Eclipse Plug-in Developer Guide (Galileo) - DefaultOperationHistory (Eclipse Platform API Specification)

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org.eclipse.core.commands.operations
Class DefaultOperationHistory


java.lang.Object
  
org.eclipse.core.commands.operations.DefaultOperationHistory

All Implemented Interfaces:: IOperationHistory

public final class DefaultOperationHistory
extends Object
implements IOperationHistory
extends Object
implements IOperationHistory

A base implementation of IOperationHistory that implements a linear undo and redo model . The most recently added operation is available for undo, and the most recently undone operation is available for redo.

If the operation eligible for undo is not in a state where it can be undone, then no undo is available. No other operations are considered. Likewise, if the operation available for redo cannot be redone, then no redo is available.

Implementations for the direct undo and redo of a specified operation are available. If a strict linear undo is to be enforced, than an IOperationApprover should be installed that prevents undo and redo of any operation that is not the most recently undone or redone operation in all of its undo contexts.

The data structures used by the DefaultOperationHistory are synchronized, and entry points that modify the undo and redo history concurrently are also synchronized. This means that the DefaultOperationHistory is relatively "thread-friendly" in its implementation. Outbound notifications or operation approval requests will occur on the thread that initiated the request. Clients may use DefaultOperationHistory API from any thread; however, listeners or operation approvers that receive notifications from the DefaultOperationHistory must be prepared to receive these notifications from a background thread. Any UI access occurring inside these notifications must be properly synchronized using the techniques specified by the client's widget library.

This implementation is not intended to be subclassed.

Since:: 3.1
See Also:: IOperationHistory, IOperationApprover

Field Summary

static boolean DEBUG_OPERATION_HISTORY_APPROVAL
          This flag can be set to true if the history should print information to System.out whenever an operation is not approved.

static boolean DEBUG_OPERATION_HISTORY_DISPOSE
          This flag can be set to true if the history should print information to System.out whenever an undo context is disposed.

static boolean DEBUG_OPERATION_HISTORY_NOTIFICATION
          This flag can be set to true if the history should print information to System.out whenever notifications about changes to the history occur.

static boolean DEBUG_OPERATION_HISTORY_OPENOPERATION
          This flag can be set to true if the history should print information to System.out during the open/close sequence.

static boolean DEBUG_OPERATION_HISTORY_UNEXPECTED
          This flag can be set to true if the history should print information to System.out whenever an unexpected condition arises.

Fields inherited from interface org.eclipse.core.commands.operations. IOperationHistory

EXECUTE, GLOBAL_UNDO_CONTEXT, NOTHING_TO_REDO_STATUS, NOTHING_TO_UNDO_STATUS, OPERATION_INVALID_STATUS, REDO, UNDO

Constructor Summary

DefaultOperationHistory ()
          Create an instance of DefaultOperationHistory.

Method Summary

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 allowed to proceed.

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.

Methods inherited from class java.lang. Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEBUG_OPERATION_HISTORY_NOTIFICATION

public static boolean DEBUG_OPERATION_HISTORY_NOTIFICATION

This flag can be set to true if the history should print information to System.out whenever notifications about changes to the history occur. This flag should be used for debug purposes only.

DEBUG_OPERATION_HISTORY_UNEXPECTED

public static boolean DEBUG_OPERATION_HISTORY_UNEXPECTED

This flag can be set to true if the history should print information to System.out whenever an unexpected condition arises. This flag should be used for debug purposes only.

DEBUG_OPERATION_HISTORY_DISPOSE

public static boolean DEBUG_OPERATION_HISTORY_DISPOSE

This flag can be set to true if the history should print information to System.out whenever an undo context is disposed. This flag should be used for debug purposes only.

DEBUG_OPERATION_HISTORY_OPENOPERATION

public static boolean DEBUG_OPERATION_HISTORY_OPENOPERATION

This flag can be set to true if the history should print information to System.out during the open/close sequence. This flag should be used for debug purposes only.

DEBUG_OPERATION_HISTORY_APPROVAL

public static boolean DEBUG_OPERATION_HISTORY_APPROVAL

This flag can be set to true if the history should print information to System.out whenever an operation is not approved. This flag should be used for debug purposes only.

Constructor Detail

DefaultOperationHistory

public DefaultOperationHistory()

Create an instance of DefaultOperationHistory.

Method Detail

add

public void add(
IUndoableOperation operation)

Description copied from interface: IOperationHistory

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).

Specified by:: add in interface IOperationHistory

Parameters:: operation - the operation to be added to the history

addOperationApprover

public 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 allowed to proceed. This method has no effect if the instance being added is already in the list.

