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org.eclipse.emf.workspace
Class AbstractResourceUndoContextPolicy

java.lang.Object
  extended by 
org.eclipse.emf.workspace.AbstractResourceUndoContextPolicy
All Implemented Interfaces:
IResourceUndoContextPolicy

public abstract class AbstractResourceUndoContextPolicy
extends Object
implements IResourceUndoContextPolicy

The default implementation of the resource undo-context policy, suitable for clients to extend/override as required. The default policy is to consider any resource as affected by an operation if either

  1. A non-touch Notification is received from a contained object or from the resource, itself, or
  2. A notification matching (1) is received from a uni-directional EReference (i.e., one having no opposite) has an old value or a new value in the resource

In the first case, above, a subclass can choose to include only changes to a resource's contents-list and URI as being significant (other resource properties not affecting the serialization of the resource).

The second case, above, is intended for applications that use ResourceUndoContexts to manage the Undo menus of their editors. It is a pessimistic assumption that the referenced resource may either have derived attributes whose values influenced precursor or successor operations, or that such operations are influenced by the references incoming to the resource. Thus, the concern is not so much with the dirty state of the resource as it is with the integrity of the undo history for the associated editor and the dependencies between successive operations. Subclasses can disable this case by overriding the pessimisticCrossReferences() method.

Since:
1.3
See Also:
pessimisticCrossReferences(), considerAllResourceChanges()

Field Summary
 
Fields inherited from interface org.eclipse.emf.workspace. IResourceUndoContextPolicy
DEFAULT
 
Constructor Summary
protected AbstractResourceUndoContextPolicy ()
          Initializes me.
 
Method Summary
protected  boolean considerAllResourceChanges ()
          May be overridden by subclasses to consider changes to any feature of a resource, not just its contents-list or URI, as affecting it.
protected  void crossResourceReference ( Set< Resource> resources, EObject owner, Notification notification)
          Handles notifications that can potentially represent cross-resource references.
  Set< Resource> getContextResources ( IUndoableOperation operation, List<? extends Notification> notifications)
          Determines the resources in the undo context of the specified operation, during which execution the changes indicated by the given notifications occurred.
protected  boolean isAbstractChange ( Notification notification)
          Queries whether the specified notification signals an abstract change to a resource, which would potentially put that resource into the operation context.
protected  void objectChange ( Set< Resource> resources, EObject object, Notification notification)
          Adds to the collection of resources any that are affected by the specified notification from an object.
protected  boolean pessimisticCrossReferences ()
          May be overridden by subclasses to disable pessimistic handling of cross-resource references.
protected  void resourceChange ( Set< Resource> resources, Resource resource, Notification notification)
          Adds to the collection of resources any that are affected by the specified notification from a resource.
protected  void resourceSetChange ( Set< Resource> resources, ResourceSet resourceSet, Notification notification)
          Adds to the collection of resources any that are affected by the specified notification from a resourceSet.
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

AbstractResourceUndoContextPolicy

protected AbstractResourceUndoContextPolicy()
Initializes me.

Method Detail

getContextResources

public 
Set<
Resource> getContextResources(
IUndoableOperation operation,
                                         
List<? extends 
Notification> notifications)
Description copied from interface: IResourceUndoContextPolicy
Determines the resources in the undo context of the specified operation, during which execution the changes indicated by the given notifications occurred. This operation may be called several times for the same operation, but always with different notifications.

Specified by:
getContextResources in interface IResourceUndoContextPolicy
Parameters:
operation - the operation. It may or may not have finished executing. Must not be null
notifications - a list of notifications of changes caused by the operation during its execution, in the order in which they occurred. This may be an empty list, but never null
Returns:
the resources that are the undo context of this operation, or an empty list if none. Never ruterns null

isAbstractChange

protected boolean isAbstractChange(
Notification notification)
Queries whether the specified notification signals an abstract change to a resource, which would potentially put that resource into the operation context. Subclasses may override or extend as needed.

Parameters:
notification - a notification of some concrete change in the resource set
Returns:
whether this change is an abstract change to some resource, for the purpose of tracking undo context

pessimisticCrossReferences

protected boolean pessimisticCrossReferences()
May be overridden by subclasses to disable pessimistic handling of cross-resource references. The default implementation returns true always.

Returns:
whether to consider changes to directed cross-resource references as affecting the referenced resource

considerAllResourceChanges

protected boolean considerAllResourceChanges()
May be overridden by subclasses to consider changes to any feature of a resource, not just its contents-list or URI, as affecting it.

Returns:
true if all changes to a resource are considered as affecting it for the purposes of undo context; false if only the contents-list and URI are

resourceChange

protected void resourceChange(
Set<
Resource> resources,
                              
Resource resource,
                              
Notification notification)
Adds to the collection of resources any that are affected by the specified notification from a resource.

Parameters:
resources - collects the affected resources
resource - a resource that sent a notification
notification - the notification sent by the resource

objectChange

protected void objectChange(
Set<
Resource> resources,
                            
EObject object,
                            
Notification notification)
Adds to the collection of resources any that are affected by the specified notification from an object.

Parameters:
resources - collects the affected resources
object - a object that sent a notification
notification - the notification sent by the object

resourceSetChange

protected void resourceSetChange(
Set<
Resource> resources,
                                 
ResourceSet resourceSet,
                                 
Notification notification)
Adds to the collection of resources any that are affected by the specified notification from a resourceSet.

Parameters:
resources - collects the affected resources
resourceSet - a resource set that sent a notification
notification - the notification sent by the resource set

crossResourceReference

protected void crossResourceReference(
Set<
Resource> resources,
                                      
EObject owner,
                                      
Notification notification)
Handles notifications that can potentially represent cross-resource references. Helper to the objectChange(Set, EObject, Notification) method.

Parameters:
resources - collects the affected resources
owner - the owner of the reference that changed
notification - a potential cross-resource reference change notification

Copyright 2002, 2007 IBM Corporation and others.
All Rights Reserved.


 
 
  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire