BEncoder.java

/* BDecoder - Converts an InputStream to BEValues.
   Copyright (C) 2003 Mark J. Wielaard

   This file is part of Snark.
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

package org.klomp.snark.bencode;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class BEncoder
{

  public static byte[] bencode(Object o) throws IllegalArgumentException
  {
    try
      {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bencode(o, baos);
        return baos.toByteArray();
      }
    catch (IOException ioe)
      {
        throw new InternalError(ioe.toString());
      }
  }

  public static void bencode(Object o, OutputStream out)
    throws IOException, IllegalArgumentException
  {
    if (o == null)
      throw new NullPointerException("Cannot bencode null");
    if (o instanceof String)
      bencode((String)o, out);
    else if (o instanceof byte[])
      bencode((byte[])o, out);
    else if (o instanceof Number)
      bencode((Number)o, out);
    else if (o instanceof List)
      bencode((List<?>)o, out);
    else if (o instanceof Map)
      bencode((Map<?, ?>)o, out);
    else if (o instanceof BEValue)
      bencode(((BEValue)o).getValue(), out);
    else
      throw new IllegalArgumentException("Cannot bencode: " + o.getClass());
  }

  public static byte[] bencode(String s)
  {
    try
      {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bencode(s, baos);
        return baos.toByteArray();
      }
    catch (IOException ioe)
      {
        throw new InternalError(ioe.toString());
      }
  }

  public static void bencode(String s, OutputStream out) throws IOException
  {
    byte[] bs = s.getBytes("UTF-8");
    bencode(bs, out);
  }

  public static byte[] bencode(Number n)
  {
    try
      {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bencode(n, baos);
        return baos.toByteArray();
      }
    catch (IOException ioe)
      {
        throw new InternalError(ioe.toString());
      }
  }

  public static void bencode(Number n, OutputStream out) throws IOException
  {
    out.write('i');
    String s = n.toString();
    out.write(s.getBytes("UTF-8"));
    out.write('e');
  }

  public static byte[] bencode(List<?> l)
  {
    try
      {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bencode(l, baos);
        return baos.toByteArray();
      }
    catch (IOException ioe)
      {
        throw new InternalError(ioe.toString());
      }
  }

  public static void bencode(List<?> l, OutputStream out) throws IOException
  {
    out.write('l');
    Iterator<?> it = l.iterator();
    while (it.hasNext())
      bencode(it.next(), out);
    out.write('e');
  }

  public static byte[] bencode(byte[] bs)
  {
    try
      {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bencode(bs, baos);
        return baos.toByteArray();
      }
    catch (IOException ioe)
      {
        throw new InternalError(ioe.toString());
      }
  }

  public static void bencode(byte[] bs, OutputStream out) throws IOException
  {
    String l = Integer.toString(bs.length);
    out.write(l.getBytes("UTF-8"));
    out.write(':');
    out.write(bs);
  }

  public static byte[] bencode(Map<?, ?> m)
  {
    try
      {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bencode(m, baos);
        return baos.toByteArray();
      }
    catch (IOException ioe)
      {
        throw new InternalError(ioe.toString());
      }
  }

  public static void bencode(Map<?, ?> m, OutputStream out)
    throws IOException, IllegalArgumentException
  {
    out.write('d');

    // Keys must be sorted. XXX - But is this the correct order?
    Set<?> s = m.keySet();
    List<String> l = new ArrayList<String>(s.size());
    for (Object k : s) {
      // Keys must be Strings.
      if (String.class.isAssignableFrom(k.getClass()))
        l.add((String) k);
      else
        throw new IllegalArgumentException("Cannot bencode map: contains non-String key of type " + k.getClass());
    }
    Collections.sort(l);

    Iterator<String> it = l.iterator();
    while(it.hasNext())
      {
        String key = it.next();
        bencode(key, out);
        bencode(m.get(key), out);
      }

    out.write('e');
  }
}