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Java > Open Source Codes > freemarker > template > utility > Constants


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.
28  *
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
35  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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44  * SUCH DAMAGE.
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.template.utility;
54
55 import freemarker.template.SimpleNumber;
56 import freemarker.template.TemplateBooleanModel;
57 import freemarker.template.TemplateCollectionModel;
58 import freemarker.template.TemplateHashModelEx;
59 import freemarker.template.TemplateModel;
60 import freemarker.template.TemplateModelException;
61 import freemarker.template.TemplateModelIterator;
62 import freemarker.template.TemplateNumberModel;
63 import freemarker.template.TemplateScalarModel;
64 import freemarker.template.TemplateSequenceModel;
65
66 /**
67  * Frequently used constant {@link TemplateModel} values.
68  *
69  * <p>These constants should be stored in the {@link TemplateModel}
70  * sub-interfaces, but for bacward compatibility they are stored here instead.
71  * Starting from FreeMarker 2.4 they should be copyed (not moved!) into the
72  * {@link TemplateModel} sub-interfaces, and this class should be marked as
73  * deprecated.</p>
74  *
75  * @version $Id: Constants.java,v 1.2 2004/11/28 12:58:34 ddekany Exp $
76  */
77 public class Constants {
78
79     public static final TemplateBooleanModel TRUE = TemplateBooleanModel.TRUE;
80
81     public static final TemplateBooleanModel FALSE = TemplateBooleanModel.FALSE;
82     
83     public static final TemplateScalarModel EMPTY_STRING = (TemplateScalarModel) TemplateScalarModel.EMPTY_STRING;
84
85     public static final TemplateNumberModel ZERO = new SimpleNumber(0);
86     
87     public static final TemplateNumberModel ONE = new SimpleNumber(1);
88     
89     public static final TemplateNumberModel MINUS_ONE = new SimpleNumber(-1);
90     
91     public static final TemplateModelIterator EMPTY_ITERATOR = new TemplateModelIterator() {
92
93         public TemplateModel next() throws TemplateModelException {
94             throw new TemplateModelException("The collection has no more elements.");
95         }
96
97         public boolean hasNext() throws TemplateModelException {
98             return false;
99         }
100         
101     };
102
103     public static final TemplateCollectionModel EMPTY_COLLECTION = new TemplateCollectionModel() {
104
105         public TemplateModelIterator iterator() throws TemplateModelException {
106             return EMPTY_ITERATOR;
107         }
108         
109     };
110     
111     public static final TemplateSequenceModel EMPTY_SEQUENCE
112             = new TemplateSequenceModel() {
113     
114         public TemplateModel get(int index) throws TemplateModelException {
115             return null;
116         }
117     
118         public int size() throws TemplateModelException {
119             return 0;
120         }
121         
122     };
123     
124     public static final TemplateHashModelEx EMPTY_HASH = new TemplateHashModelEx() {
125
126         public int size() throws TemplateModelException {
127             return 0;
128         }
129
130         public TemplateCollectionModel keys() throws TemplateModelException {
131             return EMPTY_COLLECTION;
132         }
133
134         public TemplateCollectionModel values() throws TemplateModelException {
135             return EMPTY_COLLECTION;
136         }
137
138         public TemplateModel get(String JavaDoc key) throws TemplateModelException {
139             return null;
140         }
141
142         public boolean isEmpty() throws TemplateModelException {
143             return true;
144         }
145         
146     };
147     
148 }
149
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