mirror of https://github.com/ByConity/ByConity
60 lines
1.4 KiB
C++
60 lines
1.4 KiB
C++
/*
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* Copyright (2022) Bytedance Ltd. and/or its affiliates
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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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namespace ext
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{
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/** Example (1):
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*
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* class Derived : public ext::singleton<Derived>
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* {
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* friend class ext::singleton<Derived>;
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* ...
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* protected:
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* Derived() {};
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* };
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*
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* Example (2):
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*
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* class Some
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* {
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* ...
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* };
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*
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* class SomeSingleton : public Some, public ext::singleton<SomeSingleton> {}
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*/
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template <typename T> class singleton
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{
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public:
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static T & instance()
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{
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/// C++11 has thread safe statics. GCC and Clang have thread safe statics by default even before C++11.
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static T instance;
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return instance;
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}
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protected:
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singleton() {}
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private:
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singleton(const singleton &);
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singleton & operator=(const singleton &);
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};
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}
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