Function apply_interval_conversion

engine/src/parser/expression_utils.cpp:1425–1460

By default Calcite returns Interval types in ms unit. So we want to convert them to the right INTERVAL unit to do correct operations TODO: any issue related with INTERVAL operations (and parsing expressions) should be handled here

// to do correct operations
// TODO: any issue related with INTERVAL operations (and parsing expressions) should be handled here
std::string apply_interval_conversion(std::string expression, std::vector<cudf::data_type> table_schema) {
	std::string interval_expr = ":INTERVAL";
	if (table_schema.size() == 0 || expression.find(interval_expr) == expression.npos) return expression;

	// op with intervals
	if (expression.find("+") != expression.npos || expression.find("-") != expression.npos) {
		std::string plus_expr = "+($", sub_expr = "-($";

		size_t start_pos = 0;
		if (expression.find(plus_expr) != expression.npos) {
			start_pos = expression.find(plus_expr) + plus_expr.size();
		} else if (expression.find(sub_expr) != expression.npos) {
			start_pos = expression.find(sub_expr) + sub_expr.size();
		}
		
		std::string new_expr = expression.substr(start_pos, expression.size() - start_pos);
		size_t last_pos = new_expr.find(", ");
		new_expr = new_expr.substr(0, last_pos);
		int col_indice =  std::stoi(new_expr);

		if (table_schema[col_indice].id() == cudf::type_id::DURATION_SECONDS) {
			return StringUtil::replace(expression, "000" + interval_expr, interval_expr);
		} else if (table_schema[col_indice].id() == cudf::type_id::DURATION_MICROSECONDS) {
			return StringUtil::replace(expression, "000" + interval_expr, "000000" + interval_expr);
		} else if (table_schema[col_indice].id() == cudf::type_id::DURATION_NANOSECONDS) {
			return StringUtil::replace(expression, "000" + interval_expr, "000000000" + interval_expr);
		} else return expression; // duration ms
	}

	// Literal interval
	if (expression.find("$") == expression.npos && expression.find("000:INTERVAL") != expression.npos) {
		return StringUtil::replace(expression, "000" + interval_expr, interval_expr);
	}

	return expression;
}

// For this function `indices` vector starts empty
// inputs: