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1   /**
2    * Copyright (c) 2008-2011, 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  
17  package org.yaml.snakeyaml.issues.issue94;
18  
19  import static org.junit.Assert.assertEquals;
20  
21  import org.junit.Test;
22  import org.yaml.snakeyaml.Yaml;
23  import org.yaml.snakeyaml.constructor.AbstractConstruct;
24  import org.yaml.snakeyaml.constructor.Construct;
25  import org.yaml.snakeyaml.constructor.Constructor;
26  import org.yaml.snakeyaml.nodes.Node;
27  
28  public class ChangeRuntimeClassTest {
29  
30      @Test
31      public void testWithGlobalTag() {
32          String yamlText = "!!org.yaml.snakeyaml.issues.issue94.Entity\n" + "name: Matt\n"
33                  + "nickName: Java\n";
34  
35          // Now here that I would like to somehow intercept the constructor of
36          // SnakeYaml and give it
37          // an fresh instance of EntityLoadingProxy(); based on today's
38          // temperature, so to speak...
39          // that is un-preditable statically which proxy I will give it.
40  
41          Yaml yaml = new Yaml(new MyConstructor());
42  
43          Entity loadedEntity = null;
44          loadedEntity = (Entity) yaml.load(yamlText);
45  
46          assertEquals("Matt", loadedEntity.getName());
47  
48          // The expectation below is from having intercepted setNickName() with
49          // the artifical subclass and
50          // performed the calculation.
51          assertEquals("JJ-Java", loadedEntity.getNickName());
52          assertEquals(EntityLoadingProxy.class, loadedEntity.getClass());
53      }
54  
55      @Test
56      public void testNoTag() {
57          String yamlText = "name: Matt\n" + "nickName: Java\n";
58          Yaml yaml = new Yaml(new MyConstructor(Entity.class));
59          Entity loadedEntity = null;
60          loadedEntity = (Entity) yaml.load(yamlText);
61          assertEquals("Matt", loadedEntity.getName());
62          assertEquals("JJ-Java", loadedEntity.getNickName());
63      }
64  
65      /**
66       * @see Constructor.ConstructYamlObject
67       */
68      private class MyConstructor extends Constructor {
69          public MyConstructor() {
70              super();
71              this.yamlConstructors.put(null, new ConstructProxy());
72          }
73  
74          public MyConstructor(Class<?> clazz) {
75              super(clazz);
76              this.yamlConstructors.put(null, new ConstructProxy());
77          }
78  
79          private class ConstructProxy extends AbstractConstruct {
80              private Construct getConstructor(Node node) {
81                  Class<?> cl = getClassForNode(node);
82                  if (cl.equals(Entity.class) && true) {
83                      // today's temperature is high :)
84                      cl = EntityLoadingProxy.class;
85                  }
86                  node.setType(cl);
87                  // call the constructor as if the runtime class is defined
88                  Construct constructor = yamlClassConstructors.get(node.getNodeId());
89                  return constructor;
90              }
91  
92              public Object construct(Node node) {
93                  return getConstructor(node).construct(node);
94              }
95          }
96      }
97  }