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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef ULTIMA4_CORE_OBSERVABLE_H
#define ULTIMA4_CORE_OBSERVABLE_H
#include "ultima/ultima4/core/observer.h"
#include "ultima/shared/std/containers.h"
namespace Ultima {
namespace Ultima4 {
/**
* Classes can report updates to a list of decoupled Observers by
* extending this class.
*
* The O class parameter should be a pointer to the class of the
* observable itself, so it can be passed in a typesafe manner to the
* observers update method.
*
* The A class can be any additional information to pass to observers.
* Observables that don't need to pass an argument when they update
* observers should use the default "NoArg" class for the second
* template parameter and pass nullptr to notifyObservers.
*/
template <class O, class A = NoArg *>
class Observable {
public:
Observable() : _changed(false) {}
void addObserver(Observer<O, A> *o) {
typename Std::vector< Observer<O, A> *>::iterator i;
i = Common::find(_observers.begin(), _observers.end(), o);
if (i == _observers.end())
_observers.push_back(o);
}
int countObservers() const {
return _observers.size();
}
void deleteObserver(Observer<O, A> *o) {
typename Std::vector< Observer<O, A> *>::iterator i;
i = Common::find(_observers.begin(), _observers.end(), o);
if (i != _observers.end())
_observers.erase(i);
}
void deleteObservers() {
_observers.clear();
}
bool hasChanged() const {
return _changed;
}
void notifyObservers(A arg) {
if (!_changed)
return;
// vector iterators are invalidated if erase is called, so a copy
// is used to prevent problems if the observer removes itself (or
// otherwise changes the observer list)
typename Std::vector< Observer<O, A> *> tmp = _observers;
typename Std::vector< Observer<O, A> *>::iterator i;
clearChanged();
for (i = tmp.begin(); i != tmp.end(); i++) {
Observer<O, A> *observer = *i;
observer->update(static_cast<O>(this), arg);
}
}
protected:
void clearChanged() {
_changed = false;
}
void setChanged() {
_changed = true;
}
private:
bool _changed;
Std::vector< Observer<O, A> *> _observers;
};
} // End of namespace Ultima4
} // End of namespace Ultima
#endif
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