content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to you under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.calcite.rel;
  
  /**
   * Exception that indicates that a relational expression would be invalid
   * with given parameters.
   *
   * <p>This exception is thrown by the constructor of a subclass of
   * {@link RelNode} when given parameters it cannot accept. For example,
   * {@code EnumerableJoinRel} can only implement equi-joins, so its constructor
   * throws {@code InvalidRelException} when given the condition
   * {@code input0.x - input1.y = 2}.
   *
   * <p>Because the exception is checked (i.e. extends {@link Exception} but not
   * {@link RuntimeException}), constructors that throw this exception will
   * declare this exception in their {@code throws} clause, and rules that create
   * those relational expressions will need to handle it. Usually a rule will
   * not take the exception personally, and will fail to match. The burden of
   * checking is removed from the rule, which means less code for the author of
   * the rule to maintain.
   *
   * <p>The caller that receives an {@code InvalidRelException} (typically a rule
   * attempting to create a relational expression) should log it at
   * the DEBUG level.
   */
  public class InvalidRelException extends Exception {
    /**
     * Creates an InvalidRelException.
     */
    public InvalidRelException(String message) {
      super(message);
    }
  
    /**
     * Creates an InvalidRelException with a cause.
     */
    public InvalidRelException(String message, Throwable cause) {
      super(message, cause);
    }
  }
  