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1   /*
2    * Copyright (c) 2011.  The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  
21  package org.apache.expreval.expr.nullcomp;
22  
23  import org.apache.expreval.client.NullColumnValueException;
24  import org.apache.expreval.client.ResultMissingColumnException;
25  import org.apache.expreval.expr.ExpressionType;
26  import org.apache.expreval.expr.NotValue;
27  import org.apache.expreval.expr.node.BooleanValue;
28  import org.apache.expreval.expr.node.GenericValue;
29  import org.apache.hadoop.hbase.hbql.client.HBqlException;
30  import org.apache.hadoop.hbase.hbql.impl.HConnectionImpl;
31  
32  public abstract class GenericNullCompare extends NotValue<GenericNullCompare> implements BooleanValue {
33  
34      protected GenericNullCompare(final ExpressionType type, final boolean not, final GenericValue arg0) {
35          super(type, not, arg0);
36      }
37  
38      public String asString() {
39          return this.getExprArg(0).asString() + " IS" + notAsString() + " NULL";
40      }
41  
42      public Boolean getValue(final HConnectionImpl conn, final Object object) throws HBqlException,
43                                                                                      ResultMissingColumnException {
44          boolean retval;
45          try {
46              final Object val = this.getExprArg(0).getValue(conn, object);
47              retval = (val == null);
48          }
49          catch (NullColumnValueException e) {
50              retval = true;
51          }
52          return (this.isNot()) ? !retval : retval;
53      }
54  }