1/* 2 * Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26#warn This file is preprocessed before being compiled 27 28package java.nio.charset; 29 30import java.nio.Buffer; 31import java.nio.ByteBuffer; 32import java.nio.CharBuffer; 33import java.nio.BufferOverflowException; 34import java.nio.BufferUnderflowException; 35import java.lang.ref.WeakReference; 36import java.nio.charset.CoderMalfunctionError; // javadoc 37import java.util.Arrays; 38 39 40/** 41 * An engine that can transform a sequence of $itypesPhrase$ into a sequence of 42 * $otypesPhrase$. 43 * 44 * <a id="steps"></a> 45 * 46 * <p> The input $itype$ sequence is provided in a $itype$ buffer or a series 47 * of such buffers. The output $otype$ sequence is written to a $otype$ buffer 48 * or a series of such buffers. $A$ $coder$ should always be used by making 49 * the following sequence of method invocations, hereinafter referred to as $a$ 50 * <i>$coding$ operation</i>: 51 * 52 * <ol> 53 * 54 * <li><p> Reset the $coder$ via the {@link #reset reset} method, unless it 55 * has not been used before; </p></li> 56 * 57 * <li><p> Invoke the {@link #$code$ $code$} method zero or more times, as 58 * long as additional input may be available, passing {@code false} for the 59 * {@code endOfInput} argument and filling the input buffer and flushing the 60 * output buffer between invocations; </p></li> 61 * 62 * <li><p> Invoke the {@link #$code$ $code$} method one final time, passing 63 * {@code true} for the {@code endOfInput} argument; and then </p></li> 64 * 65 * <li><p> Invoke the {@link #flush flush} method so that the $coder$ can 66 * flush any internal state to the output buffer. </p></li> 67 * 68 * </ol> 69 * 70 * Each invocation of the {@link #$code$ $code$} method will $code$ as many 71 * $itype$s as possible from the input buffer, writing the resulting $otype$s 72 * to the output buffer. The {@link #$code$ $code$} method returns when more 73 * input is required, when there is not enough room in the output buffer, or 74 * when $a$ $coding$ error has occurred. In each case a {@link CoderResult} 75 * object is returned to describe the reason for termination. An invoker can 76 * examine this object and fill the input buffer, flush the output buffer, or 77 * attempt to recover from $a$ $coding$ error, as appropriate, and try again. 78 * 79 * <a id="ce"></a> 80 * 81 * <p> There are two general types of $coding$ errors. If the input $itype$ 82 * sequence is $notLegal$ then the input is considered <i>malformed</i>. If 83 * the input $itype$ sequence is legal but cannot be mapped to a valid 84 * $outSequence$ then an <i>unmappable character</i> has been encountered. 85 * 86 * <a id="cae"></a> 87 * 88 * <p> How $a$ $coding$ error is handled depends upon the action requested for 89 * that type of error, which is described by an instance of the {@link 90 * CodingErrorAction} class. The possible error actions are to {@linkplain 91 * CodingErrorAction#IGNORE ignore} the erroneous input, {@linkplain 92 * CodingErrorAction#REPORT report} the error to the invoker via 93 * the returned {@link CoderResult} object, or {@linkplain CodingErrorAction#REPLACE 94 * replace} the erroneous input with the current value of the 95 * replacement $replTypeName$. The replacement 96 * 97#if[encoder] 98 * is initially set to the $coder$'s default replacement, which often 99 * (but not always) has the initial value $defaultReplName$; 100#end[encoder] 101#if[decoder] 102 * has the initial value $defaultReplName$; 103#end[decoder] 104 * 105 * its value may be changed via the {@link #replaceWith($replFQType$) 106 * replaceWith} method. 107 * 108 * <p> The default action for malformed-input and unmappable-character errors 109 * is to {@linkplain CodingErrorAction#REPORT report} them. The 110 * malformed-input error action may be changed via the {@link 111 * #onMalformedInput(CodingErrorAction) onMalformedInput} method; the 112 * unmappable-character action may be changed via the {@link 113 * #onUnmappableCharacter(CodingErrorAction) onUnmappableCharacter} method. 114 * 115 * <p> This class is designed to handle many of the details of the $coding$ 116 * process, including the implementation of error actions. $A$ $coder$ for a 117 * specific charset, which is a concrete subclass of this class, need only 118 * implement the abstract {@link #$code$Loop $code$Loop} method, which 119 * encapsulates the basic $coding$ loop. A subclass that maintains internal 120 * state should, additionally, override the {@link #implFlush implFlush} and 121 * {@link #implReset implReset} methods. 