ClickHouse/base/poco/Foundation/include/Poco/Observer.h

109 lines
2.6 KiB
C++

//
// Observer.h
//
// Library: Foundation
// Package: Notifications
// Module: NotificationCenter
//
// Definition of the Observer class template.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_Observer_INCLUDED
#define Foundation_Observer_INCLUDED
#include "Poco/AbstractObserver.h"
#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
namespace Poco
{
template <class C, class N>
class Observer : public AbstractObserver
/// This template class implements an adapter that sits between
/// a NotificationCenter and an object receiving notifications
/// from it. It is quite similar in concept to the
/// RunnableAdapter, but provides some NotificationCenter
/// specific additional methods.
/// See the NotificationCenter class for information on how
/// to use this template class.
///
/// Instead of the Observer class template, you might want to
/// use the NObserver class template, which uses an AutoPtr to
/// pass the Notification to the callback function, thus freeing
/// you from memory management issues.
{
public:
typedef void (C::*Callback)(N *);
Observer(C & object, Callback method) : _pObject(&object), _method(method) { }
Observer(const Observer & observer) : AbstractObserver(observer), _pObject(observer._pObject), _method(observer._method) { }
~Observer() { }
Observer & operator=(const Observer & observer)
{
if (&observer != this)
{
_pObject = observer._pObject;
_method = observer._method;
}
return *this;
}
void notify(Notification * pNf) const
{
Poco::Mutex::ScopedLock lock(_mutex);
if (_pObject)
{
N * pCastNf = dynamic_cast<N *>(pNf);
if (pCastNf)
{
pCastNf->duplicate();
(_pObject->*_method)(pCastNf);
}
}
}
bool equals(const AbstractObserver & abstractObserver) const
{
const Observer * pObs = dynamic_cast<const Observer *>(&abstractObserver);
return pObs && pObs->_pObject == _pObject && pObs->_method == _method;
}
bool accepts(Notification * pNf) const { return dynamic_cast<N *>(pNf) != 0; }
AbstractObserver * clone() const { return new Observer(*this); }
void disable()
{
Poco::Mutex::ScopedLock lock(_mutex);
_pObject = 0;
}
private:
Observer();
C * _pObject;
Callback _method;
mutable Poco::Mutex _mutex;
};
} // namespace Poco
#endif // Foundation_Observer_INCLUDED