| /* |
| * 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 org.apache.geode.cache.query.QueryService; |
| import org.apache.geode.cache.query.internal.index.IndexManager; |
| import org.apache.geode.internal.DataSerializableFixedID; |
| import org.apache.geode.internal.Version; |
| |
| /** |
| * A Token representing null. |
| * |
| * @since GemFire cedar |
| * |
| */ |
| public class NullToken implements DataSerializableFixedID, Comparable { |
| |
| public NullToken() { |
| Support.assertState(IndexManager.NULL == null, "NULL constant already instantiated"); |
| } |
| |
| @Override |
| public int compareTo(Object o) { |
| // A Null token is equal to other Null token and less than any other object |
| // except UNDEFINED |
| if (o.equals(this)) { |
| return 0; |
| } else if (o.equals(QueryService.UNDEFINED)) { |
| return 1; |
| } else { |
| return -1; |
| } |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| return o instanceof NullToken; |
| } |
| |
| @Override |
| public int hashCode() { |
| return NullToken.class.hashCode(); |
| } |
| |
| @Override |
| public int getDSFID() { |
| return NULL_TOKEN; |
| } |
| |
| @Override |
| public void toData(DataOutput out) throws IOException { |
| |
| } |
| |
| @Override |
| public void fromData(DataInput in) throws IOException, ClassNotFoundException {} |
| |
| @Override |
| public Version[] getSerializationVersions() { |
| return null; |
| } |
| } |