/*******************************************************************************
* Copyright (c) 2005, 2006 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
*******************************************************************************/
package org.eclipse.core.commands.operations;
import java.util.ArrayList;
import java.util.List;
/**
* <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 children = new ArrayList();
/**
* 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.
*
* @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;
}
/*
* (non-Javadoc)
*
* @see org.eclipse.core.commands.operations.IUndoContext#getLabel()
*/
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.
*
* @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.
*
* @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.
*
* @param context
* the context to be removed from the list of matches for this
* context
*/
public void removeMatch(IUndoContext context) {
children.remove(context);
}
/*
* (non-Javadoc)
*
* @see org.eclipse.core.commands.operations.IUndoContext#matches(IUndoContext
* context)
*/
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.
*
* @return The string representation.
*/
public String toString() {
return getLabel();
}
}
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