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Edit File: stl_pair.h

// 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 // <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, std::is_reference_v #endif #if __cplusplus > 201703L # 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; // 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; } }; #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 }; /// @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 : 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 <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 #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<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) { } #endif #if __cplusplus < 201103L /// There is also a templated constructor to convert from other pairs. 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. /// @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) { } #endif #if __cplusplus >= 201103L constexpr pair(const pair&) = default; ///< Copy constructor constexpr pair(pair&&) = default; ///< Move constructor // 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> _GLIBCXX20_CONSTEXPR pair(piecewise_construct_t, tuple<_Args1...>, tuple<_Args2...>); _GLIBCXX20_CONSTEXPR pair& operator=(typename conditional< __and_<is_copy_assignable<_T1>, 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<_T1>, is_move_assignable<_T2>>::value, pair&&, __nonesuch&&>::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> _GLIBCXX20_CONSTEXPR 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> _GLIBCXX20_CONSTEXPR 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; } /// 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...>); #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 /// @} _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif /* _STL_PAIR_H */