org.jgrapht.nio.gml.GmlExporter Maven / Gradle / Ivy
/*
* (C) Copyright 2006-2021, 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.gml;
import org.apache.commons.text.*;
import org.jgrapht.*;
import org.jgrapht.nio.*;
import java.io.*;
import java.util.*;
import java.util.function.*;
/**
* Exports a graph into a GML file (Graph Modeling Language).
*
*
* For a description of the format see
* https://github.com/GunterMueller/UNI_PASSAU_FMI_Graph_Drawing/blob/master/GML/gml-technical-report.pdf.
*
*
* The behavior of the exporter such as whether to print vertex labels, edge labels, and/or edge
* weights can be adjusted using the {@link #setParameter(Parameter, boolean) setParameter} method.
* When exporting labels, the exporter escapes them as Java strings.
*
* @param the graph vertex type
* @param the graph edge type
*
* @author Dimitrios Michail
*/
public class GmlExporter
extends
BaseExporter
implements
GraphExporter
{
private static final String CREATOR = "JGraphT GML Exporter";
private static final String VERSION = "1";
private static final String DELIM = " ";
private static final String TAB1 = "\t";
private static final String TAB2 = "\t\t";
private static final String LABEL_ATTRIBUTE_KEY = "label";
private static final String WEIGHT_ATTRIBUTE_KEY = "weight";
private static final Set FORBIDDEN_VERTEX_CUSTOM_ATTRIBUTE_KEYS = Set.of("id");
private static final Set FORBIDDEN_EDGE_CUSTOM_ATTRIBUTE_KEYS =
Set.of("id", "source", "target");
private final Set parameters;
/**
* Parameters that affect the behavior of the {@link GmlExporter} exporter.
*/
public enum Parameter
{
/**
* If set the exporter outputs edge labels. The labels are found from the edge attribute
* provider of the importer using the key "label".
*/
EXPORT_EDGE_LABELS,
/**
* If set the exporter outputs edge weights
*/
EXPORT_EDGE_WEIGHTS,
/**
* If set the exporter outputs all custom edge attributes. The attributes are located from
* the edge attribute provider of the importer. Note that these attributes have lowest
* priority compared to special handled ones like "label", or "weight" and cannot contain
* special keys like "id", "source" and "target".
*/
EXPORT_CUSTOM_EDGE_ATTRIBUTES,
/**
* If set the exporter outputs vertex labels. The labels are found from the vertex attribute
* provider of the importer using the key "label".
*/
EXPORT_VERTEX_LABELS,
/**
* If set the exporter outputs all custom vertex attributes. The attributes are located from
* the vertex attribute provider of the importer. Note that these attributes have lowest
* priority compared to special handled ones like "label" and cannot contain special keys
* like "id".
*/
EXPORT_CUSTOM_VERTEX_ATTRIBUTES,
/**
* If set the exporter escapes all strings as Java strings, otherwise no escaping is
* performed.
*/
ESCAPE_STRINGS_AS_JAVA,
}
/**
* Creates a new GmlExporter object with integer id providers for the vertex identifiers.
*/
public GmlExporter()
{
this(new IntegerIdProvider<>());
}
/**
* Constructs a new GmlExporter object with the given id providers.
*
* @param vertexIdProvider for generating vertex IDs. Must not be null.
*/
public GmlExporter(Function vertexIdProvider)
{
super(vertexIdProvider);
this.parameters = new HashSet<>();
}
/**
* Exports an graph into a plain text GML format.
