I have problem running input stream for my grammar, here is part of my grammar
expression
: ....
| ( '+' | '-' | '&' |) expression
| expression ('+'|'-') expression
....
;
when input stream like 2+2-2 or (2+2+2)-2, error occurs
line 10:30 extraneous input '-2' expecting {',', '^',...}
why my grammar can not distinguish between -2 and 2-2 ? anyone help me please !
It appears that you have written your lexer in such a way that -2 results in a single token. Instead of handling negative numbers in this way, treat - as a unary operator and allow your parser handle the negation operation. If you try to handle negative numbers directly in the lexer, input such as 2-2 will be sent to the parser as 2 consecutive number tokens (2 followed by -2) instead of the desired 3 tokens (2, -, 2).
