/**
 * @file threadsafe_stack.cpp
 * @brief ̰߳ȫstack
*/

#include <iostream> 
#include <stack>
#include <mutex>

using namespace std;

template<typename T>
class threadsafe_stack
{
public:
	threadsafe_stack() : data(stack<T>()) {}
	threadsafe_stack(const threadsafe_stack& other)
	{
		lock_guard<mutex> lock(other.m);
		data = other.data;
	}
	threadsafe_stack& operator=(const threadsafe_stack&) = delete;

	void push(T new_value)
	{
		lock_guard<mutex> lock(m);
		data.push(new_value);
	}
	std::shared_ptr<T> pop()
	{
		lock_guard<mutex> lock(m);
		if (data.empty()) throw ;
		shared_ptr<T> const res(make_shared<T>(data.top()));
		data.pop();
		return res;
	}
	void pop(T& value)
	{
		std::lock_guard<std::mutex> lock(m);
		if (data.empty()) throw ;
		value = data.top();
		data.pop();
	}
	bool empty() const
	{
		std::lock_guard<std::mutex> lock(m);
		return data.empty();
	}

private:
	stack<T> data;
	mutable mutex m;
};

int main()
{
	threadsafe_stack<int> si;
	si.push(5);
	si.pop();
	if (!si.empty())
	{
		int x;
		si.pop(x);
	}
	return 0;
}