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
36 * DISCLAIMED. IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
37 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
38 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
39 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
40 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
41 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
42 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
43 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 * SUCH DAMAGE.
45 * ====================================================================
46 *
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.ext.beans;
54
55 import java.util.Iterator;
56 import java.util.NoSuchElementException;
57
58 import freemarker.template.TemplateCollectionModel;
59 import freemarker.template.TemplateModel;
60 import freemarker.template.TemplateModelException;
61 import freemarker.template.TemplateModelIterator;
62
63 /**
64 * <p>A class that adds {@link TemplateModelIterator} functionality to the
65 * {@link Iterator} interface implementers.
66 * </p>
67 * <p>It differs from the {@link freemarker.template.SimpleCollection} in that
68 * it inherits from {@link BeanModel}, and therefore you can call methods on
69 * it directly, even to the effect of calling <tt>iterator.remove()</tt> in
70 * the template.</p> <p>Using the model as a collection model is NOT
71 * thread-safe, as iterators are inherently not thread-safe.
72 * Further, you can iterate over it only once. Attempts to call the
73 * {@link #iterator()} method after it was already driven to the end once will
74 * throw an exception.</p>
75 * @author Attila Szegedi
76 * @version $Id: IteratorModel.java,v 1.26 2003/06/03 13:21:32 szegedia Exp $
77 */
78
79 public class IteratorModel
80 extends
81 BeanModel
82 implements
83 TemplateModelIterator,
84 TemplateCollectionModel
85 {
86 private boolean accessed = false;
87
88 /**
89 * Creates a new model that wraps the specified iterator object.
90 * @param iterator the iterator object to wrap into a model.
91 * @param wrapper the {@link BeansWrapper} associated with this model.
92 * Every model has to have an associated {@link BeansWrapper} instance. The
93 * model gains many attributes from its wrapper, including the caching
94 * behavior, method exposure level, method-over-item shadowing policy etc.
95 */
96 public IteratorModel(Iterator iterator, BeansWrapper wrapper)
97 {
98 super(iterator, wrapper);
99 }
100
101 /**
102 * This allows the iterator to be used in a <tt><foreach></tt> block.
103 * @return "this"
104 */
105 public TemplateModelIterator iterator() throws TemplateModelException
106 {
107 synchronized(this) {
108 if(accessed) {
109 throw new TemplateModelException(
110 "This collection is stateful and can not be iterated over the" +
111 " second time.");
112 }
113 accessed = true;
114 }
115 return this;
116 }
117
118 /**
119 * Calls underlying {@link Iterator#hasNext()}.
120 */
121 public boolean hasNext() {
122 return ((Iterator)object).hasNext();
123 }
124
125
126 /**
127 * Calls underlying {@link Iterator#next()} and wraps the result.
128 */
129 public TemplateModel next()
130 throws
131 TemplateModelException
132 {
133 try {
134 return wrap(((Iterator)object).next());
135 }
136 catch(NoSuchElementException e) {
137 throw new TemplateModelException(
138 "No more elements in the iterator.", e);
139 }
140 }
141
142 /**
143 * Returns {@link Iterator#hasNext()}. Therefore, an
144 * iterator that has no more element evaluates to false, and an
145 * iterator that has further elements evaluates to true.
146 */
147 public boolean getAsBoolean() {
148 return hasNext();
149 }
150 }
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