1 // Copyright (C) 2020 The Libphonenumber Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #ifndef I18N_PHONENUMBERS_BASE_MEMORY_SINGLETON_BOOST_H_ 16 #define I18N_PHONENUMBERS_BASE_MEMORY_SINGLETON_BOOST_H_ 17 18 #include <boost/scoped_ptr.hpp> 19 #include <boost/thread/once.hpp> 20 #include <boost/utility.hpp> 21 22 namespace i18n { 23 namespace phonenumbers { 24 25 template <class T> 26 class Singleton : private boost::noncopyable { 27 public: Singleton()28 Singleton() {} ~Singleton()29 virtual ~Singleton() {} 30 GetInstance()31 static T* GetInstance() { 32 boost::call_once(Init, flag_); 33 return instance_.get(); 34 } 35 36 private: Init()37 static void Init() { 38 instance_.reset(new T()); 39 } 40 41 static boost::scoped_ptr<T> instance_; 42 static boost::once_flag flag_; 43 }; 44 45 template <class T> boost::scoped_ptr<T> Singleton<T>::instance_; 46 template <class T> boost::once_flag Singleton<T>::flag_ = BOOST_ONCE_INIT; 47 48 } // namespace phonenumbers 49 } // namespace i18n 50 51 #endif // I18N_PHONENUMBERS_BASE_MEMORY_SINGLETON_BOOST_H_ 52