Question

Given that I have the following grammar how would I add a rule to match something like 2^3 to create a power operator?

negation : '!'* term ;

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

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

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

relation : add (('=' | '!=' | '<' | '<=' | '>=' | '>') add)* ;

expression : relation (('&&' | '||') relation)* ;

// LEXER ================================================================

HEX_NUMBER : '0x' HEX_DIGIT+;

fragment 
FLOAT: ;

INTEGER : DIGIT+ ({input.LA(1)=='.' && input.LA(2)>='0' && input.LA(2)<='9'}?=> '.' DIGIT+ {$type=FLOAT;})? ;

fragment
HEX_DIGIT : (DIGIT|'a'..'f'|'A'..'F') ;

fragment
DIGIT : ('0'..'9') ;

What I have tried:

I tried something like power : ('+' | '-') unary'^' unary but that doesn’t seem to work.

I also tried mult : unary (('*' | '/' | ('%'|'mod') | '^' ) unary)* ; but that doesn’t work either.

Answer 1

To give ^ higher precedence than negation, do this:

pow      : term ('^' term)* ;

negation : '!' negation | pow ;

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