func DivideOperator(elems []*parser.Value, fields []string, point *protocol.Point) (*protocol.FieldValue, error) {
	leftValue, err := GetValue(elems[0], fields, point)
	if err != nil {
		return nil, err
	}
	rightValues, err := GetValue(elems[1], fields, point)
	if err != nil {
		return nil, err
	}
	left, right, valueType := common.CoerceValues(leftValue, rightValues)
	switch valueType {
	case common.TYPE_DOUBLE:
		value := left.(float64) / right.(float64)
		return &protocol.FieldValue{DoubleValue: &value}, nil
	case common.TYPE_INT:
		r := right.(int64)
		// prevent integer division by zero (i.e., panic)
		if r == 0 {
			l := left.(int64)
			var value float64
			if l == 0 {
				value = math.NaN()
			} else {
				value = math.Inf(1)
			}
			return &protocol.FieldValue{DoubleValue: &value}, nil
		} else {
			value := left.(int64) / r
			return &protocol.FieldValue{Int64Value: &value}, nil
		}
	}
	return nil, fmt.Errorf("/ operator doesn't work with %v types", valueType)
}
func EqualityOperator(leftValue, rightValue *protocol.FieldValue) (OperatorResult, error) {
	v1, v2, cType := common.CoerceValues(leftValue, rightValue)

	switch cType {
	case common.TYPE_STRING:
		if v1.(string) == v2.(string) {
			return MATCH, nil
		}
		return NO_MATCH, nil
	case common.TYPE_INT:
		if v1.(int64) == v2.(int64) {
			return MATCH, nil
		}
		return NO_MATCH, nil
	case common.TYPE_DOUBLE:
		if v1.(float64) == v2.(float64) {
			return MATCH, nil
		}
		return NO_MATCH, nil
	case common.TYPE_BOOL:
		if v1.(bool) == v2.(bool) {
			return MATCH, nil
		}
		return NO_MATCH, nil
	default:
		return INVALID, nil
	}
}
func InOperator(leftValue *protocol.FieldValue, rightValue []*protocol.FieldValue) (OperatorResult, error) {
	for _, v := range rightValue {
		v1, v2, cType := common.CoerceValues(leftValue, v)

		var result bool

		switch cType {
		case common.TYPE_STRING:
			result = v1.(string) == v2.(string)
		case common.TYPE_INT:
			result = v1.(int64) == v2.(int64)
		case common.TYPE_DOUBLE:
			result = v1.(float64) == v2.(float64)
		case common.TYPE_BOOL:
			result = v1.(bool) == v2.(bool)
		default:
			return INVALID, nil
		}

		if result {
			return MATCH, nil
		}
	}

	return NO_MATCH, nil
}
func RegexMatcherOperator(leftValue, rightValue *protocol.FieldValue) (OperatorResult, error) {
	v1, v2, cType := common.CoerceValues(leftValue, rightValue)

	switch cType {
	case common.TYPE_STRING:
		// TODO: assume that the regex is valid
		if ok, _ := regexp.MatchString(v2.(string), v1.(string)); ok {
			return MATCH, nil
		}
		return NO_MATCH, nil
	default:
		return INVALID, nil
	}
}
func MultiplyOperator(elems []*parser.Value, fields []string, point *protocol.Point) (*protocol.FieldValue, error) {
	leftValue, err := GetValue(elems[0], fields, point)
	if err != nil {
		return nil, err
	}
	rightValues, err := GetValue(elems[1], fields, point)
	if err != nil {
		return nil, err
	}
	left, right, valueType := common.CoerceValues(leftValue, rightValues)
	switch valueType {
	case common.TYPE_DOUBLE:
		value := left.(float64) * right.(float64)
		return &protocol.FieldValue{DoubleValue: &value}, nil
	case common.TYPE_INT:
		value := left.(int64) * right.(int64)
		return &protocol.FieldValue{Int64Value: &value}, nil
	}
	return nil, fmt.Errorf("* operator doesn't work with %v types", valueType)
}