PropertyDifferentiator.java

/**
 * (C) Copyright 2013 Jabylon (http://www.jabylon.org) and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.jabylon.resources.diff;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.eclipse.emf.common.notify.Notification;
import org.eclipse.emf.common.notify.impl.NotificationImpl;
import org.eclipse.emf.ecore.InternalEObject;
import org.eclipse.emf.ecore.impl.ENotificationImpl;

import org.jabylon.properties.PropertiesPackage;
import org.jabylon.properties.Property;
import org.jabylon.properties.PropertyFile;

public class PropertyDifferentiator {

    private PropertyFile original;

    public PropertyDifferentiator(PropertyFile original) {
        super();
        this.original = original;
    }

    public List<Notification> diff(PropertyFile modified) {
        Map<String, Property> orignalProperties = buildMap(original);
        List<Notification> noticiations = new ArrayList<Notification>();
        computeStructuralDiff(orignalProperties, modified, noticiations);
        return noticiations;
    }

    private void computeStructuralDiff(Map<String, Property> orignalProperties, PropertyFile modified, List<Notification> noticiations) {
        List<Property> additions = new ArrayList<Property>();
        List<Property> removals = new ArrayList<Property>();
        for (Property prop : modified.getProperties()) {
            Property originalProperty = orignalProperties.get(prop.getKey());
            if (originalProperty == null)
                additions.add(prop);
            else {
                orignalProperties.remove(prop.getKey());
                Notification change = computeDiff(originalProperty, prop);
                if(change!=null)
                    noticiations.add(change);
            }
        }

        removals.addAll(orignalProperties.values());
        if(!additions.isEmpty())
        {
            Notification notification = new ENotificationImpl((InternalEObject) modified,Notification.ADD_MANY, PropertiesPackage.Literals.PROPERTY_FILE__PROPERTIES,null, additions);
            noticiations.add(notification);
        }

        if(!removals.isEmpty())
        {
            Notification notification = new ENotificationImpl((InternalEObject) modified,Notification.ADD_MANY, PropertiesPackage.Literals.PROPERTY_FILE__PROPERTIES,removals, null);
            noticiations.add(notification);
        }

    }

    private Notification computeDiff(Property orignalPropertery, Property modifiedProperty) {

        if (orignalPropertery.getValue() == null && modifiedProperty.getValue() == null)
            return null; // if both are null, it's all good
        if (orignalPropertery.getValue() == null && modifiedProperty.getValue() != null) {
            return new CustomNotification(Notification.SET, null, modifiedProperty.getValue(), modifiedProperty);
        }
        if (modifiedProperty.getValue() == null && orignalPropertery.getValue() != null) {
            return new CustomNotification(Notification.UNSET, orignalPropertery.getValue(), null, modifiedProperty);
        }
        if(modifiedProperty.getValue().equals(orignalPropertery.getValue()))
            return null;
        return new CustomNotification(Notification.SET, orignalPropertery.getValue(), modifiedProperty.getValue(), modifiedProperty);
    }

    private Map<String, Property> buildMap(PropertyFile file) {
        Map<String, Property> properties = new HashMap<String, Property>(file.getProperties().size());
        for (Property property : file.getProperties()) {
            properties.put(property.getKey(), property);
        }
        return properties;
    }

}

class CustomNotification extends NotificationImpl {

    private Property notifier;

    public CustomNotification(int eventType, String oldValue, String newValue, Property notifier) {
        super(eventType, oldValue, newValue);
        this.notifier = notifier;
    }

    @Override
    public Object getFeature() {
        return PropertiesPackage.Literals.PROPERTY__VALUE;
    }

    @Override
    public Property getNotifier() {
        return notifier;
    }

}