Copyright (c) 2005, 2015 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2005, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.core.commands.operations;

import java.util.ArrayList;
import java.util.List;


An undo context that can be used to represent any given object. Clients
can add matching contexts to this context.  This class may be instantiated
by clients.

Since:
3.1/**
 * <p>
 * An undo context that can be used to represent any given object. Clients
 * can add matching contexts to this context.  This class may be instantiated
 * by clients.
 * </p>
 *
 * @since 3.1
 */
public final class ObjectUndoContext extends UndoContext {

	private Object object;

	private String label;

	private List<IUndoContext> children = new ArrayList<>();

	
Construct an operation context that represents the given object.
Params:
object – 
           the object to be represented./**
	 * Construct an operation context that represents the given object.
	 *
	 * @param object
	 *            the object to be represented.
	 */
	public ObjectUndoContext(Object object) {
		this(object, null);
	}

	
Construct an operation context that represents the given object and has a
specialized label.
Params:
object – 
           the object to be represented.
label – 
           the label for the context/**
	 * Construct an operation context that represents the given object and has a
	 * specialized label.
	 *
	 * @param object
	 *            the object to be represented.
	 * @param label
	 *            the label for the context
	 */
	public ObjectUndoContext(Object object, String label) {
		super();
		this.object = object;
		this.label = label;
	}

	@Override
	public String getLabel() {
		if (label != null) {
			return label;
		}
		if (object != null) {
			return object.toString();
		}
		return super.getLabel();
	}

	
Return the object that is represented by this context.
Returns:
the object represented by this context./**
	 * Return the object that is represented by this context.
	 *
	 * @return the object represented by this context.
	 */
	public Object getObject() {
		return object;
	}

	
Add the specified context as a match of this context. Contexts added as
matches of this context will be interpreted as a match of this context
when the history is filtered for a particular context. Adding a match
allows components to create their own contexts for implementing
specialized behavior, yet have their operations appear in a more
global context.
Params:
context – 
           the context to be added as a match of this context/**
	 * Add the specified context as a match of this context. Contexts added as
	 * matches of this context will be interpreted as a match of this context
	 * when the history is filtered for a particular context. Adding a match
	 * allows components to create their own contexts for implementing
	 * specialized behavior, yet have their operations appear in a more
	 * global context.
	 *
	 * @param context
	 *            the context to be added as a match of this context
	 */
	public void addMatch(IUndoContext context) {
		children.add(context);
	}

	
Remove the specified context as a match of this context. The context will
no longer be interpreted as a match of this context when the history is
filtered for a particular context. This method has no effect if the
specified context was never previously added as a match.
Params:
context – 
           the context to be removed from the list of matches for this
           context/**
	 * Remove the specified context as a match of this context. The context will
	 * no longer be interpreted as a match of this context when the history is
	 * filtered for a particular context. This method has no effect if the
	 * specified context was never previously added as a match.
	 *
	 * @param context
	 *            the context to be removed from the list of matches for this
	 *            context
	 */
	public void removeMatch(IUndoContext context) {
		children.remove(context);
	}

	@Override
	public boolean matches(IUndoContext context) {
		// Check first for explicit matches that have been assigned.
		if (children.contains(context)) {
			return true;
		}
		// Contexts for equal objects are considered matching
		if (context instanceof ObjectUndoContext && getObject() != null) {
			return getObject().equals(((ObjectUndoContext)context).getObject());
		}
		// Use the normal matching implementation
		return super.matches(context);
	}

	
The string representation of this operation.  Used for debugging purposes only.
This string should not be shown to an end user.
Returns:
The string representation./**
	 * The string representation of this operation.  Used for debugging purposes only.
	 * This string should not be shown to an end user.
	 *
	 * @return The string representation.
	 */
	@Override
	public String toString() {
		return getLabel();
	}


}