| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| package freemarker.template; |
| |
| import java.io.Serializable; |
| import java.util.Collection; |
| import java.util.Iterator; |
| |
| /** |
| * A simple implementation of {@link TemplateCollectionModel}. |
| * It's able to wrap <tt>java.util.Iterator</tt>-s and <tt>java.util.Collection</tt>-s. |
| * If you wrap an <tt>Iterator</tt>, the variable can be <#list>-ed only once! |
| * |
| * <p>Consider using {@link SimpleSequence} instead of this class if you want to wrap <tt>Iterator</tt>s. |
| * <tt>SimpleSequence</tt> will read all elements of the <tt>Iterator</tt>, and store them in a <tt>List</tt> |
| * (this may cause too high resource consumption in some applications), so you can list the variable |
| * for unlimited times. Also, if you want to wrap <tt>Collection</tt>s, and then list the resulting |
| * variable for many times, <tt>SimpleSequence</tt> may gives better performance, as the |
| * wrapping of non-<tt>TemplateModel</tt> objects happens only once. |
| * |
| * <p>This class is thread-safe. The returned {@link TemplateModelIterator}-s |
| * are <em>not</em> thread-safe. |
| */ |
| public class SimpleCollection extends WrappingTemplateModel |
| implements TemplateCollectionModel, Serializable { |
| |
| private boolean iteratorOwned; |
| private final Iterator iterator; |
| private final Iterable iterable; |
| |
| /** |
| * @deprecated Use {@link #SimpleCollection(Iterator, ObjectWrapper)} |
| */ |
| @Deprecated |
| public SimpleCollection(Iterator iterator) { |
| this.iterator = iterator; |
| iterable = null; |
| } |
| |
| /** |
| * @deprecated Use {@link #SimpleCollection(Iterable, ObjectWrapper)} instead. |
| */ |
| @Deprecated |
| public SimpleCollection(Iterable iterable) { |
| this.iterable = iterable; |
| iterator = null; |
| } |
| |
| /** |
| * Same as {@link SimpleCollection#SimpleCollection(Iterable)}; kept for binary compatibility. |
| * |
| * @deprecated Use {@link #SimpleCollection(Iterable, ObjectWrapper)} instead. |
| */ |
| @Deprecated |
| public SimpleCollection(Collection collection) { |
| this((Iterable) collection); |
| } |
| |
| /** |
| * Same as {@link SimpleCollection#SimpleCollection(Iterable, ObjectWrapper)}; kept for binary compatibility. |
| */ |
| public SimpleCollection(Collection collection, ObjectWrapper wrapper) { |
| this((Iterable) collection, wrapper); |
| } |
| |
| public SimpleCollection(Iterator iterator, ObjectWrapper wrapper) { |
| super(wrapper); |
| this.iterator = iterator; |
| iterable = null; |
| } |
| |
| /** |
| * @param iterable Note that this was a {@link Collection} before 2.3.27, not an {@link Iterable} |
| */ |
| public SimpleCollection(Iterable iterable, ObjectWrapper wrapper) { |
| super(wrapper); |
| this.iterable = iterable; |
| iterator = null; |
| } |
| |
| /** |
| * Retrieves a template model iterator that is used to iterate over the elements in this collection. |
| * |
| * <p>When you wrap an <tt>Iterator</tt> and you get <tt>TemplateModelIterator</tt> for multiple times, |
| * only on of the returned <tt>TemplateModelIterator</tt> instances can be really used. When you have called a |
| * method of a <tt>TemplateModelIterator</tt> instance, all other instance will throw a |
| * <tt>TemplateModelException</tt> when you try to call their methods, since the wrapped <tt>Iterator</tt> |
| * can't return the first element anymore. |
| */ |
| public TemplateModelIterator iterator() { |
| return iterator != null |
| ? new SimpleTemplateModelIterator(iterator, false) |
| : new SimpleTemplateModelIterator(iterable.iterator(), true); |
| } |
| |
| /** |
| * Wraps an {@link Iterator}; not thread-safe. The encapsulated {@link Iterator} may be accessible from multiple |
| * threads (as multiple {@link SimpleTemplateModelIterator} instance can wrap the same {@link Iterator} instance), |
| * but if the {@link Iterator} was marked in the constructor as shared, the first thread which uses the |
| * {@link Iterator} will monopolize that. |
| */ |
| private class SimpleTemplateModelIterator implements TemplateModelIterator { |
| |
| private final Iterator iterator; |
| private boolean iteratorOwnedByMe; |
| |
| SimpleTemplateModelIterator(Iterator iterator, boolean iteratorOwnedByMe) { |
| this.iterator = iterator; |
| this.iteratorOwnedByMe = iteratorOwnedByMe; |
| } |
| |
| public TemplateModel next() throws TemplateModelException { |
| if (!iteratorOwnedByMe) { |
| synchronized (SimpleCollection.this) { |
| checkIteratorOwned(); |
| iteratorOwned = true; |
| iteratorOwnedByMe = true; |
| } |
| } |
| |
| if (!iterator.hasNext()) { |
| throw new TemplateModelException("The collection has no more items."); |
| } |
| |
| Object value = iterator.next(); |
| return value instanceof TemplateModel ? (TemplateModel) value : wrap(value); |
| } |
| |
| public boolean hasNext() throws TemplateModelException { |
| // Calling hasNext may looks safe, but I have met sync. problems. |
| if (!iteratorOwnedByMe) { |
| synchronized (SimpleCollection.this) { |
| checkIteratorOwned(); |
| } |
| } |
| |
| return iterator.hasNext(); |
| } |
| |
| private void checkIteratorOwned() throws TemplateModelException { |
| if (iteratorOwned) { |
| throw new TemplateModelException( |
| "This collection value wraps a java.util.Iterator, thus it can be listed only once."); |
| } |
| } |
| |
| } |
| |
| } |