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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  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  package org.apache.commons.scxml.model;
18  
19  import java.util.ArrayList;
20  import java.util.Collection;
21  import java.util.Iterator;
22  import java.util.List;
23  
24  import org.apache.commons.logging.Log;
25  import org.apache.commons.scxml.Context;
26  import org.apache.commons.scxml.ErrorReporter;
27  import org.apache.commons.scxml.Evaluator;
28  import org.apache.commons.scxml.EventDispatcher;
29  import org.apache.commons.scxml.SCInstance;
30  import org.apache.commons.scxml.SCXMLExpressionException;
31  
32  /***
33   * The class in this SCXML object model that corresponds to the
34   * <if> SCXML element, which serves as a container for conditionally
35   * executed elements. <else> and <elseif> can optionally
36   * appear within an <if> as immediate children, and serve to partition
37   * the elements within an <if>.
38   *
39   */
40  public class If extends Action {
41  
42      /***
43       * Serial version UID.
44       */
45      private static final long serialVersionUID = 1L;
46  
47      /***
48       * An conditional expression which can be evaluated to true or false.
49       */
50      private String cond;
51  
52      /***
53       * The set of executable elements (those that inheriting from
54       * Action) that are contained in this <if> element.
55       */
56      private List actions;
57  
58      /***
59       * The boolean value that dictates whether the particular child action
60       * should be executed.
61       */
62      private boolean execute;
63  
64      /***
65       * Constructor.
66       */
67      public If() {
68          super();
69          this.actions = new ArrayList();
70          this.execute = false;
71      }
72  
73      /***
74       * Get the executable actions contained in this <if>.
75       *
76       * @return Returns the actions.
77       */
78      public final List getActions() {
79          return actions;
80      }
81  
82      /***
83       * Add an Action to the list of executable actions contained in
84       * this <if>.
85       *
86       * @param action The action to add.
87       */
88      public final void addAction(final Action action) {
89          if (action != null) {
90              this.actions.add(action);
91          }
92      }
93  
94      /***
95       * Get the conditional expression.
96       *
97       * @return Returns the cond.
98       */
99      public final String getCond() {
100         return cond;
101     }
102 
103     /***
104      * Set the conditional expression.
105      *
106      * @param cond The cond to set.
107      */
108     public final void setCond(final String cond) {
109         this.cond = cond;
110     }
111 
112     /***
113      * {@inheritDoc}
114      */
115     public void execute(final EventDispatcher evtDispatcher,
116             final ErrorReporter errRep, final SCInstance scInstance,
117             final Log appLog, final Collection derivedEvents)
118     throws ModelException, SCXMLExpressionException {
119         State parentState = getParentState();
120         Context ctx = scInstance.getContext(parentState);
121         Evaluator eval = scInstance.getEvaluator();
122         ctx.setLocal(getNamespacesKey(), getNamespaces());
123         execute = eval.evalCond(ctx, cond).booleanValue();
124         ctx.setLocal(getNamespacesKey(), null);
125         // The "if" statement is a "container"
126         for (Iterator ifiter = actions.iterator(); ifiter.hasNext();) {
127             Action aa = (Action) ifiter.next();
128             if (execute && !(aa instanceof ElseIf)
129                     && !(aa instanceof Else)) {
130                 aa.execute(evtDispatcher, errRep, scInstance, appLog,
131                     derivedEvents);
132             } else if (execute
133                     && (aa instanceof ElseIf || aa instanceof Else)) {
134                 break;
135             } else if (aa instanceof Else) {
136                 execute = true;
137             } else if (aa instanceof ElseIf) {
138                 ctx.setLocal(getNamespacesKey(), getNamespaces());
139                 execute = eval.evalCond(ctx, ((ElseIf) aa).getCond())
140                         .booleanValue();
141                 ctx.setLocal(getNamespacesKey(), null);
142             }
143         }
144     }
145 
146 }
147