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Java > Open Source Codes > org > apache > el > lang > VariableMapperFactory


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18 package org.apache.el.lang;
19
20 import javax.el.ValueExpression;
21 import javax.el.VariableMapper;
22
23 public class VariableMapperFactory extends VariableMapper {
24
25     private final VariableMapper target;
26     private VariableMapper momento;
27     
28     public VariableMapperFactory(VariableMapper target) {
29         if (target == null) {
30             throw new NullPointerException JavaDoc("Target VariableMapper cannot be null");
31         }
32         this.target = target;
33     }
34     
35     public VariableMapper create() {
36         return this.momento;
37     }
38
39     public ValueExpression resolveVariable(String JavaDoc variable) {
40         ValueExpression expr = this.target.resolveVariable(variable);
41         if (expr != null) {
42             if (this.momento == null) {
43                 this.momento = new VariableMapperImpl();
44             }
45             this.momento.setVariable(variable, expr);
46         }
47         return expr;
48     }
49
50     public ValueExpression setVariable(String JavaDoc variable, ValueExpression expression) {
51         throw new UnsupportedOperationException JavaDoc("Cannot Set Variables on Factory");
52     }
53 }
54
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