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    // GCJ LOCAL: Use RawData instead of gnu.classpath.Pointer
042    import gnu.gcj.RawData;
043    
044    import java.io.IOException;
045    
046    /**
047     * @since 1.4
048     */
049    public abstract class CharBuffer extends Buffer
050      implements Comparable<CharBuffer>, CharSequence, Readable, Appendable
051    {
052      final int array_offset;
053      final char[] backing_buffer;
054    
055      CharBuffer (int capacity, int limit, int position, int mark,
056                  RawData address, char[] backing_buffer, int array_offset)
057      {
058        super (capacity, limit, position, mark, address);
059        this.backing_buffer = backing_buffer;
060        this.array_offset = array_offset;
061      }
062    
063      /**
064       * Allocates a new <code>CharBuffer</code> object with a given capacity.
065       */
066      public static CharBuffer allocate (int capacity)
067      {
068        return new CharBufferImpl (capacity);
069      }
070    
071      /**
072       * Wraps a <code>char</code> array into a <code>CharBuffer</code>
073       * object.
074       *
075       * @param array the array to wrap
076       * @param offset the offset of the region in the array to wrap
077       * @param length the length of the region in the array to wrap
078       *
079       * @return a new <code>CharBuffer</code> object
080       *
081       * @exception IndexOutOfBoundsException If the preconditions on the offset
082       * and length parameters do not hold
083       */
084      public static final CharBuffer wrap(char[] array, int offset, int length)
085      {
086        return new CharBufferImpl(array, 0, array.length, offset + length, offset,
087                                  -1, false);
088      }
089    
090      /**
091       * Wraps a character sequence into a <code>CharBuffer</code> object.
092       *
093       * @param seq the sequence to wrap
094       *
095       * @return a new <code>CharBuffer</code> object
096       */
097      public static final CharBuffer wrap(CharSequence seq)
098      {
099        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    }