/*
* Copyright (C) 2003, 2004, 2005 Joe Walnes.
* Copyright (C) 2006, 2007, 2008, 2009, 2013, 2014 XStream Committers.
* All rights reserved.
*
* The software in this package is published under the terms of the BSD
* style license a copy of which has been included with this distribution in
* the LICENSE.txt file.
*
* Created on 26. September 2003 by Joe Walnes
*/
package com.thoughtworks.xstream.converters.collections;
import com.thoughtworks.xstream.converters.ConversionException;
import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.core.util.HierarchicalStreams;
import com.thoughtworks.xstream.io.ExtendedHierarchicalStreamWriterHelper;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.mapper.Mapper;
/**
* Base helper class for converters that need to handle collections of items (arrays, Lists, Maps, etc).
* <p>
* Typically, subclasses of this will converter the outer structure of the collection, loop through the contents and
* call readItem() or writeItem() for each item.
* </p>
*
* @author Joe Walnes
*/
public abstract class AbstractCollectionConverter implements Converter {
private final Mapper mapper;
@Override
public abstract boolean canConvert(Class<?> type);
public AbstractCollectionConverter(final Mapper mapper) {
this.mapper = mapper;
}
protected Mapper mapper() {
return mapper;
}
@Override
public abstract void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context);
@Override
public abstract Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context);
protected void writeItem(final Object item, final MarshallingContext context, final HierarchicalStreamWriter writer) {
// PUBLISHED API METHOD! If changing signature, ensure backwards compatibility.
if (item == null) {
// todo: this is duplicated in TreeMarshaller.start()
final String name = mapper().serializedClass(null);
ExtendedHierarchicalStreamWriterHelper.startNode(writer, name, Mapper.Null.class);
writer.endNode();
} else {
final String name = mapper().serializedClass(item.getClass());
ExtendedHierarchicalStreamWriterHelper.startNode(writer, name, item.getClass());
context.convertAnother(item);
writer.endNode();
}
}
protected Object readItem(final HierarchicalStreamReader reader, final UnmarshallingContext context,
final Object current) {
final Class<?> type = HierarchicalStreams.readClassType(reader, mapper());
return context.convertAnother(current, type);
}
protected Object createCollection(final Class<?> type) {
final Class<?> defaultType = mapper().defaultImplementationOf(type);
try {
return defaultType.newInstance();
} catch (final InstantiationException e) {
throw new ConversionException("Cannot instantiate " + defaultType.getName(), e);
} catch (final IllegalAccessException e) {
throw new ConversionException("Cannot instantiate " + defaultType.getName(), e);
}
}
}