org.jgrapht.nio.graphml.SimpleGraphMLEventDrivenImporter Maven / Gradle / Ivy
/*
* (C) Copyright 2016-2023, by Dimitrios Michail and Contributors.
*
* JGraphT : a free Java graph-theory library
*
* See the CONTRIBUTORS.md file distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the
* GNU Lesser General Public License v2.1 or later
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
*
* SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
*/
package org.jgrapht.nio.graphml;
import org.jgrapht.alg.util.*;
import org.jgrapht.nio.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
import javax.xml.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.stream.*;
import javax.xml.validation.*;
import java.io.*;
import java.util.*;
/**
* Imports a graph from a GraphML data source. The importer does not construct a graph but calls the
* provided consumers with the appropriate arguments. Vertices are returned simply by their vertex
* id and edges are returns as triples (source, target, weight) where weight maybe null.
*
*
* The importer notifies lazily and completely out-of-order for any additional vertex, edge or graph
* attributes in the input file. Users can register consumers for vertex, edge and graph attributes
* after construction of the importer. Finally, default attribute values are completely ignored.
* Lazily here means that an edge is first reported with a null weight and its weight is reported
* later using the edge attribute consumer. Since the same triple instance is used in all cases, an
* edge may appear having a null weight when it is first reported and having a non-null weight after
* the edge weight is reported.
*
*
* This is a simple implementation with supports only a limited set of features of the GraphML
* specification. For a more rigorous parser use {@link GraphMLImporter}. This version is oriented
* towards parsing speed.
*
*
* For a description of the format see
* http://en.wikipedia.org/wiki/ GraphML or the
* GraphML Primer.
*
*
*
* Below is small example of a graph in GraphML format.
*
*
* {@code
*
*
*
*
* green
*
*
* black
*
*
* blue
*
*
* red
*
*
* white
*
*
* turquoise
*
*
* 1.0
*
*
* 1.0
*
*
* 2.0
*
*
* 1.1
*
*
*
* }
*
*
*
* The importer by default validates the input using the 1.0
* GraphML Schema. The user can
* (not recommended) disable the validation by calling {@link #setSchemaValidation(boolean)}.
*
* @author Dimitrios Michail
*/
public class SimpleGraphMLEventDrivenImporter
extends BaseEventDrivenImporter>
implements EventDrivenImporter>
{
private static final String GRAPHML_SCHEMA_FILENAME = "graphml.xsd";
private static final String XLINK_SCHEMA_FILENAME = "xlink.xsd";
private static final String EDGE_WEIGHT_DEFAULT_ATTRIBUTE_NAME = "weight";
private boolean schemaValidation;
private String edgeWeightAttributeName = EDGE_WEIGHT_DEFAULT_ATTRIBUTE_NAME;
/**
* Constructs a new importer.
*/
public SimpleGraphMLEventDrivenImporter()
{
super();
this.schemaValidation = true;
}
/**
* Get the attribute name for edge weights
*
* @return the attribute name
*/
public String getEdgeWeightAttributeName()
{
return edgeWeightAttributeName;
}
/**
* Set the attribute name to use for edge weights.
