libjava/classpath/java/nio/CharBuffer.java

   1 /* CharBuffer.java --
   2    Copyright (C) 2002, 2003, 2004, 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
  39 package java.nio;
  40
  41 // GCJ LOCAL: Use RawData instead of gnu.classpath.Pointer
  42 import gnu.gcj.RawData;
  43
  44 import java.io.IOException;
  45
  46 /**
  47  * @since 1.4
  48  */
  49 public abstract class CharBuffer extends Buffer
  50   implements Comparable<CharBuffer>, CharSequence, Readable, Appendable
  51 {
  52   final int array_offset;
  53   final char[] backing_buffer;
  54
  55   CharBuffer (int capacity, int limit, int position, int mark,
  56               RawData address, char[] backing_buffer, int array_offset)
  57   {
  58     super (capacity, limit, position, mark, address);
  59     this.backing_buffer = backing_buffer;
  60     this.array_offset = array_offset;
  61   }
  62
  63   /**
  64    * Allocates a new <code>CharBuffer</code> object with a given capacity.
  65    */
  66   public static CharBuffer allocate (int capacity)
  67   {
  68     return new CharBufferImpl (capacity);
  69   }
  70
  71   /**
  72    * Wraps a <code>char</code> array into a <code>CharBuffer</code>
  73    * object.
  74    *
  75    * @param array the array to wrap
  76    * @param offset the offset of the region in the array to wrap
  77    * @param length the length of the region in the array to wrap
  78    *
  79    * @return a new <code>CharBuffer</code> object
  80    *
  81    * @exception IndexOutOfBoundsException If the preconditions on the offset
  82    * and length parameters do not hold
  83    */
  84   public static final CharBuffer wrap(char[] array, int offset, int length)
  85   {
  86     return new CharBufferImpl(array, 0, array.length, offset + length, offset,
  87                               -1, false);
  88   }
  89
  90   /**
  91    * Wraps a character sequence into a <code>CharBuffer</code> object.
  92    *
  93    * @param seq the sequence to wrap
  94    *
  95    * @return a new <code>CharBuffer</code> object
  96    */
  97   public static final CharBuffer wrap(CharSequence seq)
  98   {
  99     return wrap(seq, 0, seq.length());
 100   }
 101
 102   /**
 103    * Wraps a character sequence into a <code>CharBuffer</code> object.
 104    *
 105    * @param seq the sequence to wrap
 106    * @param start the index of the first character to wrap
 107    * @param end the index of the first character not to wrap
 108    *
 109    * @return a new <code>CharBuffer</code> object
 110    *
 111    * @exception IndexOutOfBoundsException If the preconditions on the offset
 112    * and length parameters do not hold
 113    */
 114   public static final CharBuffer wrap(CharSequence seq, int start, int end)
 115   {
 116     return new CharSequenceBuffer(seq, start, end);
 117   }
 118
 119   /**
 120    * Wraps a <code>char</code> array into a <code>CharBuffer</code>
 121    * object.
 122    *
 123    * @param array the array to wrap
 124    *
 125    * @return a new <code>CharBuffer</code> object
 126    */
 127   public static final CharBuffer wrap(char[] array)
 128   {
 129     return wrap(array, 0, array.length);
 130   }
 131
 132   /**
 133    * This method transfers <code>char</code>s from this buffer into the given
 134    * destination array. Before the transfer, it checks if there are fewer than
 135    * length <code>char</code>s remaining in this buffer.
 136    *
 137    * @param dst The destination array
 138    * @param offset The offset within the array of the first <code>char</code>
 139    * to be written; must be non-negative and no larger than dst.length.
 140    * @param length The maximum number of bytes to be written to the given array;
 141    * must be non-negative and no larger than dst.length - offset.
 142    *
 143    * @exception BufferUnderflowException If there are fewer than length
 144    * <code>char</code>s remaining in this buffer.
 145    * @exception IndexOutOfBoundsException If the preconditions on the offset
 146    * and length parameters do not hold.
