001: /*
002: * Copyright (c) 2003 The Visigoth Software Society. All rights
003: * reserved.
004: *
005: * Redistribution and use in source and binary forms, with or without
006: * modification, are permitted provided that the following conditions
007: * are met:
008: *
009: * 1. Redistributions of source code must retain the above copyright
010: * notice, this list of conditions and the following disclaimer.
011: *
012: * 2. Redistributions in binary form must reproduce the above copyright
013: * notice, this list of conditions and the following disclaimer in
014: * the documentation and/or other materials provided with the
015: * distribution.
016: *
017: * 3. The end-user documentation included with the redistribution, if
018: * any, must include the following acknowledgement:
019: * "This product includes software developed by the
020: * Visigoth Software Society (http://www.visigoths.org/)."
021: * Alternately, this acknowledgement may appear in the software itself,
022: * if and wherever such third-party acknowledgements normally appear.
023: *
024: * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
025: * project contributors may be used to endorse or promote products derived
026: * from this software without prior written permission. For written
027: * permission, please contact visigoths@visigoths.org.
028: *
029: * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
030: * nor may "FreeMarker" or "Visigoth" appear in their names
031: * without prior written permission of the Visigoth Software Society.
032: *
033: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
034: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
035: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
036: * DISCLAIMED. IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
037: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
038: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
039: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
040: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
041: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
042: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
043: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
044: * SUCH DAMAGE.
045: * ====================================================================
046: *
047: * This software consists of voluntary contributions made by many
048: * individuals on behalf of the Visigoth Software Society. For more
049: * information on the Visigoth Software Society, please see
050: * http://www.visigoths.org/
051: */
052:
053: package freemarker.ext.beans;
054:
055: import java.util.Iterator;
056: import java.util.NoSuchElementException;
057:
058: import freemarker.template.TemplateCollectionModel;
059: import freemarker.template.TemplateModel;
060: import freemarker.template.TemplateModelException;
061: import freemarker.template.TemplateModelIterator;
062:
063: /**
064: * <p>A class that adds {@link TemplateModelIterator} functionality to the
065: * {@link Iterator} interface implementers.
066: * </p>
067: * <p>It differs from the {@link freemarker.template.SimpleCollection} in that
068: * it inherits from {@link BeanModel}, and therefore you can call methods on
069: * it directly, even to the effect of calling <tt>iterator.remove()</tt> in
070: * the template.</p> <p>Using the model as a collection model is NOT
071: * thread-safe, as iterators are inherently not thread-safe.
072: * Further, you can iterate over it only once. Attempts to call the
073: * {@link #iterator()} method after it was already driven to the end once will
074: * throw an exception.</p>
075: * @author Attila Szegedi
076: * @version $Id: IteratorModel.java,v 1.26 2003/06/03 13:21:32 szegedia Exp $
077: */
078:
079: public class IteratorModel extends BeanModel implements
080: TemplateModelIterator, TemplateCollectionModel {
081: private boolean accessed = false;
082:
083: /**
084: * Creates a new model that wraps the specified iterator object.
085: * @param iterator the iterator object to wrap into a model.
086: * @param wrapper the {@link BeansWrapper} associated with this model.
087: * Every model has to have an associated {@link BeansWrapper} instance. The
088: * model gains many attributes from its wrapper, including the caching
089: * behavior, method exposure level, method-over-item shadowing policy etc.
090: */
091: public IteratorModel(Iterator iterator, BeansWrapper wrapper) {
092: super (iterator, wrapper);
093: }
094:
095: /**
096: * This allows the iterator to be used in a <tt><foreach></tt> block.
097: * @return "this"
098: */
099: public TemplateModelIterator iterator()
100: throws TemplateModelException {
101: synchronized (this ) {
102: if (accessed) {
103: throw new TemplateModelException(
104: "This collection is stateful and can not be iterated over the"
105: + " second time.");
106: }
107: accessed = true;
108: }
109: return this ;
110: }
111:
112: /**
113: * Calls underlying {@link Iterator#hasNext()}.
114: */
115: public boolean hasNext() {
116: return ((Iterator) object).hasNext();
117: }
118:
119: /**
120: * Calls underlying {@link Iterator#next()} and wraps the result.
121: */
122: public TemplateModel next() throws TemplateModelException {
123: try {
124: return wrap(((Iterator) object).next());
125: } catch (NoSuchElementException e) {
126: throw new TemplateModelException(
127: "No more elements in the iterator.");
128: }
129: }
130:
131: /**
132: * Returns {@link Iterator#hasNext()}. Therefore, an
133: * iterator that has no more element evaluates to false, and an
134: * iterator that has further elements evaluates to true.
135: */
136: public boolean getAsBoolean() {
137: return hasNext();
138: }
139: }
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