/*
* 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.GraphEdge;
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;
import com.thoughtworks.xstream.mapper.Mapper;
import java.util.logging.Logger;
/**
* Custom {@code XStream} converter for {@code GraphModel}s.
*
* @author <a href="mailto:leeca@google.com">Lee Carver</a>
*/
public class GraphModelConverter implements Converter {
public static final String GRAPH_DEF_TAG = "graph-model";
private static final Logger logger =
Logger.getLogger(GraphModelConverter.class.getName());
private final Mapper mapper;
public GraphModelConverter(Mapper mapper) {
this.mapper = mapper;
}
@Override
@SuppressWarnings("rawtypes") // Parent type uses raw type Class
public boolean canConvert(Class type) {
return GraphModel.class.equals(type);
}
/**
* No need to start a node, since the caller ensures we are wrapped correctly.
*/
@Override
public void marshal(Object source, HierarchicalStreamWriter writer,
MarshallingContext context) {
GraphModel graph = (GraphModel) source;
// Save all nodes.
for (GraphNode node : graph.getNodes()) {
marshalObject(node, writer, context);
}
// Save all edges.
for (GraphEdge edge : graph.getEdges()) {
marshalObject(edge, writer, context);
}
}
protected void marshalObject(Object item,
HierarchicalStreamWriter writer, MarshallingContext context) {
String nodeLabel = mapper.serializedClass(item.getClass());
writer.startNode(nodeLabel);
context.convertAnother(item);
writer.endNode();
}
/**
* {@inheritDoc}
* <p>
* This implementation temporarily injects the current {@code GraphModel}
* instance into the {@code UnmarshallingContext} with the key
* {@code GraphModel.class}. This allows the {@link EdgeConverter} to
* translate node ids directly into node references.
*
* @see EdgeConverter#unmarshal(HierarchicalStreamReader, UnmarshallingContext)
*/
@Override
public Object unmarshal(
HierarchicalStreamReader reader, UnmarshallingContext context) {
// There should not be two graphs in the same serialization,
// but just in case ....
Object prior = context.get(GraphModel.class);
try {
GraphModel result = new GraphModel();
context.put(GraphModel.class, result);
while (reader.hasMoreChildren()) {
reader.moveDown();
String childName = reader.getNodeName();
Class<?> childClass = mapper.realClass(childName);
if (GraphNode.class.isAssignableFrom(childClass)) {
GraphNode node = (GraphNode) context.convertAnother(null, childClass);
result.addNode(node);
}
else if (GraphEdge.class.isAssignableFrom(childClass)) {
GraphEdge edge =
(GraphEdge) context.convertAnother(null, childClass);
result.addEdge(edge);
} else {
logger.info("Skipped object with tag " + childName);
}
reader.moveUp();
}
return result;
} catch (RuntimeException err) {
// TODO Auto-generated catch block
err.printStackTrace();
throw err;
} finally {
context.put(GraphModel.class, prior);
}
}
}