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gcc/libstdc++-v3/include/bits/stl_pair.h
Jonathan Wakely 72ce3fd2c7 libstdc++: Remove unused std::pair helper function 
This function is no longer used since r12-6691 and can be removed.

libstdc++-v3/ChangeLog:

	* include/bits/stl_pair.h (_PCC::_DeprConsPair): Remove unused
	function.
2022-01-19 00:58:25 +00:00

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// Pair implementation -*- C++ -*-
// Copyright (C) 2001-2022 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/>.
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996,1997
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/** @file bits/stl_pair.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{utility}
*/
#ifndef _STL_PAIR_H
#define _STL_PAIR_H 1
#if __cplusplus >= 201103L
# include <type_traits> // for std::__decay_and_strip
# include <bits/move.h> // for std::move / std::forward, and std::swap
# include <bits/utility.h> // for std::tuple_element, std::tuple_size
#endif
#if __cplusplus >= 202002L
# include <compare>
# define __cpp_lib_constexpr_utility 201811L
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @addtogroup utilities
* @{
*/
#if __cplusplus >= 201103L
/// Tag type for piecewise construction of std::pair objects.
struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
/// Tag for piecewise construction of std::pair objects.
_GLIBCXX17_INLINE constexpr piecewise_construct_t piecewise_construct =
piecewise_construct_t();
/// @cond undocumented
// Forward declarations.
template<typename...>
class tuple;
template<size_t...>
struct _Index_tuple;
#if ! __cpp_lib_concepts
// Concept utility functions, reused in conditionally-explicit
// constructors.
// See PR 70437, don't look at is_constructible or
// is_convertible if the types are the same to
// avoid querying those properties for incomplete types.
template <bool, typename _T1, typename _T2>
struct _PCC
{
template <typename _U1, typename _U2>
static constexpr bool _ConstructiblePair()
{
return __and_<is_constructible<_T1, const _U1&>,
is_constructible<_T2, const _U2&>>::value;
}
template <typename _U1, typename _U2>
static constexpr bool _ImplicitlyConvertiblePair()
{
return __and_<is_convertible<const _U1&, _T1>,
is_convertible<const _U2&, _T2>>::value;
}
template <typename _U1, typename _U2>
static constexpr bool _MoveConstructiblePair()
{
return __and_<is_constructible<_T1, _U1&&>,
is_constructible<_T2, _U2&&>>::value;
}
template <typename _U1, typename _U2>
static constexpr bool _ImplicitlyMoveConvertiblePair()
{
return __and_<is_convertible<_U1&&, _T1>,
is_convertible<_U2&&, _T2>>::value;
}
};
template <typename _T1, typename _T2>
struct _PCC<false, _T1, _T2>
{
template <typename _U1, typename _U2>
static constexpr bool _ConstructiblePair()
{
return false;
}
template <typename _U1, typename _U2>
static constexpr bool _ImplicitlyConvertiblePair()
{
return false;
}
template <typename _U1, typename _U2>
static constexpr bool _MoveConstructiblePair()
{
return false;
}
template <typename _U1, typename _U2>
static constexpr bool _ImplicitlyMoveConvertiblePair()
{
return false;
}
};
#endif // lib concepts
#endif // C++11
template<typename _U1, typename _U2> class __pair_base
{
#if __cplusplus >= 201103L && ! __cpp_lib_concepts
template<typename _T1, typename _T2> friend struct pair;
__pair_base() = default;
~__pair_base() = default;
__pair_base(const __pair_base&) = default;
__pair_base& operator=(const __pair_base&) = delete;
#endif // C++11
};
/// @endcond
/**
* @brief Struct holding two objects of arbitrary type.
*
* @tparam _T1 Type of first object.
* @tparam _T2 Type of second object.
*
* <https://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
*/
template<typename _T1, typename _T2>
struct pair
: public __pair_base<_T1, _T2>
{
typedef _T1 first_type; ///< The type of the `first` member
typedef _T2 second_type; ///< The type of the `second` member
_T1 first; ///< The first member
_T2 second; ///< The second member
#if __cplusplus >= 201103L
constexpr pair(const pair&) = default; ///< Copy constructor
constexpr pair(pair&&) = default; ///< Move constructor
template<typename... _Args1, typename... _Args2>
_GLIBCXX20_CONSTEXPR
pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
/// Swap the first members and then the second members.
