content: package io.ably.lib.util;
  
  import java.nio.charset.Charset;
  
  //Copyright 2003-2010 Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland
  //www.source-code.biz, www.inventec.ch/chdh
  //
  //This module is multi-licensed and may be used under the terms
  //of any of the following licenses:
  //
  //EPL, Eclipse Public License, http://www.eclipse.org/legal
  //LGPL, GNU Lesser General Public License, http://www.gnu.org/licenses/lgpl.html
  //AL, Apache License, http://www.apache.org/licenses
  //BSD, BSD License, http://www.opensource.org/licenses/bsd-license.php
  //
  //Please contact the author if you need another license.
  //This module is provided "as is", without warranties of any kind.
  
  /**
  * A Base64 encoder/decoder.
  *
  * <p>
  * This class is used to encode and decode data in Base64 format as described in RFC 1521.
  *
  * <p>
  * Project home page: <a href="http://www.source-code.biz/base64coder/java/">www.source-code.biz/base64coder/java</a><br>
  * Author: Christian d'Heureuse, Inventec Informatik AG, Zurich, Switzerland<br>
  * Multi-licensed: EPL / LGPL / AL / BSD.
  */
  public class Base64Coder {
  
  //The line separator string of the operating system.
  private static final String systemLineSeparator = System.getProperty("line.separator");
  
  //Mapping table from 6-bit nibbles to Base64 characters.
  private static char[]    map1 = new char[64];
  static {
   int i=0;
   for (char c='A'; c<='Z'; c++) map1[i++] = c;
   for (char c='a'; c<='z'; c++) map1[i++] = c;
   for (char c='0'; c<='9'; c++) map1[i++] = c;
   map1[i++] = '+'; map1[i++] = '/'; }
  
  //Mapping table from Base64 characters to 6-bit nibbles.
  private static byte[]    map2 = new byte[128];
  static {
   for (int i=0; i<map2.length; i++) map2[i] = -1;
   for (int i=0; i<64; i++) map2[map1[i]] = (byte)i;
   /* URL safe Base 64 decoding */
   map2['-'] = map2['+']; map2['_'] = map2['/'];
  }
  
  /**
  * Encodes a string into Base64 format.
  * No blanks or line breaks are inserted.
  * @param s  A String to be encoded.
  * @return   A String containing the Base64 encoded data.
  */
  public static String encodeString (String s) {
  return new String(encode(s.getBytes(Charset.forName("UTF-8")))); }
  
  /**
  * Encodes a byte array into Base 64 format and breaks the output into lines of 76 characters.
  * This method is compatible with <code>sun.misc.BASE64Encoder.encodeBuffer(byte[])</code>.
  * @param in  An array containing the data bytes to be encoded.
  * @return    A String containing the Base64 encoded data, broken into lines.
  */
  public static String encodeLines (byte[] in) {
  return encodeLines(in, 0, in.length, 76, systemLineSeparator); }
  
  /**
  * Encodes a byte array into Base 64 format and breaks the output into lines.
  * @param in            An array containing the data bytes to be encoded.
  * @param iOff          Offset of the first byte in <code>in</code> to be processed.
  * @param iLen          Number of bytes to be processed in <code>in</code>, starting at <code>iOff</code>.
  * @param lineLen       Line length for the output data. Should be a multiple of 4.
  * @param lineSeparator The line separator to be used to separate the output lines.
  * @return              A String containing the Base64 encoded data, broken into lines.
  */
  public static String encodeLines (byte[] in, int iOff, int iLen, int lineLen, String lineSeparator) {
  int blockLen = (lineLen*3) / 4;
  if (blockLen <= 0) throw new IllegalArgumentException();
  int lines = (iLen+blockLen-1) / blockLen;
  int bufLen = ((iLen+2)/3)*4 + lines*lineSeparator.length();
  StringBuilder buf = new StringBuilder(bufLen);
  int ip = 0;
  while (ip < iLen) {
   int l = Math.min(iLen-ip, blockLen);
   buf.append (encode(in, iOff+ip, l));
   buf.append (lineSeparator);
   ip += l; }
  return buf.toString(); }
  
  /**
  * Encodes a byte array into Base64 format.
  * No blanks or line breaks are inserted in the output.
  * @param in  An array containing the data bytes to be encoded.
  * @return    A character array containing the Base64 encoded data.
  */
  public static char[] encode (byte[] in) {
  return encode(in, 0, in.length); }
  
  /**
  * Encodes a byte array into Base64 format.
  * No blanks or line breaks are inserted in the output.
  * @param in  An array containing the data bytes to be encoded.
  * @return    A String containing the Base64 encoded data.
  */
  public static String encodeToString (byte[] in) {
  return new String(encode(in, 0, in.length)); }
  
  /**
  * Encodes a byte array into Base64 format.
  * No blanks or line breaks are inserted in the output.
  * @param in    An array containing the data bytes to be encoded.
  * @param iLen  Number of bytes to process in <code>in</code>.
  * @return      A character array containing the Base64 encoded data.
  */
  public static char[] encode (byte[] in, int iLen) {
  return encode(in, 0, iLen); }
  
