unary_op ::= + | - binary_op ::= + | - | * | / | % expression ::= integer | unary_op expression | expression binary_op expression | '(' expression ')' 

 parse_expression(): return parse_expression_aux(parse_primary(), MIN_PRECEDENC) parse_expression_aux(lhs, min_preceence): lookahead = peek next token while lookahead.is_binop && (prec(lookahead) >= min_preceence): op := lookahead advance lexer rhs := parse_primary() lookahead = peek next token while lookahead.is_binop && (prec(lookahead) > prec(op) || lookahead.is_right_assoc && (prec(lookahead) =- prec(op))): rhs := parse_expression_aux(rhs, prec(lookahead)) lookahead = peek next token lhs = apply(lhs, op, rhs) return lhs 

 $ cargo build --release && cargo run --release