_GLIBCXX20_CONSTEXPR void
swap(pair& __p)
noexcept(__and_<__is_nothrow_swappable<_T1>,
__is_nothrow_swappable<_T2>>::value)
{
using std::swap;
swap(first, __p.first);
swap(second, __p.second);
}
private:
template<typename... _Args1, size_t... _Indexes1,
typename... _Args2, size_t... _Indexes2>
_GLIBCXX20_CONSTEXPR
pair(tuple<_Args1...>&, tuple<_Args2...>&,
_Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
public:
#if __cpp_lib_concepts
// C++20 implementation using concepts, explicit(bool), fully constexpr.
/// Default constructor
constexpr
explicit(__not_<__and_<__is_implicitly_default_constructible<_T1>,
__is_implicitly_default_constructible<_T2>>>())
pair()
requires is_default_constructible_v<_T1>
&& is_default_constructible_v<_T2>
: first(), second()
{ }
private:
/// @cond undocumented
template<typename _U1, typename _U2>
static constexpr bool
_S_constructible()
{
if constexpr (is_constructible_v<_T1, _U1>)
return is_constructible_v<_T2, _U2>;
return false;
}
template<typename _U1, typename _U2>
static constexpr bool
_S_nothrow_constructible()
{
if constexpr (is_nothrow_constructible_v<_T1, _U1>)
return is_nothrow_constructible_v<_T2, _U2>;
return false;
}
template<typename _U1, typename _U2>
static constexpr bool
_S_convertible()
{
if constexpr (is_convertible_v<_U1, _T1>)
return is_convertible_v<_U2, _T2>;
return false;
}
/// @endcond
public:
/// Constructor accepting lvalues of `first_type` and `second_type`
constexpr explicit(!_S_convertible<const _T1&, const _T2&>())
pair(const _T1& __x, const _T2& __y)
noexcept(_S_nothrow_constructible<const _T1&, const _T2&>())
requires (_S_constructible<const _T1&, const _T2&>())
: first(__x), second(__y)
{ }
/// Constructor accepting two values of arbitrary types
template<typename _U1, typename _U2>
requires (_S_constructible<_U1, _U2>())
constexpr explicit(!_S_convertible<_U1, _U2>())
pair(_U1&& __x, _U2&& __y)
noexcept(_S_nothrow_constructible<_U1, _U2>())
: first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y))
{ }
/// Converting constructor from a `pair<U1, U2>` lvalue
template<typename _U1, typename _U2>
requires (_S_constructible<const _U1&, const _U2&>())
constexpr explicit(!_S_convertible<const _U1&, const _U2&>())
pair(const pair<_U1, _U2>& __p)
noexcept(_S_nothrow_constructible<const _U1&, const _U2&>())
: first(__p.first), second(__p.second)
{ }
/// Converting constructor from a `pair<U1, U2>` rvalue
template<typename _U1, typename _U2>
requires (_S_constructible<_U1, _U2>())
constexpr explicit(!_S_convertible<_U1, _U2>())
pair(pair<_U1, _U2>&& __p)
noexcept(_S_nothrow_constructible<_U1, _U2>())
: first(std::forward<_U1>(__p.first)),
second(std::forward<_U2>(__p.second))
{ }
private:
/// @cond undocumented
template<typename _U1, typename _U2>
static constexpr bool
_S_assignable()
{
if constexpr (is_assignable_v<_T1&, _U1>)
return is_assignable_v<_T2&, _U2>;
return false;
}
template<typename _U1, typename _U2>
static constexpr bool
_S_nothrow_assignable()
{
if constexpr (is_nothrow_assignable_v<_T1&, _U1>)
return is_nothrow_assignable_v<_T2&, _U2>;
return false;
}
/// @endcond
public:
pair& operator=(const pair&) = delete;
/// Copy assignment operator
constexpr pair&
operator=(const pair& __p)
noexcept(_S_nothrow_assignable<const _T1&, const _T2&>())
requires (_S_assignable<const _T1&, const _T2&>())
{
first = __p.first;
second = __p.second;
return *this;
}
/// Move assignment operator
constexpr pair&
operator=(pair&& __p)
noexcept(_S_nothrow_assignable<_T1, _T2>())
requires (_S_assignable<_T1, _T2>())
{
first = std::forward<first_type>(__p.first);
second = std::forward<second_type>(__p.second);
return *this;
}
