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1   package org.apache.velocity.util.introspection;
2   
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,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.    
20   */
21  
22  import java.util.Iterator;
23  
24  /**
25   * <p>
26   * When the runtime.introspection.uberspect configuration property contains several
27   * uberspector class names, it means those uberspectors will be chained. When an
28   * uberspector in the list other than the leftmost does not implement ChainableUberspector,
29   * then this utility class is used to provide a basic default chaining where the
30   * first non-null result is kept for each introspection call.
31   * </p>
32   * 
33   * @since 1.6
34   * @see ChainableUberspector
35   * @version $Id: LinkingUberspector.java 10959 2008-07-01 00:12:29Z sdumitriu $
36   */
37  public class LinkingUberspector extends AbstractChainableUberspector
38  {
39      private Uberspect leftUberspect;
40      private Uberspect rightUberspect;
41  
42      /**
43       * Constructor that takes the two uberspectors to link
44       */
45      public LinkingUberspector(Uberspect left,Uberspect right) {
46          leftUberspect = left;
47          rightUberspect = right;
48      }
49  
50      /**
51       * {@inheritDoc}
52       * <p>
53       * Init both wrapped uberspectors
54       * </p>
55       * 
56       * @see org.apache.velocity.util.introspection.Uberspect#init()
57       */
58      //@Override
59      public void init()
60      {
61          leftUberspect.init();
62          rightUberspect.init();
63      }
64  
65      /**
66       * {@inheritDoc}
67       * 
68       * @see org.apache.velocity.util.introspection.Uberspect#getIterator(java.lang.Object,
69       *      org.apache.velocity.util.introspection.Info)
70       */
71      //@SuppressWarnings("unchecked")
72      //@Override
73      public Iterator getIterator(Object obj, Info i) throws Exception
74      {
75          Iterator it = leftUberspect.getIterator(obj,i);
76          return it != null ? it : rightUberspect.getIterator(obj,i);
77      }
78  
79      /**
80       * {@inheritDoc}
81       * 
82       * @see org.apache.velocity.util.introspection.Uberspect#getMethod(java.lang.Object, java.lang.String,
83       *      java.lang.Object[], org.apache.velocity.util.introspection.Info)
84       */
85      //@Override
86      public VelMethod getMethod(Object obj, String methodName, Object[] args, Info i)
87          throws Exception
88      {
89          VelMethod method = leftUberspect.getMethod(obj,methodName,args,i);
90          return method != null ? method : rightUberspect.getMethod(obj,methodName,args,i);
91      }
92  
93      /**
94       * {@inheritDoc}
95       * 
96       * @see org.apache.velocity.util.introspection.Uberspect#getPropertyGet(java.lang.Object, java.lang.String,
97       *      org.apache.velocity.util.introspection.Info)
98       */
99      //@Override
100     public VelPropertyGet getPropertyGet(Object obj, String identifier, Info i)
101         throws Exception
102     {
103         VelPropertyGet getter = leftUberspect.getPropertyGet(obj,identifier,i);
104         return getter != null ? getter : rightUberspect.getPropertyGet(obj,identifier,i);
105     }
106 
107     /**
108      * {@inheritDoc}
109      * 
110      * @see org.apache.velocity.util.introspection.Uberspect#getPropertySet(java.lang.Object, java.lang.String,
111      *      java.lang.Object, org.apache.velocity.util.introspection.Info)
112      */
113     //@Override
114     public VelPropertySet getPropertySet(Object obj, String identifier, Object arg, Info i)
115         throws Exception
116     {
117         VelPropertySet setter = leftUberspect.getPropertySet(obj,identifier,arg,i);
118         return setter != null ? setter : rightUberspect.getPropertySet(obj,identifier,arg,i);
119     }
120 }