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Java > Open Source Codes > freemarker > core > Identifier


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.
16  *
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.
32  *
33  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
34  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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45  * ====================================================================
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47  * This software consists of voluntary contributions made by many
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 freemarker.template.*;
56
57 /**
58  * A reference to a top-level variable
59  */
60 final class Identifier extends Expression {
61
62     private final String JavaDoc name;
63
64     Identifier(String JavaDoc name) {
65         this.name = name;
66     }
67
68     TemplateModel _getAsTemplateModel(Environment env) throws TemplateException {
69         try {
70             return env.getVariable(name);
71         } catch (NullPointerException JavaDoc e) {
72             if (env == null) {
73                 throw new TemplateException("Variables are not available "
74                 + "(certainly you are in a parse-time executed directive). The name of the variable "
75                 + "you tried to read: " + name, null);
76             } else {
77                 throw e;
78             }
79         }
80     }
81
82     public String JavaDoc toString() {
83         return name;
84     }
85
86     public String JavaDoc getCanonicalForm() {
87         return name;
88     }
89
90     boolean isLiteral() {
91         return false;
92     }
93
94     Expression _deepClone(String JavaDoc name, Expression subst) {
95         if(this.name.equals(name)) {
96             return subst.deepClone(null, null);
97         }
98         return new Identifier(this.name);
99     }
100
101 }
102
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