ptolemy.moml
Class MoMLUndoEntry

java.lang.Object
  ptolemy.moml.MoMLUndoEntry

All Implemented Interfaces:

UndoAction, ChangeListener

public class MoMLUndoEntry
extends java.lang.Object
implements UndoAction, ChangeListener

This is an undo action on the undo/redo stack. The undo/redo stack is stored in an instance of UndoInfoAttribute associated with the top-level of a model. If undo/redo is enabled, a MoMLParser will create entries automatically and put them on the stack whenever it parses MoML. So the easiest mechanism to perform undoable actions is to specify those actions in MoML and issue a MoMLChangeRequest to execute them. An alternative, however, is to create an instance of this class with no MoML, using the single argument constructor, and to override execute() to directly perform the undo.

Since:

Ptolemy II 2.1

Version:

$Id: MoMLUndoEntry.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Neil Smyth and Edward A. Lee

See Also:

MoMLParser, UndoStackAttribute, MoMLChangeRequest

Accepted Rating:

Red (cxh)

Proposed Rating:

Yellow (eal)

Field Summary

private NamedObj	_context
private java.lang.Exception	_exception
private java.lang.String	_undoMoML

Constructor Summary

MoMLUndoEntry(NamedObj context, java.lang.String undoMoML)
Create an undo entry comprised of the specified MoML code.

Method Summary

void	changeExecuted(ChangeRequest change) Do nothing.
void	changeFailed(ChangeRequest change, java.lang.Exception exception) Record the exception so that execute() can throw it.
void	execute() Parse the MoML specified in the constructor call in the context specified in the constructor call using the parser associated with the context (as determined by ParserAttribute.getParser()).
java.lang.String	toString() Return the MoML of the undo action.

Methods inherited from class java.lang.Object

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

Field Detail

_context

private NamedObj _context

_exception

private java.lang.Exception _exception

_undoMoML

private java.lang.String _undoMoML

Constructor Detail

MoMLUndoEntry

public MoMLUndoEntry(NamedObj context,
                     java.lang.String undoMoML)

Create an undo entry comprised of the specified MoML code.

Parameters:

context - The context in which to execute the undo.

undoMoML - The MoML specification of the undo action.

Method Detail

changeExecuted

public void changeExecuted(ChangeRequest change)

Do nothing. This method is called when a change is successfully executed.

Specified by:

changeExecuted in interface ChangeListener

Parameters:

change - The change that was successfully executed.

changeFailed

public void changeFailed(ChangeRequest change,
                         java.lang.Exception exception)

Record the exception so that execute() can throw it.

Specified by:

changeFailed in interface ChangeListener

Parameters:

change - The change that failed.

exception - The exception that occurred.

See Also:

execute()

execute

public void execute()
             throws java.lang.Exception

Parse the MoML specified in the constructor call in the context specified in the constructor call using the parser associated with the context (as determined by ParserAttribute.getParser()).

Specified by:

execute in interface UndoAction

Throws:

java.lang.Exception - If something goes wrong.

See Also:

ParserAttribute.getParser(NamedObj)

toString

public java.lang.String toString()

Return the MoML of the undo action.

Overrides:

toString in class java.lang.Object

Returns:

MoML for the undo action.