On Monday 07 September 2009 16:52:31 Damian Conway wrote: > Mike Diehl pondered: > > Well, I've continued to think about this and I've got some more > > questions. > > > > I did read up on the <defer: directive. I don't think that will help me. > > If I'm missing something, please let me know. > > No, it won't help. The problem is that you want to *parse* every command, > but not *execute* every command (only the ones in the correct branches of > the if). > > > So, I've come up with two different ways to handle this situation: > > > > 1. Pass in a boolean areguement to each production, and if that > > arguement is "true" process the action, otherwise, simply return the TEXT > > of the matched expression. > > > > This way, my if statement passes [1] and [0] to the two clauses. This > > introduces substantial logic into my grammar, though. > > > > 2. The other way is to build the "parse tree" inside the grammar and > > then "walk" the tree. This would entail almost completely rewriting my > > grammar actions. But this way would also, potentially?, allow me to > > compile my language and forgo the parser step alltogether. > > > > Which method would you recommend? > > Definitely, the second approach. There's a good reason that people > usually separate compilation and execution: namely that mixing them is > both vastly more complex and considerably more error-prone. > > Damian
I did finally, rewrite the whole thing using the second approach. This was CONSIDERABLY more complex, as I had to navigate a fairly complex parse tree. I think I've done something wrong, as I'm still finding bugs... I'll do some more reading, though. Anyway, this is a nice final design, though. Because I now have a parse tree, I have the potential of serializing that data structure to an external file and saving the expense of launching the parser each time my program runs. This amounts to creating a JIT compiler! Should be MUCH more efficient, right? Any recommendations between the various modules for this purpose? Data::Dumper, Storable, Serialize? BTW Damian, RD is a nice piece of work. It's almost FUN to use. -- Take care and have fun, Mike Diehl.
