[antlr-interest] executing actions during backtrack

[Micheal J]

Ter,

> What if we could auto unroll any object/data-structured you  
> identified somehow as transactional?  You would give me an undo()  
> method for each object, like a hashtable.  I could record the  
> arguments to pass to undo so it knows how to undo.  This 
> would not be  
> perfect as the arguments could point at stuff that could 
> change (like  
> a stringbuffer), but would be a poor man's transactions.
.....
.....
.....
> undoActions.add(new Action324(scope,$ID.text));
> 
> Later we can walk undoActions and undo everything.
> 
> Hmm...would this work?  Surely in this case.  The key is passing all  
> necessary data to the undo as evaluated in its original context.

The value of the 'backtracking' attribute already serves as a state flag to
ANTLR users concerned about the interactions of actions and backtracking. I
vote we leave it there.

Stripped down, fast-as-possible, easy to read/debug source code (well easier
to read than LR equivalents) for ANTLR generated language processors remains
the goal right?


Micheal