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

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Eclipse Platform
Release 3.5

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org.eclipse.core.commands.operations
Class TriggeredOperations


java.lang.Object
  

org.eclipse.core.commands.operations.AbstractOperation
      
org.eclipse.core.commands.operations.TriggeredOperations

All Implemented Interfaces:: IAdvancedUndoableOperation, ICompositeOperation, IContextReplacingOperation, IUndoableOperation

public final class TriggeredOperations
extends AbstractOperation
implements ICompositeOperation, IAdvancedUndoableOperation, IContextReplacingOperation
extends AbstractOperation
implements ICompositeOperation, IAdvancedUndoableOperation, IContextReplacingOperation

Triggered operations are a specialized implementation of a composite operation that keeps track of operations triggered by the execution of some primary operation. The composite knows which operation was the trigger for subsequent operations, and adds all triggered operations as children. When execution, undo, or redo is performed, only the triggered operation is executed, undone, or redone if it is still present. If the trigger is removed from the triggered operations, then the child operations will replace the triggered operations in the history.

This class may be instantiated by clients.

Since:: 3.1

Constructor Summary

TriggeredOperations ( IUndoableOperation operation, IOperationHistory history)
          Construct a composite triggered operations using the specified undoable operation as the trigger.

Method Summary

void aboutToNotify ( OperationHistoryEvent event)
           An operation history notification about this operation is about to be sent to operation history listeners.

void add ( IUndoableOperation operation)
           Add the specified operation as a child of this operation.

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.

IStatus computeRedoableStatus ( IProgressMonitor monitor)
          Return a status indicating the projected outcome of redoing the receiver.

IStatus computeUndoableStatus ( IProgressMonitor monitor)
          Return a status indicating the projected outcome of undoing the receiver.

void dispose ()
          Dispose of the operation.

IStatus execute ( IProgressMonitor monitor, IAdaptable info)
          Execute the operation.

Object[] getAffectedObjects ()
           Return an array of objects that are affected by executing, undoing, or redoing this operation.

IUndoableOperation getTriggeringOperation ()
          Return the operation that triggered the other operations in this composite.

IStatus redo ( IProgressMonitor monitor, IAdaptable info)
          Redo the operation.

void remove ( IUndoableOperation operation)
           Remove the specified operation from this operation.

void removeContext ( IUndoContext context)
          Remove the specified context from the receiver.

void replaceContext ( IUndoContext original, IUndoContext replacement)
          Replace the undo context of the receiver with the provided replacement undo context.

IStatus undo ( IProgressMonitor monitor, IAdaptable info)
          Undo the operation.

Methods inherited from class org.eclipse.core.commands.operations. AbstractOperation

getContexts, getLabel, hasContext, setLabel, toString

Methods inherited from class java.lang. Object

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

Methods inherited from interface org.eclipse.core.commands.operations. IUndoableOperation

getContexts, getLabel, hasContext

Constructor Detail

TriggeredOperations

public TriggeredOperations(
IUndoableOperation operation,
                           
IOperationHistory history)

Construct a composite triggered operations using the specified undoable operation as the trigger. Use the label of this trigger as the label of the operation.

Parameters:: operation - the operation that will trigger other operations.; history - the operation history containing the triggered operations.

Method Detail

add

public void add(
IUndoableOperation operation)

Description copied from interface: ICompositeOperation

Add the specified operation as a child of this operation.

Specified by:: add in interface ICompositeOperation

Parameters:: operation - the operation to be added. If the operation instance has already been added, this method will have no effect.

remove

public void remove(
IUndoableOperation operation)

Description copied from interface: ICompositeOperation

Remove the specified operation from this operation.

The composite operation should dispose the operation as part of removing it.

Specified by:: remove in interface ICompositeOperation

Parameters:: operation - the operation to be removed. The operation should be disposed by the receiver. This method will have no effect if the operation instance is not already a child.

removeContext

public void removeContext(
IUndoContext context)

Remove the specified context from the receiver. This method is typically invoked when the history is being flushed for a certain context. In the case of triggered operations, if the only context for the triggering operation is being removed, then the triggering operation must be replaced in the operation history with the atomic operations that it triggered. If the context being removed is not the only context for the triggering operation, the triggering operation will remain, and the children will each be similarly checked.

Specified by:: removeContext in interface IUndoableOperation
Overrides:: removeContext in class AbstractOperation

Parameters:: context - the undo context being removed from the receiver.

execute

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

Description copied from interface: IUndoableOperation

Execute the operation. This method should only be called the first time that an operation is executed.

Specified by:: execute in interface IUndoableOperation
Specified by:: execute in class AbstractOperation

Parameters:: 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.
Returns:: the IStatus of the execution. The status severity should be set to OK if the operation was successful, and ERROR if it was not. Any other status is assumed to represent an incompletion of the execution.
Throws:: ExecutionException - if an exception occurred during execution.

redo

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

Description copied from interface: IUndoableOperation

Redo the operation. This method should only be called after an operation has been undone.

Specified by:: redo in interface IUndoableOperation
Specified by:: redo in class AbstractOperation

Parameters:: 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.
Returns:: the IStatus of the redo. The status severity should be set to OK if the redo was successful, and ERROR if it was not. Any other status is assumed to represent an incompletion of the redo.
Throws:: ExecutionException - if an exception occurred during redo.

undo

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

Description copied from interface: IUndoableOperation

Undo the operation. This method should only be called after an operation has been executed.

Specified by:: undo in interface IUndoableOperation
Specified by:: undo in class AbstractOperation

Parameters:: 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.
Returns:: the IStatus of the undo. The status severity should be set to OK if the redo was successful, and ERROR if it was not. Any other status is assumed to represent an incompletion of the undo.
Throws:: ExecutionException - if an exception occurred during undo.

canUndo

public boolean canUndo()

Description copied from interface: IUndoableOperation

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.