122 * 123 * <p> Instances of this class are not safe for use by multiple concurrent 124 * threads. </p> 125 * 126 * 127 * @author Mark Reinhold 128 * @author JSR-51 Expert Group 129 * @since 1.4 130 * 131 * @see ByteBuffer 132 * @see CharBuffer 133 * @see Charset 134 * @see Charset$OtherCoder$ 135 */ 136 137public abstract class Charset$Coder$ { 138 139 private final Charset charset; 140 private final float average$ItypesPerOtype$; 141 private final float max$ItypesPerOtype$; 142 143 private $replType$ replacement; 144 private CodingErrorAction malformedInputAction 145 = CodingErrorAction.REPORT; 146 private CodingErrorAction unmappableCharacterAction 147 = CodingErrorAction.REPORT; 148 149 // Internal states 150 // 151 private static final int ST_RESET = 0; 152 private static final int ST_CODING = 1; 153 private static final int ST_END = 2; 154 private static final int ST_FLUSHED = 3; 155 156 private int state = ST_RESET; 157 158 private static String stateNames[] 159 = { "RESET", "CODING", "CODING_END", "FLUSHED" }; 160 161 162 /** 163 * Initializes a new $coder$. The new $coder$ will have the given 164 * $otypes-per-itype$ and replacement values. 165 * 166 * @param cs 167 * The charset that created this $coder$ 168 * 169 * @param average$ItypesPerOtype$ 170 * A positive float value indicating the expected number of 171 * $otype$s that will be produced for each input $itype$ 172 * 173 * @param max$ItypesPerOtype$ 174 * A positive float value indicating the maximum number of 175 * $otype$s that will be produced for each input $itype$ 176 * 177 * @param replacement 178 * The initial replacement; must not be {@code null}, must have 179 * non-zero length, must not be longer than max$ItypesPerOtype$, 180 * and must be {@linkplain #isLegalReplacement legal} 181 * 182 * @throws IllegalArgumentException 183 * If the preconditions on the parameters do not hold 184 */ 185 {#if[encoder]?protected:private} 186 Charset$Coder$(Charset cs, 187 float average$ItypesPerOtype$, 188 float max$ItypesPerOtype$, 189 $replType$ replacement) 190 { 191 this.charset = cs; 192 // Use !(a > 0.0f) rather than (a <= 0.0f) to exclude NaN values 193 if (!(average$ItypesPerOtype$ > 0.0f)) 194 throw new IllegalArgumentException("Non-positive " 195 + "average$ItypesPerOtype$"); 196 // Use !(a > 0.0f) rather than (a <= 0.0f) to exclude NaN values 197 if (!(max$ItypesPerOtype$ > 0.0f)) 198 throw new IllegalArgumentException("Non-positive " 199 + "max$ItypesPerOtype$"); 200 if (average$ItypesPerOtype$ > max$ItypesPerOtype$) 201 throw new IllegalArgumentException("average$ItypesPerOtype$" 202 + " exceeds " 203 + "max$ItypesPerOtype$"); 204 this.replacement = replacement; 205 this.average$ItypesPerOtype$ = average$ItypesPerOtype$; 206 this.max$ItypesPerOtype$ = max$ItypesPerOtype$; 207 replaceWith(replacement); 208 } 209 210 /** 211 * Initializes a new $coder$. The new $coder$ will have the given 212 * $otypes-per-itype$ values and its replacement will be the 213 * $replTypeName$ $defaultReplName$. 214 * 215 * @param cs 216 * The charset that created this $coder$ 217 * 218 * @param average$ItypesPerOtype$ 219 * A positive float value indicating the expected number of 220 * $otype$s that will be produced for each input $itype$ 221 * 222 * @param max$ItypesPerOtype$ 223 * A positive float value indicating the maximum number of 224 * $otype$s that will be produced for each input $itype$ 225 * 226 * @throws IllegalArgumentException 227 * If the preconditions on the parameters do not hold 228 */ 229 protected Charset$Coder$(Charset cs, 230 float average$ItypesPerOtype$, 231 float max$ItypesPerOtype$) 232 { 233 this(cs, 234 average$ItypesPerOtype$, max$ItypesPerOtype$, 235 $defaultRepl$); 236 } 237 238 /** 239 * Returns the charset that created this $coder$. 240 * 241 * @return This $coder$'s charset 242 */ 243 public final Charset charset() { 244 return charset; 245 } 246 247 /** 248 * Returns this $coder$'s replacement value. 249 * 250 * @return This $coder$'s current replacement, 251 * which is never {@code null} and is never empty 252 */ 253 public final $replType$ replacement() { 254#if[decoder] 255 return replacement; 256#end[decoder] 257#if[encoder] 258 return Arrays.copyOf(replacement, replacement.$replLength$); 259#end[encoder] 260 } 261 262 /** 263 * Changes this $coder$'s replacement value. 