001/* CharsetEncoder.java --
002   Copyright (C) 2002 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package java.nio.charset;
039
040import java.nio.ByteBuffer;
041import java.nio.CharBuffer;
042
043/**
044 * @author Jesse Rosenstock
045 * @since 1.4
046 */
047public abstract class CharsetEncoder
048{
049  private static final int STATE_RESET   = 0;
050  private static final int STATE_CODING  = 1;
051  private static final int STATE_END     = 2;
052  private static final int STATE_FLUSHED = 3;
053
054  private static final byte[] DEFAULT_REPLACEMENT = {(byte)'?'};
055
056  private final Charset charset;
057  private final float averageBytesPerChar;
058  private final float maxBytesPerChar;
059  private byte[] replacement;
060
061  private int state = STATE_RESET;
062
063  private CodingErrorAction malformedInputAction
064    = CodingErrorAction.REPORT;
065  private CodingErrorAction unmappableCharacterAction
066    = CodingErrorAction.REPORT;
067
068  protected CharsetEncoder (Charset cs, float averageBytesPerChar,
069                            float maxBytesPerChar)
070  {
071    this (cs, averageBytesPerChar, maxBytesPerChar, DEFAULT_REPLACEMENT);
072  }
073
074  protected CharsetEncoder (Charset cs, float averageBytesPerChar,
075                            float maxBytesPerChar, byte[] replacement)
076  {
077    if (averageBytesPerChar <= 0.0f)
078      throw new IllegalArgumentException ("Non-positive averageBytesPerChar");
079    if (maxBytesPerChar <= 0.0f)
080      throw new IllegalArgumentException ("Non-positive maxBytesPerChar");
081
082    this.charset = cs;
083    this.averageBytesPerChar
084      = averageBytesPerChar;
085    this.maxBytesPerChar
086      = maxBytesPerChar;
087    this.replacement = replacement;
088    implReplaceWith (replacement);
089  }
090
091  public final float averageBytesPerChar ()
092  {
093    return averageBytesPerChar;
094  }
095
096  public boolean canEncode (char c)
097  {
098    CharBuffer cb = CharBuffer.allocate (1).put (c);
099    cb.flip ();
100    return canEncode (cb);
101  }
102
103  public boolean canEncode (CharSequence cs)
104  {
105    CharBuffer cb;
106    if (cs instanceof CharBuffer)
107      cb = ((CharBuffer) cs).duplicate ();
108    else
109      cb = CharBuffer.wrap (cs);
110    return canEncode (cb);
111  }
112
113  private boolean canEncode (CharBuffer cb)
114  {
115    // It is an error if a coding operation is "in progress"
116    // I take that to mean the state is not reset or flushed.
117    // XXX: check "in progress" everywhere
118    if (state == STATE_FLUSHED)
119      reset ();
120    else if (state != STATE_RESET)
121      throw new IllegalStateException ();
122
123    CodingErrorAction oldMalformedInputAction = malformedInputAction;
124    CodingErrorAction oldUnmappableCharacterAction
125      = unmappableCharacterAction;
126
127    try
128      {
129        if (oldMalformedInputAction != CodingErrorAction.REPORT)
130          onMalformedInput (CodingErrorAction.REPORT);
131        if (oldUnmappableCharacterAction != CodingErrorAction.REPORT)
132          onUnmappableCharacter (CodingErrorAction.REPORT);
133      }
134    catch (Exception e)
135      {
136        return false;
137      }
138    finally
139      {
140        if (oldMalformedInputAction != CodingErrorAction.REPORT)
141          onMalformedInput (oldMalformedInputAction);
142        if (oldUnmappableCharacterAction != CodingErrorAction.REPORT)
143          onUnmappableCharacter (oldUnmappableCharacterAction);
144      }
145
146    return true;
147  }
148
149  public final Charset charset ()
150  {
151    return charset;
152  }
153
154  public final ByteBuffer encode (CharBuffer in)
155    throws CharacterCodingException
156  {
157    // XXX: Sun's Javadoc seems to contradict itself saying an
158    // IllegalStateException is thrown "if a decoding operation is already
159    // in progress" and also that "it resets this Encoder".
160    // Should we check to see that the state is reset, or should we
161    // call reset()?
162    if (state != STATE_RESET)
163      throw new IllegalStateException ();
164
165    // REVIEW: Using max instead of average may allocate a very large
166    // buffer.  Maybe we should do something more efficient?
167    int remaining = in.remaining ();
168    int n = (int) (remaining * maxBytesPerChar ());
169    ByteBuffer out = ByteBuffer.allocate (n);
170
171    if (remaining == 0)
172      {
173        state = STATE_FLUSHED;
174        return out;
175      }
176
177    CoderResult cr = encode (in, out, true);
178    if (cr.isError ())
179      cr.throwException ();
180
181    cr = flush (out);
182    if (cr.isError ())
183      cr.throwException ();
184
185    out.flip ();
186
187    // Unfortunately, resizing the actual bytebuffer array is required.
