[antlr-interest] Lexer rule match keyword or identifier depending on the previous token

[Guillaume Chavanon]

Hi all,

I am writing a grammar for a language that allow some keywords to be 
identifiers if they are preceded by a special character.
Is it possible to add gated semantic predicate in a lexer rule that will 
test the previous token ?
I would like to do something like this :

IDENTIFIER
    : { previousToken != ... }?=> 'KEYWORD1' {$type=KEYWORD1;}
    | { previousToken != ... }?=> 'KEYWORD2' {$type=KEYWORD2;}
    | 'A'..'Z' ( '_'? ( 'A'..'Z' | '0'..'9' ) )*
    ;

Thanks in advance,
Guillaume Chavanon