(expression | FLOAT) '(' -> (expression | FLOAT) '*('

grammar Test;

expression
: //FLOAT '(' -> (FLOAT '*(')+
| add EOF!
;
term
:
| '(' add ')'
| FLOAT
| IMULT
;

IMULT
:   (add ('(' add)*) -> (add ('*' add)*)
;
negation
:   '-'* term
;

unary
:   ('+' | '-')* negation
;

mult
:   unary (('*' | '/') unary)*
;

add
:   mult (('+' | '-') mult)*
;

ID  :   ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'0'..'9'|'_')*
;

FLOAT
:   ('0'..'9')+ '.' ('0'..'9')*// EXPONENT?
|   '.' ('0'..'9')+ //EXPONENT?
|   ('0'..'9')+ //EXPONENT
;

WS  :   ( ' '
    | 't'
    | 'r'
    | 'n'
    ) {$channel=HIDDEN;}
;

imult
: FLOAT '(' -> FLOAT '*('
;

IMULT / imult
: expression '(' -> expression '*'
;

tokens { ABSTRACTTOKEN; }

imult
: FLOAT '(' -> ^(ABSTRACTTOKEN FLOAT)
;