188    byte[] resized = new byte[out.remaining()];
189    out.get(resized);
190    return ByteBuffer.wrap(resized);
191  }
192
193  public final CoderResult encode (CharBuffer in, ByteBuffer out,
194                                   boolean endOfInput)
195  {
196    int newState = endOfInput ? STATE_END : STATE_CODING;
197    // XXX: Need to check for "previous step was an invocation [not] of
198    // this method with a value of true for the endOfInput parameter but
199    // a return value indicating an incomplete decoding operation"
200    // XXX: We will not check the previous return value, just
201    // that the previous call passed true for endOfInput
202    if (state != STATE_RESET && state != STATE_CODING
203        && !(endOfInput && state == STATE_END))
204      throw new IllegalStateException ();
205    state = newState;
206
207    for (;;)
208      {
209        CoderResult cr;
210        try
211          {
212            cr = encodeLoop (in, out);
213          }
214        catch (RuntimeException e)
215          {
216            throw new CoderMalfunctionError (e);
217          }
218
219        if (cr.isOverflow ())
220          return cr;
221
222        if (cr.isUnderflow ())
223          {
224            if (endOfInput && in.hasRemaining ())
225              cr = CoderResult.malformedForLength (in.remaining ());
226            else
227              return cr;
228          }
229
230        CodingErrorAction action = cr.isMalformed ()
231                                     ? malformedInputAction
232                                     : unmappableCharacterAction;
233
234        if (action == CodingErrorAction.REPORT)
235          return cr;
236
237        if (action == CodingErrorAction.REPLACE)
238          {
239            if (out.remaining () < replacement.length)
240              return CoderResult.OVERFLOW;
241            out.put (replacement);
242          }
243
244        in.position (in.position () + cr.length ());
245      }
246  }
247
248  protected abstract CoderResult encodeLoop (CharBuffer in, ByteBuffer out);
249
250  public final CoderResult flush (ByteBuffer out)
251  {
252    // It seems weird that you can flush after reset, but Sun's javadoc
253    // says an IllegalStateException is thrown "If the previous step of the
254    // current decoding operation was an invocation neither of the reset
255    // method nor ... of the three-argument encode method with a value of
256    // true for the endOfInput parameter."
257    // Further note that flush() only requires that there not be
258    // an IllegalStateException if the previous step was a call to
259    // encode with true as the last argument.  It does not require
260    // that the call succeeded.  encode() does require that it succeeded.
261    // XXX: test this to see if reality matches javadoc
262    if (state != STATE_RESET && state != STATE_END)
263      throw new IllegalStateException ();
264
265    state = STATE_FLUSHED;
266    return implFlush (out);
267  }
268
269  protected CoderResult implFlush (ByteBuffer out)
270  {
271    return CoderResult.UNDERFLOW;
272  }
273
274  protected void implOnMalformedInput (CodingErrorAction newAction)
275  {
276    // default implementation does nothing
277  }
278
279  protected void implOnUnmappableCharacter (CodingErrorAction newAction)
280  {
281    // default implementation does nothing
282  }
283
284  protected void implReplaceWith (byte[] newReplacement)
285  {
286    // default implementation does nothing
287  }
288
289  protected void implReset ()
290  {
291    // default implementation does nothing
292  }
293
294  public boolean isLegalReplacement (byte[] replacement)
295  {
296    // TODO: cache the decoder
297    // error actions will be REPORT after construction
298    CharsetDecoder decoder = charset.newDecoder ();
299    ByteBuffer bb = ByteBuffer.wrap (replacement);
300    CharBuffer cb
301      = CharBuffer.allocate ((int) (replacement.length
302                                    * decoder.maxCharsPerByte ()));
303    return !decoder.decode (bb, cb, true).isError ();
304  }
305
306  public CodingErrorAction malformedInputAction ()
307  {
308    return malformedInputAction;
309  }
310
311  public final float maxBytesPerChar ()
312  {
313    return maxBytesPerChar;
314  }
315
316  public final CharsetEncoder onMalformedInput (CodingErrorAction newAction)
317  {
318    if (newAction == null)
319      throw new IllegalArgumentException ("Null action");
320
321    malformedInputAction = newAction;
322    implOnMalformedInput (newAction);
323    return this;
324  }
325
326  public CodingErrorAction unmappableCharacterAction ()
327  {
328    return unmappableCharacterAction;
329  }
330
331  public final CharsetEncoder onUnmappableCharacter
332    (CodingErrorAction newAction)
333  {
334    if (newAction == null)
335      throw new IllegalArgumentException ("Null action");
336
337    unmappableCharacterAction = newAction;
338    implOnUnmappableCharacter (newAction);
339    return this;
340  }
341
342  public final byte[] replacement ()
343  {
344    return replacement;
345  }
346
347  public final CharsetEncoder replaceWith (byte[] newReplacement)
348  {
349    if (newReplacement == null)
350      throw new IllegalArgumentException ("Null replacement");
351    if (newReplacement.length == 0)
352      throw new IllegalArgumentException ("Empty replacement");
353    // XXX: what about maxBytesPerChar?
354
355      if (!isLegalReplacement (newReplacement))
356        throw new IllegalArgumentException ("Illegal replacement");
357
358    this.replacement = newReplacement;
359    implReplaceWith (newReplacement);
360    return this;
361  }
362
363  public final CharsetEncoder reset ()
364  {
365    state = STATE_RESET;
366    implReset ();
367    return this;
368  }
369}