data structure used to implement UNDO and REDO option

data-structures design-patterns undo-redo
SyncMaster picture SyncMaster · Mar 31, 2009 · Viewed 35.6k times · Source

I want to implement UNDO and REDO option(as we see in MS word etc). Can you suggest me a data structure for it, and how can i implement it.?

Answer

Jason Punyon picture Jason Punyon · Mar 31, 2009

It isn't a data structure but a design pattern. You're looking for the Command Pattern.

The standard is to keep the Command objects in a stack to support multi level undo. In order to support redo, a second stack keeps all the commands you've Undone. So when you pop the undo stack to undo a command, you push the same command you popped into the redo stack. You do the same thing in reverse when you redo a command. You pop the redo stack and push the popped command back into the undo stack.

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