Source for java.nio.CharBuffer

   1: /* CharBuffer.java -- 
   2:    Copyright (C) 2002, 2003, 2004  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: 
  39: package java.nio;
  40: 
  41: /**
  42:  * @since 1.4
  43:  */
  44: public abstract class CharBuffer extends Buffer
  45:   implements Comparable, CharSequence
  46: {
  47:   int array_offset;
  48:   char[] backing_buffer;
  49: 
  50:   CharBuffer (int capacity, int limit, int position, int mark)
  51:   {
  52:     super (capacity, limit, position, mark);
  53:     array_offset = 0;
  54:   }
  55: 
  56:   /**
  57:    * Allocates a new <code>CharBuffer</code> object with a given capacity.
  58:    */
  59:   public static CharBuffer allocate (int capacity)
  60:   {
  61:     return new CharBufferImpl (capacity);
  62:   }
  63: 
  64:   /**
  65:    * Wraps a <code>char</code> array into a <code>CharBuffer</code>
  66:    * object.
  67:    *
  68:    * @param array the array to wrap
  69:    * @param offset the offset of the region in the array to wrap
  70:    * @param length the length of the region in the array to wrap
  71:    *
  72:    * @return a new <code>CharBuffer</code> object
  73:    * 
  74:    * @exception IndexOutOfBoundsException If the preconditions on the offset
  75:    * and length parameters do not hold
  76:    */
  77:   public static final CharBuffer wrap(char[] array, int offset, int length)
  78:   {
  79:     return new CharBufferImpl(array, 0, array.length, offset + length, offset, -1, false);
  80:   }
  81:   
  82:   /**
  83:    * Wraps a character sequence into a <code>CharBuffer</code> object.
  84:    *
  85:    * @param seq the sequence to wrap
  86:    *
  87:    * @return a new <code>CharBuffer</code> object
  88:    */
  89:   public static final CharBuffer wrap(CharSequence seq)
  90:   {
  91:     return wrap(seq, 0, seq.length());
  92:   }
  93:   
  94:   /**
  95:    * Wraps a character sequence into a <code>CharBuffer</code> object.
  96:    * 
  97:    * @param seq the sequence to wrap
  98:    * @param start the index of the first character to wrap
  99:    * @param end the index of the first character not to wrap
 100:    *
 101:    * @return a new <code>CharBuffer</code> object
 102:    * 
 103:    * @exception IndexOutOfBoundsException If the preconditions on the offset
 104:    * and length parameters do not hold
 105:    */
 106:   public static final CharBuffer wrap(CharSequence seq, int start, int end)
 107:   {
 108:     // FIXME: implement better handling of java.lang.String.
 109:     // Probably share data with String via reflection.
 110:          
 111:     int len = end - start;
 112: 
 113:     if( len < 0 )
 114:       throw new IndexOutOfBoundsException();
 115: 
 116:     char[] buffer = new char[len];
 117:     
 118:     for (int i = 0; i < len; i++)
 119:       buffer[i] = seq.charAt(i + start);
 120:     
 121:     return wrap(buffer, 0, len).asReadOnlyBuffer();
 122:   }
 123: 
 124:   /**
 125:    * Wraps a <code>char</code> array into a <code>CharBuffer</code>
 126:    * object.
 127:    *
 128:    * @param array the array to wrap
 129:    *
 130:    * @return a new <code>CharBuffer</code> object
 131:    */
 132:   public static final CharBuffer wrap(char[] array)
 133:   {
 134:     return wrap(array, 0, array.length);
 135:   }
 136:   
 137:   /**
 138:    * This method transfers <code>char</code>s from this buffer into the given
 139:    * destination array. Before the transfer, it checks if there are fewer than
 140:    * length <code>char</code>s remaining in this buffer. 
 141:    *
 142:    * @param dst The destination array
 143:    * @param offset The offset within the array of the first <code>char</code>
 144:    * to be written; must be non-negative and no larger than dst.length.
 145:    * @param length The maximum number of bytes to be written to the given array;
 146:    * must be non-negative and no larger than dst.length - offset.
