[antlr-interest] Re: Newbie Question about Syntactic Predicates

[hawkwall]

Why is it I can't figure something out until I post to the newsgroup?

I think I have a solution.  My predicate was wrong on the type
STANDOFF.  Changing it too:

SURFACE_OR_STANDOFF
: ("NUMBER" DOT "OF" DOT "SURFACE" ) =>
"NUMBER" DOT "OF" DOT "SURFACE" DOT "TO" DOT "AIR" DOT "THREAT" DOT
"CLASSES" COLON
{$setType(SURFACE); }
| ("NUMBER" DOT "OF" DOT "STANDOFF" ) =>
"NUMBER" DOT "OF" DOT "STANDOFF" DOT "RANGE" DOT "AIRCRAFT" DOT
"CLASSES" COLON
{$setType(STANDOFF);}
;

and then making the original SURFACE and STANDOFF protected seems have
 fixed my problem.  I read that the protected keeps the tokens from
being sent to the parser, but I still don't quite understand it.  Is
this the correct way to handle large tokens without a large k value?

Thanks for your time.

Mike 


> Hello,
> 
> I need to match the following data
> 
> NUMBER.OF.SURFACE: 3
> NUMBER.OF.STANDALONE: 5
> 
> Where all I am really concered about is that the surface has a number
> 3, and the standalone has a number 5. I put the following in my Lexer
> 
> DIGITS : (0..9)+ ;
> 
> DOT : '.' ;
> 
> COLON : ':' ;
> 
> SURFACE : "NUMBER" DOT "OF" DOT "SURFACE" COLON ;
> 
> STANDALONE : "NUMBER" DOT "OF" DOT "STANDALONE" COLON;
> 
> WS : ( ' '
> | '\t'
> | '\f'
> | ( options {generateAmbigWarnings=false;}
> : "\r\n" // DOS
> | '\r' // Macintosh
> | '\n' // Unix
> )
> {newline();}
> )+
> 
> // now the overall whitespace action -- skip it!
> { $setType(Token.SKIP); }
> ;
> 
> And my Parser looks like:
> 
> start : rule1 rule2;
> 
> rule1 : SURFACE DIGITS ;
> 
> rule2 : STANDALONE DIGITS ;
> 
> with some actions to print out the number it finds. If k<12 in the
> lexer, I get a nondeterminism error, and can see the problem in the

> [snip]

> SURFACE_OR_STANDOFF
> : ("NUMBER" DOT "OF" DOT "SURFACE" ) =>
> "NUMBER" DOT "OF" DOT "SURFACE" DOT "TO" DOT "AIR" DOT "THREAT" DOT
> "CLASSES" COLON
> {$setType(SURFACE); }
> | ("NUMBER" DOT "OF" DOT "STANDOFF" DOT "RANGE" DOT "AIRCRAFT" DOT
> "CLASSES" COLON ) =>
> "NUMBER" DOT "OF" DOT "STANDOFF"
> {$setType(STANDOFF);}
> ;
> 
> [snip] 



 

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