tokens:
\s+ # Do nothing
( OPEN_PAREN
) CLOSE_PAREN
{ OPEN_CURL
} CLOSE_CURL
+ ADD
- SUB
* MUL
/ DIV
= EQUALS
, COMMA
; SEMICOLON
"[^"]*" STRING
def DEF
return RETURN
\d+ NUMBER
\w+ IDENT
grammar:
program: block
block: { statement }
statement: IDENT EQUALS expression SEMICOLON # ident=expression; : x=10;
| DEF IDENT OPEN_CURL block CLOSE_CURL # def ident { block } : def hi{return 10}
| RETURN expression SEMICOLON # return expression; : return 10;
| expression SEMICOLON # expression; : 1+2;
expression: term { addop term } # 1+2-3+400-67...
term: factor { mulop factor } # 7*3*67/4*8*3...
factor: IDENT OPEN_PAREN CLOSE_PAREN # ident() : hi()
| IDENT # ident : hi
| OPEN_PAREN expression CLOSE_PAREN # (expression): (1+2)
| SUB NUMBER # -number : -10
| NUMBER # number : 10
| STRING # string : "hi"
addop: ADD | SUB
mulop: MUL | DIV