71 lines
2.0 KiB
C
71 lines
2.0 KiB
C
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <cstdint>
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#include <typeinfo>
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#include <folly/detail/StaticSingletonManager.h>
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namespace folly {
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namespace detail {
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class UniqueInstance {
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public:
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template <typename... Key, typename... Mapped>
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FOLLY_EXPORT explicit UniqueInstance(
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char const* tmpl,
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tag_t<Key...>,
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tag_t<Mapped...>) noexcept {
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static Ptr const ptrs[] = {&typeid(Key)..., &typeid(Mapped)...};
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auto& global = createGlobal<Value, tag_t<Tag, Key...>>();
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enforce(tmpl, ptrs, sizeof...(Key), sizeof...(Mapped), global);
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}
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UniqueInstance(UniqueInstance const&) = delete;
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UniqueInstance(UniqueInstance&&) = delete;
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UniqueInstance& operator=(UniqueInstance const&) = delete;
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UniqueInstance& operator=(UniqueInstance&&) = delete;
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private:
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struct Tag {};
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using Ptr = std::type_info const*;
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struct PtrRange {
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Ptr const* b;
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Ptr const* e;
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};
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struct Value {
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char const* tmpl;
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Ptr const* ptrs;
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std::uint32_t key_size;
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std::uint32_t mapped_size;
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};
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// Under Clang, this call signature shrinks the aligned and padded size of
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// call-sites, as compared to a call signature taking Value or Value const&.
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static void enforce(
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char const* tmpl,
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Ptr const* ptrs,
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std::uint32_t key_size,
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std::uint32_t mapped_size,
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Value& global) noexcept;
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};
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} // namespace detail
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} // namespace folly
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