264 * 265 * <p> This method invokes the {@link #implReplaceWith implReplaceWith} 266 * method, passing the new replacement, after checking that the new 267 * replacement is acceptable. </p> 268 * 269 * @param newReplacement The new replacement; must not be 270 * {@code null}, must have non-zero length, 271#if[decoder] 272 * and must not be longer than the value returned by the 273 * {@link #max$ItypesPerOtype$() max$ItypesPerOtype$} method 274#end[decoder] 275#if[encoder] 276 * must not be longer than the value returned by the 277 * {@link #max$ItypesPerOtype$() max$ItypesPerOtype$} method, and 278 * must be {@link #isLegalReplacement legal} 279#end[encoder] 280 * 281 * @return This $coder$ 282 * 283 * @throws IllegalArgumentException 284 * If the preconditions on the parameter do not hold 285 */ 286 public final Charset$Coder$ replaceWith($replType$ newReplacement) { 287 if (newReplacement == null) 288 throw new IllegalArgumentException("Null replacement"); 289 int len = newReplacement.$replLength$; 290 if (len == 0) 291 throw new IllegalArgumentException("Empty replacement"); 292 if (len > max$ItypesPerOtype$) 293 throw new IllegalArgumentException("Replacement too long"); 294#if[decoder] 295 this.replacement = newReplacement; 296#end[decoder] 297#if[encoder] 298 if (!isLegalReplacement(newReplacement)) 299 throw new IllegalArgumentException("Illegal replacement"); 300 this.replacement = Arrays.copyOf(newReplacement, newReplacement.$replLength$); 301#end[encoder] 302 implReplaceWith(this.replacement); 303 return this; 304 } 305 306 /** 307 * Reports a change to this $coder$'s replacement value. 308 * 309 * <p> The default implementation of this method does nothing. This method 310 * should be overridden by $coder$s that require notification of changes to 311 * the replacement. </p> 312 * 313 * @param newReplacement The replacement value 314 */ 315 protected void implReplaceWith($replType$ newReplacement) { 316 } 317 318#if[encoder] 319 320 private WeakReference<CharsetDecoder> cachedDecoder = null; 321 322 /** 323 * Tells whether or not the given byte array is a legal replacement value 324 * for this encoder. 325 * 326 * <p> A replacement is legal if, and only if, it is a legal sequence of 327 * bytes in this encoder's charset; that is, it must be possible to decode 328 * the replacement into one or more sixteen-bit Unicode characters. 329 * 330 * <p> The default implementation of this method is not very efficient; it 331 * should generally be overridden to improve performance. </p> 332 * 333 * @param repl The byte array to be tested 334 * 335 * @return {@code true} if, and only if, the given byte array 336 * is a legal replacement value for this encoder 337 */ 338 public boolean isLegalReplacement(byte[] repl) { 339 WeakReference<CharsetDecoder> wr = cachedDecoder; 340 CharsetDecoder dec = null; 341 if ((wr == null) || ((dec = wr.get()) == null)) { 342 dec = charset().newDecoder(); 343 dec.onMalformedInput(CodingErrorAction.REPORT); 344 dec.onUnmappableCharacter(CodingErrorAction.REPORT); 345 cachedDecoder = new WeakReference<CharsetDecoder>(dec); 346 } else { 347 dec.reset(); 348 } 349 ByteBuffer bb = ByteBuffer.wrap(repl); 350 CharBuffer cb = CharBuffer.allocate((int)(bb.remaining() 351 * dec.maxCharsPerByte())); 352 CoderResult cr = dec.decode(bb, cb, true); 353 return !cr.isError(); 354 } 355 356#end[encoder] 357 358 /** 359 * Returns this $coder$'s current action for malformed-input errors. 360 * 361 * @return The current malformed-input action, which is never {@code null} 362 */ 363 public CodingErrorAction malformedInputAction() { 364 return malformedInputAction; 365 } 366 367 /** 368 * Changes this $coder$'s action for malformed-input errors. 369 * 370 * <p> This method invokes the {@link #implOnMalformedInput 371 * implOnMalformedInput} method, passing the new action. </p> 372 * 373 * @param newAction The new action; must not be {@code null} 374 * 375 * @return This $coder$ 376 * 377 * @throws IllegalArgumentException 378 * If the precondition on the parameter does not hold 379 */ 380 public final Charset$Coder$ onMalformedInput(CodingErrorAction newAction) { 381 if (newAction == null) 382 throw new IllegalArgumentException("Null action"); 383 malformedInputAction = newAction; 384 implOnMalformedInput(newAction); 385 return this; 386 } 387 388 /** 389 * Reports a change to this $coder$'s malformed-input action. 