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1   /*
2    * Copyright (c) 2010.  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.literal;
22  
23  import org.apache.expreval.expr.node.GenericValue;
24  import org.apache.expreval.expr.node.ObjectValue;
25  
26  import java.io.Serializable;
27  
28  public class NullLiteral extends GenericLiteral<Serializable> implements ObjectValue {
29  
30      public NullLiteral() {
31          super(null);
32      }
33  
34      protected Class<? extends GenericValue> getReturnType() {
35          return ObjectValue.class;
36      }
37  
38      public String asString() {
39          return "NULL";
40      }
41  }