observable.h

/* 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 {

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