stl_pair.h
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// Pair implementation -*- C++ -*-
// Copyright (C) 2001-2019 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
#include <bits/move.h> // for std::move / std::forward, and std::swap
#if __cplusplus >= 201103L
#include <type_traits> // for std::__decay_and_strip too
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @addtogroup utilities
* @{
*/
#if __cplusplus >= 201103L
/// piecewise_construct_t
struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
/// piecewise_construct
_GLIBCXX17_INLINE constexpr piecewise_construct_t piecewise_construct =
piecewise_construct_t();
// Forward declarations.
template<typename...>
class tuple;
template<std::size_t...>
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 <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 <bool __implicit, typename _U1, typename _U2>
static constexpr bool _CopyMovePair()
{
using __do_converts = __and_<is_convertible<const _U1&, _T1>,
is_convertible<_U2&&, _T2>>;
using __converts = typename conditional<__implicit,
__do_converts,
__not_<__do_converts>>::type;
return __and_<is_constructible<_T1, const _U1&>,
is_constructible<_T2, _U2&&>,
__converts
>::value;
}
template <bool __implicit, typename _U1, typename _U2>
static constexpr bool _MoveCopyPair()
{
using __do_converts = __and_<is_convertible<_U1&&, _T1>,
is_convertible<const _U2&, _T2>>;
using __converts = typename conditional<__implicit,
__do_converts,
__not_<__do_converts>>::type;
return __and_<is_constructible<_T1, _U1&&>,
is_constructible<_T2, const _U2&&>,
__converts
>::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;
}
};
// PR libstdc++/79141, a utility type for preventing
// initialization of an argument of a disabled assignment
// operator from a pair of empty braces.
struct __nonesuch_no_braces : std::__nonesuch {
explicit __nonesuch_no_braces(const __nonesuch&) = delete;
};
#endif // C++11
template<typename _U1, typename _U2> class __pair_base
{
#if __cplusplus >= 201103L
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
};
/**
* @brief Struct holding two objects of arbitrary type.
*
* @tparam _T1 Type of first object.
* @tparam _T2 Type of second object.
*/
template<typename _T1, typename _T2>
struct pair
: private __pair_base<_T1, _T2>
{
typedef _T1 first_type; /// @c first_type is the first bound type
typedef _T2 second_type; /// @c second_type is the second bound type
_T1 first; /// @c first is a copy of the first object
_T2 second; /// @c second is a copy of the second object
// _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 <typename _U1 = _T1,
typename _U2 = _T2,
typename enable_if<__and_<
__is_implicitly_default_constructible<_U1>,
__is_implicitly_default_constructible<_U2>>
::value, bool>::type = true>
#endif
_GLIBCXX_CONSTEXPR pair()
: first(), second() { }
#if __cplusplus >= 201103L
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() { }
#endif
/** Two objects may be passed to a @c pair constructor to be copied. */
#if __cplusplus < 201103L
pair(const _T1& __a, const _T2& __b)
: first(__a), second(__b) { }
#else
// Shortcut for constraining the templates that don't take pairs.
using _PCCP = _PCC<true, _T1, _T2>;
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) { }
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) { }
#endif
/** There is also a templated copy ctor for the @c pair class itself. */
#if __cplusplus < 201103L
template<typename _U1, typename _U2>
pair(const pair<_U1, _U2>& __p)
: first(__p.first), second(__p.second) { }
#else
// Shortcut for constraining the templates that take pairs.
template <typename _U1, typename _U2>
using _PCCFP = _PCC<!is_same<_T1, _U1>::value
|| !is_same<_T2, _U2>::value,
_T1, _T2>;
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) { }
constexpr pair(const pair&) = default;
constexpr pair(pair&&) = default;
// DR 811.