*
* @param edgeWeightAttributeName the attribute name
*/
public void setEdgeWeightAttributeName(String edgeWeightAttributeName)
{
this.edgeWeightAttributeName = Objects
.requireNonNull(edgeWeightAttributeName, "Edge weight attribute name cannot be null");
}
/**
* Whether the importer validates the input
*
* @return true if the importer validates the input
*/
public boolean isSchemaValidation()
{
return schemaValidation;
}
/**
* Set whether the importer should validate the input
*
* @param schemaValidation value for schema validation
*/
public void setSchemaValidation(boolean schemaValidation)
{
this.schemaValidation = schemaValidation;
}
@Override
public void importInput(Reader input)
{
try {
// parse
XMLReader xmlReader = createXMLReader();
GraphMLHandler handler = new GraphMLHandler();
xmlReader.setContentHandler(handler);
xmlReader.setErrorHandler(handler);
notifyImportEvent(ImportEvent.START);
xmlReader.parse(new InputSource(input));
notifyImportEvent(ImportEvent.END);
} catch (Exception e) {
throw new ImportException("Failed to parse GraphML", e);
}
}
private XMLReader createXMLReader()
{
try {
SchemaFactory schemaFactory =
SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
// create parser
SAXParserFactory spf = SAXParserFactory.newInstance();
if (schemaValidation) {
// load schema
InputStream xsdStream =
Thread.currentThread().getContextClassLoader().getResourceAsStream(
GRAPHML_SCHEMA_FILENAME);
if (xsdStream == null) {
throw new ImportException("Failed to locate GraphML xsd");
}
InputStream xlinkStream =
Thread.currentThread().getContextClassLoader().getResourceAsStream(
XLINK_SCHEMA_FILENAME);
if (xlinkStream == null) {
throw new ImportException("Failed to locate XLink xsd");
}
Source[] sources = new Source[2];
sources[0] = new StreamSource(xlinkStream);
sources[1] = new StreamSource(xsdStream);
Schema schema = schemaFactory.newSchema(sources);
spf.setSchema(schema);
}
spf.setNamespaceAware(true);
SAXParser saxParser = spf.newSAXParser();
// create reader
return saxParser.getXMLReader();
} catch (Exception e) {
throw new ImportException("Failed to parse GraphML", e);
}
}
// content handler
private class GraphMLHandler
extends DefaultHandler
{
private static final String GRAPH = "graph";
private static final String GRAPH_ID = "id";
private static final String GRAPH_EDGE_DEFAULT = "edgedefault";
private static final String NODE = "node";
private static final String NODE_ID = "id";
private static final String EDGE = "edge";
private static final String EDGE_ID = "id";
private static final String EDGE_SOURCE = "source";
private static final String EDGE_TARGET = "target";
private static final String ALL = "all";
private static final String KEY = "key";
private static final String KEY_FOR = "for";
private static final String KEY_ATTR_NAME = "attr.name";
private static final String KEY_ATTR_TYPE = "attr.type";
private static final String KEY_ID = "id";
private static final String DEFAULT = "default";
private static final String DATA = "data";
private static final String DATA_KEY = "key";
// parser state
private int insideData;
private int insideGraph;
private int insideNode;
private String currentNode;
private int insideEdge;
private Triple currentEdge;
private Key currentKey;
private String currentDataKey;
private StringBuilder currentDataValue;
private Map nodeValidKeys;
private Map edgeValidKeys;
private Map graphValidKeys;
public GraphMLHandler()
{
}
@Override
public void startDocument()
throws SAXException
{
insideData = 0;
insideGraph = 0;
insideNode = 0;
currentNode = null;
insideEdge = 0;
currentEdge = null;
currentKey = null;
currentDataKey = null;
currentDataValue = new StringBuilder();
nodeValidKeys = new HashMap<>();
edgeValidKeys = new HashMap<>();
graphValidKeys = new HashMap<>();
}
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes)
throws SAXException
{
switch (localName) {
case GRAPH:
if (insideGraph > 0) {
throw new IllegalArgumentException(
"This importer does not support nested graphs");
}
insideGraph++;
findAttribute(GRAPH_ID, attributes).ifPresent(
value -> notifyGraphAttribute(
GRAPH_ID, DefaultAttribute.createAttribute(value)));
findAttribute(GRAPH_EDGE_DEFAULT, attributes).ifPresent(
value -> notifyGraphAttribute(
GRAPH_EDGE_DEFAULT, DefaultAttribute.createAttribute(value)));
break;
case NODE:
if (insideNode > 0 || insideEdge > 0) {
throw new IllegalArgumentException(
"Nodes cannot be inside other nodes or edges");
}
insideNode++;
String nodeId = findAttribute(NODE_ID, attributes).orElseThrow(
() -> new IllegalArgumentException("Node must have an identifier"));
currentNode = nodeId;