390 * 391 * <p> The default implementation of this method does nothing. This method 392 * should be overridden by $coder$s that require notification of changes to 393 * the malformed-input action. </p> 394 * 395 * @param newAction The new action 396 */ 397 protected void implOnMalformedInput(CodingErrorAction newAction) { } 398 399 /** 400 * Returns this $coder$'s current action for unmappable-character errors. 401 * 402 * @return The current unmappable-character action, which is never 403 * {@code null} 404 */ 405 public CodingErrorAction unmappableCharacterAction() { 406 return unmappableCharacterAction; 407 } 408 409 /** 410 * Changes this $coder$'s action for unmappable-character errors. 411 * 412 * <p> This method invokes the {@link #implOnUnmappableCharacter 413 * implOnUnmappableCharacter} method, passing the new action. </p> 414 * 415 * @param newAction The new action; must not be {@code null} 416 * 417 * @return This $coder$ 418 * 419 * @throws IllegalArgumentException 420 * If the precondition on the parameter does not hold 421 */ 422 public final Charset$Coder$ onUnmappableCharacter(CodingErrorAction 423 newAction) 424 { 425 if (newAction == null) 426 throw new IllegalArgumentException("Null action"); 427 unmappableCharacterAction = newAction; 428 implOnUnmappableCharacter(newAction); 429 return this; 430 } 431 432 /** 433 * Reports a change to this $coder$'s unmappable-character action. 434 * 435 * <p> The default implementation of this method does nothing. This method 436 * should be overridden by $coder$s that require notification of changes to 437 * the unmappable-character action. </p> 438 * 439 * @param newAction The new action 440 */ 441 protected void implOnUnmappableCharacter(CodingErrorAction newAction) { } 442 443 /** 444 * Returns the average number of $otype$s that will be produced for each 445 * $itype$ of input. This heuristic value may be used to estimate the size 446 * of the output buffer required for a given input sequence. 447 * 448 * @return The average number of $otype$s produced 449 * per $itype$ of input 450 */ 451 public final float average$ItypesPerOtype$() { 452 return average$ItypesPerOtype$; 453 } 454 455 /** 456 * Returns the maximum number of $otype$s that will be produced for each 457 * $itype$ of input. This value may be used to compute the worst-case size 458 * of the output buffer required for a given input sequence. This value 459 * accounts for any necessary content-independent prefix or suffix 460#if[encoder] 461 * $otype$s, such as byte-order marks. 462#end[encoder] 463#if[decoder] 464 * $otype$s. 465#end[decoder] 466 * 467 * @return The maximum number of $otype$s that will be produced per 468 * $itype$ of input 469 */ 470 public final float max$ItypesPerOtype$() { 471 return max$ItypesPerOtype$; 472 } 473 474 /** 475 * $Code$s as many $itype$s as possible from the given input buffer, 476 * writing the results to the given output buffer. 477 * 478 * <p> The buffers are read from, and written to, starting at their current 479 * positions. At most {@link Buffer#remaining in.remaining()} $itype$s 480 * will be read and at most {@link Buffer#remaining out.remaining()} 481 * $otype$s will be written. The buffers' positions will be advanced to 482 * reflect the $itype$s read and the $otype$s written, but their marks and 483 * limits will not be modified. 484 * 485 * <p> In addition to reading $itype$s from the input buffer and writing 486 * $otype$s to the output buffer, this method returns a {@link CoderResult} 487 * object to describe its reason for termination: 488 * 489 * <ul> 490 * 491 * <li><p> {@link CoderResult#UNDERFLOW} indicates that as much of the 492 * input buffer as possible has been $code$d. If there is no further 493 * input then the invoker can proceed to the next step of the 494 * <a href="#steps">$coding$ operation</a>. Otherwise this method 495 * should be invoked again with further input. </p></li> 496 * 497 * <li><p> {@link CoderResult#OVERFLOW} indicates that there is 498 * insufficient space in the output buffer to $code$ any more $itype$s. 499 * This method should be invoked again with an output buffer that has 500 * more {@linkplain Buffer#remaining remaining} $otype$s. This is 501 * typically done by draining any $code$d $otype$s from the output 502 * buffer. </p></li> 503 * 504 * <li><p> A {@linkplain CoderResult#malformedForLength 505 * malformed-input} result indicates that a malformed-input 506 * error has been detected. The malformed $itype$s begin at the input 507 * buffer's (possibly incremented) position; the number of malformed 508 * $itype$s may be determined by invoking the result object's {@link 509 * CoderResult#length() length} method. This case applies only if the 510 * {@linkplain #onMalformedInput malformed action} of this $coder$ 511 * is {@link CodingErrorAction#REPORT}; otherwise the malformed input 512 * will be ignored or replaced, as requested. </p></li> 513 * 514 * <li><p> An {@linkplain CoderResult#unmappableForLength 515 * unmappable-character} result indicates that an 516 * unmappable-character error has been detected. The $itype$s that 517 * $code$ the unmappable character begin at the input buffer's (possibly 518 * incremented) position; the number of such $itype$s may be determined 519 * by invoking the result object's {@link CoderResult#length() length} 520 * method. This case applies only if the {@linkplain #onUnmappableCharacter 521 * unmappable action} of this $coder$ is {@link 522 * CodingErrorAction#REPORT}; otherwise the unmappable character will be 523 * ignored or replaced, as requested. </p></li> 524 * 525 * </ul> 526 * 527 * In any case, if this method is to be reinvoked in the same $coding$ 528 * operation then care should be taken to preserve any $itype$s remaining 529 * in the input buffer so that they are available to the next invocation. 530 * 531 * <p> The {@code endOfInput} parameter advises this method as to whether 532 * the invoker can provide further input beyond that contained in the given 533 * input buffer. If there is a possibility of providing additional input 534 * then the invoker should pass {@code false} for this parameter; if there 535 * is no possibility of providing further input then the invoker should 536 * pass {@code true}. It is not erroneous, and in fact it is quite 537 * common, to pass {@code false} in one invocation and later discover that 538 * no further input was actually available. It is critical, however, that 539 * the final invocation of this method in a sequence of invocations always 540 * pass {@code true} so that any remaining un$code$d input will be treated 541 * as being malformed. 542 * 543 * <p> This method works by invoking the {@link #$code$Loop $code$Loop} 544 * method, interpreting its results, handling error conditions, and 545 * reinvoking it as necessary. </p> 546 * 547 * 548 * @param in 549 * The input $itype$ buffer 550 * 551 * @param out 552 * The output $otype$ buffer 553 * 554 * @param endOfInput 555 * {@code true} if, and only if, the invoker can provide no 556 * additional input $itype$s beyond those in the given buffer 557 * 558 * @return A coder-result object describing the reason for termination 559 * 560 * @throws IllegalStateException 561 * If $a$ $coding$ operation is already in progress and the previous 562 * step was an invocation neither of the {@link #reset reset} 563 * method, nor of this method with a value of {@code false} for 564 * the {@code endOfInput} parameter, nor of this method with a 565 * value of {@code true} for the {@code endOfInput} parameter 566 * but a return value indicating an incomplete $coding$ operation 567 * 568 * @throws CoderMalfunctionError 569 * If an invocation of the $code$Loop method threw 570 * an unexpected exception 571 */ 572 public final CoderResult $code$($Itype$Buffer in, $Otype$Buffer out, 573 boolean endOfInput) 574 { 575 int newState = endOfInput ? ST_END : ST_CODING; 576 if ((state != ST_RESET) && (state != ST_CODING) 577 && !(endOfInput && (state == ST_END))) 578 throwIllegalStateException(state, newState); 579 state = newState; 580 581 for (;;) { 582 583 CoderResult cr; 584 try { 585 cr = $code$Loop(in, out); 586 } catch (RuntimeException x) { 587 throw new CoderMalfunctionError(x); 588 } 589 590 if (cr.isOverflow()) 591 return cr; 592 593 if (cr.isUnderflow()) { 594 if (endOfInput && in.hasRemaining()) { 595 cr = CoderResult.malformedForLength(in.remaining()); 596 // Fall through to malformed-input case 597 } else { 598 return cr; 599 } 600 } 601 602 CodingErrorAction action = null; 603 if (cr.isMalformed()) 604 action = malformedInputAction; 605 else if (cr.isUnmappable()) 606 action = unmappableCharacterAction; 607 else 608 assert false : cr.toString(); 609 610 if (action == CodingErrorAction.REPORT) 611 return cr; 612 613 if (action == CodingErrorAction.REPLACE) { 614 if (out.remaining() < replacement.$replLength$) 615 return CoderResult.OVERFLOW; 616 out.put(replacement); 617 } 618 619 if ((action == CodingErrorAction.IGNORE) 620 || (action == CodingErrorAction.REPLACE)) { 621 // Skip erroneous input either way 622 in.position(in.position() + cr.length()); 623 continue; 624 } 625 626 assert false; 627 } 628 629 } 630 631 /** 632 * Flushes this $coder$. 