  /**
  * Encodes a byte array into Base64 format.
  * No blanks or line breaks are inserted in the output.
  * @param in    An array containing the data bytes to be encoded.
  * @param iOff  Offset of the first byte in <code>in</code> to be processed.
  * @param iLen  Number of bytes to process in <code>in</code>, starting at <code>iOff</code>.
  * @return      A character array containing the Base64 encoded data.
  */
  public static char[] encode (byte[] in, int iOff, int iLen) {
  int oDataLen = (iLen*4+2)/3;       // output length without padding
  int oLen = ((iLen+2)/3)*4;         // output length including padding
  char[] out = new char[oLen];
  int ip = iOff;
  int iEnd = iOff + iLen;
  int op = 0;
  while (ip < iEnd) {
   int i0 = in[ip++] & 0xff;
   int i1 = ip < iEnd ? in[ip++] & 0xff : 0;
   int i2 = ip < iEnd ? in[ip++] & 0xff : 0;
   int o0 = i0 >>> 2;
   int o1 = ((i0 &   3) << 4) | (i1 >>> 4);
   int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
   int o3 = i2 & 0x3F;
   out[op++] = map1[o0];
   out[op++] = map1[o1];
   out[op] = op < oDataLen ? map1[o2] : '='; op++;
   out[op] = op < oDataLen ? map1[o3] : '='; op++; }
  return out; }
  
  /**
  * Decodes a string from Base64 format.
  * No blanks or line breaks are allowed within the Base64 encoded input data.
  * @param s  A Base64 String to be decoded.
  * @return   A String containing the decoded data.
  * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
  */
  public static String decodeString (String s) {
  return new String(decode(s)); }
  
  /**
  * Decodes a byte array from Base64 format and ignores line separators, tabs and blanks.
  * CR, LF, Tab and Space characters are ignored in the input data.
  * This method is compatible with <code>sun.misc.BASE64Decoder.decodeBuffer(String)</code>.
  * @param s  A Base64 String to be decoded.
  * @return   An array containing the decoded data bytes.
  * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
  */
  public static byte[] decodeLines (String s) {
  char[] buf = new char[s.length()];
  int p = 0;
  for (int ip = 0; ip < s.length(); ip++) {
   char c = s.charAt(ip);
   if (c != ' ' && c != '\r' && c != '\n' && c != '\t')
      buf[p++] = c; }
  return decode(buf, 0, p); }
  
  /**
  * Decodes a byte array from Base64 format.
  * No blanks or line breaks are allowed within the Base64 encoded input data.
  * @param s  A Base64 String to be decoded.
  * @return   An array containing the decoded data bytes.
  * @throws   IllegalArgumentException If the input is not valid Base64 encoded data.
  */
  public static byte[] decode (String s) {
  return decode(s.toCharArray()); }
  
  /**
  * Decodes a byte array from Base64 format.
  * No blanks or line breaks are allowed within the Base64 encoded input data.
  * @param in  A character array containing the Base64 encoded data.
  * @return    An array containing the decoded data bytes.
  * @throws    IllegalArgumentException If the input is not valid Base64 encoded data.
  */
  public static byte[] decode (char[] in) {
  return decode(in, 0, in.length); }
  
  /**
  * Decodes a byte array from Base64 format.
  * No blanks or line breaks are allowed within the Base64 encoded input data.
  * @param in    A character array containing the Base64 encoded data.
  * @param iOff  Offset of the first character in <code>in</code> to be processed.
  * @param iLen  Number of characters to process in <code>in</code>, starting at <code>iOff</code>.
  * @return      An array containing the decoded data bytes.
  * @throws      IllegalArgumentException If the input is not valid Base64 encoded data.
  */
  public static byte[] decode (char[] in, int iOff, int iLen) {
  if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4.");
  while (iLen > 0 && in[iOff+iLen-1] == '=') iLen--;
  int oLen = (iLen*3) / 4;
  byte[] out = new byte[oLen];
  int ip = iOff;
  int iEnd = iOff + iLen;
  int op = 0;
  while (ip < iEnd) {
   int i0 = in[ip++];
   int i1 = in[ip++];
   int i2 = ip < iEnd ? in[ip++] : 'A';
   int i3 = ip < iEnd ? in[ip++] : 'A';
   if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
      throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
   int b0 = map2[i0];
   int b1 = map2[i1];
   int b2 = map2[i2];
   int b3 = map2[i3];
   if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
      throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
   int o0 = ( b0       <<2) | (b1>>>4);
   int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
   int o2 = ((b2 &   3)<<6) |  b3;
   out[op++] = (byte)o0;
   if (op<oLen) out[op++] = (byte)o1;
   if (op<oLen) out[op++] = (byte)o2; }
  return out; }
  
  //Dummy constructor.
  private Base64Coder() {}
  
  } // end class Base64Coder