1 /* CharsetDecoder.java -- 2 Copyright (C) 2002 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., 59 Temple Place, Suite 330, Boston, MA 19 02111-1307 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 package java.nio.charset; 39 40 import java.nio.ByteBuffer; 41 import java.nio.CharBuffer; 42 43 /** 44 * @author Jesse Rosenstock 45 * @since 1.4 46 */ 47 public abstract class CharsetDecoder 48 { 49 private static final int STATE_RESET = 0; 50 private static final int STATE_CODING = 1; 51 private static final int STATE_END = 2; 52 private static final int STATE_FLUSHED = 3; 53 54 private static final String DEFAULT_REPLACEMENT = "\uFFFD"; 55 56 private final Charset charset; 57 private final float averageCharsPerByte; 58 private final float maxCharsPerByte; 59 private String replacement; 60 61 private int state = STATE_RESET; 62 63 private CodingErrorAction malformedInputAction 64 = CodingErrorAction.REPORT; 65 private CodingErrorAction unmappableCharacterAction 66 = CodingErrorAction.REPORT; 67 CharsetDecoder(Charset cs, float averageCharsPerByte, float maxCharsPerByte, String replacement)68 private CharsetDecoder (Charset cs, float averageCharsPerByte, 69 float maxCharsPerByte, String replacement) 70 { 71 if (averageCharsPerByte <= 0.0f) 72 throw new IllegalArgumentException ("Non-positive averageCharsPerByte"); 73 if (maxCharsPerByte <= 0.0f) 74 throw new IllegalArgumentException ("Non-positive maxCharsPerByte"); 75 76 this.charset = cs; 77 this.averageCharsPerByte 78 = averageCharsPerByte; 79 this.maxCharsPerByte 80 = maxCharsPerByte; 81 this.replacement = replacement; 82 implReplaceWith (replacement); 83 } 84 CharsetDecoder(Charset cs, float averageCharsPerByte, float maxCharsPerByte)85 protected CharsetDecoder (Charset cs, float averageCharsPerByte, 86 float maxCharsPerByte) 87 { 88 this (cs, averageCharsPerByte, maxCharsPerByte, DEFAULT_REPLACEMENT); 89 } 90 averageCharsPerByte()91 public final float averageCharsPerByte () 92 { 93 return averageCharsPerByte; 94 } 95 charset()96 public final Charset charset () 97 { 98 return charset; 99 } 100 decode(ByteBuffer in)101 public final CharBuffer decode (ByteBuffer in) 102 throws CharacterCodingException 103 { 104 // XXX: Sun's Javadoc seems to contradict itself saying an 105 // IllegalStateException is thrown "if a decoding operation is already 106 // in progress" and also that "it resets this Decoder". 107 // Should we check to see that the state is reset, or should we 108 // call reset()? 109 if (state != STATE_RESET) 110 throw new IllegalStateException (); 111 112 // REVIEW: Using max instead of average may allocate a very large 113 // buffer. Maybe we should do something more efficient? 114 int remaining = in.remaining (); 115 int n = (int) (remaining * maxCharsPerByte ()); 116 CharBuffer out = CharBuffer.allocate (n); 117 118 if (remaining == 0) 119 { 120 state = STATE_FLUSHED; 121 return out; 122 } 123 124 CoderResult cr = decode (in, out, true); 125 if (cr.isError ()) 126 cr.throwException (); 127 128 cr = flush (out); 129 if (cr.isError ()) 130 cr.throwException (); 131 132 out.flip (); 133 return out; 134 } 135 decode(ByteBuffer in, CharBuffer out, boolean endOfInput)136 public final CoderResult decode (ByteBuffer in, CharBuffer out, 137 boolean endOfInput) 138 { 139 int newState = endOfInput ? STATE_END : STATE_CODING; 140 // XXX: Need to check for "previous step was an invocation [not] of 141 // this method with a value of true for the endOfInput parameter but 142 // a return value indicating an incomplete decoding operation" 143 // XXX: We will not check the previous return value, just 144 // that the previous call passed true for endOfInput 145 if (state != STATE_RESET && state != STATE_CODING 146 && !