633 * 634 * <p> Some $coder$s maintain internal state and may need to write some 635 * final $otype$s to the output buffer once the overall input sequence has 636 * been read. 637 * 638 * <p> Any additional output is written to the output buffer beginning at 639 * its current position. At most {@link Buffer#remaining out.remaining()} 640 * $otype$s will be written. The buffer's position will be advanced 641 * appropriately, but its mark and limit will not be modified. 642 * 643 * <p> If this method completes successfully then it returns {@link 644 * CoderResult#UNDERFLOW}. If there is insufficient room in the output 645 * buffer then it returns {@link CoderResult#OVERFLOW}. If this happens 646 * then this method must be invoked again, with an output buffer that has 647 * more room, in order to complete the current <a href="#steps">$coding$ 648 * operation</a>. 649 * 650 * <p> If this $coder$ has already been flushed then invoking this method 651 * has no effect. 652 * 653 * <p> This method invokes the {@link #implFlush implFlush} method to 654 * perform the actual flushing operation. </p> 655 * 656 * @param out 657 * The output $otype$ buffer 658 * 659 * @return A coder-result object, either {@link CoderResult#UNDERFLOW} or 660 * {@link CoderResult#OVERFLOW} 661 * 662 * @throws IllegalStateException 663 * If the previous step of the current $coding$ operation was an 664 * invocation neither of the {@link #flush flush} method nor of 665 * the three-argument {@link 666 * #$code$($Itype$Buffer,$Otype$Buffer,boolean) $code$} method 667 * with a value of {@code true} for the {@code endOfInput} 668 * parameter 669 */ 670 public final CoderResult flush($Otype$Buffer out) { 671 if (state == ST_END) { 672 CoderResult cr = implFlush(out); 673 if (cr.isUnderflow()) 674 state = ST_FLUSHED; 675 return cr; 676 } 677 678 if (state != ST_FLUSHED) 679 throwIllegalStateException(state, ST_FLUSHED); 680 681 return CoderResult.UNDERFLOW; // Already flushed 682 } 683 684 /** 685 * Flushes this $coder$. 686 * 687 * <p> The default implementation of this method does nothing, and always 688 * returns {@link CoderResult#UNDERFLOW}. This method should be overridden 689 * by $coder$s that may need to write final $otype$s to the output buffer 690 * once the entire input sequence has been read. </p> 691 * 692 * @param out 693 * The output $otype$ buffer 694 * 695 * @return A coder-result object, either {@link CoderResult#UNDERFLOW} or 696 * {@link CoderResult#OVERFLOW} 697 */ 698 protected CoderResult implFlush($Otype$Buffer out) { 699 return CoderResult.UNDERFLOW; 700 } 701 702 /** 703 * Resets this $coder$, clearing any internal state. 704 * 705 * <p> This method resets charset-independent state and also invokes the 706 * {@link #implReset() implReset} method in order to perform any 707 * charset-specific reset actions. </p> 708 * 709 * @return This $coder$ 710 * 711 */ 712 public final Charset$Coder$ reset() { 713 implReset(); 714 state = ST_RESET; 715 return this; 716 } 717 718 /** 719 * Resets this $coder$, clearing any charset-specific internal state. 720 * 721 * <p> The default implementation of this method does nothing. This method 722 * should be overridden by $coder$s that maintain internal state. </p> 723 */ 724 protected void implReset() { } 725 726 /** 727 * $Code$s one or more $itype$s into one or more $otype$s. 728 * 729 * <p> This method encapsulates the basic $coding$ loop, $coding$ as many 730 * $itype$s as possible until it either runs out of input, runs out of room 731 * in the output buffer, or encounters $a$ $coding$ error. This method is 732 * invoked by the {@link #$code$ $code$} method, which handles result 733 * interpretation and error recovery. 734 * 735 * <p> The buffers are read from, and written to, starting at their current 736 * positions. At most {@link Buffer#remaining in.remaining()} $itype$s 737 * will be read, and at most {@link Buffer#remaining out.remaining()} 738 * $otype$s will be written. The buffers' positions will be advanced to 739 * reflect the $itype$s read and the $otype$s written, but their marks and 740 * limits will not be modified. 741 * 742 * <p> This method returns a {@link CoderResult} object to describe its 743 * reason for termination, in the same manner as the {@link #$code$ $code$} 744 * method. Most implementations of this method will handle $coding$ errors 745 * by returning an appropriate result object for interpretation by the 746 * {@link #$code$ $code$} method. An optimized implementation may instead 747 * examine the relevant error action and implement that action itself. 