NullConverter.java

/*
 * Copyright (C) 2003, 2004 Joe Walnes.
 * Copyright (C) 2006, 2007, 2012, 2014, 2018 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 03. October 2003 by Joe Walnes
 */
package com.thoughtworks.xstream.converters.basic;

import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.mapper.Mapper;


/**
 * Special converter to signify nulls at the root level or in collection types.
 *
 * @author Joe Walnes
 */
public class NullConverter implements Converter {

    @Override
    public boolean canConvert(final Class<?> type) {
        return type == null || Mapper.Null.class.isAssignableFrom(type);
    }

    @Override
    public void marshal(final Object source, final HierarchicalStreamWriter writer, final MarshallingContext context) {
        writer.startNode("null", Mapper.Null.class);
        writer.endNode();
    }

    @Override
    public Object unmarshal(final HierarchicalStreamReader reader, final UnmarshallingContext context) {
        return null;
    }
}