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/*
Copyright (C) 2000, 2001, 2002 RiskMap srl
This file is part of QuantLib, a free-software/open-source library
for financial quantitative analysts and developers - http://quantlib.org/
QuantLib is free software: you can redistribute it and/or modify it under the
terms of the QuantLib license. You should have received a copy of the
license along with this program; if not, please email ferdinando@ametrano.net
The license is also available online at http://quantlib.org/html/license.html
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 license for more details.
*/
/*! \file observable.hpp
\brief observer/observable pattern
\fullpath
ql/Patterns/%observable.hpp
*/
// $Id: observable.hpp,v 1.9 2002/03/06 14:59:37 nando Exp $
#ifndef quantlib_observable_h
#define quantlib_observable_h
#include <ql/handle.hpp>
#include <list>
#include <algorithm>
namespace QuantLib {
//! Implementations of design patterns
/*! See sect. \ref patterns */
namespace Patterns {
//! Object that notifies its changes to a set of observables
class Observable {
friend class Observer;
public:
virtual ~Observable() {}
/*! This method should be called at the end of non-const methods
or when the programmer desires to notify any changes.
*/
void notifyObservers();
private:
void registerObserver(Observer*);
void unregisterObserver(Observer*);
std::list<Observer*> observers_;
typedef std::list<Observer*>::iterator iterator;
};
//! Object that gets notified when a given observable changes
class Observer {
public:
// constructors, assignment, destructor
Observer() {}
Observer(const Observer&);
Observer& operator=(const Observer&);
virtual ~Observer();
// observer interface
void registerWith(const Handle<Observable>&);
void unregisterWith(const Handle<Observable>&);
/*! This method must be implemented in derived classes. An
instance of %Observer does not call this method directly:
instead, it will be called by the observables the instance
registered with when they need to notify any changes.
*/
virtual void update() = 0;
private:
std::list<Handle<Observable> > observables_;
typedef std::list<Handle<Observable> >::iterator iterator;
};
// inline definitions
inline void Observable::registerObserver(Observer* o) {
observers_.push_front(o);
}
inline void Observable::unregisterObserver(Observer* o) {
iterator i = std::find(observers_.begin(),observers_.end(),o);
if (i != observers_.end())
observers_.erase(i);
}
inline void Observable::notifyObservers() {
for (iterator i=observers_.begin(); i!=observers_.end(); ++i)
(*i)->update();
}
inline Observer::Observer(const Observer& o)
: observables_(o.observables_) {
for (iterator i=observables_.begin(); i!=observables_.end(); ++i)
(*i)->registerObserver(this);
}
inline Observer& Observer::operator=(const Observer& o) {
iterator i;
for (i=observables_.begin(); i!=observables_.end(); ++i)
(*i)->unregisterObserver(this);
observables_ = o.observables_;
for (i=observables_.begin(); i!=observables_.end(); ++i)
(*i)->registerObserver(this);
return *this;
}
inline Observer::~Observer() {
for (iterator i=observables_.begin(); i!=observables_.end(); ++i)
(*i)->unregisterObserver(this);
}
inline void Observer::registerWith(const Handle<Observable>& h) {
if (!h.isNull()) {
observables_.push_front(h);
h->registerObserver(this);
}
}
inline void Observer::unregisterWith(const Handle<Observable>& h) {
if (!h.isNull()) {
for (iterator i=observables_.begin();
i!=observables_.end();
++i) {
if (h.shareSameObject(*i)) {
(*i)->unregisterObserver(this);
observables_.erase(i);
return;
}
}
}
}
}
}
#endif
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