| /* |
| * 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.geode.cache.query.internal; |
| |
| import java.io.DataInput; |
| import java.io.DataOutput; |
| import java.io.IOException; |
| import java.io.Serializable; |
| |
| import org.apache.geode.cache.query.QueryService; |
| import org.apache.geode.internal.DataSerializableFixedID; |
| import org.apache.geode.internal.Version; |
| |
| /** |
| * An UNDEFINED value is the result of accessing an attribute of a null-valued attribute. If you |
| * access an attribute that has an explicit value of null, then it is not undefined. For example, if |
| * a query accesses the attribute address.city and address is null, then the result is undefined. If |
| * the query accesses address, then the result is not undefined, it is null. |
| * |
| * @version $Revision: 1.1 $ |
| * |
| */ |
| |
| public class Undefined implements DataSerializableFixedID, Comparable, Serializable { |
| |
| private static final long serialVersionUID = 6643107525908324141L; |
| |
| public Undefined() { |
| Support.assertState(QueryService.UNDEFINED == null, "UNDEFINED constant already instantiated"); |
| |
| // org.apache.persistence.CanonicalizationHelper |
| // .putCanonicalObj("com/gemstone/persistence/query/QueryService.UNDEFINED", |
| // this); |
| } |
| |
| @Override |
| public String toString() { |
| return "UNDEFINED"; |
| } |
| |
| @Override |
| public int getDSFID() { |
| return UNDEFINED; |
| } |
| |
| @Override |
| public void fromData(DataInput in) throws IOException, ClassNotFoundException { |
| // Serialized simply as a one-byte class id, as a class well known to |
| // DataSerializer |
| } |
| |
| @Override |
| public void toData(DataOutput out) throws IOException {} |
| |
| @Override |
| public int compareTo(Object o) { |
| // An Undefined is equal to other Undefined and less than any other object |
| if (o instanceof Undefined) { |
| return 0; |
| } else { |
| return -1; |
| } |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| return (o instanceof Undefined); |
| } |
| |
| @Override |
| public int hashCode() { |
| return Undefined.class.hashCode(); |
| } |
| |
| |
| |
| @Override |
| public Version[] getSerializationVersions() { |
| return null; |
| } |
| |
| } |