748 * 749 * <p> An implementation of this method may perform arbitrary lookahead by 750 * returning {@link CoderResult#UNDERFLOW} until it receives sufficient 751 * input. </p> 752 * 753 * @param in 754 * The input $itype$ buffer 755 * 756 * @param out 757 * The output $otype$ buffer 758 * 759 * @return A coder-result object describing the reason for termination 760 */ 761 protected abstract CoderResult $code$Loop($Itype$Buffer in, 762 $Otype$Buffer out); 763 764 /** 765 * Convenience method that $code$s the remaining content of a single input 766 * $itype$ buffer into a newly-allocated $otype$ buffer. 767 * 768 * <p> This method implements an entire <a href="#steps">$coding$ 769 * operation</a>; that is, it resets this $coder$, then it $code$s the 770 * $itype$s in the given $itype$ buffer, and finally it flushes this 771 * $coder$. This method should therefore not be invoked if $a$ $coding$ 772 * operation is already in progress. </p> 773 * 774 * @param in 775 * The input $itype$ buffer 776 * 777 * @return A newly-allocated $otype$ buffer containing the result of the 778 * $coding$ operation. The buffer's position will be zero and its 779 * limit will follow the last $otype$ written. 780 * 781 * @throws IllegalStateException 782 * If $a$ $coding$ operation is already in progress 783 * 784 * @throws MalformedInputException 785 * If the $itype$ sequence starting at the input buffer's current 786 * position is $notLegal$ and the current malformed-input action 787 * is {@link CodingErrorAction#REPORT} 788 * 789 * @throws UnmappableCharacterException 790 * If the $itype$ sequence starting at the input buffer's current 791 * position cannot be mapped to an equivalent $otype$ sequence and 792 * the current unmappable-character action is {@link 793 * CodingErrorAction#REPORT} 794 */ 795 public final $Otype$Buffer $code$($Itype$Buffer in) 796 throws CharacterCodingException 797 { 798 int n = (int)(in.remaining() * average$ItypesPerOtype$()); 799 $Otype$Buffer out = $Otype$Buffer.allocate(n); 800 801 if ((n == 0) && (in.remaining() == 0)) 802 return out; 803 reset(); 804 for (;;) { 805 CoderResult cr = in.hasRemaining() ? 806 $code$(in, out, true) : CoderResult.UNDERFLOW; 807 if (cr.isUnderflow()) 808 cr = flush(out); 809 810 if (cr.isUnderflow()) 811 break; 812 if (cr.isOverflow()) { 813 n = 2*n + 1; // Ensure progress; n might be 0! 814 $Otype$Buffer o = $Otype$Buffer.allocate(n); 815 out.flip(); 816 o.put(out); 817 out = o; 818 continue; 819 } 820 cr.throwException(); 821 } 822 out.flip(); 823 return out; 824 } 825 826#if[decoder] 827 828 /** 829 * Tells whether or not this decoder implements an auto-detecting charset. 830 * 831 * <p> The default implementation of this method always returns 832 * {@code false}; it should be overridden by auto-detecting decoders to 833 * return {@code true}. </p> 834 * 835 * @return {@code true} if, and only if, this decoder implements an 836 * auto-detecting charset 837 */ 838 public boolean isAutoDetecting() { 839 return false; 840 } 841 842 /** 843 * Tells whether or not this decoder has yet detected a 844 * charset <i>(optional operation)</i>. 845 * 846 * <p> If this decoder implements an auto-detecting charset then at a 847 * single point during a decoding operation this method may start returning 848 * {@code true} to indicate that a specific charset has been detected in 849 * the input byte sequence. Once this occurs, the {@link #detectedCharset 850 * detectedCharset} method may be invoked to retrieve the detected charset. 851 * 852 * <p> That this method returns {@code false} does not imply that no bytes 853 * have yet been decoded. Some auto-detecting decoders are capable of 854 * decoding some, or even all, of an input byte sequence without fixing on 855 * a particular charset. 856 * 857 * <p> The default implementation of this method always throws an {@link 858 * UnsupportedOperationException}; it should be overridden by 859 * auto-detecting decoders to return {@code true} once the input charset 860 * has been determined. </p> 861 * 862 * @return {@code true} if, and only if, this decoder has detected a 863 * specific charset 864 * 865 * @throws UnsupportedOperationException 866 * If this decoder does not implement an auto-detecting charset 867 */ 868 public boolean isCharsetDetected() { 869 throw new UnsupportedOperationException(); 870 } 871 872 /** 873 * Retrieves the charset that was detected by this 874 * decoder <i>(optional operation)</i>. 