 147    */
 148   public CharBuffer get (char[] dst, int offset, int length)
 149   {
 150     checkArraySize(dst.length, offset, length);
 151     checkForUnderflow(length);
 152
 153     for (int i = offset; i < offset + length; i++)
 154       {
 155         dst [i] = get ();
 156       }
 157
 158     return this;
 159   }
 160
 161   /** @since 1.5 */
 162   public int read(CharBuffer buffer) throws IOException
 163   {
 164     // We want to call put(), so we don't manipulate the CharBuffer
 165     // directly.
 166     int rem = Math.min(buffer.remaining(), remaining());
 167     char[] buf = new char[rem];
 168     get(buf);
 169     buffer.put(buf);
 170     return rem;
 171   }
 172
 173   /**
 174    * This method transfers <code>char</code>s from this buffer into the given
 175    * destination array.
 176    *
 177    * @param dst The byte array to write into.
 178    *
 179    * @exception BufferUnderflowException If there are fewer than dst.length
 180    * <code>char</code>s remaining in this buffer.
 181    */
 182   public CharBuffer get (char[] dst)
 183   {
 184     return get (dst, 0, dst.length);
 185   }
 186
 187   /**
 188    * Writes the content of the the <code>CharBUFFER</code> src
 189    * into the buffer. Before the transfer, it checks if there is fewer than
 190    * <code>src.remaining()</code> space remaining in this buffer.
 191    *
 192    * @param src The source data.
 193    *
 194    * @exception BufferOverflowException If there is insufficient space in this
 195    * buffer for the remaining <code>char</code>s in the source buffer.
 196    * @exception IllegalArgumentException If the source buffer is this buffer.
 197    * @exception ReadOnlyBufferException If this buffer is read-only.
 198    */
 199   public CharBuffer put (CharBuffer src)
 200   {
 201     if (src == this)
 202       throw new IllegalArgumentException ();
 203
 204     checkForOverflow(src.remaining());
 205
 206     if (src.remaining () > 0)
 207       {
 208         char[] toPut = new char [src.remaining ()];
 209         src.get (toPut);
 210         put (toPut);
 211       }
 212
 213     return this;
 214   }
 215
 216   /**
 217    * Writes the content of the the <code>char array</code> src
 218    * into the buffer. Before the transfer, it checks if there is fewer than
 219    * length space remaining in this buffer.
 220    *
 221    * @param src The array to copy into the buffer.
 222    * @param offset The offset within the array of the first byte to be read;
 223    * must be non-negative and no larger than src.length.
 224    * @param length The number of bytes to be read from the given array;
 225    * must be non-negative and no larger than src.length - offset.
 226    *
 227    * @exception BufferOverflowException If there is insufficient space in this
 228    * buffer for the remaining <code>char</code>s in the source array.
 229    * @exception IndexOutOfBoundsException If the preconditions on the offset
 230    * and length parameters do not hold
 231    * @exception ReadOnlyBufferException If this buffer is read-only.
 232    */
 233   public CharBuffer put (char[] src, int offset, int length)
 234   {
 235     checkArraySize(src.length, offset, length);
 236     checkForOverflow(length);
 237
 238     for (int i = offset; i < offset + length; i++)
 239       put (src [i]);
 240
 241     return this;
 242   }
 243
 244   /**
 245    * Writes the content of the the <code>char array</code> src
 246    * into the buffer.
 247    *
 248    * @param src The array to copy into the buffer.
 249    *
 250    * @exception BufferOverflowException If there is insufficient space in this
 251    * buffer for the remaining <code>char</code>s in the source array.
 252    * @exception ReadOnlyBufferException If this buffer is read-only.
 253    */
 254   public final CharBuffer put (char[] src)
 255   {
 256     return put (src, 0, src.length);
 257   }
 258
 259   /**
 260    * Tells whether ot not this buffer is backed by an accessible
 261    * <code>char</code> array.
