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Java > Open Source Codes > freemarker > core > SwitchBlock


1 /*
2  * Copyright (c) 2003 The Visigoth Software Society. All rights
3  * reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  *
12  * 2. Redistributions in binary form must reproduce the above copyright
13  * notice, this list of conditions and the following disclaimer in
14  * the documentation and/or other materials provided with the
15  * distribution.
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17  * 3. The end-user documentation included with the redistribution, if
18  * any, must include the following acknowledgement:
19  * "This product includes software developed by the
20  * Visigoth Software Society (http://www.visigoths.org/)."
21  * Alternately, this acknowledgement may appear in the software itself,
22  * if and wherever such third-party acknowledgements normally appear.
23  *
24  * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
25  * project contributors may be used to endorse or promote products derived
26  * from this software without prior written permission. For written
27  * permission, please contact visigoths@visigoths.org.
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29  * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
30  * nor may "FreeMarker" or "Visigoth" appear in their names
31  * without prior written permission of the Visigoth Software Society.
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45  * ====================================================================
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48  * individuals on behalf of the Visigoth Software Society. For more
49  * information on the Visigoth Software Society, please see
50  * http://www.visigoths.org/
51  */
52
53 package freemarker.core;
54
55 import java.util.*;
56 import java.io.IOException JavaDoc;
57 import freemarker.template.*;
58
59 /**
60  * An instruction representing a switch-case structure.
61  */
62 final class SwitchBlock extends TemplateElement {
63
64     private Case defaultCase;
65     private Expression testExpression;
66
67     /**
68      * @param testExpression the expression to be tested.
69      */
70     SwitchBlock(Expression testExpression) {
71         this.testExpression = testExpression;
72         nestedElements = new LinkedList();
73     }
74
75     /**
76      * @param cas a Case element.
77      */
78     void addCase(Case cas) {
79         if (cas.isDefault) {
80             defaultCase = cas;
81         }
82         nestedElements.add(cas);
83     }
84
85     void accept(Environment env)
86         throws TemplateException, IOException JavaDoc
87     {
88         boolean processedCase = false;
89         Iterator iterator = nestedElements.iterator();
90         try {
91             while (iterator.hasNext()) {
92                 Case cas = (Case)iterator.next();
93                 boolean processCase = false;
94
95                 // Fall through if a previous case tested true.
96 if (processedCase) {
97                     processCase = true;
98                 } else if (!cas.isDefault) {
99                     // Otherwise, if this case isn't the default, test it.
100 ComparisonExpression equalsOp = new ComparisonExpression(testExpression, cas.expression, "==");
101                     processCase = equalsOp.isTrue(env);
102                 }
103                 if (processCase) {
104                     env.visit(cas);
105                     processedCase = true;
106                 }
107             }
108
109             // If we didn't process any nestedElements, and we have a default,
110 // process it.
111 if (!processedCase && defaultCase != null) {
112                 env.visit(defaultCase);
113             }
114         }
115         catch (BreakInstruction.Break br) {}
116     }
117
118     public String JavaDoc getCanonicalForm() {
119         StringBuffer JavaDoc buf = new StringBuffer JavaDoc("<#switch ");
120         buf.append(testExpression.getCanonicalForm());
121         buf.append(">");
122         for (int i = 0; i<nestedElements.size(); i++) {
123             Case cas = (Case) nestedElements.get(i);
124             buf.append(cas.getCanonicalForm());
125         }
126         if (defaultCase != null) {
127             buf.append(defaultCase.getCanonicalForm());
128         }
129         buf.append("</#switch>");
130         return buf.toString();
131     }
132
133     public String JavaDoc getDescription() {
134         return "switch " + testExpression;
135     }
136 }
137
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