| /******************************************************************************* |
| * Copyright (c) 2006, 2008 IBM Corporation 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: |
| * IBM Corporation - initial API and implementation |
| * Matthew Hall - bug 208858 |
| *******************************************************************************/ |
| |
| package org.eclipse.core.databinding.observable.list; |
| |
| import org.eclipse.core.internal.databinding.Util; |
| |
| /** |
| * Object describing a diff between two lists. |
| * |
| * @since 1.0 |
| */ |
| public abstract class ListDiff { |
| |
| /** |
| * Returns a ListDiffEntry array representing the differences in the list, |
| * in the order they are to be processed. |
| * |
| * @return a ListDiffEntry array representing the differences in the list, |
| * in the order they are to be processed. |
| */ |
| public abstract ListDiffEntry[] getDifferences(); |
| |
| /** |
| * Traverses the {@link #getDifferences()} array, calling the appropriate |
| * method in <code>visitor</code> for each difference. |
| * <ol> |
| * <li>{@link ListDiffVisitor#handleReplace(int, Object, Object)} is called |
| * whenever a remove entry is immediately followed by an add entry which |
| * shares the same list index. |
| * <li>{@link ListDiffVisitor#handleMove(int, int, Object)} is called |
| * whenever a remove entry is immediately followed by an add entry with an |
| * equivalent element. |
| * <li>{@link ListDiffVisitor#handleRemove(int, Object)} is called whenever |
| * a remove entry does not match conditions 1 or 2. |
| * <li>{@link ListDiffVisitor#handleAdd(int, Object)} is called whenever an |
| * add entry does not match conditions in 1 or 2. |
| * </ol> |
| * |
| * @param visitor |
| * the visitor to receive callbacks. |
| * @see ListDiffVisitor |
| * @since 1.1 |
| */ |
| public void accept(ListDiffVisitor visitor) { |
| ListDiffEntry[] differences = getDifferences(); |
| for (int i = 0; i < differences.length; i++) { |
| ListDiffEntry entry = differences[i]; |
| int position = entry.getPosition(); |
| Object element = entry.getElement(); |
| boolean addition = entry.isAddition(); |
| |
| if (!addition && i + 1 < differences.length) { |
| ListDiffEntry entry2 = differences[i + 1]; |
| if (entry2.isAddition()) { |
| int position2 = entry2.getPosition(); |
| Object element2 = entry2.getElement(); |
| if (position == position2) { |
| visitor.handleReplace(position, element, element2); |
| i++; |
| continue; |
| } |
| if (Util.equals(element, element2)) { |
| visitor.handleMove(position, position2, element); |
| i++; |
| continue; |
| } |
| } |
| } |
| if (addition) |
| visitor.handleAdd(position, element); |
| else |
| visitor.handleRemove(position, element); |
| } |
| } |
| |
| /** |
| * @see java.lang.Object#toString() |
| */ |
| public String toString() { |
| ListDiffEntry[] differences = getDifferences(); |
| StringBuffer buffer = new StringBuffer(); |
| buffer.append(getClass().getName()); |
| |
| if (differences == null || differences.length == 0) { |
| buffer |
| .append("{}"); //$NON-NLS-1$ |
| } else { |
| buffer |
| .append("{"); //$NON-NLS-1$ |
| |
| for (int i = 0; i < differences.length; i++) { |
| if (i > 0) |
| buffer.append(", "); //$NON-NLS-1$ |
| |
| buffer |
| .append("difference[") //$NON-NLS-1$ |
| .append(i) |
| .append("] [") //$NON-NLS-1$ |
| .append(differences[i] != null ? differences[i].toString() : "null") //$NON-NLS-1$ |
| .append("]"); //$NON-NLS-1$ |
| } |
| buffer.append("}"); //$NON-NLS-1$ |
| } |
| |
| return buffer.toString(); |
| } |
| } |