001 /* CharBuffer.java --
002 Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.nio;
040
041 import java.io.IOException;
042
043 /**
044 * @since 1.4
045 */
046 public abstract class CharBuffer extends Buffer
047 implements Comparable<CharBuffer>, CharSequence, Readable, Appendable
048 {
049 int array_offset;
050 char[] backing_buffer;
051
052 CharBuffer (int capacity, int limit, int position, int mark)
053 {
054 super (capacity, limit, position, mark);
055 array_offset = 0;
056 }
057
058 /**
059 * Allocates a new <code>CharBuffer</code> object with a given capacity.
060 */
061 public static CharBuffer allocate (int capacity)
062 {
063 return new CharBufferImpl (capacity);
064 }
065
066 /**
067 * Wraps a <code>char</code> array into a <code>CharBuffer</code>
068 * object.
069 *
070 * @param array the array to wrap
071 * @param offset the offset of the region in the array to wrap
072 * @param length the length of the region in the array to wrap
073 *
074 * @return a new <code>CharBuffer</code> object
075 *
076 * @exception IndexOutOfBoundsException If the preconditions on the offset
077 * and length parameters do not hold
078 */
079 public static final CharBuffer wrap(char[] array, int offset, int length)
080 {
081 return new CharBufferImpl(array, 0, array.length, offset + length, offset, -1, false);
082 }
083
084 /**
085 * Wraps a character sequence into a <code>CharBuffer</code> object.
086 *
087 * @param seq the sequence to wrap
088 *
089 * @return a new <code>CharBuffer</code> object
090 */
091 public static final CharBuffer wrap(CharSequence seq)
092 {
093 return wrap(seq, 0, seq.length());
094 }
095
096 /**
097 * Wraps a character sequence into a <code>CharBuffer</code> object.
098 *
099 * @param seq the sequence to wrap
100 * @param start the index of the first character to wrap
101 * @param end the index of the first character not to wrap
102 *
103 * @return a new <code>CharBuffer</code> object
104 *
105 * @exception IndexOutOfBoundsException If the preconditions on the offset
106 * and length parameters do not hold
107 */
108 public static final CharBuffer wrap(CharSequence seq, int start, int end)
109 {
110 return new CharSequenceBuffer(seq, start, end);
111 }
112
113 /**
114 * Wraps a <code>char</code> array into a <code>CharBuffer</code>
115 * object.
116 *
117 * @param array the array to wrap
118 *
119 * @return a new <code>CharBuffer</code> object
120 */
121 public static final CharBuffer wrap(char[] array)
122 {
123 return wrap(array, 0, array.length);
124 }
125
126 /**
127 * This method transfers <code>char</code>s from this buffer into the given
128 * destination array. Before the transfer, it checks if there are fewer than
129 * length <code>char</code>s remaining in this buffer.
130 *
131 * @param dst The destination array
132 * @param offset The offset within the array of the first <code>char</code>
133 * to be written; must be non-negative and no larger than dst.length.
134 * @param length The maximum number of bytes to be written to the given array;
135 * must be non-negative and no larger than dst.length - offset.
136 *
137 * @exception BufferUnderflowException If there are fewer than length
138 * <code>char</code>s remaining in this buffer.
139 * @exception IndexOutOfBoundsException If the preconditions on the offset
140 * and length parameters do not hold.
141 */
142 public CharBuffer get (char[] dst, int offset, int length)
143 {
144 checkArraySize(dst.length, offset, length);
145 checkForUnderflow(length);
146
147 for (int i = offset; i < offset + length; i++)
148 {
149 dst [i] = get ();
150 }
151
152 return this;
153 }
154
155 /** @since 1.5 */
156 public int read(CharBuffer buffer) throws IOException
157 {
158 // We want to call put(), so we don't manipulate the CharBuffer
159 // directly.
160 int rem = Math.min(buffer.remaining(), remaining());
161 char[] buf = new char[rem];
162 get(buf);
163 buffer.put(buf);
164 return rem;
165 }
166
167 /**
168 * This method transfers <code>char</code>s from this buffer into the given
169 * destination array.
170 *
171 * @param dst The byte array to write into.
172 *
173 * @exception BufferUnderflowException If there are fewer than dst.length
174 * <code>char</code>s remaining in this buffer.
175 */
176 public CharBuffer get (char[] dst)
177 {
178 return get (dst, 0, dst.length);
179 }
180
181 /**
182 * Writes the content of the the <code>CharBUFFER</code> src
183 * into the buffer. Before the transfer, it checks if there is fewer than
184 * <code>src.remaining()</code> space remaining in this buffer.
185 *
186 * @param src The source data.
187 *
188 * @exception BufferOverflowException If there is insufficient space in this
189 * buffer for the remaining <code>char</code>s in the source buffer.
