Source for gnu.java.nio.charset.ByteEncodeLoopHelper

   1: /* ByteCharset.java -- Abstract class for generic 1-byte encodings.
   2:    Copyright (C) 2005 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: package gnu.java.nio.charset;
  39: 
  40: import java.nio.ByteBuffer;
  41: import java.nio.CharBuffer;
  42: import java.nio.charset.CoderResult;
  43: 
  44: /**
  45:  * Helper class to deal with encoding loops that write a byte at a time
  46:  *
  47:  * @author Ian Rogers
  48:  */
  49: public abstract class ByteEncodeLoopHelper
  50: {
  51:   /**
  52:    * @return can the given character be encoded
  53:    */
  54:   protected abstract boolean isMappable(char c);
  55: 
  56:   /**
  57:    * Map the given character to a byte, the given character is guaranteed to be
  58:    * mappable
  59:    */
  60:   protected abstract byte mapToByte(char c);
  61: 
  62:   /**
  63:    * Encodes one or more characters into one or more bytes, mapping each
  64:    * character to only one byte
  65:    *
  66:    * @param in character buffer to read from
  67:    * @param out byte buffer to write to
  68:    * @return the result state of the encoder
  69:    */
  70:   CoderResult encodeLoop(CharBuffer in, ByteBuffer out)
  71:   {
  72:     if (in.hasArray() && out.hasArray())
  73:       {
  74:         return arrayEncodeLoop(in, out);
  75:       } else
  76:       {
  77:         return normalEncodeLoop(in, out);
  78:       }
  79:   }
  80: 
  81:   /**
  82:    * Encode loop using get and put operations
  83:    */
  84:   private CoderResult normalEncodeLoop(CharBuffer in, ByteBuffer out)
  85:   {
  86:     int outRemaining = out.remaining();
  87:     int inRemaining = in.remaining();
  88:     while (inRemaining > 0 && outRemaining > 0)
  89:       {
  90:         char c = in.get();
  91:         inRemaining--;
  92: 
  93:         if (!isMappable(c))
  94:           {
  95:             in.position(in.position() - 1);
  96:             return CoderResult.unmappableForLength(1);
  97:           }
  98:         byte b = mapToByte(c);
  99:         out.put(b);
 100:         outRemaining--;
 101:       }
 102:     if (inRemaining > 0)
 103:       {
 104:         return CoderResult.OVERFLOW;
 105:       } else
 106:       {
 107:         return CoderResult.UNDERFLOW;
 108:       }
 109:   }
 110: 
 111:   /**
 112:    * Encode loop using array read and write operations
 113:    */
 114:   private CoderResult arrayEncodeLoop(CharBuffer in, ByteBuffer out)
 115:   {
 116:     char[] inArray = in.array();
 117:     byte[] outArray = out.array();
 118:     int inPos = in.arrayOffset() + in.position();
 119:     int outPos = out.arrayOffset() + out.position();
 120:     int inRemaining = in.remaining();
 121:     int outRemaining = out.remaining();
 122:     CoderResult result;
 123: 
 124:         bailOut:
 125:     if (inRemaining <= outRemaining)
 126:       {
 127:         for (int i = 0; i < inRemaining; i++)
 128:           {
 129:             char inChar = inArray[inPos];
 130:             inPos++;
 131:             if (!isMappable(inChar))
 132:               {
 133:                 inPos--;
 134:                 result = CoderResult.unmappableForLength(1);
 135:                 break bailOut;
 136:               }
 137:             byte b = mapToByte(inChar);
 138:             outArray[outPos] = b;
 139:             outPos++;
 140:           }
 141:         result = CoderResult.UNDERFLOW;
 142:       }
 143:     else
 144:       {
 145:         for (int i = 0; i < outRemaining; i++)
 146:           {
 147:             char inChar = inArray[inPos];
 148:             inPos++;
 149:             if (!isMappable(inChar))
 150:               {
 151:                 inPos--;
 152:                 result = CoderResult.unmappableForLength(1);
 153:                 break bailOut;
 154:               }
 155:             byte b = mapToByte(inChar);
 156:             outArray[outPos] = b;
 157:             outPos++;
 158:           }
 159:         result = CoderResult.OVERFLOW;
 160:       }
 161:     in.position(inPos - in.arrayOffset());
 162:     out.position(outPos - out.arrayOffset());
 163:     return result;
 164:   }
 165: }