template<typename _U1, typename
enable_if<_PCCP::template
_MoveCopyPair<true, _U1, _T2>(),
bool>::type=true>
constexpr pair(_U1&& __x, const _T2& __y)
: first(std::forward<_U1>(__x)), second(__y) { }
template<typename _U1, typename
enable_if<_PCCP::template
_MoveCopyPair<false, _U1, _T2>(),
bool>::type=false>
explicit constexpr pair(_U1&& __x, const _T2& __y)
: first(std::forward<_U1>(__x)), second(__y) { }
template<typename _U2, typename
enable_if<_PCCP::template
_CopyMovePair<true, _T1, _U2>(),
bool>::type=true>
constexpr pair(const _T1& __x, _U2&& __y)
: first(__x), second(std::forward<_U2>(__y)) { }
template<typename _U2, typename
enable_if<_PCCP::template
_CopyMovePair<false, _T1, _U2>(),
bool>::type=false>
explicit pair(const _T1& __x, _U2&& __y)
: first(__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=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)) { }
template<typename... _Args1, typename... _Args2>
pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>);
pair&
operator=(typename conditional<
__and_<is_copy_assignable<_T1>,
is_copy_assignable<_T2>>::value,
const pair&, const __nonesuch_no_braces&>::type __p)
{
first = __p.first;
second = __p.second;
return *this;
}
pair&
operator=(typename conditional<
__and_<is_move_assignable<_T1>,
is_move_assignable<_T2>>::value,
pair&&, __nonesuch_no_braces&&>::type __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;
}
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, std::size_t... _Indexes1,
typename... _Args2, std::size_t... _Indexes2>
pair(tuple<_Args1...>&, tuple<_Args2...>&,
_Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
#endif
};
#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; }
/// <http://gcc.gnu.org/onlinedocs/libstdc++/manual/utilities.html>
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); }
#if __cplusplus >= 201103L
/// See std::pair::swap().
// Note: no std::swap overloads in C++03 mode, this has performance
// implications, see, eg, libstdc++/38466.
template<typename _T1, typename _T2>
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
/**
* @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 standard requires that the objects be passed by reference-to-const,
* but LWG issue #181 says they should be passed by const value. We follow
* the LWG by default.
*/
// _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
/// @}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif /* _STL_PAIR_H */
move.h
std::piecewise_construct
constexpr _GLIBCXX17_INLINE piecewise_construct_t piecewise_construct
piecewise_construct
Definition: stl_pair.h:79
std::make_pair
constexpr pair< typename __decay_and_strip< _T1 >::__type, typename __decay_and_strip< _T2 >::__type > make_pair(_T1 &&__x, _T2 &&__y)
A convenience wrapper for creating a pair from two objects.
Definition: stl_pair.h:524
std::forward
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
Definition: move.h:74
std
ISO C++ entities toplevel namespace is std.
std::tuple
Primary class template, tuple.
Definition: tuple:524
std::is_constructible
is_constructible
Definition: type_traits:885
std::is_default_constructible
is_default_constructible
Definition: type_traits:891
std::is_same
is_same
Definition: type_traits:1286
std::enable_if
Define a member typedef type only if a boolean constant is true.
Definition: type_traits:2040
std::piecewise_construct_t
piecewise_construct_t
Definition: stl_pair.h:76
std::pair
Struct holding two objects of arbitrary type.
Definition: stl_pair.h:210
std::pair::first
_T1 first
second_type is the second bound type
Definition: stl_pair.h:214
std::pair::_PCCP
_PCC< true, _T1, _T2 > _PCCP
Definition: stl_pair.h:252
std::pair::_PCCFP
_PCC<!is_same< _T1, _U1 >::value||!is_same< _T2, _U2 >::value, _T1, _T2 > _PCCFP
Definition: stl_pair.h:283
std::pair::pair
constexpr pair()
second is a copy of the second object
Definition: stl_pair.h:229
std::pair::second_type
_T2 second_type
first_type is the first bound type
Definition: stl_pair.h:212
std::pair::second
_T2 second
first is a copy of the first object
Definition: stl_pair.h:215
type_traits