This file is indexed.

/usr/include/thunderbird/unicode/translit.h is in thunderbird-dev 1:52.8.0-1~deb8u1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
// Copyright (C) 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
**********************************************************************
* Copyright (C) 1999-2014, International Business Machines
* Corporation and others. All Rights Reserved.
**********************************************************************
*   Date        Name        Description
*   11/17/99    aliu        Creation.
**********************************************************************
*/
#ifndef TRANSLIT_H
#define TRANSLIT_H

#include "unicode/utypes.h"

/**
 * \file 
 * \brief C++ API: Tranforms text from one format to another.
 */
 
#if !UCONFIG_NO_TRANSLITERATION

#include "unicode/uobject.h"
#include "unicode/unistr.h"
#include "unicode/parseerr.h"
#include "unicode/utrans.h" // UTransPosition, UTransDirection
#include "unicode/strenum.h"

U_NAMESPACE_BEGIN

class UnicodeFilter;
class UnicodeSet;
class CompoundTransliterator;
class TransliteratorParser;
class NormalizationTransliterator;
class TransliteratorIDParser;

/**
 *
 * <code>Transliterator</code> is an abstract class that
 * transliterates text from one format to another.  The most common
 * kind of transliterator is a script, or alphabet, transliterator.
 * For example, a Russian to Latin transliterator changes Russian text
 * written in Cyrillic characters to phonetically equivalent Latin
 * characters.  It does not <em>translate</em> Russian to English!
 * Transliteration, unlike translation, operates on characters, without
 * reference to the meanings of words and sentences.
 *
 * <p>Although script conversion is its most common use, a
 * transliterator can actually perform a more general class of tasks.
 * In fact, <code>Transliterator</code> defines a very general API
 * which specifies only that a segment of the input text is replaced
 * by new text.  The particulars of this conversion are determined
 * entirely by subclasses of <code>Transliterator</code>.
 *
 * <p><b>Transliterators are stateless</b>
 *
 * <p><code>Transliterator</code> objects are <em>stateless</em>; they
 * retain no information between calls to
 * <code>transliterate()</code>.  (However, this does <em>not</em>
 * mean that threads may share transliterators without synchronizing
 * them.  Transliterators are not immutable, so they must be
 * synchronized when shared between threads.)  This might seem to
 * limit the complexity of the transliteration operation.  In
 * practice, subclasses perform complex transliterations by delaying
 * the replacement of text until it is known that no other
 * replacements are possible.  In other words, although the
 * <code>Transliterator</code> objects are stateless, the source text
 * itself embodies all the needed information, and delayed operation
 * allows arbitrary complexity.
 *
 * <p><b>Batch transliteration</b>
 *
 * <p>The simplest way to perform transliteration is all at once, on a
 * string of existing text.  This is referred to as <em>batch</em>
 * transliteration.  For example, given a string <code>input</code>
 * and a transliterator <code>t</code>, the call
 *
 * \htmlonly<blockquote>\endhtmlonly<code>String result = t.transliterate(input);
 * </code>\htmlonly</blockquote>\endhtmlonly
 *
 * will transliterate it and return the result.  Other methods allow
 * the client to specify a substring to be transliterated and to use
 * {@link Replaceable } objects instead of strings, in order to
 * preserve out-of-band information (such as text styles).
 *
 * <p><b>Keyboard transliteration</b>
 *
 * <p>Somewhat more involved is <em>keyboard</em>, or incremental
 * transliteration.  This is the transliteration of text that is
 * arriving from some source (typically the user's keyboard) one
 * character at a time, or in some other piecemeal fashion.
 *
 * <p>In keyboard transliteration, a <code>Replaceable</code> buffer
 * stores the text.  As text is inserted, as much as possible is
 * transliterated on the fly.  This means a GUI that displays the
 * contents of the buffer may show text being modified as each new
 * character arrives.
 *
