IChangeEventHandler.java example

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/**
 * Copyright 2004-2016 Riccardo Solmi. All rights reserved.
 * This file is part of the Whole Platform.
 *
 * The Whole Platform is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * The Whole Platform 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the Whole Platform. If not, see <http://www.gnu.org/licenses/>.
 */
package org.whole.lang.events;

import java.io.Serializable;
import java.util.Date;

import org.whole.lang.model.EnumValue;
import org.whole.lang.model.ICompoundModel;
import org.whole.lang.model.IEntity;
import org.whole.lang.reflect.FeatureDescriptor;

/**
 * Data driven event notification mechanism
 * 
 * invariants:
 * 		oldValue != newValue
 * 		oldValue xor newValue can be null
 * 
 * @author Riccardo Solmi
 */
public interface IChangeEventHandler extends Serializable {
    public IChangeEventHandler cloneChangeEventHandler(IChangeEventHandler parentEventHandler);
    public IChangeEventHandler addChangeEventHandler(IChangeEventHandler eventHandler);
    public IChangeEventHandler removeChangeEventHandler(IChangeEventHandler eventHandler);

    public boolean hasSharingEventHandler();
    public SharingChangeEventHandler getSharingEventHandler(IEntity entity);

    public void notifyAdded(IEntity source, FeatureDescriptor fd, int index, IEntity newValue);
    public void notifyRemoved(IEntity source, FeatureDescriptor fd, int index, IEntity oldValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, int index, IEntity oldValue, IEntity newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, IEntity oldValue, IEntity newValue);

    public void notifyChanged(IEntity source, FeatureDescriptor fd, boolean oldValue, boolean newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, byte oldValue, byte newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, char oldValue, char newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, double oldValue, double newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, float oldValue, float newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, int oldValue, int newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, long oldValue, long newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, short oldValue, short newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, String oldValue, String newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, Date oldValue, Date newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, EnumValue oldValue, EnumValue newValue);
    public void notifyChanged(IEntity source, FeatureDescriptor fd, Object oldValue, Object newValue);

	default boolean needsHistoryManager() {
		return false;
	};
	default boolean handleHistoryEvents() {
		return true;
	};

//	public boolean isEventHandlerEnabled();
//	public boolean setEventHandlerEnabled(boolean value);

	//TODO ? or static helper
	default IChangeEventHandler getActualEventHandler(IChangeEventHandler eventHandler, IEntity source) {
		if (isActualEventHandler(eventHandler, source))
			return eventHandler;
		else
			return IdentityChangeEventHandler.instance;
	}
	default boolean isActualEventHandler(IChangeEventHandler eventHandler, IEntity source) {
		ICompoundModel compoundModel = source.wGetModel().getCompoundModel();
		return (compoundModel.isHistoryEnabled() || !eventHandler.needsHistoryManager()) &&
				(!compoundModel.isHistoryEvent() || eventHandler.handleHistoryEvents());
	}
}