[antlr-interest] XPath - identifiers are keywords

[John Merrells]

This is probably simple, but I've failed to find an explicit answer
in the documentation or the FAQ. I have a language (XPath) and
it has some keywords that can also be identifiers. How do I set
up my lexer rules for this? The identifier is called NCNAME and
is defined thus:

k=2;

NCNAME
 : (LETTER|'_') (NCNAMECHAR)*
 ;

protected
NCNAMECHAR: LETTER|'0'..'9'|'.'|'-'|'_';

protected
LETTER: ('a'..'z'|'A'..'Z');

The keyword is 'comment', and when it's a keyword it is always
followed by '(' ')'. So I tried just adding...

COMMENT: "comment()";

But that's ambiguous, so I tried adding a lexer rule to disambiguate
between them, but I either got that wrong, or it didn't work. Should
I increase k to be length("comment()")? That seems like overkill.
I'm sure there's something obvious that I'm missing here...

John


 

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