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

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Eclipse Platform
Release 3.5

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org.eclipse.text.undo
Interface IDocumentUndoManager

All Known Implementing Classes:: DocumentUndoManager

public interface IDocumentUndoManager

Interface for a document undo manager. Tracks changes in a document and builds a history of text commands that describe the undoable changes to the document.

Clients must explicitly connect to the undo manager to express their interest in the undo history. Clients should disconnect from the undo manager when they are no longer interested in tracking the undo history. If there are no clients connected to the undo manager, it will not track the document's changes and will dispose of any history that was previously kept.

Clients may also listen to the undo manager for notifications before and after undo or redo events are performed. Clients must connect to the undo manager in addition to registering listeners.

Clients may implement this interface.

Since:: 3.2
See Also:: DocumentUndoManagerRegistry, IDocumentUndoListener, IDocument

Method Summary

void addDocumentUndoListener ( IDocumentUndoListener listener)
          Adds the specified listener to the list of document undo listeners that are notified before and after changes are undone or redone in the document.

void beginCompoundChange ()
          Signals the undo manager that all subsequent changes until endCompoundChange is called are to be undone in one piece.

void commit ()
          Closes the currently open text edit and open a new one.

void connect ( Object client)
          Connects to the undo manager.

void disconnect ( Object client)
          Disconnects from the undo manager.

void endCompoundChange ()
          Signals the undo manager that the sequence of changes which started with beginCompoundChange has been finished.

IUndoContext getUndoContext ()
          Returns the undo context registered for this document

void redo ()
          Repeats the most recently rolled back text change.

boolean redoable ()
          Returns whether at least one text change can be repeated.

void removeDocumentUndoListener ( IDocumentUndoListener listener)
          Removes the specified listener from the list of document undo listeners.

void reset ()
          Resets the history of the undo manager.

void setMaximalUndoLevel (int undoLimit)
          Sets the limit of the undo history to the specified value.

void transferUndoHistory ( IDocumentUndoManager manager)
          Transfers the undo history from the specified document undo manager to this undo manager.

void undo ()
          Rolls back the most recently executed text change.

boolean undoable ()
          Returns whether at least one text change can be rolled back.

Method Detail

addDocumentUndoListener

void addDocumentUndoListener(
IDocumentUndoListener listener)

Adds the specified listener to the list of document undo listeners that are notified before and after changes are undone or redone in the document. This method has no effect if the instance being added is already in the list.

Notifications will not be received if there are no clients connected to the receiver. Registering a document undo listener does not implicitly connect the listener to the receiver.

Document undo 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.

Parameters:: listener - the document undo listener to be added as a listener

removeDocumentUndoListener

void removeDocumentUndoListener(
IDocumentUndoListener listener)

Removes the specified listener from the list of document undo listeners.

Removing a listener which is not registered has no effect

Parameters:: listener - the document undo listener to be removed

getUndoContext


IUndoContext getUndoContext()

Returns the undo context registered for this document

Returns:: the undo context registered for this document

commit

void commit()

Closes the currently open text edit and open a new one.

connect

void connect(
Object client)

Connects to the undo manager. Used to signify that a client is monitoring the history kept by the undo manager. This message has no effect if the client is already connected.

Parameters:: client - the object connecting to the undo manager

disconnect

void disconnect(
Object client)

Disconnects from the undo manager. Used to signify that a client is no longer monitoring the history kept by the undo manager. If all clients have disconnected from the undo manager, the undo history will be deleted.

Parameters:: client - the object disconnecting from the undo manager

beginCompoundChange

void beginCompoundChange()

Signals the undo manager that all subsequent changes until endCompoundChange is called are to be undone in one piece.

endCompoundChange

void endCompoundChange()

Signals the undo manager that the sequence of changes which started with beginCompoundChange has been finished. All subsequent changes are considered to be individually undo-able.

setMaximalUndoLevel

void setMaximalUndoLevel(int undoLimit)

Sets the limit of the undo history to the specified value. The provided limit will supersede any previously set limit.

Parameters:: undoLimit - the length of this undo manager's history

reset

void reset()

Resets the history of the undo manager. After that call, there aren't any undo-able or redo-able text changes.

undoable

boolean undoable()

Returns whether at least one text change can be rolled back.

Returns:: true if at least one text change can be rolled back

redoable

boolean redoable()

Returns whether at least one text change can be repeated. A text change can be repeated only if it was executed and rolled back.

Returns:: true if at least on text change can be repeated

undo

void undo()
          throws 
ExecutionException

Rolls back the most recently executed text change.

Throws:: ExecutionException - if an exception occurred during undo

redo

void redo()
          throws 
ExecutionException

Repeats the most recently rolled back text change.

Throws:: ExecutionException - if an exception occurred during redo

transferUndoHistory

void transferUndoHistory(
IDocumentUndoManager manager)

Transfers the undo history from the specified document undo manager to this undo manager. This message should only be used when it is known that the content of the document of the original undo manager when the last undo operation was recorded is the same as this undo manager's current document content, since the undo history is based on document indexes. It is the responsibility of the caller to ensure that this call is used correctly.

Parameters:: manager - the document undo manger whose history is to be transferred to the receiver