/*******************************************************************************
 * Copyright (c) 2007 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)
 ******************************************************************************/

module org.eclipse.core.databinding.observable.list.ListDiffVisitor;

import java.lang.all;

import java.util.List;

/**
 * A visitor for processing differences in a ListDiff.
 * 
 * @see ListDiff#acceptcast(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);
    }
}