public interface IOperationHistory
IOperationHistory tracks a history of operations that can be undone or redone. Operations are added to the history once they have been initially executed. Clients may choose whether to have the operations history perform the initial execution or to simply add an already-executed operation to the history.
Once operations are added to the history, the methods
canRedo(IUndoContext)
and canUndo(IUndoContext)
are used to
determine whether there is an operation available for undo and redo in a
given undo context. The context-based protocol implies that there is only one
operation that can be undone or redone at a given time in a given context.
This is typical of a linear undo model, when only the most recently executed
operation is available for undo. When this protocol is used, a linear model
is enforced by the history.
It is up to clients to determine how to maintain a history that is invalid or stale. For example, when the most recent operation for a context cannot be performed, clients may wish to dispose the history for that context.
Additional protocol allows direct undo and redo of a specified operation, regardless of its position in the history. When a more flexible undo model is supported, these methods can be implemented to undo and redo directly specified operations. If an implementer of IOperationHistory does not allow direct undo and redo, these methods can return a status indicating that it is not allowed.
Listeners (IOperationHistoryListener
) can listen for notifications
about changes in the history (operations added or removed), and for
notification before and after any operation is executed, undone or redone.
Notification of operation execution only occurs when clients direct the
history to execute the operation. If the operation is added after it is
executed, there can be no notification of its execution.
IOperationApprover
defines an interface for approving an undo or redo
before it occurs. This is useful for injecting policy-decisions into the undo
model - whether direct undo and redo are supported, or warning the user about
certain kinds of operations. It can also be used when clients maintain state
related to an operation and need to determine whether an undo or redo will
cause any conflicts with their local state.
Modifier and Type | Field and Description |
---|---|
static int |
EXECUTE
An operation is to be opened or closed for execution.
|
static IUndoContext |
GLOBAL_UNDO_CONTEXT
An undo context that can be used to refer to the global undo history.
|
static IStatus |
NOTHING_TO_REDO_STATUS
An operation info status describing the condition that there is no
available operation for redo.
|
static IStatus |
NOTHING_TO_UNDO_STATUS
An operation info status describing the condition that there is no
available operation for undo.
|
static IStatus |
OPERATION_INVALID_STATUS
An operation error status describing the condition that the operation
available for execution, undo or redo is not in a valid state for the
action to be performed.
|
static int |
REDO
An operation is to be opened for redo.
|
static int |
UNDO
An operation is to be opened for undo.
|
Modifier and Type | Method and Description |
---|---|
void |
add(IUndoableOperation operation)
Add the specified operation to the history without executing it.
|
void |
addOperationApprover(IOperationApprover approver)
Add the specified approver to the list of operation approvers consulted
by the operation history before an undo or redo is attempted.
|
void |
addOperationHistoryListener(IOperationHistoryListener listener)
Add the specified listener to the list of operation history listeners
that are notified about changes in the history or operations that are
executed, undone, or redone.
|
boolean |
canRedo(IUndoContext context)
Return whether there is a valid redoable operation available in the given
context.
|
boolean |
canUndo(IUndoContext context)
Return whether there is a valid undoable operation available in the given
context
|
void |
closeOperation(boolean operationOK,
boolean addToHistory,
int mode)
Close the current operation.
|
void |
dispose(IUndoContext context,
boolean flushUndo,
boolean flushRedo,
boolean flushContext)
Dispose of the specified context in the history.
|
IStatus |
execute(IUndoableOperation operation,
IProgressMonitor monitor,
IAdaptable info)
Execute the specified operation and add it to the operations history if
successful.
|
int |
getLimit(IUndoContext context)
Return the limit on the undo and redo history for a particular context.
|
IUndoableOperation[] |
getRedoHistory(IUndoContext context)
Get the array of operations in the redo history for a the specified undo
context.
|
IUndoableOperation |
getRedoOperation(IUndoContext context)
Get the operation that will next be redone in the given undo context.
|
IUndoableOperation[] |
getUndoHistory(IUndoContext context)
Get the array of operations in the undo history for the specified undo
context.
|
IUndoableOperation |
getUndoOperation(IUndoContext context)
Get the operation that will next be undone in the given undo context.
|
void |
openOperation(ICompositeOperation operation,
int mode)
Open this composite operation and consider it an operation that contains
other related operations.
|
void |
operationChanged(IUndoableOperation operation)
The specified operation has changed in some way since it was added to the
operation history.
|
IStatus |
redo(IUndoContext context,
IProgressMonitor monitor,
IAdaptable info)
Redo the most recently undone operation in the given context.
|
IStatus |
redoOperation(IUndoableOperation operation,
IProgressMonitor monitor,
IAdaptable info)
Redo the specified operation.
