Edit: /usr/include/c++/11/bits/stl_pair.h (20135B)
// Pair implementation -*- C++ -*-
// Copyright (C) 2001-2021 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
//
.
/*
*
* 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
#include
// for std::move / std::forward, and std::swap
#if __cplusplus >= 201103L
# include // for std::__decay_and_strip, std::is_reference_v
#endif
#if __cplusplus > 201703L
# include
# 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
class tuple;
template
struct _Index_tuple;
// 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
struct _PCC
{
template
static constexpr bool _ConstructiblePair()
{
return __and_,
is_constructible<_T2, const _U2&>>::value;
}
template
static constexpr bool _ImplicitlyConvertiblePair()
{
return __and_,
is_convertible>::value;
}
template
static constexpr bool _MoveConstructiblePair()
{
return __and_,
is_constructible<_T2, _U2&&>>::value;
}
template
static constexpr bool _ImplicitlyMoveConvertiblePair()
{
return __and_,
is_convertible<_U2&&, _T2>>::value;
}
template
static constexpr bool _CopyMovePair()
{
using __do_converts = __and_,
is_convertible<_U2&&, _T2>>;
using __converts = typename conditional<__implicit,
__do_converts,
__not_<__do_converts>>::type;
return __and_,
is_constructible<_T2, _U2&&>,
__converts
>::value;
}
template
static constexpr bool _MoveCopyPair()
{
using __do_converts = __and_,
is_convertible>;
using __converts = typename conditional<__implicit,
__do_converts,
__not_<__do_converts>>::type;
return __and_,
is_constructible<_T2, const _U2&&>,
__converts
>::value;
}
};
template
struct _PCC
{
template
static constexpr bool _ConstructiblePair()
{
return false;
}
template
static constexpr bool _ImplicitlyConvertiblePair()
{
return false;
}
template
static constexpr bool _MoveConstructiblePair()
{
return false;
}
template
static constexpr bool _ImplicitlyMoveConvertiblePair()
{
return false;
}
};
#endif // C++11
template class __pair_base
{
#if __cplusplus >= 201103L
template 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.
*
*
*/
template
struct pair
: private __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
// _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. */
#if __cplusplus >= 201103L
template ,
__is_implicitly_default_constructible<_U2>>
::value, bool>::type = true>
#endif
_GLIBCXX_CONSTEXPR pair()
: first(), second() { }
#if __cplusplus >= 201103L
template ,
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() { }
#endif
#if __cplusplus < 201103L
/// Two objects may be passed to a @c pair constructor to be copied.
pair(const _T1& __a, const _T2& __b)
: first(__a), second(__b) { }
#else
// Shortcut for constraining the templates that don't take pairs.
/// @cond undocumented
using _PCCP = _PCC;
/// @endcond
/// Construct from two const lvalues, allowing implicit conversions.
template()
&& _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()
&& !_PCCP::template
_ImplicitlyConvertiblePair<_U1, _U2>(),
bool>::type=false>
explicit constexpr pair(const _T1& __a, const _T2& __b)
: first(__a), second(__b) { }
#endif
#if __cplusplus < 201103L
/// There is also a templated constructor to convert from other pairs.
template
pair(const pair<_U1, _U2>& __p)
: first(__p.first), second(__p.second) { }
#else
// Shortcut for constraining the templates that take pairs.
/// @cond undocumented
template
using _PCCFP = _PCC::value
|| !is_same<_T2, _U2>::value,
_T1, _T2>;
/// @endcond
template::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::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) { }
#endif
#if __cplusplus >= 201103L
constexpr pair(const pair&) = default; ///< Copy constructor
constexpr pair(pair&&) = default; ///< Move constructor
// DR 811.
template(),
bool>::type=true>
constexpr pair(_U1&& __x, const _T2& __y)
: first(std::forward<_U1>(__x)), second(__y) { }
template(),
bool>::type=false>
explicit constexpr pair(_U1&& __x, const _T2& __y)
: first(std::forward<_U1>(__x)), second(__y) { }
template(),
bool>::type=true>
constexpr pair(const _T1& __x, _U2&& __y)
: first(__x), second(std::forward<_U2>(__y)) { }
template(),
bool>::type=false>
explicit pair(const _T1& __x, _U2&& __y)
: first(__x), second(std::forward<_U2>(__y)) { }
template()
&& _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()
&& !_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::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::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)) { }
template
_GLIBCXX20_CONSTEXPR
pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
_GLIBCXX20_CONSTEXPR pair&
operator=(typename conditional<
__and_,
is_copy_assignable<_T2>>::value,
const pair&, const __nonesuch&>::type __p)
{
first = __p.first;
second = __p.second;
return *this;
}
_GLIBCXX20_CONSTEXPR pair&
operator=(typename conditional<
__and_,
is_move_assignable<_T2>>::value,
pair&&, __nonesuch&&>::type __p)
noexcept(__and_,
is_nothrow_move_assignable<_T2>>::value)
{
first = std::forward(__p.first);
second = std::forward(__p.second);
return *this;
}
template
_GLIBCXX20_CONSTEXPR
typename enable_if<__and_,
is_assignable<_T2&, const _U2&>>::value,
pair&>::type
operator=(const pair<_U1, _U2>& __p)
{
first = __p.first;
second = __p.second;
return *this;
}
template
_GLIBCXX20_CONSTEXPR
typename enable_if<__and_,
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;
}
/// 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
_GLIBCXX20_CONSTEXPR
pair(tuple<_Args1...>&, tuple<_Args2...>&,
_Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
#endif // C++11
};
/// @relates pair @{
#if __cpp_deduction_guides >= 201606
template pair(_T1, _T2) -> pair<_T1, _T2>;
#endif
/// Two pairs of the same type are equal iff their members are equal.
template
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
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
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
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
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
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
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
_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 enable_if,
__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
constexpr pair::__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
inline pair<_T1, _T2>
make_pair(_T1 __x, _T2 __y)
{ return pair<_T1, _T2>(__x, __y); }
#endif
/// @}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif /* _STL_PAIR_H */