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IUndoableOperation defines an operation that can be executed, undone, and redone. Operations typically have fully defined parameters. That is, they are usually created after the user has been queried for any input needed to define the operation.
Operations determine their ability to execute, undo, or redo according to the current state of the application. They do not make decisions about their validity based on where they occur in the operation history. That is left to the particular operation history.
Method Summary | |
---|---|
void |
addContext(IUndoContext context)
Add the specified context to the operation. |
boolean |
canExecute()
Returns whether the operation can be executed in its current state. |
boolean |
canRedo()
Returns whether the operation can be redone in its current state. |
boolean |
canUndo()
Returns whether the operation can be undone in its current state. |
void |
dispose()
Dispose of the operation. |
IStatus |
execute(IProgressMonitor monitor,
IAdaptable info)
Execute the operation. |
IUndoContext[] |
getContexts()
Returns the array of contexts that have been assigned to the operation. |
String |
getLabel()
Return the label that should be used to show the name of the operation to the user. |
boolean |
hasContext(IUndoContext context)
Returns whether the operation has a matching context for the specified context. |
IStatus |
redo(IProgressMonitor monitor,
IAdaptable info)
Redo the operation. |
void |
removeContext(IUndoContext context)
Remove the specified context from the operation. |
IStatus |
undo(IProgressMonitor monitor,
IAdaptable info)
Undo the operation. |
Method Detail |
public void addContext(IUndoContext context)
Add the specified context to the operation. If a context equal to the
specified context is already present, do not add it again. Note that
determining whether a context is already present is based on equality,
not whether the context matches (IUndoContext.matches(IUndoContext)
)
another context.
context
- the context to be addedpublic boolean canExecute()
Returns whether the operation can be executed in its current state.
Note: The computation for this method must be fast, as it is called frequently. If necessary, this method can be optimistic in its computation (returning true) and later perform more time-consuming computations during the actual execution of the operation, returning the appropriate status if the operation cannot actually execute at that time.
true
if the operation can be executed;
false
otherwise.public boolean canRedo()
Returns whether the operation can be redone in its current state.
Note: The computation for this method must be fast, as it is called frequently. If necessary, this method can be optimistic in its computation (returning true) and later perform more time-consuming computations during the actual redo of the operation, returning the appropriate status if the operation cannot actually be redone at that time.
true
if the operation can be redone;
false
otherwise.public boolean canUndo()
Returns whether the operation can be undone in its current state.
Note: The computation for this method must be fast, as it is called frequently. If necessary, this method can be optimistic in its computation (returning true) and later perform more time-consuming computations during the actual undo of the operation, returning the appropriate status if the operation cannot actually be undone at that time.
true
if the operation can be undone;
false
otherwise.public void dispose()
public IStatus execute(IProgressMonitor monitor, IAdaptable info) throws ExecutionException
monitor
- the progress monitor (or null
) to use for
reporting progress to the user.info
- the IAdaptable (or null
) provided by the
caller in order to supply UI information for prompting the
user if necessary. When this parameter is not
null
, it should minimally contain an adapter
for the org.eclipse.swt.widgets.Shell.class.
OK
if the operation was successful, and
ERROR
if it was not. Any other status is assumed
to represent an incompletion of the execution.
ExecutionException
- if an exception occurred during execution.public IUndoContext[] getContexts()
Returns the array of contexts that have been assigned to the operation.
This method may be called by the operation history from inside a synchronized block. To avoid deadlock conditions, implementers of this method must avoid dispatching and waiting on threads that modify the operation history during this method.
public String getLabel()
public boolean hasContext(IUndoContext context)
Returns whether the operation has a matching context for the specified context.
This method may be called by the operation history from inside a synchronized block. To avoid deadlock conditions, implementers of this method must avoid dispatching and waiting on threads that modify the operation history during this method.
context
- the context in question
true
if the context is present, false
if it is not.IUndoContext.matches(IUndoContext)
public IStatus redo(IProgressMonitor monitor, IAdaptable info) throws ExecutionException
monitor
- the progress monitor (or null
) to use for
reporting progress to the user.info
- the IAdaptable (or null
) provided by the
caller in order to supply UI information for prompting the
user if necessary. When this parameter is not
null
, it should minimally contain an adapter
for the org.eclipse.swt.widgets.Shell.class.
OK
if the redo was successful, and
ERROR
if it was not. Any other status is assumed
to represent an incompletion of the redo.
ExecutionException
- if an exception occurred during redo.public void removeContext(IUndoContext context)
IUndoContext.matches(IUndoContext)
) another context.
context
- the context to be removedpublic IStatus undo(IProgressMonitor monitor, IAdaptable info) throws ExecutionException
monitor
- the progress monitor (or null
) to use for
reporting progress to the user.info
- the IAdaptable (or null
) provided by the
caller in order to supply UI information for prompting the
user if necessary. When this parameter is not
null
, it should minimally contain an adapter
for the org.eclipse.swt.widgets.Shell.class.
OK
if the redo was successful, and
ERROR
if it was not. Any other status is assumed
to represent an incompletion of the undo.
ExecutionException
- if an exception occurred during undo.
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Guidelines for using Eclipse APIs.
Copyright (c) IBM Corp. and others 2000, 2005. All rights reserved.