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- /* Copyright (C) 2017-2022 Free Software Foundation, Inc.
- This file is part of GDB.
- This program 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 of the License, or
- (at your option) any later version.
- This program 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.
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
- #ifndef COMMON_DEFAULT_INIT_ALLOC_H
- #define COMMON_DEFAULT_INIT_ALLOC_H
- namespace gdb {
- /* An allocator that default constructs using default-initialization
- rather than value-initialization. The idea is to use this when you
- don't want to default construct elements of containers of trivial
- types using zero-initialization. */
- /* Mostly as implementation convenience, this is implemented as an
- adapter that given an allocator A, overrides 'A::construct()'. 'A'
- defaults to std::allocator<T>. */
- template<typename T, typename A = std::allocator<T>>
- class default_init_allocator : public A
- {
- public:
- /* Pull in A's ctors. */
- using A::A;
- /* Override rebind. */
- template<typename U>
- struct rebind
- {
- /* A couple helpers just to make it a bit more readable. */
- typedef std::allocator_traits<A> traits_;
- typedef typename traits_::template rebind_alloc<U> alloc_;
- /* This is what we're after. */
- typedef default_init_allocator<U, alloc_> other;
- };
- /* Make the base allocator's construct method(s) visible. */
- using A::construct;
- /* .. and provide an override/overload for the case of default
- construction (i.e., no arguments). This is where we construct
- with default-init. */
- template <typename U>
- void construct (U *ptr)
- noexcept (std::is_nothrow_default_constructible<U>::value)
- {
- ::new ((void *) ptr) U; /* default-init */
- }
- };
- } /* namespace gdb */
- #endif /* COMMON_DEFAULT_INIT_ALLOC_H */
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