(endOfInput && state == STATE_END)) 147 throw new IllegalStateException (); 148 state = newState; 149 150 for (;;) 151 { 152 CoderResult cr; 153 try 154 { 155 cr = decodeLoop (in, out); 156 } 157 catch (RuntimeException e) 158 { 159 throw new CoderMalfunctionError (e); 160 } 161 162 if (cr.isOverflow ()) 163 return cr; 164 165 if (cr.isUnderflow ()) 166 { 167 if (endOfInput && in.hasRemaining ()) 168 cr = CoderResult.malformedForLength (in.remaining ()); 169 else 170 return cr; 171 } 172 173 CodingErrorAction action = cr.isMalformed () 174 ? malformedInputAction 175 : unmappableCharacterAction; 176 177 if (action == CodingErrorAction.REPORT) 178 return cr; 179 180 if (action == CodingErrorAction.REPLACE) 181 { 182 if (out.remaining () < replacement.length ()) 183 return CoderResult.OVERFLOW; 184 out.put (replacement); 185 } 186 187 in.position (in.position () + cr.length ()); 188 } 189 } 190 decodeLoop(ByteBuffer in, CharBuffer out)191 protected abstract CoderResult decodeLoop (ByteBuffer in, CharBuffer out); 192 detectedCharset()193 public Charset detectedCharset () 194 { 195 throw new UnsupportedOperationException (); 196 } 197 flush(CharBuffer out)198 public final CoderResult flush (CharBuffer out) 199 { 200 // It seems weird that you can flush after reset, but Sun's javadoc 201 // says an IllegalStateException is thrown "If the previous step of the 202 // current decoding operation was an invocation neither of the reset 203 // method nor ... of the three-argument decode method with a value of 204 // true for the endOfInput parameter." 205 // Further note that flush() only requires that there not be 206 // an IllegalStateException if the previous step was a call to 207 // decode with true as the last argument. It does not require 208 // that the call succeeded. decode() does require that it succeeded. 209 // XXX: test this to see if reality matches javadoc 210 if (state != STATE_RESET && state != STATE_END) 211 throw new IllegalStateException (); 212 213 state = STATE_FLUSHED; 214 return implFlush (out); 215 } 216 implFlush(CharBuffer out)217 protected CoderResult implFlush (CharBuffer out) 218 { 219 return CoderResult.UNDERFLOW; 220 } 221 onMalformedInput(CodingErrorAction newAction)222 public final CharsetDecoder onMalformedInput (CodingErrorAction newAction) 223 { 224 if (newAction == null) 225 throw new IllegalArgumentException ("Null action"); 226 227 malformedInputAction = newAction; 228 implOnMalformedInput (newAction); 229 return this; 230 } 231 implOnMalformedInput(CodingErrorAction newAction)232 protected void implOnMalformedInput (CodingErrorAction newAction) 233 { 234 // default implementation does nothing 235 } 236 implOnUnmappableCharacter(CodingErrorAction newAction)237 protected void implOnUnmappableCharacter (CodingErrorAction newAction) 238 { 239 // default implementation does nothing 240 } 241 implReplaceWith(String newReplacement)242 protected void implReplaceWith (String newReplacement) 243 { 244 // default implementation does nothing 245 } 246 implReset()247 protected void implReset () 248 { 249 // default implementation does nothing 250 } 251 isAutoDetecting()252 public boolean isAutoDetecting () 253 { 254 return false; 255 } 256 isCharsetDetected()257 public boolean isCharsetDetected () 258 { 259 throw new UnsupportedOperationException (); 260 } 261 malformedInputAction()262 public CodingErrorAction malformedInputAction () 263 { 264 return malformedInputAction; 265 } 266 maxCharsPerByte()267 public final float maxCharsPerByte () 268 { 269 return maxCharsPerByte; 270 } 271 onUnmappableCharacter(CodingErrorAction newAction)272 public final CharsetDecoder onUnmappableCharacter 273 (CodingErrorAction newAction) 274 { 275 if (newAction == null) 276 throw new IllegalArgumentException ("Null action"); 277 278 unmappableCharacterAction = newAction; 279 implOnUnmappableCharacter (newAction); 280 return this; 281 } 282 replacement()283 public final String replacement () 284 { 285 return replacement; 286 } 287 replaceWith(String newReplacement)288 public final CharsetDecoder replaceWith (String newReplacement) 289 { 290 if (newReplacement == null) 291 throw new IllegalArgumentException ("Null replacement"); 292 if (newReplacement.length () == 0) 293 throw new IllegalArgumentException ("Empty replacement"); 294 // XXX: what about maxCharsPerByte? 295 296 this.replacement = newReplacement; 297 implReplaceWith (newReplacement); 298 return this; 299 } 300 reset()301 public final CharsetDecoder reset () 302 { 303 state = STATE_RESET; 304 implReset (); 305 return this; 306 } 307 unmappableCharacterAction()308 public CodingErrorAction unmappableCharacterAction () 309 { 310 return unmappableCharacterAction; 311 } 312 } 313