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.Enumeration;
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 Enumeration} interface implementers.
066: * </p> <p>Using the model as a collection model is NOT thread-safe, as
067: * enumerations are inherently not thread-safe.
068: * Further, you can iterate over it only once. Attempts to call the
069: * {@link #iterator()} method after it was already driven to the end once will
070: * throw an exception.</p>
071: * @author Attila Szegedi
072: * @version $Id: EnumerationModel.java,v 1.24 2003/06/03 13:21:32 szegedia Exp $
073: */
074:
075: public class EnumerationModel extends BeanModel implements
076: TemplateModelIterator, TemplateCollectionModel {
077: private boolean accessed = false;
078:
079: /**
080: * Creates a new model that wraps the specified enumeration object.
081: * @param enumeration the enumeration object to wrap into a model.
082: * @param wrapper the {@link BeansWrapper} associated with this model.
083: * Every model has to have an associated {@link BeansWrapper} instance. The
084: * model gains many attributes from its wrapper, including the caching
085: * behavior, method exposure level, method-over-item shadowing policy etc.
086: */
087: public EnumerationModel(Enumeration enumeration,
088: BeansWrapper wrapper) {
089: super (enumeration, wrapper);
090: }
091:
092: /**
093: * This allows the enumeration to be used in a <tt><foreach></tt> block.
094: * @return "this"
095: */
096: public TemplateModelIterator iterator()
097: throws TemplateModelException {
098: synchronized (this ) {
099: if (accessed) {
100: throw new TemplateModelException(
101: "This collection is stateful and can not be iterated over the"
102: + " second time.");
103: }
104: accessed = true;
105: }
106: return this ;
107: }
108:
109: /**
110: * Calls underlying {@link Enumeration#nextElement()}.
111: */
112: public boolean hasNext() {
113: return ((Enumeration) object).hasMoreElements();
114: }
115:
116: /**
117: * Calls underlying {@link Enumeration#nextElement()} and wraps the result.
118: */
119: public TemplateModel next() throws TemplateModelException {
120: try {
121: return wrap(((Enumeration) object).nextElement());
122: } catch (NoSuchElementException e) {
123: throw new TemplateModelException(
124: "No more elements in the enumeration.");
125: }
126: }
127:
128: /**
129: * Returns {@link Enumeration#hasMoreElements()}. Therefore, an
130: * enumeration that has no more element evaluates to false, and an
131: * enumeration that has further elements evaluates to true.
132: */
133: public boolean getAsBoolean() {
134: return hasNext();
135: }
136: }
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