/// Converting assignment from a `pair<U1, U2>` lvalue
template<typename _U1, typename _U2>
constexpr pair&
operator=(const pair<_U1, _U2>& __p)
noexcept(_S_nothrow_assignable<const _U1&, const _U2&>())
requires (_S_assignable<const _U1&, const _U2&>())
{
first = __p.first;
second = __p.second;
return *this;
}
/// Converting assignment from a `pair<U1, U2>` rvalue
template<typename _U1, typename _U2>
constexpr pair&
operator=(pair<_U1, _U2>&& __p)
noexcept(_S_nothrow_assignable<_U1, _U2>())
requires (_S_assignable<_U1, _U2>())
{
first = std::forward<_U1>(__p.first);
second = std::forward<_U2>(__p.second);
return *this;
}
#else
// C++11/14/17 implementation using enable_if, partially constexpr.
/** The default constructor creates @c first and @c second using their
* respective default constructors. */
template <typename _U1 = _T1,
typename _U2 = _T2,
typename enable_if<__and_<
__is_implicitly_default_constructible<_U1>,
__is_implicitly_default_constructible<_U2>>
::value, bool>::type = true>
constexpr pair()
: first(), second() { }
template <typename _U1 = _T1,
typename _U2 = _T2,
typename enable_if<__and_<
is_default_constructible<_U1>,
is_default_constructible<_U2>,
__not_<
__and_<__is_implicitly_default_constructible<_U1>,
__is_implicitly_default_constructible<_U2>>>>
::value, bool>::type = false>
explicit constexpr pair()
: first(), second() { }
// Shortcut for constraining the templates that don't take pairs.
/// @cond undocumented
using _PCCP = _PCC<true, _T1, _T2>;
/// @endcond
/// Construct from two const lvalues, allowing implicit conversions.
template<typename _U1 = _T1, typename _U2=_T2, typename
enable_if<_PCCP::template
_ConstructiblePair<_U1, _U2>()
&& _PCCP::template
_ImplicitlyConvertiblePair<_U1, _U2>(),
bool>::type=true>
constexpr pair(const _T1& __a, const _T2& __b)
: first(__a), second(__b) { }
/// Construct from two const lvalues, disallowing implicit conversions.
template<typename _U1 = _T1, typename _U2=_T2, typename
enable_if<_PCCP::template
_ConstructiblePair<_U1, _U2>()
&& !_PCCP::template
_ImplicitlyConvertiblePair<_U1, _U2>(),
bool>::type=false>
explicit constexpr pair(const _T1& __a, const _T2& __b)
: first(__a), second(__b) { }
// Shortcut for constraining the templates that take pairs.
/// @cond undocumented
template <typename _U1, typename _U2>
using _PCCFP = _PCC<!is_same<_T1, _U1>::value
|| !is_same<_T2, _U2>::value,
_T1, _T2>;
/// @endcond
template<typename _U1, typename _U2, typename
enable_if<_PCCFP<_U1, _U2>::template
_ConstructiblePair<_U1, _U2>()
&& _PCCFP<_U1, _U2>::template
_ImplicitlyConvertiblePair<_U1, _U2>(),
bool>::type=true>
constexpr pair(const pair<_U1, _U2>& __p)
: first(__p.first), second(__p.second) { }
template<typename _U1, typename _U2, typename
enable_if<_PCCFP<_U1, _U2>::template
_ConstructiblePair<_U1, _U2>()
&& !_PCCFP<_U1, _U2>::template
_ImplicitlyConvertiblePair<_U1, _U2>(),
bool>::type=false>
explicit constexpr pair(const pair<_U1, _U2>& __p)
: first(__p.first), second(__p.second) { }
#if _GLIBCXX_USE_DEPRECATED
#if defined(__DEPRECATED)
# define _GLIBCXX_DEPRECATED_PAIR_CTOR \
__attribute__ ((__deprecated__ ("use 'nullptr' instead of '0' to " \
"initialize std::pair of move-only " \
"type and pointer")))
#else
# define _GLIBCXX_DEPRECATED_PAIR_CTOR
#endif
private:
/// @cond undocumented
// A type which can be constructed from literal zero, but not nullptr
struct __zero_as_null_pointer_constant
{
__zero_as_null_pointer_constant(int __zero_as_null_pointer_constant::*)
{ }
template<typename _Tp,
typename = __enable_if_t<is_null_pointer<_Tp>::value>>
__zero_as_null_pointer_constant(_Tp) = delete;
};
/// @endcond
public:
// Deprecated extensions to DR 811.
