struct Mutex::Lock {
	Mutex& s;
	Lock(Mutex& s) : s(s) { s.Enter(); }
	~Lock()               { s.Leave(); }
private:
	Lock( const Lock& );
};

struct RWMutex::ReadLock {
	RWMutex& s;
	ReadLock(RWMutex& s) : s(s) { s.EnterRead(); }
	~ReadLock()                 { s.LeaveRead(); }
private:
	ReadLock( const ReadLock& );
};

struct RWMutex::WriteLock {
	RWMutex& s;
	WriteLock(RWMutex& s) : s(s) { s.EnterWrite(); }
	~WriteLock()                 { s.LeaveWrite(); }
private:
	WriteLock( const WriteLock& );
};