Specified by:: canUndo in interface IUndoableOperation
Overrides:: canUndo in class AbstractOperation

Returns:: true if the operation can be undone; false otherwise.

canExecute

public boolean canExecute()

Description copied from interface: IUndoableOperation

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.

Specified by:: canExecute in interface IUndoableOperation
Overrides:: canExecute in class AbstractOperation

Returns:: true if the operation can be executed; false otherwise.

canRedo

public boolean canRedo()

Description copied from interface: IUndoableOperation

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.

Specified by:: canRedo in interface IUndoableOperation
Overrides:: canRedo in class AbstractOperation

Returns:: true if the operation can be redone; false otherwise.

dispose

public void dispose()

Description copied from interface: IUndoableOperation

Dispose of the operation. This method is used when the operation is no longer kept in the history. Implementers of this method typically unregister any listeners.

Specified by:: dispose in interface IUndoableOperation
Overrides:: dispose in class AbstractOperation

getTriggeringOperation

public 
IUndoableOperation getTriggeringOperation()

Return the operation that triggered the other operations in this composite.

Returns:: the IUndoableOperation that triggered the other children.

getAffectedObjects

public 
Object[] getAffectedObjects()

Description copied from interface: IAdvancedUndoableOperation

Return an array of objects that are affected by executing, undoing, or redoing this operation. If it cannot be determined which objects are affected, return null.

Specified by:: getAffectedObjects in interface IAdvancedUndoableOperation

Returns:: the array of Objects modified by this operation, or null if the affected objects cannot be determined.

aboutToNotify

public void aboutToNotify(
OperationHistoryEvent event)

Description copied from interface: IAdvancedUndoableOperation

An operation history notification about this operation is about to be sent to operation history listeners. Any preparation needed before listeners are notified about this operation should be performed here.

This method has been added to support legacy undo frameworks that are adapting to IUndoableOperation. Operations that previously relied on notification from their containing history or stack before any listeners are notified about changes to the operation should implement this interface.

Specified by:: aboutToNotify in interface IAdvancedUndoableOperation

Parameters:: event - the event that is about to be sent with the pending notification

computeUndoableStatus

public 
IStatus computeUndoableStatus(
IProgressMonitor monitor)
                              throws 
ExecutionException

Description copied from interface: IAdvancedUndoableOperation

Return a status indicating the projected outcome of undoing the receiver. This method should be used to report the possible outcome of an undo and is used when computing the validity of an undo is too expensive to perform in IUndoableOperation.canUndo(). It is not called by the operation history, but instead is used by clients (such as implementers of IOperationApprover) who wish to perform advanced validation of an operation before attempting to undo it. If the result of this method is the discovery that an operation can in fact not be undone, then the operation is expected to correctly answer false on subsequent calls to IUndoableOperation.canUndo().

Specified by:: computeUndoableStatus in interface IAdvancedUndoableOperation

Parameters:: monitor - the progress monitor (or null) to use for reporting progress to the user while computing the validity.
Returns:: the IStatus indicating the validity of the undo. The status severity should be set to OK if the undo can successfully be performed, and ERROR if it cannnot. Any other status is assumed to represent an ambiguous state.
Throws:: ExecutionException - if an exception occurs while computing the validity.

computeRedoableStatus

public 
IStatus computeRedoableStatus(
IProgressMonitor monitor)
                              throws 
ExecutionException

Description copied from interface: IAdvancedUndoableOperation

Return a status indicating the projected outcome of redoing the receiver. This method should be used to report the possible outcome of a redo and is used when computing the validity of a redo is too expensive to perform in IUndoableOperation.canRedo(). It is not called by the operation history, but instead is used by clients (such as implementers of IOperationApprover) who wish to perform advanced validation of an operation before attempting to redo it. If the result of this method is the discovery that an operation can in fact not be redone, then the operation is expected to correctly answer false on subsequent calls to IUndoableOperation.canRedo().

Specified by:: computeRedoableStatus in interface IAdvancedUndoableOperation

Parameters:: monitor - the progress monitor (or null) to use for reporting progress to the user while computing the validity.
Returns:: the IStatus indicating the validity of the redo. The status severity should be set to OK if the redo can successfully be performed, and ERROR if it cannnot. Any other status is assumed to represent an ambiguous state.
Throws:: ExecutionException - if an exception occurs while computing the validity.

replaceContext

public void replaceContext(
IUndoContext original,
                           
IUndoContext replacement)

Replace the undo context of the receiver with the provided replacement undo context. In the case of triggered operations, all contained operations are checked and any occurrence of the original context is replaced with the new undo context.

This message has no effect if the original undo context is not present in the receiver.

Specified by:: replaceContext in interface IContextReplacingOperation

Parameters:: original - the undo context which is to be replaced; replacement - the undo context which is replacing the original
Since:: 3.2

addContext

public void addContext(
IUndoContext context)

Add the specified context to the operation. Overridden in TriggeredOperations to add the specified undo context to the triggering operation.

Specified by:: addContext in interface IUndoableOperation
Overrides:: addContext in class AbstractOperation

Parameters:: context - the context to be added
Since:: 3.2

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Eclipse Platform
Release 3.5

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Guidelines for using Eclipse APIs.

org.eclipse.core.commands.operations Class TriggeredOperations

TriggeredOperations

add

remove

removeContext

execute

redo

undo

canUndo

canExecute

canRedo

dispose

getTriggeringOperation

getAffectedObjects

aboutToNotify

computeUndoableStatus

computeRedoableStatus

replaceContext

addContext

org.eclipse.core.commands.operations
Class TriggeredOperations