Make + and - left-associative

lib/reader.c

@@ -29,40 +29,40 @@ static int parse_expression(
 {
 	int result, used = 0;
 
-	expression_t *number;
-	result = parse_number(pool, input, len, &number);
-	if (0 >= result)
-		return 0;
-	used += result;
-	if (used >= len) {
-		*out = number;
-		return used;
-	}
-
-	operator_t operator;
-	switch (input[used]) {
-	case '+':
-		operator= OPERATOR_ADD;
-		break;
-	case '-':
-		operator= OPERATOR_SUBTRACT;
-		break;
-	default:
-		return 0;
-	}
-	++used;
-
-	expression_t *subexpr;
-	result = parse_expression(pool, input + used, len - used, &subexpr);
+	expression_t *expr;
+	result = parse_number(pool, input, len, &expr);
 	if (0 >= result)
 		return 0;
 	used += result;
 
-	expression_t *expr = allocate_expression(pool);
-	expr->is_number = false;
-	expr->application.operator= operator;
-	expr->application.operands[0] = number;
-	expr->application.operands[1] = subexpr;
+	while (len > used) {
+		const expression_t *term0 = expr;
+
+		operator_t operator;
+		switch (input[used]) {
+		case '+':
+			operator= OPERATOR_ADD;
+			break;
+		case '-':
+			operator= OPERATOR_SUBTRACT;
+			break;
+		default:
+			return 0;
+		}
+		++used;
+
+		expression_t *term1;
+		result = parse_number(pool, input + used, len - used, &term1);
+		if (0 >= result)
+			return 0;
+		used += result;
+
+		expr = allocate_expression(pool);
+		expr->is_number = false;
+		expr->application.operator= operator;
+		expr->application.operands[0] = term0;
+		expr->application.operands[1] = term1;
+	}
 
 	*out = expr;
 	return used;