 262    */
 263   public final boolean hasArray ()
 264   {
 265     return (backing_buffer != null
 266             && !isReadOnly ());
 267   }
 268
 269   /**
 270    * Returns the <code>char</code> array that backs this buffer.
 271    *
 272    * @exception ReadOnlyBufferException If this buffer is read-only.
 273    * @exception UnsupportedOperationException If this buffer is not backed
 274    * by an accessible array.
 275    */
 276   public final char[] array ()
 277   {
 278     if (backing_buffer == null)
 279       throw new UnsupportedOperationException ();
 280
 281     checkIfReadOnly();
 282
 283     return backing_buffer;
 284   }
 285
 286   /**
 287    * Returns the offset within this buffer's backing array of the first element.
 288    *
 289    * @exception ReadOnlyBufferException If this buffer is read-only.
 290    * @exception UnsupportedOperationException If this buffer is not backed
 291    * by an accessible array.
 292    */
 293   public final int arrayOffset ()
 294   {
 295     if (backing_buffer == null)
 296       throw new UnsupportedOperationException ();
 297
 298     checkIfReadOnly();
 299
 300     return array_offset;
 301   }
 302
 303   /**
 304    * Calculates a hash code for this buffer.
 305    *
 306    * This is done with int arithmetic,
 307    * where ** represents exponentiation, by this formula:<br>
 308    * <code>s[position()] + 31 + (s[position()+1] + 30)*31**1 + ... +
 309    * (s[limit()-1]+30)*31**(limit()-1)</code>.
 310    * Where s is the buffer data. Note that the hashcode is dependent
 311    * on buffer content, and therefore is not useful if the buffer
 312    * content may change.
 313    */
 314   public int hashCode ()
 315   {
 316     int hashCode = get(position()) + 31;
 317     int multiplier = 1;
 318     for (int i = position() + 1; i < limit(); ++i)
 319       {
 320           multiplier *= 31;
 321           hashCode += (get(i) + 30)*multiplier;
 322       }
 323     return hashCode;
 324   }
 325
 326   /**
 327    * Checks if this buffer is equal to obj.
 328    */
 329   public boolean equals (Object obj)
 330   {
 331     if (obj instanceof CharBuffer)
 332       {
 333         return compareTo ((CharBuffer) obj) == 0;
 334       }
 335
 336     return false;
 337   }
 338
 339   /**
 340    * Compares two <code>CharBuffer</code> objects.
 341    *
 342    * @exception ClassCastException If obj is not an object derived from
 343    * <code>CharBuffer</code>.
 344    */
 345   public int compareTo (CharBuffer other)
 346   {
 347     int num = Math.min(remaining(), other.remaining());
 348     int pos_this = position();
 349     int pos_other = other.position();
 350
 351     for (int count = 0; count < num; count++)
 352       {
 353          char a = get(pos_this++);
 354          char b = other.get(pos_other++);
 355
 356          if (a == b)
 357            continue;
 358
 359          if (a < b)
 360            return -1;
 361
 362          return 1;
 363       }
 364
 365      return remaining() - other.remaining();
 366   }
 367
 368   /**
 369    * Returns the byte order of this buffer.
 370    */
 371   public abstract ByteOrder order ();
 372
 373   /**
 374    * Reads the <code>char</code> at this buffer's current position,
 375    * and then increments the position.
 376    *
 377    * @exception BufferUnderflowException If there are no remaining
 378    * <code>char</code>s in this buffer.
 379    */
 380   public abstract char get ();
 381
 382   /**
 383    * Writes the <code>char</code> at this buffer's current position,
 384    * and then increments the position.
 385    *
 386    * @exception BufferOverflowException If there no remaining
 387    * <code>char</code>s in this buffer.
 388    * @exception ReadOnlyBufferException If this buffer is read-only.
 389    */
 390   public abstract CharBuffer put (char b);
 391
 392   /**
 393    * Absolute get method.
 394    *
 395    * @exception IndexOutOfBoundsException If index is negative or not smaller
 396    * than the buffer's limit.
