4f3c75ba3a
The erased_type condition is only true for code using the Library Fundamentals TS, so assume it's less common and only check it after checking for convertibility. This does mean for types using erased_type the more expensive convertibility check is done first, but such types are rare. * include/bits/uses_allocator.h (__is_erased_or_convertible): Reorder conditions. Add comments. * testsuite/20_util/uses_allocator/69293_neg.cc: Adjust dg-error line. * testsuite/20_util/uses_allocator/cons_neg.cc: Likewise. * testsuite/20_util/scoped_allocator/69293_neg.cc: Likewise. From-SVN: r262945
191 lines
6.5 KiB
C++
191 lines
6.5 KiB
C++
// Uses-allocator Construction -*- C++ -*-
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// Copyright (C) 2010-2018 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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#ifndef _USES_ALLOCATOR_H
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#define _USES_ALLOCATOR_H 1
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#if __cplusplus < 201103L
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# include <bits/c++0x_warning.h>
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#else
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#include <type_traits>
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#include <bits/move.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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// This is used for std::experimental::erased_type from Library Fundamentals.
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struct __erased_type { };
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// This also supports the "type-erased allocator" protocol from the
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// Library Fundamentals TS, where allocator_type is erased_type.
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// The second condition will always be false for types not using the TS.
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template<typename _Alloc, typename _Tp>
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using __is_erased_or_convertible
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= __or_<is_convertible<_Alloc, _Tp>, is_same<_Tp, __erased_type>>;
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/// [allocator.tag]
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struct allocator_arg_t { explicit allocator_arg_t() = default; };
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_GLIBCXX17_INLINE constexpr allocator_arg_t allocator_arg =
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allocator_arg_t();
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template<typename _Tp, typename _Alloc, typename = __void_t<>>
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struct __uses_allocator_helper
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: false_type { };
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template<typename _Tp, typename _Alloc>
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struct __uses_allocator_helper<_Tp, _Alloc,
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__void_t<typename _Tp::allocator_type>>
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: __is_erased_or_convertible<_Alloc, typename _Tp::allocator_type>::type
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{ };
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/// [allocator.uses.trait]
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template<typename _Tp, typename _Alloc>
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struct uses_allocator
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: __uses_allocator_helper<_Tp, _Alloc>::type
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{ };
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struct __uses_alloc_base { };
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struct __uses_alloc0 : __uses_alloc_base
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{
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struct _Sink { void operator=(const void*) { } } _M_a;
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};
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template<typename _Alloc>
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struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; };
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template<typename _Alloc>
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struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; };
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template<bool, typename _Tp, typename _Alloc, typename... _Args>
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struct __uses_alloc;
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template<typename _Tp, typename _Alloc, typename... _Args>
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struct __uses_alloc<true, _Tp, _Alloc, _Args...>
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: conditional<
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is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value,
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__uses_alloc1<_Alloc>,
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__uses_alloc2<_Alloc>>::type
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{
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static_assert(__or_<
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is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>,
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is_constructible<_Tp, _Args..., _Alloc>>::value, "construction with"
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" an allocator must be possible if uses_allocator is true");
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};
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template<typename _Tp, typename _Alloc, typename... _Args>
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struct __uses_alloc<false, _Tp, _Alloc, _Args...>
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: __uses_alloc0 { };
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template<typename _Tp, typename _Alloc, typename... _Args>
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using __uses_alloc_t =
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__uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>;
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template<typename _Tp, typename _Alloc, typename... _Args>
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inline __uses_alloc_t<_Tp, _Alloc, _Args...>
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__use_alloc(const _Alloc& __a)
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{
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__uses_alloc_t<_Tp, _Alloc, _Args...> __ret;
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__ret._M_a = std::__addressof(__a);
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return __ret;
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}
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template<typename _Tp, typename _Alloc, typename... _Args>
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void
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__use_alloc(const _Alloc&&) = delete;
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#if __cplusplus > 201402L
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template <typename _Tp, typename _Alloc>
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inline constexpr bool uses_allocator_v =
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uses_allocator<_Tp, _Alloc>::value;
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#endif // C++17
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template<template<typename...> class _Predicate,
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typename _Tp, typename _Alloc, typename... _Args>
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struct __is_uses_allocator_predicate
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: conditional<uses_allocator<_Tp, _Alloc>::value,
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__or_<_Predicate<_Tp, allocator_arg_t, _Alloc, _Args...>,
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_Predicate<_Tp, _Args..., _Alloc>>,
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_Predicate<_Tp, _Args...>>::type { };
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template<typename _Tp, typename _Alloc, typename... _Args>
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struct __is_uses_allocator_constructible
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: __is_uses_allocator_predicate<is_constructible, _Tp, _Alloc, _Args...>
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{ };
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#if __cplusplus >= 201402L
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template<typename _Tp, typename _Alloc, typename... _Args>
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_GLIBCXX17_INLINE constexpr bool __is_uses_allocator_constructible_v =
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__is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
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#endif // C++14
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template<typename _Tp, typename _Alloc, typename... _Args>
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struct __is_nothrow_uses_allocator_constructible
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: __is_uses_allocator_predicate<is_nothrow_constructible,
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_Tp, _Alloc, _Args...>
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{ };
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#if __cplusplus >= 201402L
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template<typename _Tp, typename _Alloc, typename... _Args>
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_GLIBCXX17_INLINE constexpr bool
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__is_nothrow_uses_allocator_constructible_v =
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__is_nothrow_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
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#endif // C++14
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template<typename _Tp, typename... _Args>
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void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr,
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_Args&&... __args)
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{ ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)...); }
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template<typename _Tp, typename _Alloc, typename... _Args>
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void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp* __ptr,
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_Args&&... __args)
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{
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::new ((void*)__ptr) _Tp(allocator_arg, *__a._M_a,
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std::forward<_Args>(__args)...);
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}
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template<typename _Tp, typename _Alloc, typename... _Args>
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void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp* __ptr,
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_Args&&... __args)
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{ ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)..., *__a._M_a); }
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template<typename _Tp, typename _Alloc, typename... _Args>
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void __uses_allocator_construct(const _Alloc& __a, _Tp* __ptr,
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_Args&&... __args)
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{
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__uses_allocator_construct_impl(__use_alloc<_Tp, _Alloc, _Args...>(__a),
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__ptr, std::forward<_Args>(__args)...);
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}
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#endif
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#endif
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