ANTLR 4 $channel = HIDDEN and options

Question

I need help with my ANTLR 4 grammar after deciding to switch to v4 from v3. I am not very experienced with ANTLR so I am really sorry if my question is dumb ;)

In v3

Answer 1

The v4 equivalent would look like:

COMMENT
    :   ( '//' ~[\r\n]* '\r'? '\n'
        | '/*' .*? '*/'
        ) -> channel(HIDDEN)
    ;

which will put all single- and multi line comment on the HIDDEN channel. However, if you're not doing anything with these HIDDEN-tokens, you could also skip these tokens, which would look like this:

COMMENT
    :   ( '//' ~[\r\n]* '\r'? '\n'
        | '/*' .*? '*/'
        ) -> skip
    ;

Note that to tell the lexer or parser to match ungreedy, you don't use options {greedy=false;} anymore, but append a ?, similar to many regex implementations.