*
* @param writer the writer
* @param g the graph
*/
@Override
public void exportGraph(Graph g, Writer writer)
{
PrintWriter out = new PrintWriter(writer);
for (V from : g.vertexSet()) {
// assign ids in vertex set iteration order
getVertexId(from);
}
exportHeader(out);
out.println("graph");
out.println("[");
out.println(TAB1 + "label" + DELIM + quoted(""));
if (g.getType().isDirected()) {
out.println(TAB1 + "directed" + DELIM + "1");
} else {
out.println(TAB1 + "directed" + DELIM + "0");
}
exportVertices(out, g);
exportEdges(out, g);
out.println("]");
out.flush();
}
/**
* Return if a particular parameter of the exporter is enabled
*
* @param p the parameter
* @return {@code true} if the parameter is set, {@code false} otherwise
*/
public boolean isParameter(Parameter p)
{
return parameters.contains(p);
}
/**
* Set the value of a parameter of the exporter
*
* @param p the parameter
* @param value the value to set
*/
public void setParameter(Parameter p, boolean value)
{
if (value) {
parameters.add(p);
} else {
parameters.remove(p);
}
}
private String quoted(final String s)
{
boolean escapeStringAsJava = parameters.contains(Parameter.ESCAPE_STRINGS_AS_JAVA);
if (escapeStringAsJava) {
return "\"" + StringEscapeUtils.escapeJava(s) + "\"";
} else {
return "\"" + s + "\"";
}
}
private void exportHeader(PrintWriter out)
{
out.println("Creator" + DELIM + quoted(CREATOR));
out.println("Version" + DELIM + VERSION);
}
private void exportAttribute(PrintWriter out, String key, Attribute attribute)
{
AttributeType type = attribute.getType();
switch (type) {
case INT:
out.println(TAB2 + key + DELIM + Integer.valueOf(attribute.getValue()));
break;
case LONG:
out.println(TAB2 + key + DELIM + Long.valueOf(attribute.getValue()));
break;
case FLOAT:
out.println(TAB2 + key + DELIM + Float.valueOf(attribute.getValue()));
break;
case DOUBLE:
out.println(TAB2 + key + DELIM + Double.valueOf(attribute.getValue()));
break;
default:
out.println(TAB2 + key + DELIM + quoted(attribute.getValue()));
break;
}
}
private void exportVertices(PrintWriter out, Graph g)
{
boolean exportVertexLabels = parameters.contains(Parameter.EXPORT_VERTEX_LABELS);
boolean exportCustomVertexAttributes =
parameters.contains(Parameter.EXPORT_CUSTOM_VERTEX_ATTRIBUTES);
for (V from : g.vertexSet()) {
out.println(TAB1 + "node");
out.println(TAB1 + "[");
out.println(TAB2 + "id" + DELIM + getVertexId(from));
if (exportVertexLabels) {
String label = getVertexAttribute(from, LABEL_ATTRIBUTE_KEY)
.map(Attribute::getValue).orElse(from.toString());
out.println(TAB2 + "label" + DELIM + quoted(label));
}
if (exportCustomVertexAttributes) {
getVertexAttributes(from).ifPresent(vertexAttributes -> {
vertexAttributes.entrySet().stream().forEach(e -> {
String customAttributeKey = e.getKey();
Attribute customAttributeValue = e.getValue();
if (FORBIDDEN_VERTEX_CUSTOM_ATTRIBUTE_KEYS.contains(customAttributeKey)) {
throw new IllegalArgumentException(
"Key " + customAttributeKey + " is reserved");
}
if (LABEL_ATTRIBUTE_KEY.equals(customAttributeKey) && exportVertexLabels) {
// give higher priority to vertex labels
return;
}
exportAttribute(out, customAttributeKey, customAttributeValue);
});
});
}
out.println(TAB1 + "]");
}
}
private void exportEdges(PrintWriter out, Graph g)
{
boolean exportEdgeWeights = parameters.contains(Parameter.EXPORT_EDGE_WEIGHTS);
boolean exportEdgeLabels = parameters.contains(Parameter.EXPORT_EDGE_LABELS);
boolean exportCustomEdgeAttributes =
parameters.contains(Parameter.EXPORT_CUSTOM_EDGE_ATTRIBUTES);
for (E edge : g.edgeSet()) {
out.println(TAB1 + "edge");
out.println(TAB1 + "[");
getEdgeId(edge).ifPresent(eId -> {
out.println(TAB2 + "id" + DELIM + eId);
});
String s = getVertexId(g.getEdgeSource(edge));
out.println(TAB2 + "source" + DELIM + s);
String t = getVertexId(g.getEdgeTarget(edge));
out.println(TAB2 + "target" + DELIM + t);
if (exportEdgeLabels) {
Attribute label = getEdgeAttribute(edge, LABEL_ATTRIBUTE_KEY)
.orElse(DefaultAttribute.createAttribute(edge.toString()));
exportAttribute(out, "label", label);
}
if (exportEdgeWeights && g.getType().isWeighted()) {
exportAttribute(
out, "weight", DefaultAttribute.createAttribute(g.getEdgeWeight(edge)));
}
if (exportCustomEdgeAttributes) {
getEdgeAttributes(edge).ifPresent(edgeAttributes -> {
edgeAttributes.entrySet().stream().forEach(e -> {
String customAttributeKey = e.getKey();
Attribute customAttributeValue = e.getValue();
if (FORBIDDEN_EDGE_CUSTOM_ATTRIBUTE_KEYS.contains(customAttributeKey)) {
throw new IllegalArgumentException(
"Key " + customAttributeKey + " is reserved");
}
if (LABEL_ATTRIBUTE_KEY.equals(customAttributeKey) && exportEdgeLabels) {
// give higher priority to edge labels
return;
}
if (WEIGHT_ATTRIBUTE_KEY.equals(customAttributeKey) && exportEdgeWeights) {
// give higher priority to edge weights
return;
}
exportAttribute(out, customAttributeKey, customAttributeValue);
});
});
}
out.println(TAB1 + "]");
}
}
}