190 * @exception IllegalArgumentException If the source buffer is this buffer.
191 * @exception ReadOnlyBufferException If this buffer is read-only.
192 */
193 public CharBuffer put (CharBuffer src)
194 {
195 if (src == this)
196 throw new IllegalArgumentException ();
197
198 checkForOverflow(src.remaining());
199
200 if (src.remaining () > 0)
201 {
202 char[] toPut = new char [src.remaining ()];
203 src.get (toPut);
204 put (toPut);
205 }
206
207 return this;
208 }
209
210 /**
211 * Writes the content of the the <code>char array</code> src
212 * into the buffer. Before the transfer, it checks if there is fewer than
213 * length space remaining in this buffer.
214 *
215 * @param src The array to copy into the buffer.
216 * @param offset The offset within the array of the first byte to be read;
217 * must be non-negative and no larger than src.length.
218 * @param length The number of bytes to be read from the given array;
219 * must be non-negative and no larger than src.length - offset.
220 *
221 * @exception BufferOverflowException If there is insufficient space in this
222 * buffer for the remaining <code>char</code>s in the source array.
223 * @exception IndexOutOfBoundsException If the preconditions on the offset
224 * and length parameters do not hold
225 * @exception ReadOnlyBufferException If this buffer is read-only.
226 */
227 public CharBuffer put (char[] src, int offset, int length)
228 {
229 checkArraySize(src.length, offset, length);
230 checkForOverflow(length);
231
232 for (int i = offset; i < offset + length; i++)
233 put (src [i]);
234
235 return this;
236 }
237
238 /**
239 * Writes the content of the the <code>char array</code> src
240 * into the buffer.
241 *
242 * @param src The array to copy into the buffer.
243 *
244 * @exception BufferOverflowException If there is insufficient space in this
245 * buffer for the remaining <code>char</code>s in the source array.
246 * @exception ReadOnlyBufferException If this buffer is read-only.
247 */
248 public final CharBuffer put (char[] src)
249 {
250 return put (src, 0, src.length);
251 }
252
253 /**
254 * Tells whether ot not this buffer is backed by an accessible
255 * <code>char</code> array.
256 */
257 public final boolean hasArray ()
258 {
259 return (backing_buffer != null
260 && !isReadOnly ());
261 }
262
263 /**
264 * Returns the <code>char</code> array that backs this buffer.
265 *
266 * @exception ReadOnlyBufferException If this buffer is read-only.
267 * @exception UnsupportedOperationException If this buffer is not backed
268 * by an accessible array.
269 */
270 public final char[] array ()
271 {
272 if (backing_buffer == null)
273 throw new UnsupportedOperationException ();
274
275 checkIfReadOnly();
276
277 return backing_buffer;
278 }
279
280 /**
281 * Returns the offset within this buffer's backing array of the first element.
282 *
283 * @exception ReadOnlyBufferException If this buffer is read-only.
284 * @exception UnsupportedOperationException If this buffer is not backed
285 * by an accessible array.
286 */
287 public final int arrayOffset ()
288 {
289 if (backing_buffer == null)
290 throw new UnsupportedOperationException ();
291
292 checkIfReadOnly();
293
294 return array_offset;
295 }
296
297 /**
298 * Calculates a hash code for this buffer.
299 *
300 * This is done with int arithmetic,
301 * where ** represents exponentiation, by this formula:<br>
302 * <code>s[position()] + 31 + (s[position()+1] + 30)*31**1 + ... +
303 * (s[limit()-1]+30)*31**(limit()-1)</code>.
304 * Where s is the buffer data. Note that the hashcode is dependent
305 * on buffer content, and therefore is not useful if the buffer
306 * content may change.
307 */
308 public int hashCode ()
309 {
310 int hashCode = get(position()) + 31;
311 int multiplier = 1;
312 for (int i = position() + 1; i < limit(); ++i)
313 {
314 multiplier *= 31;
315 hashCode += (get(i) + 30)*multiplier;
316 }
317 return hashCode;
318 }
319
320 /**
321 * Checks if this buffer is equal to obj.
322 */
323 public boolean equals (Object obj)
324 {
325 if (obj instanceof CharBuffer)
326 {
327 return compareTo ((CharBuffer) obj) == 0;
328 }
329
330 return false;
331 }
332
333 /**
334 * Compares two <code>CharBuffer</code> objects.
335 *
336 * @exception ClassCastException If obj is not an object derived from
337 * <code>CharBuffer</code>.
