mirror of https://github.com/grpc/grpc.git
Craig Tiller
7 years ago
parent
313f36fd06
commit
922260656a
20 changed files with 243 additions and 165 deletions
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/*
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* |
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* Copyright 2016 gRPC authors. |
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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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*/ |
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// manually construct a region of memory with some type
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#include <stddef.h> |
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#include <new> |
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#include <type_traits> |
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#include <utility> |
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namespace grpc_core { |
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template <typename Type> |
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class ManualConstructor { |
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public: |
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// No constructor or destructor because one of the most useful uses of
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// this class is as part of a union, and members of a union could not have
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// constructors or destructors till C++11. And, anyway, the whole point of
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// this class is to bypass constructor and destructor.
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Type* get() { return reinterpret_cast<Type*>(&space_); } |
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const Type* get() const { return reinterpret_cast<const Type*>(&space_); } |
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Type* operator->() { return get(); } |
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const Type* operator->() const { return get(); } |
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Type& operator*() { return *get(); } |
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const Type& operator*() const { return *get(); } |
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void Init() { new (&space_) Type; } |
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// Init() constructs the Type instance using the given arguments
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// (which are forwarded to Type's constructor).
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//
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// Note that Init() with no arguments performs default-initialization,
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// not zero-initialization (i.e it behaves the same as "new Type;", not
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// "new Type();"), so it will leave non-class types uninitialized.
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template <typename... Ts> |
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void Init(Ts&&... args) { |
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new (&space_) Type(std::forward<Ts>(args)...); |
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} |
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// Init() that is equivalent to copy and move construction.
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// Enables usage like this:
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// ManualConstructor<std::vector<int>> v;
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// v.Init({1, 2, 3});
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void Init(const Type& x) { new (&space_) Type(x); } |
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void Init(Type&& x) { new (&space_) Type(std::move(x)); } |
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void Destroy() { get()->~Type(); } |
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private: |
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typename std::aligned_storage<sizeof(Type), alignof(Type)>::type space_; |
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}; |
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} // namespace grpc_core
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