I'm trying to write a grammar capable of parsing something like the
following:
$sum = number_1 * number_2 / (number_3 + $temp);
>From this, I want to generate this AST:
(ASSIGN
$sum
(MUL_OP
number_1
(DIV_OP
number_2
(ADD_OP
number_3
$temp))))
This is (the relevant part of) what I currently have -
statement : assignment_expression ';'!;
assignment_expression : variable '=' expression -> ^(ASSIGN variable
expression);
expression
: mul_expression (add_operator mul_expression)? -> ^(add_operator
mul_expression mul_expression?);
mul_expression : term (mul_operator term)* -> ^(mul_operator term term*);
term : '('! expression ')'! | variable | constant;
add_operator : '+' -> ADD_OP | '-' -> SUB_OP;
mul_operator : '*' -> MUL_OP | '/' -> DIV_OP;
It's obviously very wrong. :) The main things I can't figure out are how to
have chained operations (eg. a * b / c) that create new child nodes for each
new operator (eg. (MUL a (DIV b c))), or how to properly support
parenthesis. All my attempts have given me a grammar with mutual
left-recursion that I can't seem to solve. There must be a clean and clear
way to do this. :)
Thanks in advance for any help, and sorry for such a noobie question.
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