 147:    *
 148:    * @exception BufferUnderflowException If there are fewer than length
 149:    * <code>char</code>s remaining in this buffer.
 150:    * @exception IndexOutOfBoundsException If the preconditions on the offset
 151:    * and length parameters do not hold.
 152:    */
 153:   public CharBuffer get (char[] dst, int offset, int length)
 154:   {
 155:     checkArraySize(dst.length, offset, length);
 156:     checkForUnderflow(length);
 157: 
 158:     for (int i = offset; i < offset + length; i++)
 159:       {
 160:         dst [i] = get ();
 161:       }
 162: 
 163:     return this;
 164:   }
 165: 
 166:   /**
 167:    * This method transfers <code>char</code>s from this buffer into the given
 168:    * destination array.
 169:    *
 170:    * @param dst The byte array to write into.
 171:    *
 172:    * @exception BufferUnderflowException If there are fewer than dst.length
 173:    * <code>char</code>s remaining in this buffer.
 174:    */
 175:   public CharBuffer get (char[] dst)
 176:   {
 177:     return get (dst, 0, dst.length);
 178:   }
 179: 
 180:   /**
 181:    * Writes the content of the the <code>CharBUFFER</code> src
 182:    * into the buffer. Before the transfer, it checks if there is fewer than
 183:    * <code>src.remaining()</code> space remaining in this buffer.
 184:    *
 185:    * @param src The source data.
 186:    *
 187:    * @exception BufferOverflowException If there is insufficient space in this
 188:    * buffer for the remaining <code>char</code>s in the source buffer.
 189:    * @exception IllegalArgumentException If the source buffer is this buffer.
 190:    * @exception ReadOnlyBufferException If this buffer is read-only.
 191:    */
 192:   public CharBuffer put (CharBuffer src)
 193:   {
 194:     if (src == this)
 195:       throw new IllegalArgumentException ();
 196: 
 197:     checkForOverflow(src.remaining());
 198: 
 199:     if (src.remaining () > 0)
 200:       {
 201:         char[] toPut = new char [src.remaining ()];
 202:         src.get (toPut);
 203:     put (toPut);
 204:       }
 205: 
 206:     return this;
 207:   }
 208: 
 209:   /**
 210:    * Writes the content of the the <code>char array</code> src
 211:    * into the buffer. Before the transfer, it checks if there is fewer than
 212:    * length space remaining in this buffer.
 213:    *
 214:    * @param src The array to copy into the buffer.
 215:    * @param offset The offset within the array of the first byte to be read;
 216:    * must be non-negative and no larger than src.length.
 217:    * @param length The number of bytes to be read from the given array;
 218:    * must be non-negative and no larger than src.length - offset.
 219:    * 
 220:    * @exception BufferOverflowException If there is insufficient space in this
 221:    * buffer for the remaining <code>char</code>s in the source array.
 222:    * @exception IndexOutOfBoundsException If the preconditions on the offset
 223:    * and length parameters do not hold
 224:    * @exception ReadOnlyBufferException If this buffer is read-only.
 225:    */
 226:   public CharBuffer put (char[] src, int offset, int length)
 227:   {
 228:     checkArraySize(src.length, offset, length);
 229:     checkForOverflow(length);
 230:             
 231:     for (int i = offset; i < offset + length; i++)
 232:       put (src [i]);
 233: 
 234:     return this;
 235:   }
 236: 
 237:   /**
 238:    * Writes the content of the the <code>char array</code> src
 239:    * into the buffer.
 240:    *
 241:    * @param src The array to copy into the buffer.
 242:    * 
 243:    * @exception BufferOverflowException If there is insufficient space in this
 244:    * buffer for the remaining <code>char</code>s in the source array.
 245:    * @exception ReadOnlyBufferException If this buffer is read-only.
 246:    */
 247:   public final CharBuffer put (char[] src)
 248:   {
 249:     return put (src, 0, src.length);
 250:   }
 251: 
 252:   /**
 253:    * Tells whether ot not this buffer is backed by an accessible
 254:    * <code>char</code> array.