// These allow construction from an rvalue and a literal zero,
// in cases where the standard says the zero should be deduced as int
template<typename _U1,
__enable_if_t<__and_<__not_<is_reference<_U1>>,
is_pointer<_T2>,
is_constructible<_T1, _U1>,
__not_<is_constructible<_T1, const _U1&>>,
is_convertible<_U1, _T1>>::value,
bool> = true>
_GLIBCXX_DEPRECATED_PAIR_CTOR
constexpr
pair(_U1&& __x, __zero_as_null_pointer_constant, ...)
: first(std::forward<_U1>(__x)), second(nullptr) { }
template<typename _U1,
__enable_if_t<__and_<__not_<is_reference<_U1>>,
is_pointer<_T2>,
is_constructible<_T1, _U1>,
__not_<is_constructible<_T1, const _U1&>>,
__not_<is_convertible<_U1, _T1>>>::value,
bool> = false>
_GLIBCXX_DEPRECATED_PAIR_CTOR
explicit constexpr
pair(_U1&& __x, __zero_as_null_pointer_constant, ...)
: first(std::forward<_U1>(__x)), second(nullptr) { }
template<typename _U2,
__enable_if_t<__and_<is_pointer<_T1>,
__not_<is_reference<_U2>>,
is_constructible<_T2, _U2>,
__not_<is_constructible<_T2, const _U2&>>,
is_convertible<_U2, _T2>>::value,
bool> = true>
_GLIBCXX_DEPRECATED_PAIR_CTOR
constexpr
pair(__zero_as_null_pointer_constant, _U2&& __y, ...)
: first(nullptr), second(std::forward<_U2>(__y)) { }
template<typename _U2,
__enable_if_t<__and_<is_pointer<_T1>,
__not_<is_reference<_U2>>,
is_constructible<_T2, _U2>,
__not_<is_constructible<_T2, const _U2&>>,
__not_<is_convertible<_U2, _T2>>>::value,
bool> = false>
_GLIBCXX_DEPRECATED_PAIR_CTOR
explicit constexpr
pair(__zero_as_null_pointer_constant, _U2&& __y, ...)
