[antlr-interest] IBM MVS JCL recognition

Jim O'Connor Jim.OConnor at microfocus.com
Fri Mar 14 06:14:59 PST 2003

Thanks Silvain,
  Your advice does help.  I'm worried about retaining positional/file
information, i.e. "Where does this text come from?", but I have more than
enough work to do with the preprocessor/lexer/grammar.  
  Thanks for the wise words.


-----Original Message-----
From: Silvain Piree
To: antlr-interest at yahoogroups.com
Sent: 3/14/03 3:34 AM
Subject: Re: [antlr-interest] IBM MVS JCL recognition


>  JCL has a number of fun recognition problems for which
> ANTLR might have solutions. 

We've built a IBM JCL parser for our re-engineering services
and I would advise you to take the preprocessor route.

We've built a preprocessor using ANTLR lexer to handle 
constructs like:

- EXEC PROC=name, symbols
- PROC name, symbols
- DD *, DLM=...
- SET symbols
- etc.

It would be VERY difficult to build a one-pass parser that does
both preprocessing and parsing.

In fact, even the preprocessing is pretty complex. We usually
build multiple small preprocessors to handle the different
preprocessing constructs (i.e. multi-pass preprocessing), 
but for JCL the only solution was to build a one-pass preprocessor
because everything depends on everything.

Hope this helps, kind greetings,

Silvain Piree
Refactive (www.refactive.com)


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