[antlr-interest] Lexer: C-style comments with DOS/UNIX newlines

[Nigel Sheridan-Smith]

Hi there,

I'm a relative newcomer to ANTLR. I am trying to define C/C++/Java style
comments, and having some trouble.

I have the following rule, similar to that in the manual (with k=3 and ANTLR
2.7.4):


/* COMMENT rules */
CCOMMENT: "/*"
        ( options {greedy=false;}
        
         : '\r' ('\n')? {newline();}
         | '\n' {newline();}
         | . 
        )*
       "*/";



I get the following messages:

ANTLR Parser Generator   Version 2.7.4   1989-2004 jGuru.com
PersistenceGrammar.g:70:17: warning:lexical nondeterminism between alts 1
and 2 of block upon
PersistenceGrammar.g:70:17:     k==1:'\n'
PersistenceGrammar.g:70:17:     k==2:'\t','\n','\r','
'..'"','%'..'?','A'..'_','
a'..'~'
PersistenceGrammar.g:70:17:     k==3:'\t','\n','\r','
'..'"','%'..'?','A'..'_','
a'..'~'


If I remove the  ('\n')?  from the 5th line then the problem goes away.
However, this isn't actually what seems to be reported as the error.
Changing the "/*" and "*/" to "{" and "}" do not make any difference; nor
does increasing the value of k in the lexer.

Any help would be appreciated! The rest of the grammar is attached.

Thanks

Nigel

--
Nigel Sheridan-Smith
PhD research student

Faculty of Engineering
University of Technology, Sydney
Phone: 02 9514 7946
Fax: 02 9514 2435
 



 
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