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/*****************************************************************************
* Copyright (c) 2013 Cedric Dumoulin.
*
*
* 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
*
* Contributors:
* Cedric Dumoulin Cedric.dumoulin@lifl.fr - Initial API and implementation
*
*****************************************************************************/
package org.eclipse.papyrus.layers.stackmodel.util;
import java.util.ArrayList;
import java.util.Collection;
import com.google.common.collect.Collections2;
/**
* Set of utility methods for Collections.
*
* @see Collections2
*
* @author cedric dumoulin
*
*/
public class Collections3 {
/**
* Reset the toChange list to the content of the newContent list.
* Minimize the change calls on the toChange list.
* This method ensure that there is at most 2 writing calls to the list to modify: one
* removeAll(toBeRemoved) and one addAll(toBeAdded).
*
* @param toChange
* @param newContent
*/
public static <E> void resetListTo(Collection<E> toChange, Collection<E> newContent) {
// Compute removed and added
Collection<E> elementsToRemove = new ArrayList<E>();
Collection<E> elementsToAdd = new ArrayList<E>();
// Compute added and removed elements. Walk both list 2 times.
// This could certainly be improved.
// TODO improve the algorithm
// Compute added elements
for (E o : newContent) {
if (!toChange.contains(o)) {
elementsToAdd.add(o);
continue;
}
}
// Compute removed elements
for (E o : toChange) {
if (!newContent.contains(o)) {
elementsToRemove.add(o);
continue;
}
}
// Change the list
if (!elementsToRemove.isEmpty()) {
toChange.removeAll(elementsToRemove);
}
if (!elementsToAdd.isEmpty()) {
toChange.addAll(elementsToAdd);
}
}
}
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