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1   /*
2    * Copyright 2002,2004 The Apache Software Foundation.
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.apache.commons.jelly.tags.core;
17  
18  import org.apache.commons.jelly.JellyTagException;
19  import org.apache.commons.jelly.MissingAttributeException;
20  import org.apache.commons.jelly.TagSupport;
21  import org.apache.commons.jelly.XMLOutput;
22  import org.apache.commons.jelly.expression.Expression;
23  
24  
25  /***
26   * Executes the child <case> tag whose value equals my on attribute.
27   * Executes a child <default> tag when present and no <case> tag has
28   * yet matched.
29   *
30   * @see CaseTag
31   * @see DefaultTag
32   *
33   * @author Rodney Waldhoff
34   * @version $Revision: 155420 $ $Date: 2005-02-26 14:06:03 +0100 (Sat, 26 Feb 2005) $
35   */
36  public class SwitchTag extends TagSupport {
37  
38      public SwitchTag() {
39      }
40  
41      // Tag interface
42      //-------------------------------------------------------------------------
43  
44      /***
45       * Sets the value to switch on.
46       * Note that the {@link Expression} is evaluated only once, when the
47       * <switch> tag is evaluated.
48       * @param on the value to switch on
49       */
50      public void setOn(Expression on) {
51          this.on = on;
52      }
53  
54      public void doTag(XMLOutput output) throws MissingAttributeException, JellyTagException {
55          this.defaultEncountered = false;
56          this.someCaseMatched = false;
57          this.fallingThru = false;
58                  
59          if(null == on) {
60              throw new MissingAttributeException("on");
61          } else {
62              value = on.evaluate(context);
63              invokeBody(output);
64          }
65      }
66  
67      // Protected properties
68      //-------------------------------------------------------------------------
69      protected boolean hasSomeCaseMatched() {
70          return this.someCaseMatched;
71      }
72  
73      protected void caseMatched() {
74          this.someCaseMatched = true;
75      }
76  
77      protected boolean isFallingThru() {
78          return this.fallingThru;
79      }
80  
81      protected void setFallingThru(boolean fallingThru) {
82          this.fallingThru = fallingThru;
83      }
84  
85      protected Object getValue() {
86          return value;
87      }
88  
89      protected boolean hasDefaultBeenEncountered() {
90          return defaultEncountered;
91      }
92  
93      protected void defaultEncountered() {
94          this.defaultEncountered = true;
95      }
96  
97      // Attributes
98      //-------------------------------------------------------------------------
99      private boolean someCaseMatched = false;
100     private boolean fallingThru = false;
101     private boolean defaultEncountered = false;
102     private Expression on = null;
103     private Object value = null;
104 
105 }