|
void |
removeOperationApprover(IOperationApprover approver)
Remove the specified operation approver from the list of operation
approvers that are consulted before an operation is undone or redone.
|
void |
removeOperationHistoryListener(IOperationHistoryListener listener)
Remove the specified listener from the list of operation history
listeners.
|
void |
replaceOperation(IUndoableOperation operation,
IUndoableOperation[] replacements)
Replace the specified operation in the undo or redo history with the
provided list of replacements.
|
void |
setLimit(IUndoContext context,
int limit)
Set the limit on the undo and redo history for a particular context.
|
IStatus |
undo(IUndoContext context,
IProgressMonitor monitor,
IAdaptable info)
Undo the most recently executed operation in the given context.
|
IStatus |
undoOperation(IUndoableOperation operation,
IProgressMonitor monitor,
IAdaptable info)
Undo the specified operation.
|
static final int EXECUTE
static final int UNDO
static final int REDO
static final IUndoContext GLOBAL_UNDO_CONTEXT
static final IStatus NOTHING_TO_REDO_STATUS
static final IStatus NOTHING_TO_UNDO_STATUS
static final IStatus OPERATION_INVALID_STATUS
void add(IUndoableOperation operation)
Add the specified operation to the history without executing it. The
operation should have already been executed by the time it is added to
the history. Listeners will be notified that the operation was added to
the history (OPERATION_ADDED
).
operation
- the operation to be added to the historyvoid addOperationApprover(IOperationApprover approver)
Add the specified approver to the list of operation approvers consulted by the operation history before an undo or redo is attempted.
approver
- the IOperationApprover to be added as an approver.the instance
to remove. Must not be null
. If an attempt is
made to register an instance which is already registered with
this instance, this method has no effect.IOperationApprover
void addOperationHistoryListener(IOperationHistoryListener listener)
Add the specified listener to the list of operation history listeners that are notified about changes in the history or operations that are executed, undone, or redone.
listener
- the IOperationHistoryListener to be added as a listener. Must
not be null
. If an attempt is made to register
an instance which is already registered with this instance,
this method has no effect.IOperationHistoryListener
,
OperationHistoryEvent
void closeOperation(boolean operationOK, boolean addToHistory, int mode)
Close the current operation. If the operation has successfully completed,
send listeners a DONE
, UNDONE
, or
REDONE
notification, depending on the mode. Otherwise send
an OPERATION_NOT_OK
notification. Add the operation to the
history if specified and send an OPERATION_ADDED
notification.
Any operations that are executed and added after this operation is closed will no longer be considered part of this operation.
This method has no effect if the caller has not previously called
openOperation(org.eclipse.core.commands.operations.ICompositeOperation, int)
.
operationOK
- true
if the operation successfully completed.
Listeners should be notified with DONE
,
UNDONE
, or REDONE
.
false
if the operation did not successfully
complete. Listeners should be notified with
OPERATION_NOT_OK
.addToHistory
- true
if the operation should be added to the
history, false
if it should not. If the
operationOK
parameter is false
,
the operation will never be added to the history.mode
- the mode the operation was opened in. Can be one of
EXECUTE
, UNDO
, or
REDO
. This determines what notifications are
sent.boolean canRedo(IUndoContext context)
Return whether there is a valid redoable operation available in the given context.
context
- the context to be checkedtrue
if there is a redoable operation,
false
otherwise.boolean canUndo(IUndoContext context)
Return whether there is a valid undoable operation available in the given context
context
- the context to be checkedtrue
if there is an undoable operation,
false
otherwise.void dispose(IUndoContext context, boolean flushUndo, boolean flushRedo, boolean flushContext)
Dispose of the specified context in the history. All operations that have only the given context will be disposed. References to the context in operations that have more than one context will also be removed. A history notification for the removal of each operation being disposed will be sent.
context
- the context to be disposedflushUndo
- true
if the context should be flushed from the
undo history, false
if it should notflushRedo
- true
if the context should be flushed from the
redo history, false
if it should not.flushContext
- true
if the context is no longer in use and
references to it should be flushed.IStatus execute(IUndoableOperation operation, IProgressMonitor monitor, IAdaptable info) throws ExecutionException
Execute the specified operation and add it to the operations history if
successful. This method is used by clients who wish operation history
listeners to receive notifications before and after the execution of the
operation. Execution of the operation is subject to approval by any
registered IOperationApprover2
. If execution is approved,
listeners will be notified before (ABOUT_TO_EXECUTE
) and
after (DONE
or OPERATION_NOT_OK
).
If the operation successfully executes, an additional notification that
the operation has been added to the history (OPERATION_ADDED
)
will be sent.
operation
- the operation to be executed and then added to the historymonitor
- the progress monitor to be used (or null
)
during the operation.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.
