class FilterTypeValidator {

  public void validateFilterExpression(final Expression exp) {
    final SqlType type = getExpressionReturnType(exp);
    if (!SqlTypes.BOOLEAN.equals(type)) {
      throw new KsqlException("Type error in " + filterType.name() + " expression: "
          + "Should evaluate to boolean but is " + exp.toString()
          + " (" + type.toString(FormatOptions.none()) + ") instead.");
    }
  }

  public  FilterTypeValidator(
      final LogicalSchema schema,
      final FunctionRegistry functionRegistry,
      final FilterType filterType
  );

}