Re: newbie question regarding lookahead (I think)

Hi, I'm trying to fix a JJTree parser but am I little confused as to the source of the problem.

First: the parser tries to parse SMARTS, which are query patterns for molecular substructure matching.

Given a string: Sc1ccccc1

the parser should recognize S and c as two separate atom (tokens). The problem is that Sc is also a valid token - but the specification says that it must be enclosed in [ and ] - which is not the case here.

As a result, the parser only sees the S and c as Sc and then reports the pattern as invalid.
So I'm trying to work out how to make the parser recognize the Sc as two separate tokens - S & c.

(I have probably not given enough information but I've tried to keep the description simple and generic. The entire parser code is available at http://cdk.git.sourceforge.net/git/gitweb.cgi?p=cdk;a=blob_plain;f=src/main/org/openscience/cdk/smiles/smarts/parser/SMARTSParser.jjt;hb=master)

Any pointers would be approciated

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Rajarshi Guha  <rguha@...>
GPG Fingerprint: D070 5427 CC5B 7938 929C  DD13 66A1 922C 51E7 9E84
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Q:  What's polite and works for the phone company?
A:  A deferential operator.



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