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Prefuse is a set of software tools for creating rich interactive data visualizations in the Java programming language.

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/**
 * Copyright (c) 2004-2006 Regents of the University of California.
 * See "license-prefuse.txt" for licensing terms.
 */
package prefuse.data.io;

import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Date;
import java.util.HashMap;

import prefuse.data.Graph;
import prefuse.data.Node;
import prefuse.data.Schema;
import prefuse.util.io.XMLWriter;

/**
 * GraphWriter instance that writes a tree file formatted using the
 * TreeML file format. TreeML is an XML format originally created for
 * the 2003 InfoVis conference contest. A DTD (Document Type Definition) for
 * TreeML is
 * 
 *  available online.
 * 
 * The GraphML spec only supports the data types Int,
 * Long, Float, Real (double),
 * Boolean, String, and Date.
 * An exception will be thrown if a data type outside these allowed
 * types is encountered.
 * 
 * @author jeffrey heer
 */
public class TreeMLWriter extends AbstractGraphWriter {

    /**
     * String tokens used in the TreeML format.
     */
    public interface Tokens extends TreeMLReader.Tokens {}
    
    /**
     * Map containing legal data types and their names in the GraphML spec
     */
    private static final HashMap TYPES = new HashMap();
    static {
        TYPES.put(int.class, Tokens.INT);
        TYPES.put(long.class, Tokens.LONG);
        TYPES.put(float.class, Tokens.FLOAT);
        TYPES.put(double.class, Tokens.REAL);
        TYPES.put(boolean.class, Tokens.BOOLEAN);
        TYPES.put(String.class, Tokens.STRING);
        TYPES.put(Date.class, Tokens.DATE);
    }
    
    /**
     * @see prefuse.data.io.GraphWriter#writeGraph(prefuse.data.Graph, java.io.OutputStream)
     */
    public void writeGraph(Graph graph, OutputStream os) throws DataIOException
    {
        // first, check the schemas to ensure GraphML compatibility
        Schema ns = graph.getNodeTable().getSchema();
        checkTreeMLSchema(ns);
        
        XMLWriter xml = new XMLWriter(new PrintWriter(os));
        xml.begin();
        
        xml.comment("prefuse TreeML Writer | "
                + new Date(System.currentTimeMillis()));
                
        // print the tree contents
        xml.start(Tokens.TREE);
        
        // print the tree node schema
        xml.start(Tokens.DECLS);
        String[] attr = new String[] {Tokens.NAME, Tokens.TYPE };
        String[] vals = new String[2];

        for ( int i=0; i 0 ) {
                for ( int i=0; iint,
     * long, float, double,
     * boolean, string, and date.
     * @param s the Schema to check
     */
    private void checkTreeMLSchema(Schema s) throws DataIOException {
        for ( int i=0; i