875 * 876 * <p> If this decoder implements an auto-detecting charset then this 877 * method returns the actual charset once it has been detected. After that 878 * point, this method returns the same value for the duration of the 879 * current decoding operation. If not enough input bytes have yet been 880 * read to determine the actual charset then this method throws an {@link 881 * IllegalStateException}. 882 * 883 * <p> The default implementation of this method always throws an {@link 884 * UnsupportedOperationException}; it should be overridden by 885 * auto-detecting decoders to return the appropriate value. </p> 886 * 887 * @return The charset detected by this auto-detecting decoder, 888 * or {@code null} if the charset has not yet been determined 889 * 890 * @throws IllegalStateException 891 * If insufficient bytes have been read to determine a charset 892 * 893 * @throws UnsupportedOperationException 894 * If this decoder does not implement an auto-detecting charset 895 */ 896 public Charset detectedCharset() { 897 throw new UnsupportedOperationException(); 898 } 899 900#end[decoder] 901 902#if[encoder] 903 904 private boolean canEncode(CharBuffer cb) { 905 if (state == ST_FLUSHED) 906 reset(); 907 else if (state != ST_RESET) 908 throwIllegalStateException(state, ST_CODING); 909 CodingErrorAction ma = malformedInputAction(); 910 CodingErrorAction ua = unmappableCharacterAction(); 911 try { 912 onMalformedInput(CodingErrorAction.REPORT); 913 onUnmappableCharacter(CodingErrorAction.REPORT); 914 encode(cb); 915 } catch (CharacterCodingException x) { 916 return false; 917 } finally { 918 onMalformedInput(ma); 919 onUnmappableCharacter(ua); 920 reset(); 921 } 922 return true; 923 } 924 925 /** 926 * Tells whether or not this encoder can encode the given character. 927 * 928 * <p> This method returns {@code false} if the given character is a 929 * surrogate character; such characters can be interpreted only when they 930 * are members of a pair consisting of a high surrogate followed by a low 931 * surrogate. The {@link #canEncode(java.lang.CharSequence) 932 * canEncode(CharSequence)} method may be used to test whether or not a 933 * character sequence can be encoded. 934 * 935 * <p> This method may modify this encoder's state; it should therefore not 936 * be invoked if an <a href="#steps">encoding operation</a> is already in 937 * progress. 938 * 939 * <p> The default implementation of this method is not very efficient; it 940 * should generally be overridden to improve performance. </p> 941 * 942 * @param c 943 * The given character 944 * 945 * @return {@code true} if, and only if, this encoder can encode 946 * the given character 947 * 948 * @throws IllegalStateException 949 * If $a$ $coding$ operation is already in progress 950 */ 951 public boolean canEncode(char c) { 952 CharBuffer cb = CharBuffer.allocate(1); 953 cb.put(c); 954 cb.flip(); 955 return canEncode(cb); 956 } 957 958 /** 959 * Tells whether or not this encoder can encode the given character 960 * sequence. 961 * 962 * <p> If this method returns {@code false} for a particular character 963 * sequence then more information about why the sequence cannot be encoded 964 * may be obtained by performing a full <a href="#steps">encoding 965 * operation</a>. 966 * 967 * <p> This method may modify this encoder's state; it should therefore not 968 * be invoked if an encoding operation is already in progress. 969 * 970 * <p> The default implementation of this method is not very efficient; it 971 * should generally be overridden to improve performance. </p> 972 * 973 * @param cs 974 * The given character sequence 975 * 976 * @return {@code true} if, and only if, this encoder can encode 977 * the given character without throwing any exceptions and without 978 * performing any replacements 979 * 980 * @throws IllegalStateException 981 * If $a$ $coding$ operation is already in progress 982 */ 983 public boolean canEncode(CharSequence cs) { 984 CharBuffer cb; 985 if (cs instanceof CharBuffer) 986 cb = ((CharBuffer)cs).duplicate(); 987 else 988 cb = CharBuffer.wrap(cs.toString()); 989 return canEncode(cb); 990 } 991 992#end[encoder] 993 994 995 private void throwIllegalStateException(int from, int to) { 996 throw new IllegalStateException("Current state = " + stateNames[from] 997 + ", new state = " + stateNames[to]); 998 } 999 1000} 1001