[antlr-interest] Problem with lexical nondeterminism - ANTLR 2.7.7

clive.i.hill at jpmorgan.com clive.i.hill at jpmorgan.com
Thu Jan 3 05:24:35 PST 2008


Hi,

I get the following warning when building my lexer from stragegy.g:

/Grammar/strategy.g: warning:lexical nondeterminism between rules NUMBER 
and APAC_NUMERIC_TICKER upon
./Grammar/strategy.g:     k==1:'0'..'9'
./Grammar/strategy.g:     k==2:'0'..'9'
./Grammar/strategy.g:     k==3:'0'..'9'
./Grammar/strategy.g:     k==4:'0'..'9'

Passing the following string fails:

"spx dec 1350 c 43 44"

As it takes 1350 to be an APAC_NUMERIC_TICKER when I it to be considered 
to be a NUMBER.  Interestingly, the following works:

"spx dec 135 c 43 44"

My definition for the lexer rule is:

APAC_NUMERIC_TICKER
    : ((DIGIT)+ (COMMA) (CHAR) (CHAR))
    ;

I want this to only be used if a string entered "has at least one DIGIT 
and is followed by a COMMA then two CHARs".  This is clearly not the case 
for the string 1350 - and yet it matches,  and then throws the exception:


antlr.TokenStreamRecognitionException: expecting ',', found ' '


Can anyone suggest a way to only match this rule if it is in the correct 
format ((DIGIT)+ (COMMA) (CHAR) (CHAR)) ?

Thanks in advance,

Clive



Attached is my grammar file.




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