The severity code in the returned status describes whether the operation
succeeded and whether it was added to the history. OK
severity indicates that the execute operation was successful and that the
operation has been added to the history. Listeners will receive
notifications about the operation's success (DONE
) and
about the operation being added to the history (OPERATION_ADDED
).
CANCEL
severity indicates that the user cancelled the
operation and that the operation was not added to the history.
ERROR
severity indicates that the operation did not
successfully execute and that it was not added to the history. Any other
severity code is not specifically interpreted by the history, and the
operation will not be added to the history. For all severities other than
OK
, listeners will receive the
OPERATION_NOT_OK
notification instead of the
DONE
notification if the execution was approved and
attempted.
ExecutionException
- if an exception occurred during execution.int getLimit(IUndoContext context)
Return the limit on the undo and redo history for a particular context.
context
- the context whose limit is requestedIUndoableOperation[] getRedoHistory(IUndoContext context)
Get the array of operations in the redo history for a the specified undo context. The operations are in the order that they were added to the history, with the most recently undone operation appearing last in the array. This history is used LIFO (last in, first out) when successive "Redo" commands are invoked.
context
- the context for the redoIUndoableOperation getRedoOperation(IUndoContext context)
Get the operation that will next be redone in the given undo context.
context
- the context for the redonull
if there is no
operation available. There is no guarantee that the returned
operation is valid for redo.IUndoableOperation[] getUndoHistory(IUndoContext context)
Get the array of operations in the undo history for the specified undo context. The operations are in the order that they were added to the history, with the most recently added operation appearing last in the array. This history is used LIFO (last in, first out) when successive "Undo" commands are invoked.
context
- the context for the undovoid openOperation(ICompositeOperation operation, int mode)
Open this composite operation and consider it an operation that contains
other related operations. Consider all operations that are subsequently
executed or added to be part of this operation. When an operation is
opened, listeners will immediately receive a notification for the opened
operation. The specific notification depends on the mode in which the
operation is opened (ABOUT_TO_EXECUTE
,
ABOUT_TO_UNDO
, ABOUT_TO_REDO
).
Notifications for any other execute or add while this operation is open
will not occur. Instead, those operations will be added to the current
operation.
Note: This method is intended to be used by legacy undo frameworks that do not expect related undo operations to appear in the same undo history as the triggering undo operation. When an operation is open, any subsequent requests to execute, add, undo, or redo another operation will result in that operation being added to the open operation. Once the operation is closed, the composite will be considered an atomic operation. Clients should not modify the composite directly (by adding and removing children) while it is open.
When a composite is open, operations that are added to the history will be considered part of the open operation instead. Operations that are executed while a composite is open will first be executed and then added to the composite.
Open operations cannot be nested. If this method is called when a different operation is open, it is presumed to be an application coding error and this method will throw an IllegalStateException.
operation
- the composite operation to be considered as the parent for all
subsequent operations.mode
- the mode the operation is executing in. Can be one of
EXECUTE
, UNDO
, or
REDO
. This determines what notifications are
sent.void operationChanged(IUndoableOperation operation)
The specified operation has changed in some way since it was added to the operation history. Notify listeners with an OPERATION_CHANGED event.
operation
- the operation that has changed.IUndoableOperation getUndoOperation(IUndoContext context)
Get the operation that will next be undone in the given undo context.
context
- the context for the undonull
if there is no
operation available. There is no guarantee that the available
operation is valid for the undo.IStatus redo(IUndoContext context, IProgressMonitor monitor, IAdaptable info) throws ExecutionException
Redo the most recently undone operation in the given context. The redo of
the operation is subject to approval by any registered
IOperationApprover
before it is attempted.
context
- the context to be redonemonitor
- the progress monitor to be used for the redo, or
null
if no progress monitor is provided.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.
The severity code in the returned status describes whether the operation
succeeded and whether it remains in the history. OK
severity indicates that the redo operation was successful and (since
release 3.2), that the operation will be placed in the undo history.
(Prior to 3.2, a successfully redone operation would not be placed on the
undo history if it could not be undone. Since 3.2, this is relaxed, and
all successfully redone operations are placed in the undo history.)
Listeners will receive the REDONE
notification.
Other severity codes (CANCEL
, ERROR
,
INFO
, etc.) are not specifically interpreted by the
history. The operation will remain in the history and the returned status
is simply passed back to the caller. For all severities other than
OK
, listeners will receive the
OPERATION_NOT_OK
notification instead of the
REDONE
notification if the redo was approved and
attempted.
