/*
* Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
*
* Licensed 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.AbstractSequentialList;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
import freemarker.ext.util.WrapperTemplateModel;
import freemarker.template.utility.ObjectWrapperWithAPISupport;
import freemarker.template.utility.RichObjectWrapper;
/**
* Adapts a {@link List} to the corresponding {@link TemplateModel} interface(s), most importantly to
* {@link TemplateSequenceModel}. If you aren't wrapping an already existing {@link List}, but build a sequence
* specifically to be used from a template, also consider using {@link SimpleSequence} (see comparison there).
*
* <p>
* Thread safety: A {@link DefaultListAdapter} is as thread-safe as the {@link List} 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).
*
* <p>
* 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.
*
* @see SimpleSequence
* @see DefaultArrayAdapter
* @see TemplateSequenceModel
*
* @since 2.3.22
*/
public class DefaultListAdapter extends WrappingTemplateModel implements TemplateSequenceModel,
AdapterTemplateModel, WrapperTemplateModel, TemplateModelWithAPISupport, Serializable {
protected final List list;
/**
* Factory method for creating new adapter instances.
*
* @param list
* The list to adapt; can't be {@code null}.
* @param wrapper
* The {@link ObjectWrapper} used to wrap the items in the array.
*/
public static DefaultListAdapter adapt(List list, RichObjectWrapper wrapper) {
// [2.4] DefaultListAdapter should implement TemplateCollectionModelEx, so this choice becomes unnecessary
return list instanceof AbstractSequentialList
? new DefaultListAdapterWithCollectionSupport(list, wrapper)
: new DefaultListAdapter(list, wrapper);
}
private DefaultListAdapter(List list, RichObjectWrapper wrapper) {
super(wrapper);
this.list = list;
}
public TemplateModel get(int index) throws TemplateModelException {
return index >= 0 && index < list.size() ? wrap(list.get(index)) : null;
}
public int size() throws TemplateModelException {
return list.size();
}
public Object getAdaptedObject(Class hint) {
return getWrappedObject();
}
public Object getWrappedObject() {
return list;
}
private static class DefaultListAdapterWithCollectionSupport extends DefaultListAdapter implements
TemplateCollectionModel {
private DefaultListAdapterWithCollectionSupport(List list, RichObjectWrapper wrapper) {
super(list, wrapper);
}
public TemplateModelIterator iterator() throws TemplateModelException {
return new IteratorAdapter(list.iterator(), getObjectWrapper());
}
}
private static class IteratorAdapter implements TemplateModelIterator {
private final Iterator it;
private final ObjectWrapper wrapper;
private IteratorAdapter(Iterator it, ObjectWrapper wrapper) {
this.it = it;
this.wrapper = wrapper;
}
public TemplateModel next() throws TemplateModelException {
try {
return wrapper.wrap(it.next());
} catch (NoSuchElementException e) {
throw new TemplateModelException("The collection has no more items.", e);
}
}
public boolean hasNext() throws TemplateModelException {
return it.hasNext();
}
}
public TemplateModel getAPI() throws TemplateModelException {
return ((ObjectWrapperWithAPISupport) getObjectWrapper()).wrapAsAPI(list);
}
}