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39 lines
1.2 KiB
C++
39 lines
1.2 KiB
C++
// SPDX-License-Identifier: MIT
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#ifndef RGBDS_DEFAULT_INIT_ALLOC_HPP
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#define RGBDS_DEFAULT_INIT_ALLOC_HPP
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#include <memory>
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#include <vector>
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// Allocator adaptor that interposes construct() calls to convert value-initialization
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// (which is what you get with e.g. `vector::resize`) into default-initialization (which does not
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// zero out non-class types).
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// From
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// https://stackoverflow.com/questions/21028299/is-this-behavior-of-vectorresizesize-type-n-under-c11-and-boost-container/21028912#21028912
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template<typename T, typename A = std::allocator<T>>
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class default_init_allocator : public A {
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using a_t = std::allocator_traits<A>;
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public:
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template<typename U>
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struct rebind {
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using other = default_init_allocator<U, typename a_t::template rebind_alloc<U>>;
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};
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using A::A; // Inherit the allocator's constructors
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template<typename U>
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void construct(U *ptr) noexcept(std::is_nothrow_default_constructible_v<U>) {
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::new (static_cast<void *>(ptr)) U;
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}
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template<typename U, typename... Args>
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void construct(U *ptr, Args &&...args) {
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a_t::construct(static_cast<A &>(*this), ptr, std::forward<Args>(args)...);
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}
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};
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template<typename T>
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using DefaultInitVec = std::vector<T, default_init_allocator<T>>;
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#endif // RGBDS_DEFAULT_INIT_ALLOC_HPP
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