338 */
339 public int compareTo (CharBuffer other)
340 {
341 int num = Math.min(remaining(), other.remaining());
342 int pos_this = position();
343 int pos_other = other.position();
344
345 for (int count = 0; count < num; count++)
346 {
347 char a = get(pos_this++);
348 char b = other.get(pos_other++);
349
350 if (a == b)
351 continue;
352
353 if (a < b)
354 return -1;
355
356 return 1;
357 }
358
359 return remaining() - other.remaining();
360 }
361
362 /**
363 * Returns the byte order of this buffer.
364 */
365 public abstract ByteOrder order ();
366
367 /**
368 * Reads the <code>char</code> at this buffer's current position,
369 * and then increments the position.
370 *
371 * @exception BufferUnderflowException If there are no remaining
372 * <code>char</code>s in this buffer.
373 */
374 public abstract char get ();
375
376 /**
377 * Writes the <code>char</code> at this buffer's current position,
378 * and then increments the position.
379 *
380 * @exception BufferOverflowException If there no remaining
381 * <code>char</code>s in this buffer.
382 * @exception ReadOnlyBufferException If this buffer is read-only.
383 */
384 public abstract CharBuffer put (char b);
385
386 /**
387 * Absolute get method.
388 *
389 * @exception IndexOutOfBoundsException If index is negative or not smaller
390 * than the buffer's limit.
391 */
392 public abstract char get (int index);
393
394 /**
395 * Absolute put method.
396 *
397 * @exception IndexOutOfBoundsException If index is negative or not smaller
398 * than the buffer's limit.
399 * @exception ReadOnlyBufferException If this buffer is read-only.
400 */
401 public abstract CharBuffer put (int index, char b);
402
403 /**
404 * Compacts this buffer.
405 *
406 * @exception ReadOnlyBufferException If this buffer is read-only.
407 */
408 public abstract CharBuffer compact ();
409
410 /**
411 * Tells wether or not this buffer is direct.
412 */
413 public abstract boolean isDirect ();
414
415 /**
416 * Creates a new <code>CharBuffer</code> whose content is a shared
417 * subsequence of this buffer's content.
418 */
419 public abstract CharBuffer slice ();
420
421 /**
422 * Creates a new <code>CharBuffer</code> that shares this buffer's
423 * content.
424 */
425 public abstract CharBuffer duplicate ();
426
427 /**
428 * Creates a new read-only <code>CharBuffer</code> that shares this
429 * buffer's content.
430 */
431 public abstract CharBuffer asReadOnlyBuffer ();
432
433 /**
434 * Returns the remaining content of the buffer as a string.
435 */
436 public String toString ()
437 {
438 if (hasArray ())
439 return new String (array (), position (), length ());
440
441 char[] buf = new char [length ()];
442 int pos = position ();
443 get (buf, 0, buf.length);
444 position (pos);
445 return new String (buf);
446 }
447
448 /**
449 * Returns the length of the remaining chars in this buffer.
450 */
451 public final int length ()
452 {
453 return remaining ();
454 }
455
456 /**
457 * Creates a new character buffer that represents the specified subsequence
458 * of this buffer, relative to the current position.
459 *
460 * @exception IndexOutOfBoundsException If the preconditions on start and
461 * end do not hold.
462 */
463 public abstract CharSequence subSequence (int start, int length);
464
465 /**
466 * Relative put method.
467 *
468 * @exception BufferOverflowException If there is insufficient space in this
469 * buffer.
470 * @exception IndexOutOfBoundsException If the preconditions on the start
471 * and end parameters do not hold.
472 * @exception ReadOnlyBufferException If this buffer is read-only.
473 */
474 public CharBuffer put (String str, int start, int length)
475 {
476 return put (str.toCharArray (), start, length);
477 }
478
479 /**
480 * Relative put method.
481 *
482 * @exception BufferOverflowException If there is insufficient space in this
483 * buffer.
484 * @exception ReadOnlyBufferException If this buffer is read-only.
485 */
486 public final CharBuffer put (String str)
487 {
488 return put (str.toCharArray (), 0, str.length ());
489 }
490
491 /**
492 * Returns the character at <code>position() + index</code>.
493 *
494 * @exception IndexOutOfBoundsException If index is negative not smaller than
495 * <code>remaining()</code>.
496 */
497 public final char charAt (int index)
498 {
499 if (index < 0
500 || index >= remaining ())
501 throw new IndexOutOfBoundsException ();
502
503 return get (position () + index);
504 }
505
506 /** @since 1.5 */
507 public CharBuffer append(char c)
508 {
509 put(c);
510 return this;
511 }
512
513 /** @since 1.5 */
514 public CharBuffer append(CharSequence cs)
515 {
516 put(cs == null ? "null" : cs.toString());
517 return this;
518 }
519
520 /** @since 1.5 */
521 public CharBuffer append(CharSequence cs, int start, int end)
522 {
523 put(cs == null ? "null" : cs.subSequence(start, end).toString());
524 return this;
525 }
526 }