: first(nullptr), second(std::forward<_U2>(__y)) { }
#undef _GLIBCXX_DEPRECATED_PAIR_CTOR
#endif
template<typename _U1, typename _U2, typename
enable_if<_PCCP::template
_MoveConstructiblePair<_U1, _U2>()
&& _PCCP::template
_ImplicitlyMoveConvertiblePair<_U1, _U2>(),
bool>::type=true>
constexpr pair(_U1&& __x, _U2&& __y)
: first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
template<typename _U1, typename _U2, typename
enable_if<_PCCP::template
_MoveConstructiblePair<_U1, _U2>()
&& !_PCCP::template
_ImplicitlyMoveConvertiblePair<_U1, _U2>(),
bool>::type=false>
explicit constexpr pair(_U1&& __x, _U2&& __y)
: first(std::forward<_U1>(__x)), second(std::forward<_U2>(__y)) { }
template<typename _U1, typename _U2, typename
enable_if<_PCCFP<_U1, _U2>::template
_MoveConstructiblePair<_U1, _U2>()
&& _PCCFP<_U1, _U2>::template
_ImplicitlyMoveConvertiblePair<_U1, _U2>(),
bool>::type=true>
constexpr pair(pair<_U1, _U2>&& __p)
: first(std::forward<_U1>(__p.first)),
second(std::forward<_U2>(__p.second)) { }
template<typename _U1, typename _U2, typename
enable_if<_PCCFP<_U1, _U2>::template
_MoveConstructiblePair<_U1, _U2>()
&& !_PCCFP<_U1, _U2>::template
_ImplicitlyMoveConvertiblePair<_U1, _U2>(),
bool>::type=false>
explicit constexpr pair(pair<_U1, _U2>&& __p)
: first(std::forward<_U1>(__p.first)),
second(std::forward<_U2>(__p.second)) { }
pair&
operator=(__conditional_t<__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>::value,
const pair&, const __nonesuch&> __p)
{
first = __p.first;
second = __p.second;
return *this;
}
pair&
operator=(__conditional_t<__and_<is_move_assignable<_T1>,
is_move_assignable<_T2>>::value,
pair&&, __nonesuch&&> __p)
noexcept(__and_<is_nothrow_move_assignable<_T1>,
is_nothrow_move_assignable<_T2>>::value)
{
first = std::forward<first_type>(__p.first);
second = std::forward<second_type>(__p.second);
return *this;
}
template<typename _U1, typename _U2>
typename enable_if<__and_<is_assignable<_T1&, const _U1&>,
is_assignable<_T2&, const _U2&>>::value,
pair&>::type
operator=(const pair<_U1, _U2>& __p)
{
first = __p.first;
second = __p.second;
return *this;
}
template<typename _U1, typename _U2>
typename enable_if<__and_<is_assignable<_T1&, _U1&&>,
is_assignable<_T2&, _U2&&>>::value,
pair&>::type
operator=(pair<_U1, _U2>&& __p)
{
first = std::forward<_U1>(__p.first);
second = std::forward<_U2>(__p.second);
return *this;
}
#endif // lib concepts
#else
// C++03 implementation
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 265. std::pair::pair() effects overly restrictive
/** The default constructor creates @c first and @c second using their
* respective default constructors. */
pair() : first(), second() { }
/// Two objects may be passed to a `pair` constructor to be copied.
pair(const _T1& __a, const _T2& __b)
: first(__a), second(__b) { }
/// Templated constructor to convert from other pairs.
template<typename _U1, typename _U2>
pair(const pair<_U1, _U2>& __p)
: first(__p.first), second(__p.second) { }
#endif // C++11
};
/// @relates pair @{
#if __cpp_deduction_guides >= 201606
template<typename _T1, typename _T2> pair(_T1, _T2) -> pair<_T1, _T2>;
#endif
/// Two pairs of the same type are equal iff their members are equal.
template<typename _T1, typename _T2>
inline _GLIBCXX_CONSTEXPR bool
operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
{ return __x.first == __y.first && __x.second == __y.second; }
#if __cpp_lib_three_way_comparison && __cpp_lib_concepts
template<typename _T1, typename _T2>
constexpr common_comparison_category_t<__detail::__synth3way_t<_T1>,
__detail::__synth3way_t<_T2>>
operator<=>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
{
if (auto __c = __detail::__synth3way(__x.first, __y.first); __c != 0)
return __c;
return __detail::__synth3way(__x.second, __y.second);
}
#else
/** Defines a lexicographical order for pairs.
*
* For two pairs of the same type, `P` is ordered before `Q` if
* `P.first` is less than `Q.first`, or if `P.first` and `Q.first`
* are equivalent (neither is less than the other) and `P.second` is less
* than `Q.second`.
