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1   /**
2    * Copyright (c) 2008-2012, http://www.snakeyaml.org
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.yaml.snakeyaml.issues.issue94;
17  
18  import static org.junit.Assert.assertEquals;
19  
20  import org.junit.Test;
21  import org.yaml.snakeyaml.Yaml;
22  import org.yaml.snakeyaml.constructor.AbstractConstruct;
23  import org.yaml.snakeyaml.constructor.Construct;
24  import org.yaml.snakeyaml.constructor.Constructor;
25  import org.yaml.snakeyaml.nodes.Node;
26  
27  public class ChangeRuntimeClassTest {
28  
29      @Test
30      public void testWithGlobalTag() {
31          String yamlText = "!!org.yaml.snakeyaml.issues.issue94.Entity\n" + "name: Matt\n"
32                  + "nickName: Java\n";
33  
34          // Now here that I would like to somehow intercept the constructor of
35          // SnakeYaml and give it
36          // an fresh instance of EntityLoadingProxy(); based on today's
37          // temperature, so to speak...
38          // that is un-preditable statically which proxy I will give it.
39  
40          Yaml yaml = new Yaml(new MyConstructor());
41  
42          Entity loadedEntity = null;
43          loadedEntity = (Entity) yaml.load(yamlText);
44  
45          assertEquals("Matt", loadedEntity.getName());
46  
47          // The expectation below is from having intercepted setNickName() with
48          // the artifical subclass and
49          // performed the calculation.
50          assertEquals("JJ-Java", loadedEntity.getNickName());
51          assertEquals(EntityLoadingProxy.class, loadedEntity.getClass());
52      }
53  
54      @Test
55      public void testNoTag() {
56          String yamlText = "name: Matt\n" + "nickName: Java\n";
57          Yaml yaml = new Yaml(new MyConstructor(Entity.class));
58          Entity loadedEntity = null;
59          loadedEntity = (Entity) yaml.load(yamlText);
60          assertEquals("Matt", loadedEntity.getName());
61          assertEquals("JJ-Java", loadedEntity.getNickName());
62      }
63  
64      /**
65       * @see Constructor.ConstructYamlObject
66       */
67      private class MyConstructor extends Constructor {
68          public MyConstructor() {
69              super();
70              this.yamlConstructors.put(null, new ConstructProxy());
71          }
72  
73          public MyConstructor(Class<?> clazz) {
74              super(clazz);
75              this.yamlConstructors.put(null, new ConstructProxy());
76          }
77  
78          private class ConstructProxy extends AbstractConstruct {
79              private Construct getConstructor(Node node) {
80                  Class<?> cl = getClassForNode(node);
81                  if (cl.equals(Entity.class) && true) {
82                      // today's temperature is high :)
83                      cl = EntityLoadingProxy.class;
84                  }
85                  node.setType(cl);
86                  // call the constructor as if the runtime class is defined
87                  Construct constructor = yamlClassConstructors.get(node.getNodeId());
88                  return constructor;
89              }
90  
91              public Object construct(Node node) {
92                  return getConstructor(node).construct(node);
93              }
94          }
95      }
96  }