/*
* Copyright 2009 Google Inc.
*
* 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 com.google.devtools.depan.eclipse.persist;
import com.google.devtools.depan.model.GraphModel;
import com.google.devtools.depan.model.GraphNode;
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;
/**
* {@code XStream} converter to handle {@code GraphEdge}s. This converter
* assumes that the {@code UnmarshallingContext} has an {@code GraphModel}
* entry that can be retrieved by the {@code GraphModel.class} key.
*
* @author <a href="mailto:leeca@google.com">Lee Carver</a>
*/
public class NodeReferenceConverter implements Converter {
public static final String NODE_REF_TAG = "node-ref";
private final ViewDocumentConverter viewConverter;
/**
* @param viewConverter
*/
public NodeReferenceConverter(ViewDocumentConverter viewConverter) {
this.viewConverter = viewConverter;
}
@Override
@SuppressWarnings("rawtypes") // Parent type uses raw type Class
public boolean canConvert(Class type) {
return GraphNode.class.isAssignableFrom(type);
}
@Override
public void marshal(Object source, HierarchicalStreamWriter writer,
MarshallingContext context) {
context.convertAnother(((GraphNode) source).getId());
}
@Override
public Object unmarshal(HierarchicalStreamReader reader,
UnmarshallingContext context) {
GraphModel graph = viewConverter.getGraphModel(context);
String nodeId = reader.getValue();
GraphNode result = (GraphNode) graph.findNode(nodeId);
if (null == result) {
throw new IllegalStateException(
"Edge reference to undefined node " + nodeId);
}
return result;
}
}