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https://github.com/xiaoyifang/goldendict-ng.git
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76 lines
1.7 KiB
C++
76 lines
1.7 KiB
C++
/*
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* Open Chinese Convert
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*
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* Copyright 2010-2014 Carbo Kuo <byvoid@byvoid.com>
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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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namespace opencc {
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/**
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* A class that wraps type T into a nullable type.
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* @ingroup opencc_cpp_api
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*/
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template <typename T> class Optional {
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public:
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/**
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* The constructor of Optional.
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*/
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Optional(T actual) : isNull(false), data(actual) {}
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/**
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* Returns true if the instance is null.
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*/
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bool IsNull() const { return isNull; }
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/**
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* Returns the containing data of the instance.
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*/
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const T& Get() const { return data; }
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/**
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* Constructs a null instance.
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*/
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static Optional<T> Null() { return Optional(); }
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private:
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Optional() : isNull(true) {}
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bool isNull;
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T data;
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};
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/**
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* Specialization of Optional for pointers.
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*
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* Reduce a bool.
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*/
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template <typename T> class Optional<T*> {
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private:
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Optional() : data(nullptr) {}
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typedef T* TPtr;
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TPtr data;
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public:
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Optional(TPtr actual) : data(actual) {}
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bool IsNull() const { return data == nullptr; }
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const TPtr& Get() const { return data; }
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static Optional<TPtr> Null() { return Optional(); }
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};
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} // namespace opencc
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