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/*******************************************************************************
* Copyright (c) 2007, 2008 Matthew Hall 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
*
* Contributors:
* Matthew Hall - initial API and implementation (bug 208858)
******************************************************************************/
package org.eclipse.core.databinding.observable.list;
import java.util.List;
/**
* A visitor for processing differences in a ListDiff.
*
* @see ListDiff#accept(ListDiffVisitor)
* @since 1.1
*/
public abstract class ListDiffVisitor {
/**
* Notifies the visitor that <code>element</code> was added to the list at
* position <code>index</code>.
*
* @param index
* the index where the element was added
* @param element
* the element that was added
*/
public abstract void handleAdd(int index, Object element);
/**
* Notifies the visitor that <code>element</code> was removed from the
* list at position <code>index</code>.
*
* @param index
* the index where the element was removed
* @param element
* the element that was removed
*/
public abstract void handleRemove(int index, Object element);
/**
* Notifies the visitor that <code>element</code> was moved in the list
* from position <code>oldIndex</code> to position <code>newIndex</code>.
* <p>
* The default implementation of this method calls
* {@link #handleRemove(int, Object)} with the old position, then
* {@link #handleAdd(int, Object)} with the new position. Clients which are
* interested in recognizing "moves" in a list (i.e. calls to
* {@link IObservableList#move(int, int)}) should override this method.
*
* @param oldIndex
* the index that the element was moved from.
* @param newIndex
* the index that the element was moved to.
* @param element
* the element that was moved
* @see IObservableList#move(int, int)
*/
public void handleMove(int oldIndex, int newIndex, Object element) {
handleRemove(oldIndex, element);
handleAdd(newIndex, element);
}
/**
* Notifies the visitor that <code>oldElement</code>, located at position
* <code>index</code> in the list, was replaced by <code>newElement</code>.
* <p>
* The default implementation of this method calls
* {@link #handleRemove(int, Object)} with the old element, then
* {@link #handleAdd(int, Object)} with the new element. Clients which are
* interested in recognizing "replaces" in a list (i.e. calls to
* {@link List#set(int, Object)}) should override this method.
*
* @param index
* the index where the element was replaced.
* @param oldElement
* the element being replaced.
* @param newElement
* the element that replaced oldElement.
* @see List#set(int, Object)
*/
public void handleReplace(int index, Object oldElement, Object newElement) {
handleRemove(index, oldElement);
handleAdd(index, newElement);
}
}
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