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1   /*
2    *
3    *   Copyright 2005 The Apache Software Foundation.
4    *
5    *  Licensed under the Apache License, Version 2.0 (the "License");
6    *  you may not use this file except in compliance with the License.
7    *  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.commons.scxml.model;
19  
20  import java.util.ArrayList;
21  import java.util.Collection;
22  import java.util.Iterator;
23  import java.util.List;
24  
25  import org.apache.commons.logging.Log;
26  import org.apache.commons.scxml.Context;
27  import org.apache.commons.scxml.ErrorReporter;
28  import org.apache.commons.scxml.Evaluator;
29  import org.apache.commons.scxml.EventDispatcher;
30  import org.apache.commons.scxml.SCInstance;
31  import org.apache.commons.scxml.SCXMLExpressionException;
32  
33  /***
34   * The class in this SCXML object model that corresponds to the
35   * <if> SCXML element, which serves as a container for conditionally
36   * executed elements. <else> and <elseif> can optionally
37   * appear within an <if> as immediate children, and serve to partition
38   * the elements within an <if>.
39   *
40   */
41  public class If extends Action {
42  
43      /***
44       * An conditional expression which can be evaluated to true or false.
45       */
46      private String cond;
47  
48      /***
49       * The set of executable elements (those that inheriting from
50       * Action) that are contained in this <if> element.
51       */
52      private List actions;
53  
54      /***
55       * The boolean value that dictates whether the particular child action
56       * should be executed.
57       */
58      private boolean execute;
59  
60      /***
61       * Constructor.
62       */
63      public If() {
64          super();
65          this.actions = new ArrayList();
66          this.execute = false;
67      }
68  
69      /***
70       * Get the executable actions contained in this <if>.
71       *
72       * @return Returns the actions.
73       */
74      public final List getActions() {
75          return actions;
76      }
77  
78      /***
79       * Add an Action to the list of executable actions contained in
80       * this <if>.
81       *
82       * @param action The action to add.
83       */
84      public final void addAction(final Action action) {
85          if (action != null) {
86              this.actions.add(action);
87          }
88      }
89  
90      /***
91       * Get the conditional expression.
92       *
93       * @return Returns the cond.
94       */
95      public final String getCond() {
96          return cond;
97      }
98  
99      /***
100      * Set the conditional expression.
101      *
102      * @param cond The cond to set.
103      */
104     public final void setCond(final String cond) {
105         this.cond = cond;
106     }
107 
108     /***
109      * {@inheritDoc}
110      */
111     public void execute(final EventDispatcher evtDispatcher,
112             final ErrorReporter errRep, final SCInstance scInstance,
113             final Log appLog, final Collection derivedEvents)
114     throws ModelException, SCXMLExpressionException {
115         State parentState = getParentState();
116         Context ctx = scInstance.getContext(parentState);
117         Evaluator eval = scInstance.getEvaluator();
118         execute = eval.evalCond(ctx, cond).booleanValue();
119         // The "if" statement is a "container"
120         for (Iterator ifiter = actions.iterator(); ifiter.hasNext();) {
121             Action aa = (Action) ifiter.next();
122             if (execute && !(aa instanceof ElseIf)
123                     && !(aa instanceof Else)) {
124                 aa.execute(evtDispatcher, errRep, scInstance, appLog,
125                     derivedEvents);
126             } else if (execute
127                     && (aa instanceof ElseIf || aa instanceof Else)) {
128                 break;
129             } else if (aa instanceof Else) {
130                 execute = true;
131             } else if (aa instanceof ElseIf) {
132                 execute = eval.evalCond(ctx, ((ElseIf) aa).getCond())
133                         .booleanValue();
134             }
135         }
136     }
137 
138 }
139