Save deletes undo history in ParseGenApp - Githubissues

itod / pegkit

'Parsing Expression Grammar' toolkit for Cocoa/Objective-C

MIT License

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Save deletes undo history in ParseGenApp #52

Open yepher opened 7 years ago

yepher commented 7 years ago

BUG

When clicking File->Saveor Generate in ParseGenApp the undo history is lost.

This makes it hard to quickly test a new grammar entry and then rollback to pre-edit condition.

The app should maintain undo history while it is running in the same document.

Some research notes on issue

NSTextView is bound to grammar as KVO in interface builder
NSTextView editable is bound to busy as KVO in interface builder
Saving doc caret jumps to top of doc
When saving NSTextView looses focus
Disable busy logic keeps undo history after generate but still broken for File->Save
(void)done { ... // self.busy = NO; // [self focusTextView]; ... }
(IBAction)generate:(id)sender { ... //self.busy = YES; ... }

yepher commented 7 years ago

Looking through the code there are defensive copies of NSString which does not make sense to me since NSString is immutable anyway.

I am not exactly clear why there is KVO for grammar<->NSTextView.