freemarker.template.DefaultIteratorAdapter Maven / Gradle / Ivy
Show all versions of org.apache.servicemix.bundles.freemarker
/*
* 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.Iterator;
import freemarker.ext.util.WrapperTemplateModel;
import freemarker.template.utility.ObjectWrapperWithAPISupport;
/**
* Adapts an {@link Iterator} to the corresponding {@link TemplateModel} interface(s), most importantly to
* {@link TemplateCollectionModel}. The resulting {@link TemplateCollectionModel} can only be listed (iterated) once.
* If the user tries list the variable for a second time, an exception will be thrown instead of silently gettig an
* empty (or partial) listing.
*
*
* Thread safety: A {@link DefaultListAdapter} is as thread-safe as the array that it wraps is. Normally you only
* have to consider read-only access, as the FreeMarker template language doesn't allow writing these sequences (though
* of course, Java methods called from the template can violate this rule).
*
*
* This adapter is used by {@link DefaultObjectWrapper} if its {@code useAdaptersForCollections} property is
* {@code true}, which is the default when its {@code incompatibleImprovements} property is 2.3.22 or higher.
*
* @since 2.3.22
*/
public class DefaultIteratorAdapter extends WrappingTemplateModel implements TemplateCollectionModel,
AdapterTemplateModel, WrapperTemplateModel, TemplateModelWithAPISupport, Serializable {
@SuppressFBWarnings(value="SE_BAD_FIELD", justification="We hope it's Seralizable")
private final Iterator iterator;
private boolean iteratorOwnedBySomeone;
/**
* Factory method for creating new adapter instances.
*
* @param iterator
* The iterator to adapt; can't be {@code null}.
*/
public static DefaultIteratorAdapter adapt(Iterator iterator, ObjectWrapper wrapper) {
return new DefaultIteratorAdapter(iterator, wrapper);
}
private DefaultIteratorAdapter(Iterator iterator, ObjectWrapper wrapper) {
super(wrapper);
this.iterator = iterator;
}
@Override
public Object getWrappedObject() {
return iterator;
}
@Override
public Object getAdaptedObject(Class hint) {
return getWrappedObject();
}
@Override
public TemplateModelIterator iterator() throws TemplateModelException {
return new SimpleTemplateModelIterator();
}
@Override
public TemplateModel getAPI() throws TemplateModelException {
return ((ObjectWrapperWithAPISupport) getObjectWrapper()).wrapAsAPI(iterator);
}
/**
* Not thread-safe.
*/
private class SimpleTemplateModelIterator implements TemplateModelIterator {
private boolean iteratorOwnedByMe;
@Override
public TemplateModel next() throws TemplateModelException {
if (!iteratorOwnedByMe) {
checkNotOwner();
iteratorOwnedBySomeone = 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);
}
@Override
public boolean hasNext() throws TemplateModelException {
// Calling hasNext may looks safe, but I have met sync. problems.
if (!iteratorOwnedByMe) {
checkNotOwner();
}
return iterator.hasNext();
}
private void checkNotOwner() throws TemplateModelException {
if (iteratorOwnedBySomeone) {
throw new TemplateModelException(
"This collection value wraps a java.util.Iterator, thus it can be listed only once.");
}
}
}
}