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