*/
template<typename _T1, typename _T2>
inline _GLIBCXX_CONSTEXPR bool
operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
{ return __x.first < __y.first
|| (!(__y.first < __x.first) && __x.second < __y.second); }
/// Uses @c operator== to find the result.
template<typename _T1, typename _T2>
inline _GLIBCXX_CONSTEXPR bool
operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
{ return !(__x == __y); }
/// Uses @c operator< to find the result.
template<typename _T1, typename _T2>
inline _GLIBCXX_CONSTEXPR bool
operator>(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
{ return __y < __x; }
/// Uses @c operator< to find the result.
template<typename _T1, typename _T2>
inline _GLIBCXX_CONSTEXPR bool
operator<=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
{ return !(__y < __x); }
/// Uses @c operator< to find the result.
template<typename _T1, typename _T2>
inline _GLIBCXX_CONSTEXPR bool
operator>=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
{ return !(__x < __y); }
#endif // !(three_way_comparison && concepts)
#if __cplusplus >= 201103L
/** Swap overload for pairs. Calls std::pair::swap().
*
* @note This std::swap overload is not declared in C++03 mode,
* which has performance implications, e.g. see https://gcc.gnu.org/PR38466
*/
template<typename _T1, typename _T2>
_GLIBCXX20_CONSTEXPR inline
#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
// Constrained free swap overload, see p0185r1
typename enable_if<__and_<__is_swappable<_T1>,
__is_swappable<_T2>>::value>::type
#else
void
#endif
swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
noexcept(noexcept(__x.swap(__y)))
{ __x.swap(__y); }
#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
template<typename _T1, typename _T2>
typename enable_if<!__and_<__is_swappable<_T1>,
__is_swappable<_T2>>::value>::type
swap(pair<_T1, _T2>&, pair<_T1, _T2>&) = delete;
#endif
#endif // __cplusplus >= 201103L
/// @} relates pair
/**
* @brief A convenience wrapper for creating a pair from two objects.
* @param __x The first object.
* @param __y The second object.
* @return A newly-constructed pair<> object of the appropriate type.
*
* The C++98 standard says the objects are passed by reference-to-const,
* but C++03 says they are passed by value (this was LWG issue #181).
*
* Since C++11 they have been passed by forwarding reference and then
* forwarded to the new members of the pair. To create a pair with a
* member of reference type, pass a `reference_wrapper` to this function.
*/
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 181. make_pair() unintended behavior
#if __cplusplus >= 201103L
// NB: DR 706.
template<typename _T1, typename _T2>
constexpr pair<typename __decay_and_strip<_T1>::__type,
typename __decay_and_strip<_T2>::__type>
make_pair(_T1&& __x, _T2&& __y)
{
typedef typename __decay_and_strip<_T1>::__type __ds_type1;
typedef typename __decay_and_strip<_T2>::__type __ds_type2;
typedef pair<__ds_type1, __ds_type2> __pair_type;
return __pair_type(std::forward<_T1>(__x), std::forward<_T2>(__y));
}
#else
template<typename _T1, typename _T2>
inline pair<_T1, _T2>
make_pair(_T1 __x, _T2 __y)
{ return pair<_T1, _T2>(__x, __y); }
#endif
/// @}
#if __cplusplus >= 201103L
// Various functions which give std::pair a tuple-like interface.
template<typename _T1, typename _T2>
struct __is_tuple_like_impl<pair<_T1, _T2>> : true_type
{ };
/// Partial specialization for std::pair
template<class _Tp1, class _Tp2>
struct tuple_size<pair<_Tp1, _Tp2>>
: public integral_constant<size_t, 2> { };
/// Partial specialization for std::pair
template<class _Tp1, class _Tp2>
struct tuple_element<0, pair<_Tp1, _Tp2>>
{ typedef _Tp1 type; };
/// Partial specialization for std::pair
template<class _Tp1, class _Tp2>
struct tuple_element<1, pair<_Tp1, _Tp2>>
{ typedef _Tp2 type; };
#if __cplusplus >= 201703L
template<typename _Tp1, typename _Tp2>
