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From "Andrew C. Oliver" <acoli...@apache.org>
Subject [RT] Reactive formula parser (esp Avik)
Date Thu, 12 Dec 2002 20:02:02 GMT
Hi All,

I find myself ill-motivated to work on formulas lately and I think I 
know why.  We've seperated the issues in the formula parser poorly based 
on my earlier incorrect assumptions which makes it a real pain to work 
on.  Avik has done a fine job on the parser but I think we need to 
seperate out some of the extra things its doing.

I suggest:

FormulaParser
   Role: parses strings and throws token events

PTGParser
   Role: parses PTGs and throws token events

FormulaDigester
   Role: receives token events and outputs PTGs in RPN

PTGDigester
   Role: receives token events and outputs formula strings

Token:
   Role: Symbolic represnetation of a parsed portion of an expression.

PTG
   Role: Binary representation created by PTG Digester no direct 
correllation to tokens.

The goal is to seperate out the areas of concern.  PTGs don't directly 
correspond to tokens in the formula string and vise versa.  The order is 
therefore not *directly* RPN.  This more distributed system should make 
it easier to do IFs and other constructs.

What do you guys think, esp Avik?  Any additional formula volunteers?

Thanks,

Andy



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