/*! \file piprotectedvariable.h
 * \ingroup Thread
 * \~\brief
 * \~english Thread-safe variable
 * \~russian Потокобезопасная переменная
 */
/*
	PIP - Platform Independent Primitives
	Thread-safe variable
	Ivan Pelipenko peri4ko@yandex.ru, Stephan Fomenko, Andrey Bychkov work.a.b@yandex.ru

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef PIPROTECTEDVARIABLE_H
#define PIPROTECTEDVARIABLE_H

#include "pimutex.h"


template<typename T>
class PIP_EXPORT PIProtectedVariable {
public:
	//! \~english
	//! \~russian
	class PIP_EXPORT Pointer {
		friend class PIProtectedVariable<T>;

	public:
		Pointer(const Pointer & v): pv(v.pv), counter(v.counter + 1) {}
		~Pointer() {
			if (counter == 0) pv.mutex.unlock();
		}

		T * operator->() { return &pv.var; }
		T & operator*() { return pv.var; }

	private:
		Pointer() = delete;
		Pointer(PIProtectedVariable<T> & v): pv(v) {}

		PIProtectedVariable<T> & pv;
		int counter = 0;
	};

	//! \~english Sets value to \"v\"
	//! \~russian Устанавливает значение как \"v\"
	void set(T v) {
		PIMutexLocker _ml(mutex);
		var = std::move(v);
	}

	//! \~english Lock mutex and returns reference wrapper of value. Unlock on variable destructor.
	//! \~russian Блокирует мьютекс и возвращает класс-обертку на значение. Разблокирует в деструкторе переменной.
	Pointer getRef() {
		mutex.lock();
		return Pointer(*this);
	}

	//! \~english Returns copy of value
	//! \~russian Возвращает копию значения
	T get() const {
		PIMutexLocker _ml(mutex);
		return var;
	}

	//! \~english Sets value to \"v\"
	//! \~russian Устанавливает значение как \"v\"
	PIProtectedVariable<T> & operator=(T v) {
		set(std::move(v));
		return *this;
	}


private:
	mutable PIMutex mutex;
	T var;
};


#endif