 255:    */
 256:   public final boolean hasArray ()
 257:   {
 258:     return (backing_buffer != null
 259:             && !isReadOnly ());
 260:   }
 261: 
 262:   /**
 263:    * Returns the <code>char</code> array that backs this buffer.
 264:    *
 265:    * @exception ReadOnlyBufferException If this buffer is read-only.
 266:    * @exception UnsupportedOperationException If this buffer is not backed
 267:    * by an accessible array.
 268:    */
 269:   public final char[] array ()
 270:   {
 271:     if (backing_buffer == null)
 272:       throw new UnsupportedOperationException ();
 273: 
 274:     checkIfReadOnly();
 275: 
 276:     return backing_buffer;
 277:   }
 278: 
 279:   /**
 280:    * Returns the offset within this buffer's backing array of the first element.
 281:    *
 282:    * @exception ReadOnlyBufferException If this buffer is read-only.
 283:    * @exception UnsupportedOperationException If this buffer is not backed
 284:    * by an accessible array.
 285:    */
 286:   public final int arrayOffset ()
 287:   {
 288:     if (backing_buffer == null)
 289:       throw new UnsupportedOperationException ();
 290: 
 291:     checkIfReadOnly();
 292:     
 293:     return array_offset;
 294:   }
 295: 
 296:   /**
 297:    * Calculates a hash code for this buffer.
 298:    *
 299:    * This is done with int arithmetic,
 300:    * where ** represents exponentiation, by this formula:<br>
 301:    * <code>s[position()] + 31 + (s[position()+1] + 30)*31**1 + ... +
 302:    * (s[limit()-1]+30)*31**(limit()-1)</code>.
 303:    * Where s is the buffer data. Note that the hashcode is dependent
 304:    * on buffer content, and therefore is not useful if the buffer
 305:    * content may change.
 306:    */
 307:   public int hashCode ()
 308:   {
 309:     int hashCode = get(position()) + 31;
 310:     int multiplier = 1;
 311:     for (int i = position() + 1; i < limit(); ++i)
 312:       {
 313:       multiplier *= 31;
 314:       hashCode += (get(i) + 30)*multiplier;
 315:       }
 316:     return hashCode;
 317:   }
 318: 
 319:   /**
 320:    * Checks if this buffer is equal to obj.
 321:    */
 322:   public boolean equals (Object obj)
 323:   {
 324:     if (obj instanceof CharBuffer)
 325:       {
 326:         return compareTo (obj) == 0;
 327:       }
 328: 
 329:     return false;
 330:   }
 331: 
 332:   /**
 333:    * Compares two <code>CharBuffer</code> objects.
 334:    *
 335:    * @exception ClassCastException If obj is not an object derived from
 336:    * <code>CharBuffer</code>.
 337:    */
 338:   public int compareTo (Object obj)
 339:   {
 340:     CharBuffer other = (CharBuffer) obj;
 341: 
 342:     int num = Math.min(remaining(), other.remaining());
 343:     int pos_this = position();
 344:     int pos_other = other.position();
 345:     
 346:     for (int count = 0; count < num; count++)
 347:       {
 348:      char a = get(pos_this++);
 349:      char b = other.get(pos_other++);
 350:            
 351:      if (a == b)
 352:        continue;
 353:              
 354:      if (a < b)
 355:        return -1;
 356:              
 357:      return 1;
 358:       }
 359:       
 360:      return remaining() - other.remaining();
 361:   }
 362: 
 363:   /**
 364:    * Returns the byte order of this buffer.
 365:    */
 366:   public abstract ByteOrder order ();
 367: 
 368:   /**
 369:    * Reads the <code>char</code> at this buffer's current position,
 370:    * and then increments the position.
 371:    *
 372:    * @exception BufferUnderflowException If there are no remaining
 373:    * <code>char</code>s in this buffer.
 374:    */
 375:   public abstract char get ();
 376: 
 377:   /**
 378:    * Writes the <code>char</code> at this buffer's current position,
 379:    * and then increments the position.
 380:    *
 381:    * @exception BufferOverflowException If there no remaining 
 382:    * <code>char</code>s in this buffer.