Operation approvers must be prepared to receive these the operation approval messages from a background thread. Any UI access occurring inside the implementation must be properly synchronized using the techniques specified by the client's widget library.

Specified by:: addOperationApprover in interface IOperationHistory

Parameters:: approver - the IOperationApprover to be added as an approver.
See Also:: IOperationApprover

addOperationHistoryListener

public 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. This method has no effect if the instance being added is already in the list.

Operation history listeners must be prepared to receive notifications from a background thread. Any UI access occurring inside the implementation must be properly synchronized using the techniques specified by the client's widget library.

Specified by:: addOperationHistoryListener in interface IOperationHistory

Parameters:: listener - the IOperationHistoryListener to be added as a listener.
See Also:: IOperationHistoryListener, OperationHistoryEvent

canRedo

public boolean canRedo(
IUndoContext context)

Description copied from interface: IOperationHistory

Return whether there is a valid redoable operation available in the given context.

Specified by:: canRedo in interface IOperationHistory

Parameters:: context - the context to be checked
Returns:: true if there is a redoable operation, false otherwise.

canUndo

public boolean canUndo(
IUndoContext context)

Description copied from interface: IOperationHistory

Return whether there is a valid undoable operation available in the given context

Specified by:: canUndo in interface IOperationHistory

Parameters:: context - the context to be checked
Returns:: true if there is an undoable operation, false otherwise.

dispose

public void dispose(
IUndoContext context,
                    boolean flushUndo,
                    boolean flushRedo,
                    boolean flushContext)

Description copied from interface: IOperationHistory

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.

Specified by:: dispose in interface IOperationHistory

Parameters:: context - the context to be disposed; flushUndo - true if the context should be flushed from the undo history, false if it should not; flushRedo - 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.

execute

public 
IStatus execute(
IUndoableOperation operation,
                       
IProgressMonitor monitor,
                       
IAdaptable info)
                throws 
ExecutionException

Description copied from interface: IOperationHistory

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.

Specified by:: execute in interface IOperationHistory

Parameters:

operation - the operation to be executed and then added to the history

monitor - 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.

Returns:

the IStatus indicating whether the execution succeeded.

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.

Throws:



ExecutionException

- if an exception occurred during execution.

getLimit

public int getLimit(
IUndoContext context)

Description copied from interface: IOperationHistory

Return the limit on the undo and redo history for a particular context.

Specified by:: getLimit in interface IOperationHistory

Parameters:: context - the context whose limit is requested
Returns:: the undo and redo history limit for the specified context.

getRedoHistory

public 
IUndoableOperation[] getRedoHistory(
IUndoContext context)

Description copied from interface: IOperationHistory

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.

Specified by:: getRedoHistory in interface IOperationHistory

Parameters:: context - the context for the redo
Returns:: the array of operations in the history

getRedoOperation

public 
IUndoableOperation getRedoOperation(
IUndoContext context)

Description copied from interface: IOperationHistory

Get the operation that will next be redone in the given undo context.

Specified by:: getRedoOperation in interface IOperationHistory

Parameters:: context - the context for the redo
Returns:: the operation to be redone or null if there is no operation available. There is no guarantee that the returned operation is valid for redo.

getUndoHistory

public 
IUndoableOperation[] getUndoHistory(
IUndoContext context)

Description copied from interface: IOperationHistory

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.

Specified by:: getUndoHistory in interface IOperationHistory

Parameters:: context - the context for the undo
Returns:: the array of operations in the history

getUndoOperation

public 
IUndoableOperation getUndoOperation(
IUndoContext context)

Description copied from interface: IOperationHistory

Get the operation that will next be undone in the given undo context.

Specified by:: getUndoOperation in interface IOperationHistory

Parameters:: context - the context for the undo
Returns:: the operation to be undone or null if there is no operation available. There is no guarantee that the available operation is valid for the undo.

redo

public 
IStatus redo(
IUndoContext context,
                    
IProgressMonitor monitor,
                    
IAdaptable info)
             throws 
ExecutionException

Description copied from interface: IOperationHistory

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.

Specified by:: redo in interface IOperationHistory

Parameters:

context - the context to be redone

monitor - the progress monitor to be used for the redo, or null if no progress monitor is provided.

Returns:

the IStatus indicating whether the redo succeeded.

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.

Throws:



ExecutionException

- if an exception occurred during redo.

redoOperation

public 
IStatus redoOperation(
IUndoableOperation operation,
                             
IProgressMonitor monitor,
                             
IAdaptable info)
                      throws 
ExecutionException

Description copied from interface: IOperationHistory

Redo the specified operation. The redo of the operation is subject to approval by any registered IOperationApprover before it is attempted.

