How to match a string, but case-insensitively?

Question

Let's say that I want to match "beer", but don't care about case sensitivity.

Currently I am defining a token to be ('b'|'B' 'e'|'E' 'e'|'E' 'r'|'R') but I have a lot of such and don't really want to handle 'verilythisisaverylongtokenindeedomyyesitis'.

The antlr wiki seems to suggest that it can't be done (in antlr) ... but I just wondered if anyone had some clever tricks ...

Answer 1

I would like to add to the accepted answer: a ready -made set can be found at case insensitive antlr building blocks, and the relevant portion included below for convenience

fragment A:[aA];
fragment B:[bB];
fragment C:[cC];
fragment D:[dD];
fragment E:[eE];
fragment F:[fF];
fragment G:[gG];
fragment H:[hH];
fragment I:[iI];
fragment J:[jJ];
fragment K:[kK];
fragment L:[lL];
fragment M:[mM];
fragment N:[nN];
fragment O:[oO];
fragment P:[pP];
fragment Q:[qQ];
fragment R:[rR];
fragment S:[sS];
fragment T:[tT];
fragment U:[uU];
fragment V:[vV];
fragment W:[wW];
fragment X:[xX];
fragment Y:[yY];
fragment Z:[zZ];

So an example is

   HELLOWORLD : H E L L O W O R L D;

Answer 2

How about define a lexer token for each permissible identifier character, then construct the parser token as a series of those?

beer: B E E R;

A : 'A'|'a';
B: 'B'|'b';

etc.