NOEXCEPT_(__is_nothrow_swappable<_T1>::value && __is_nothrow_swappable<_T2>::value) {
using _VSTD::swap;
swap(first(), __x.first());
swap(second(), __x.second());
}
};
template <class _T1, class _T2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
void swap(__compressed_pair<_T1, _T2>& __x, __compressed_pair<_T1, _T2>& __y)
_NOEXCEPT_(__is_nothrow_swappable<_T1>::value && __is_nothrow_swappable<_T2>::value) {
__x.swap(__y);
}
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___MEMORY_COMPRESSED_PAIR_H