ExecutionException
- if an exception occurred during redo.IStatus redoOperation(IUndoableOperation operation, IProgressMonitor monitor, IAdaptable info) throws ExecutionException
Redo the specified operation. The redo of the operation is subject to
approval by any registered IOperationApprover
before it is
attempted.
operation
- the operation to be redonemonitor
- the progress monitor to be used for the redo, or code>null
if no progress monitor is providedinfo
- 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.
The severity code in the returned status describes whether the operation
succeeded and whether it remains in the history. OK
severity indicates that the redo operation was successful, and (since
release 3.2), that the operation will be placed in the undo history.
(Prior to 3.2, a successfully redone operation would not be placed on the
undo history if it could not be undone. Since 3.2, this is relaxed, and
all successfully redone operations are placed in the undo history.)
Listeners will receive the REDONE
notification.
Other severity codes (CANCEL
, ERROR
,
INFO
, etc.) are not specifically interpreted by the
history. The operation will remain in the history and the returned status
is simply passed back to the caller. For all severities other than OK
,
listeners will receive the OPERATION_NOT_OK
notification
instead of the REDONE
notification if the redo was
approved and attempted.
ExecutionException
- if an exception occurred during redo.void removeOperationApprover(IOperationApprover approver)
Remove the specified operation approver from the list of operation approvers that are consulted before an operation is undone or redone.
approver
- the IOperationApprover to be removed. Must not be
null
. If an attempt is made to remove an
instance which is not already registered with this instance,
this method has no effect.void removeOperationHistoryListener(IOperationHistoryListener listener)
Remove the specified listener from the list of operation history listeners.
listener
- The IOperationHistoryListener to be removed. Must not be
null
. If an attempt is made to remove an
instance which is not already registered with this instance,
this method has no effect.void replaceOperation(IUndoableOperation operation, IUndoableOperation[] replacements)
Replace the specified operation in the undo or redo history with the provided list of replacements. This protocol is typically used when a composite is broken up into its atomic parts. The replacements will be inserted so that the first replacement will be the first of the replacements to be undone or redone. Listeners will be notified about the removal of the replaced element and the addition of each replacement.
operation
- The IUndoableOperation to be replacedreplacements
- the array of IUndoableOperation to replace the first operationvoid setLimit(IUndoContext context, int limit)
Set the limit on the undo and redo history for a particular context.
context
- the context whose limit is being set.limit
- the maximum number of operations that should be kept in the
undo or redo history for the specified context. Must not be
negative.IStatus undo(IUndoContext context, IProgressMonitor monitor, IAdaptable info) throws ExecutionException
Undo the most recently executed operation in the given context. The undo
of the operation is subject to approval by any registered
IOperationApprover
before it is attempted.
context
- the context to be undonemonitor
- the progress monitor to be used for the undo, or
null
if no progress monitor is provided.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.
The severity code in the returned status describes whether the operation
succeeded and whether it remains in the history. OK
severity indicates that the undo operation was successful, and (since
release 3.2), that the operation will be placed on the redo history.
(Prior to 3.2, a successfully undone operation would not be placed on the
redo history if it could not be redone. Since 3.2, this is relaxed, and
all successfully undone operations are placed in the redo history.)
Listeners will receive the UNDONE
notification.
Other severity codes (CANCEL
, ERROR
,
INFO
, etc.) are not specifically interpreted by the
history. The operation will remain in the history and the returned status
is simply passed back to the caller. For all severities other than
OK
, listeners will receive the
OPERATION_NOT_OK
notification instead of the
UNDONE
notification if the undo was approved and
attempted.
ExecutionException
- if an exception occurred during undo.IStatus undoOperation(IUndoableOperation operation, IProgressMonitor monitor, IAdaptable info) throws ExecutionException
Undo the specified operation. The undo of the operation is subject to
approval by any registered IOperationApprover
before it is
attempted.
operation
- the operation to be undonemonitor
- the progress monitor to be used for the undo, or
null
if no progress monitor is providedinfo
- 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.
The severity code in the returned status describes whether the operation
succeeded and whether it remains in the history. OK
severity indicates that the undo operation was successful, and (since
release 3.2), that the operation will be placed on the redo history.
(Prior to 3.2, a successfully undone operation would not be placed on the
redo history if it could not be redone. Since 3.2, this is relaxed, and
all successfully undone operations are placed in the redo history.)
Listeners will receive the UNDONE
notification.
Other severity codes (CANCEL
, ERROR
,
INFO
, etc.) are not specifically interpreted by the
history. The operation will remain in the history and the returned status
is simply passed back to the caller. For all severities other than
OK
, listeners will receive the
OPERATION_NOT_OK
notification instead of the
UNDONE
notification if the undo was approved and
attempted.
ExecutionException
- if an exception occurred during undo.
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