|
The undo package is responsible for being able to undo
the refactoring operations. This package currently consists
of two objects. One is the stack that maintains a list of
all the undo actions. The second is the specific action
that can be undone.
There is no support yet for redoing actions.
Undoing a particular change to a specific file are stored
by renaming the current file with an extension,
.java.# where # is the number of times the file has been changed
by the refactoring tool. Let's call this method of
storing the previous incarnations of a file an indexed
file.
An undo action then has a number of indexed files associated
with them. It also has a description of the refactoring
so that a user interface component can display a list of
refactorings to undo.
The undo stack then holds all the undo action objects.
It uses a singleton pattern to insure that only a single
instance of the undo stack is present in the editor at
a time.
|