inline constexpr size_t tuple_size_v<pair<_Tp1, _Tp2>> = 2;
template<typename _Tp1, typename _Tp2>
inline constexpr size_t tuple_size_v<const pair<_Tp1, _Tp2>> = 2;
template<typename _Tp>
inline constexpr bool __is_pair = false;
template<typename _Tp, typename _Up>
inline constexpr bool __is_pair<pair<_Tp, _Up>> = true;
template<typename _Tp, typename _Up>
inline constexpr bool __is_pair<const pair<_Tp, _Up>> = true;
#endif
/// @cond undocumented
template<size_t _Int>
struct __pair_get;
template<>
struct __pair_get<0>
{
template<typename _Tp1, typename _Tp2>
static constexpr _Tp1&
__get(pair<_Tp1, _Tp2>& __pair) noexcept
{ return __pair.first; }
template<typename _Tp1, typename _Tp2>
static constexpr _Tp1&&
__move_get(pair<_Tp1, _Tp2>&& __pair) noexcept
{ return std::forward<_Tp1>(__pair.first); }
template<typename _Tp1, typename _Tp2>
static constexpr const _Tp1&
__const_get(const pair<_Tp1, _Tp2>& __pair) noexcept
{ return __pair.first; }
template<typename _Tp1, typename _Tp2>
static constexpr const _Tp1&&
__const_move_get(const pair<_Tp1, _Tp2>&& __pair) noexcept
{ return std::forward<const _Tp1>(__pair.first); }
};
template<>
struct __pair_get<1>
{
template<typename _Tp1, typename _Tp2>
static constexpr _Tp2&
__get(pair<_Tp1, _Tp2>& __pair) noexcept
{ return __pair.second; }
template<typename _Tp1, typename _Tp2>
static constexpr _Tp2&&
__move_get(pair<_Tp1, _Tp2>&& __pair) noexcept
{ return std::forward<_Tp2>(__pair.second); }
template<typename _Tp1, typename _Tp2>
static constexpr const _Tp2&
__const_get(const pair<_Tp1, _Tp2>& __pair) noexcept
{ return __pair.second; }
template<typename _Tp1, typename _Tp2>
static constexpr const _Tp2&&
__const_move_get(const pair<_Tp1, _Tp2>&& __pair) noexcept
{ return std::forward<const _Tp2>(__pair.second); }
};
/// @endcond
/** @{
* std::get overloads for accessing members of std::pair
*/
template<size_t _Int, class _Tp1, class _Tp2>
constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
get(pair<_Tp1, _Tp2>& __in) noexcept
{ return __pair_get<_Int>::__get(__in); }
template<size_t _Int, class _Tp1, class _Tp2>
constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
get(pair<_Tp1, _Tp2>&& __in) noexcept
{ return __pair_get<_Int>::__move_get(std::move(__in)); }
template<size_t _Int, class _Tp1, class _Tp2>
constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
get(const pair<_Tp1, _Tp2>& __in) noexcept
{ return __pair_get<_Int>::__const_get(__in); }
template<size_t _Int, class _Tp1, class _Tp2>
constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
get(const pair<_Tp1, _Tp2>&& __in) noexcept
{ return __pair_get<_Int>::__const_move_get(std::move(__in)); }
#if __cplusplus >= 201402L
#define __cpp_lib_tuples_by_type 201304L
template <typename _Tp, typename _Up>
constexpr _Tp&
get(pair<_Tp, _Up>& __p) noexcept
{ return __p.first; }
template <typename _Tp, typename _Up>
constexpr const _Tp&
get(const pair<_Tp, _Up>& __p) noexcept
{ return __p.first; }
template <typename _Tp, typename _Up>
constexpr _Tp&&
get(pair<_Tp, _Up>&& __p) noexcept
{ return std::move(__p.first); }
template <typename _Tp, typename _Up>
constexpr const _Tp&&
get(const pair<_Tp, _Up>&& __p) noexcept
{ return std::move(__p.first); }
template <typename _Tp, typename _Up>
constexpr _Tp&
get(pair<_Up, _Tp>& __p) noexcept
{ return __p.second; }
template <typename _Tp, typename _Up>
constexpr const _Tp&
get(const pair<_Up, _Tp>& __p) noexcept
{ return __p.second; }
template <typename _Tp, typename _Up>
constexpr _Tp&&
get(pair<_Up, _Tp>&& __p) noexcept
{ return std::move(__p.second); }
template <typename _Tp, typename _Up>
constexpr const _Tp&&
get(const pair<_Up, _Tp>&& __p) noexcept
{ return std::move(__p.second); }
#endif // C++14
/// @}
#endif // C++11
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif /* _STL_PAIR_H */
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