7f19d64164
git-subtree-dir: third_party/immer git-subtree-split: ad3e3556d38bb75966dd24c61a774970a7c7957e
43 lines
1 KiB
C++
43 lines
1 KiB
C++
//
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// immer: immutable data structures for C++
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// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
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//
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// This software is distributed under the Boost Software License, Version 1.0.
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// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
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//
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#pragma once
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#include <cstdio>
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namespace immer {
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/*!
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* Appends a default constructed extra object of type `T` at the
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* *before* the requested region.
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*
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* @tparam T Type of the appended data.
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* @tparam Base Type of the parent heap.
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*/
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template <typename T, typename Base>
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struct with_data : Base
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{
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using base_t = Base;
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template <typename... Tags>
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static void* allocate(std::size_t size, Tags... tags)
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{
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auto p = base_t::allocate(size + sizeof(T), tags...);
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return new (p) T{} + 1;
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}
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template <typename... Tags>
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static void deallocate(std::size_t size, void* p, Tags... tags)
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{
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auto dp = static_cast<T*>(p) - 1;
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dp->~T();
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base_t::deallocate(size + sizeof(T), dp, tags...);
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}
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};
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} // namespace immer
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