notifyVertex(currentNode);
notifyVertexAttribute(
currentNode, NODE_ID, DefaultAttribute.createAttribute(nodeId));
break;
case EDGE:
if (insideNode > 0 || insideEdge > 0) {
throw new IllegalArgumentException(
"Edges cannot be inside other nodes or edges");
}
insideEdge++;
String sourceId = findAttribute(EDGE_SOURCE, attributes)
.orElseThrow(() -> new IllegalArgumentException("Edge source missing"));
String targetId = findAttribute(EDGE_TARGET, attributes)
.orElseThrow(() -> new IllegalArgumentException("Edge target missing"));
String edgeId = findAttribute(EDGE_ID, attributes).orElse(null);
currentEdge = Triple.of(sourceId, targetId, null);
notifyEdge(currentEdge);
if (edgeId != null) {
notifyEdgeAttribute(
currentEdge, EDGE_ID, DefaultAttribute.createAttribute(edgeId));
}
notifyEdgeAttribute(
currentEdge, EDGE_SOURCE, DefaultAttribute.createAttribute(sourceId));
notifyEdgeAttribute(
currentEdge, EDGE_TARGET, DefaultAttribute.createAttribute(targetId));
break;
case KEY:
String keyId = findAttribute(KEY_ID, attributes)
.orElseThrow(() -> new IllegalArgumentException("Key id missing"));
String keyAttrName = findAttribute(KEY_ATTR_NAME, attributes)
.orElseThrow(() -> new IllegalArgumentException("Key attribute name missing"));
currentKey = new Key(
keyId,
keyAttrName, findAttribute(KEY_ATTR_TYPE, attributes)
.map(AttributeType::create).orElse(AttributeType.UNKNOWN),
findAttribute(KEY_FOR, attributes).orElse("ALL"));
break;
case DEFAULT:
break;
case DATA:
insideData++;
findAttribute(DATA_KEY, attributes).ifPresent(data -> currentDataKey = data);
break;
default:
break;
}
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException
{
switch (localName) {
case GRAPH:
insideGraph--;
break;
case NODE:
currentNode = null;
insideNode--;
break;
case EDGE:
if (currentEdge != null && currentEdge.getThird() != null) {
notifyEdgeAttribute(
currentEdge, edgeWeightAttributeName,
DefaultAttribute.createAttribute(currentEdge.getThird()));
}
currentEdge = null;
insideEdge--;
break;
case KEY:
registerKey();
currentKey = null;
break;
case DEFAULT:
break;
case DATA:
if (--insideData == 0) {
notifyData();
currentDataValue.setLength(0);
currentDataKey = null;
}
break;
default:
break;
}
}
@Override
public void characters(char ch[], int start, int length)
throws SAXException
{
if (insideData == 1) {
currentDataValue.append(ch, start, length);
}
}
@Override
public void warning(SAXParseException e)
throws SAXException
{
throw e;
}
public void error(SAXParseException e)
throws SAXException
{
throw e;
}
public void fatalError(SAXParseException e)
throws SAXException
{
throw e;
}
private Optional findAttribute(String localName, Attributes attributes)
{
for (int i = 0; i < attributes.getLength(); i++) {
String attrLocalName = attributes.getLocalName(i);
if (attrLocalName.equals(localName)) {
return Optional.ofNullable(attributes.getValue(i));
}
}
return Optional.empty();
}
private void notifyData()
{
if (currentDataKey == null || currentDataValue.length() == 0) {
return;
}
if (currentNode != null) {
Key key = nodeValidKeys.get(currentDataKey);
if (key != null) {
notifyVertexAttribute(
currentNode, key.attributeName,
new DefaultAttribute<>(currentDataValue.toString(), key.type));
}
}
if (currentEdge != null) {
Key key = edgeValidKeys.get(currentDataKey);
if (key != null) {
/*
* Handle special weight key
*/
if (key.attributeName.equals(edgeWeightAttributeName)) {
try {
currentEdge.setThird(Double.parseDouble(currentDataValue.toString()));
} catch (NumberFormatException e) {
// ignore
}
} else {
notifyEdgeAttribute(
currentEdge, key.attributeName,
new DefaultAttribute<>(currentDataValue.toString(), key.type));
}
}
}
Key key = graphValidKeys.get(currentDataKey);
if (key != null) {
notifyGraphAttribute(
key.attributeName,
new DefaultAttribute<>(currentDataValue.toString(), key.type));
}
}
private void registerKey()
{
if (currentKey.isValid()) {
switch (currentKey.target) {
case NODE:
nodeValidKeys.put(currentKey.id, currentKey);
break;
case EDGE:
edgeValidKeys.put(currentKey.id, currentKey);
break;
case GRAPH:
graphValidKeys.put(currentKey.id, currentKey);
break;
case ALL:
nodeValidKeys.put(currentKey.id, currentKey);
edgeValidKeys.put(currentKey.id, currentKey);
graphValidKeys.put(currentKey.id, currentKey);
break;
}
}
}
}
private static class Key
{
String id;
String attributeName;
String target;
AttributeType type;
public Key(String id, String attributeName, AttributeType type, String target)
{
this.id = id;
this.attributeName = attributeName;
this.type = type;
this.target = target;
}
public boolean isValid()
{
return id != null && attributeName != null && target != null;
}
}
}