Specified by:: redoOperation in interface IOperationHistory

Parameters:

operation - the operation to be redone

monitor - the progress monitor to be used for the redo, or code>null if no progress monitor is provided

Returns:

the IStatus indicating whether the redo succeeded.

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.

Throws:



ExecutionException

- if an exception occurred during redo.

removeOperationApprover

public void removeOperationApprover(
IOperationApprover approver)

Description copied from interface: IOperationHistory

Remove the specified operation approver from the list of operation approvers that are consulted before an operation is undone or redone.

Specified by:: removeOperationApprover in interface IOperationHistory

Parameters:: 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.

removeOperationHistoryListener

public void removeOperationHistoryListener(
IOperationHistoryListener listener)

Description copied from interface: IOperationHistory

Remove the specified listener from the list of operation history listeners.

Specified by:: removeOperationHistoryListener in interface IOperationHistory

Parameters:: 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.

replaceOperation

public void replaceOperation(
IUndoableOperation operation,
                             
IUndoableOperation[] replacements)

Description copied from interface: IOperationHistory

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.

Specified by:: replaceOperation in interface IOperationHistory

Parameters:: operation - The IUndoableOperation to be replaced; replacements - the array of IUndoableOperation to replace the first operation

setLimit

public void setLimit(
IUndoContext context,
                     int limit)

Description copied from interface: IOperationHistory

Set the limit on the undo and redo history for a particular context.

Specified by:: setLimit in interface IOperationHistory

Parameters:: 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.

undo

public 
IStatus undo(
IUndoContext context,
                    
IProgressMonitor monitor,
                    
IAdaptable info)
             throws 
ExecutionException

Description copied from interface: IOperationHistory

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.

Specified by:: undo in interface IOperationHistory

Parameters:

context - the context to be undone

monitor - the progress monitor to be used for the undo, or null if no progress monitor is provided.

Returns:

the IStatus indicating whether the undo succeeded.

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.

Throws:



ExecutionException

- if an exception occurred during undo.

undoOperation

public 
IStatus undoOperation(
IUndoableOperation operation,
                             
IProgressMonitor monitor,
                             
IAdaptable info)
                      throws 
ExecutionException

Description copied from interface: IOperationHistory

Undo the specified operation. The undo of the operation is subject to approval by any registered IOperationApprover before it is attempted.

Specified by:: undoOperation in interface IOperationHistory

Parameters:

operation - the operation to be undone

monitor - the progress monitor to be used for the undo, or null if no progress monitor is provided

Returns:

the IStatus indicating whether the undo succeeded.

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.

Throws:



ExecutionException

- if an exception occurred during undo.

openOperation

public void openOperation(
ICompositeOperation operation,
                          int mode)

Description copied from interface: IOperationHistory

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.

Specified by:: openOperation in interface IOperationHistory

Parameters:: 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.

closeOperation

public void closeOperation(boolean operationOK,
                           boolean addToHistory,
                           int mode)

Description copied from interface: IOperationHistory

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 IOperationHistory.openOperation(org.eclipse.core.commands.operations.ICompositeOperation, int).

Specified by:: closeOperation in interface IOperationHistory

Parameters:: 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.

operationChanged

public void operationChanged(
IUndoableOperation operation)

Description copied from interface: IOperationHistory

The specified operation has changed in some way since it was added to the operation history. Notify listeners with an OPERATION_CHANGED event.

Specified by:: operationChanged in interface IOperationHistory

Parameters:: operation - the operation that has changed.

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Guidelines for using Eclipse APIs.

org.eclipse.core.commands.operations Class DefaultOperationHistory

DEBUG_OPERATION_HISTORY_NOTIFICATION

DEBUG_OPERATION_HISTORY_UNEXPECTED

DEBUG_OPERATION_HISTORY_DISPOSE

DEBUG_OPERATION_HISTORY_OPENOPERATION

DEBUG_OPERATION_HISTORY_APPROVAL

DefaultOperationHistory

add

addOperationApprover

addOperationHistoryListener

canRedo

canUndo

dispose

execute

getLimit

getRedoHistory

getRedoOperation

getUndoHistory

getUndoOperation

redo

redoOperation

removeOperationApprover

removeOperationHistoryListener

replaceOperation

setLimit

undo

undoOperation

openOperation

closeOperation

operationChanged

org.eclipse.core.commands.operations
Class DefaultOperationHistory