 397    */
 398   public abstract char get (int index);
 399
 400   /**
 401    * Absolute put method.
 402    *
 403    * @exception IndexOutOfBoundsException If index is negative or not smaller
 404    * than the buffer's limit.
 405    * @exception ReadOnlyBufferException If this buffer is read-only.
 406    */
 407   public abstract CharBuffer put (int index, char b);
 408
 409   /**
 410    * Compacts this buffer.
 411    *
 412    * @exception ReadOnlyBufferException If this buffer is read-only.
 413    */
 414   public abstract CharBuffer compact ();
 415
 416   /**
 417    * Tells wether or not this buffer is direct.
 418    */
 419   public abstract boolean isDirect ();
 420
 421   /**
 422    * Creates a new <code>CharBuffer</code> whose content is a shared
 423    * subsequence of this buffer's content.
 424    */
 425   public abstract CharBuffer slice ();
 426
 427   /**
 428    * Creates a new <code>CharBuffer</code> that shares this buffer's
 429    * content.
 430    */
 431   public abstract CharBuffer duplicate ();
 432
 433   /**
 434    * Creates a new read-only <code>CharBuffer</code> that shares this
 435    * buffer's content.
 436    */
 437   public abstract CharBuffer asReadOnlyBuffer ();
 438
 439   /**
 440    * Returns the remaining content of the buffer as a string.
 441    */
 442   public String toString ()
 443   {
 444     if (hasArray ())
 445       return new String (array (), position (), length ());
 446
 447     char[] buf = new char [length ()];
 448     int pos = position ();
 449     get (buf, 0, buf.length);
 450     position (pos);
 451     return new String (buf);
 452   }
 453
 454   /**
 455    * Returns the length of the remaining chars in this buffer.
 456    */
 457   public final int length ()
 458   {
 459     return remaining ();
 460   }
 461
 462   /**
 463    * Creates a new character buffer that represents the specified subsequence
 464    * of this buffer, relative to the current position.
 465    *
 466    * @exception IndexOutOfBoundsException If the preconditions on start and
 467    * end do not hold.
 468    */
 469   public abstract CharSequence subSequence (int start, int length);
 470
 471   /**
 472    * Relative put method.
 473    *
 474    * @exception BufferOverflowException If there is insufficient space in this
 475    * buffer.
 476    * @exception IndexOutOfBoundsException If the preconditions on the start
 477    * and end parameters do not hold.
 478    * @exception ReadOnlyBufferException If this buffer is read-only.
 479    */
 480   public CharBuffer put (String str, int start, int length)
 481   {
 482     return put (str.toCharArray (), start, length);
 483   }
 484
 485   /**
 486    * Relative put method.
 487    *
 488    * @exception BufferOverflowException If there is insufficient space in this
 489    * buffer.
 490    * @exception ReadOnlyBufferException If this buffer is read-only.
 491    */
 492   public final CharBuffer put (String str)
 493   {
 494     return put (str.toCharArray (), 0, str.length ());
 495   }
 496
 497   /**
 498    * Returns the character at <code>position() + index</code>.
 499    *
 500    * @exception IndexOutOfBoundsException If index is negative not smaller than
 501    * <code>remaining()</code>.
 502    */
 503   public final char charAt (int index)
 504   {
 505     if (index < 0
 506         || index >= remaining ())
 507       throw new IndexOutOfBoundsException ();
 508
 509     return get (position () + index);
 510   }
 511
 512   /** @since 1.5 */
 513   public CharBuffer append(char c)
 514   {
 515     put(c);
 516     return this;
 517   }
 518
 519   /** @since 1.5 */
 520   public CharBuffer append(CharSequence cs)
 521   {
 522     put(cs == null ? "null" : cs.toString());
 523     return this;
 524   }
 525
 526   /** @since 1.5 */
 527   public CharBuffer append(CharSequence cs, int start, int end)
 528   {
 529     put(cs == null ? "null" : cs.subSequence(start, end).toString());
 530     return this;
 531   }
 532 }