/* * Open Chinese Convert * * Copyright 2010-2014 Carbo Kuo <byvoid@byvoid.com> * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #pragma once namespace opencc { /** * A class that wraps type T into a nullable type. * @ingroup opencc_cpp_api */ template <typename T> class Optional { public: /** * The constructor of Optional. */ Optional(T actual) : isNull(false), data(actual) {} /** * Returns true if the instance is null. */ bool IsNull() const { return isNull; } /** * Returns the containing data of the instance. */ const T& Get() const { return data; } /** * Constructs a null instance. */ static Optional<T> Null() { return Optional(); } private: Optional() : isNull(true) {} bool isNull; T data; }; /** * Specialization of Optional for pointers. * * Reduce a bool. */ template <typename T> class Optional<T*> { private: Optional() : data(nullptr) {} typedef T* TPtr; TPtr data; public: Optional(TPtr actual) : data(actual) {} bool IsNull() const { return data == nullptr; } const TPtr& Get() const { return data; } static Optional<TPtr> Null() { return Optional(); } }; } // namespace opencc