Difference between revisions of "Undo Redo Design"

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imported>Aurelien
(New page: == Eclipse History == To implement the history, we have based mechanism History provided by Eclipse [http://help.eclipse.org/help32/index.jsp?topic=/org.eclipse.platform.doc.isv/reference...)
 
imported>Laurent
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== Eclipse History ==
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== History Mechanism ==
  
To implement the history, we have based mechanism History provided by Eclipse [http://help.eclipse.org/help32/index.jsp?topic=/org.eclipse.platform.doc.isv/reference/api/org/eclipse/core/commands/operations/package-summary.html]. It is consist of a class History and an interface IUndoableOperation. The operations have three methods to act on the database: execute(), undo() and redo().
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Undo / Redo is built on top of the History mechanism provided by Eclipse [http://help.eclipse.org/help32/topic/org.eclipse.platform.doc.isv/guide/wrkAdv_undo.htm]. It is composed of class History and interface IUndoableOperation. Each operation has three methods to act on the database: execute(), undo() and redo().
 
 
They are saved in the historic which call execute() for the first time and then undo () and redo () as the operation is to undo or redo.
 
 
 
As a file must have its own historic, the operations have a context, here it's the name of file. A History class then manages the historic of all files.
 
  
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Operations are added to the history.  The execute() operation is called during addition. Then, operations undo() and redo() are executed by the history when an Undo or Redo action is performed.
  
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As each file has its own history, every operation has a context, which is the name of the file. The History class just manages the history of all files.
  
 
== Operations ==
 
== Operations ==
  
First, we have to make objects that implements IUndoableOperation for each transaction on the data base. We use the composite model so that each operation is composed of basic operations (add an element, delete an element, change an attribute ,...). The operations are created by class builder.
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First, we have to make objects that implement IUndoableOperation for each transaction on the database. We use the composite model so that each operation is composed of basic operations (add an element, delete an element, change an attribute ,...). The operations are created by a factory.
  
Some operations are dependent on an element in their execution (eg change an attibute). This may not be known when recording the operation in the History. To do this, operations have methods getCreatedElement () and setParent () which be called in execute()
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Some operations are dependent on an element in their execution (e.g., change an attibute). This may not be known when recording the operation in the History. To do this, operations have methods getCreatedElement() and setParent() which are called by execute()
 
  
Then to ensure the atomicity on the database, operations (TreeOperation) are encapsulated in a class AtomicOperation. It only delegate its methods but it encapsulates in the RodinCore.run().
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Then to ensure atomicity with respects to the Rodin database, composite operations (TreeOperation) are encapsulated in a class AtomicOperation. It only delegate its methods but it encapsulates in the RodinCore.run().
  
  

Revision as of 17:19, 20 October 2008

History Mechanism

Undo / Redo is built on top of the History mechanism provided by Eclipse [1]. It is composed of class History and interface IUndoableOperation. Each operation has three methods to act on the database: execute(), undo() and redo().

Operations are added to the history. The execute() operation is called during addition. Then, operations undo() and redo() are executed by the history when an Undo or Redo action is performed.

As each file has its own history, every operation has a context, which is the name of the file. The History class just manages the history of all files.

Operations

First, we have to make objects that implement IUndoableOperation for each transaction on the database. We use the composite model so that each operation is composed of basic operations (add an element, delete an element, change an attribute ,...). The operations are created by a factory.

Some operations are dependent on an element in their execution (e.g., change an attibute). This may not be known when recording the operation in the History. To do this, operations have methods getCreatedElement() and setParent() which are called by execute()

Then to ensure atomicity with respects to the Rodin database, composite operations (TreeOperation) are encapsulated in a class AtomicOperation. It only delegate its methods but it encapsulates in the RodinCore.run().


Factory

The interface provides to clients consists of three class:

  • OperationFactory
  • History
  • AtomicOperation

The factory is not instantiable and its methods are static. History implements the pattern Singleton and delegates to IOperationHistory.