 383:    * @exception ReadOnlyBufferException If this buffer is read-only.
 384:    */
 385:   public abstract CharBuffer put (char b);
 386: 
 387:   /**
 388:    * Absolute get method.
 389:    *
 390:    * @exception IndexOutOfBoundsException If index is negative or not smaller
 391:    * than the buffer's limit.
 392:    */
 393:   public abstract char get (int index);
 394:   
 395:   /**
 396:    * Absolute put method.
 397:    *
 398:    * @exception IndexOutOfBoundsException If index is negative or not smaller
 399:    * than the buffer's limit.
 400:    * @exception ReadOnlyBufferException If this buffer is read-only.
 401:    */
 402:   public abstract CharBuffer put (int index, char b);
 403: 
 404:   /**
 405:    * Compacts this buffer.
 406:    * 
 407:    * @exception ReadOnlyBufferException If this buffer is read-only.
 408:    */
 409:   public abstract CharBuffer compact ();
 410: 
 411:   /**
 412:    * Tells wether or not this buffer is direct.
 413:    */
 414:   public abstract boolean isDirect ();
 415: 
 416:   /**
 417:    * Creates a new <code>CharBuffer</code> whose content is a shared
 418:    * subsequence of this buffer's content.
 419:    */
 420:   public abstract CharBuffer slice ();
 421: 
 422:   /**
 423:    * Creates a new <code>CharBuffer</code> that shares this buffer's
 424:    * content.
 425:    */
 426:   public abstract CharBuffer duplicate ();
 427: 
 428:   /**
 429:    * Creates a new read-only <code>CharBuffer</code> that shares this
 430:    * buffer's content.
 431:    */
 432:   public abstract CharBuffer asReadOnlyBuffer ();
 433:   
 434:   /**
 435:    * Returns the remaining content of the buffer as a string.
 436:    */
 437:   public String toString ()
 438:   {
 439:     if (hasArray ())
 440:       return new String (array (), position (), length ());
 441: 
 442:     char[] buf = new char [length ()];
 443:     int pos = position ();
 444:     get (buf, 0, buf.length);
 445:     position (pos);
 446:     return new String (buf);
 447:   }
 448: 
 449:   /**
 450:    * Returns the length of the remaining chars in this buffer.
 451:    */
 452:   public final int length ()
 453:   { 
 454:     return remaining ();
 455:   }
 456: 
 457:   /**
 458:    * Creates a new character buffer that represents the specified subsequence
 459:    * of this buffer, relative to the current position.
 460:    *
 461:    * @exception IndexOutOfBoundsException If the preconditions on start and
 462:    * end do not hold.
 463:    */
 464:   public abstract CharSequence subSequence (int start, int length);
 465: 
 466:   /**
 467:    * Relative put method.
 468:    * 
 469:    * @exception BufferOverflowException If there is insufficient space in this
 470:    * buffer.
 471:    * @exception IndexOutOfBoundsException If the preconditions on the start
 472:    * and end parameters do not hold.
 473:    * @exception ReadOnlyBufferException If this buffer is read-only.
 474:    */
 475:   public CharBuffer put (String str, int start, int length)
 476:   {
 477:     return put (str.toCharArray (), start, length);
 478:   }
 479:   
 480:   /**
 481:    * Relative put method.
 482:    * 
 483:    * @exception BufferOverflowException If there is insufficient space in this
 484:    * buffer.
 485:    * @exception ReadOnlyBufferException If this buffer is read-only.
 486:    */
 487:   public final CharBuffer put (String str)
 488:   {
 489:     return put (str.toCharArray (), 0, str.length ());
 490:   }
 491:   
 492:   /**
 493:    * Returns the character at <code>position() + index</code>.
 494:    * 
 495:    * @exception IndexOutOfBoundsException If index is negative not smaller than
 496:    * <code>remaining()</code>.
 497:    */
 498:   public final char charAt (int index)
 499:   {
 500:     if (index < 0
 501:         || index >= remaining ())
 502:       throw new IndexOutOfBoundsException ();
 503:     
 504:     return get (position () + index);
 505:   }
 506: }