I'm trying to make Bison correctly evaluate expressions, however, operator precedence isn't working and thus the expression gets evaluated in the wrong order.
I already tried setting the precedence with the %left and %right directives, neither worked. Interestingly enough, they resulted in the same.
The parser.y files which is used to read the syntax:
// Declares the operators to use left precedence
// This somehow does not work here
%left T_PLUS T_MINUS T_ASTERISK T_SLASH
// T_IDENTIFIER is basically the well known identifier from
// other programming languages (variable names and so on)
// The CREATE macro instantiates the class identifier_node,
// it just stores the name of the identifier and shouldn't be
// relevant for this question
//
// Identifiers
identifier : T_IDENTIFIER { $$ = CREATE(identifier_node, $1); }
;
// This is the actual operator expression, basically an expression
// before and after an operator
operator_expression : expression operator expression { $$ = CREATE(operator_expression_node, $1, $2, $3); }
;
// This part is used for general expressions, everything except
// operator_expression and identifier can be ignored for this
// question
//
// Expressions
expression : numeric | assignment | member_access | function_call | operator_expression
| identifier { $$ = $1; }
| T_OPEN_PAREN expression T_CLOSE_PAREN { $$ = $2; }
;
The part I'm trying to parse is a - b - c, which should result in
(a - b) - c, but does result in a - (b - c). As far as I understood the %left directive should prevent this, but it doesn't seem to work for my case.
If further reference is needed, the code can be found on github:
The parser.y file: https://github.com/Janrupf/cutelang/blob/master/parser/gen-src/parser.y
The file which I'm trying to parse: https://github.com/Janrupf/cutelang/blob/master/parser/test-src/resources/source.ctl