 * <p>Consider the simple <code>RuleBasedTransliterator</code>:
 *
 * \htmlonly<blockquote>\endhtmlonly<code>
 * th&gt;{theta}<br>
 * t&gt;{tau}
 * </code>\htmlonly</blockquote>\endhtmlonly
 *
 * When the user types 't', nothing will happen, since the
 * transliterator is waiting to see if the next character is 'h'.  To
 * remedy this, we introduce the notion of a cursor, marked by a '|'
 * in the output string:
 *
 * \htmlonly<blockquote>\endhtmlonly<code>
 * t&gt;|{tau}<br>
 * {tau}h&gt;{theta}
 * </code>\htmlonly</blockquote>\endhtmlonly
 *
 * Now when the user types 't', tau appears, and if the next character
 * is 'h', the tau changes to a theta.  This is accomplished by
 * maintaining a cursor position (independent of the insertion point,
 * and invisible in the GUI) across calls to
 * <code>transliterate()</code>.  Typically, the cursor will
 * be coincident with the insertion point, but in a case like the one
 * above, it will precede the insertion point.
 *
 * <p>Keyboard transliteration methods maintain a set of three indices
 * that are updated with each call to
 * <code>transliterate()</code>, including the cursor, start,
 * and limit.  Since these indices are changed by the method, they are
 * passed in an <code>int[]</code> array. The <code>START</code> index
 * marks the beginning of the substring that the transliterator will
 * look at.  It is advanced as text becomes committed (but it is not
 * the committed index; that's the <code>CURSOR</code>).  The
 * <code>CURSOR</code> index, described above, marks the point at
 * which the transliterator last stopped, either because it reached
 * the end, or because it required more characters to disambiguate
 * between possible inputs.  The <code>CURSOR</code> can also be
 * explicitly set by rules in a <code>RuleBasedTransliterator</code>.
 * Any characters before the <code>CURSOR</code> index are frozen;
 * future keyboard transliteration calls within this input sequence
 * will not change them.  New text is inserted at the
 * <code>LIMIT</code> index, which marks the end of the substring that
 * the transliterator looks at.
 *
 * <p>Because keyboard transliteration assumes that more characters
 * are to arrive, it is conservative in its operation.  It only
 * transliterates when it can do so unambiguously.  Otherwise it waits
 * for more characters to arrive.  When the client code knows that no
 * more characters are forthcoming, perhaps because the user has
 * performed some input termination operation, then it should call
 * <code>finishTransliteration()</code> to complete any
 * pending transliterations.
 *
 * <p><b>Inverses</b>
 *
 * <p>Pairs of transliterators may be inverses of one another.  For
 * example, if transliterator <b>A</b> transliterates characters by
 * incrementing their Unicode value (so "abc" -> "def"), and
 * transliterator <b>B</b> decrements character values, then <b>A</b>
 * is an inverse of <b>B</b> and vice versa.  If we compose <b>A</b>
 * with <b>B</b> in a compound transliterator, the result is the
 * indentity transliterator, that is, a transliterator that does not
 * change its input text.
 *
 * The <code>Transliterator</code> method <code>getInverse()</code>
 * returns a transliterator's inverse, if one exists, or
 * <code>null</code> otherwise.  However, the result of
 * <code>getInverse()</code> usually will <em>not</em> be a true
 * mathematical inverse.  This is because true inverse transliterators
 * are difficult to formulate.  For example, consider two
 * transliterators: <b>AB</b>, which transliterates the character 'A'
 * to 'B', and <b>BA</b>, which transliterates 'B' to 'A'.  It might
 * seem that these are exact inverses, since
 *
 * \htmlonly<blockquote>\endhtmlonly"A" x <b>AB</b> -> "B"<br>
 * "B" x <b>BA</b> -> "A"\htmlonly</blockquote>\endhtmlonly
 *
 * where 'x' represents transliteration.  However,
 *
 * \htmlonly<blockquote>\endhtmlonly"ABCD" x <b>AB</b> -> "BBCD"<br>
 * "BBCD" x <b>BA</b> -> "AACD"\htmlonly</blockquote>\endhtmlonly
 *
 * so <b>AB</b> composed with <b>BA</b> is not the
 * identity. Nonetheless, <b>BA</b> may be usefully considered to be
 * <b>AB</b>'s inverse, and it is on this basis that
 * <b>AB</b><code>.getInverse()</code> could legitimately return
 * <b>BA</b>.
 *
 * <p><b>IDs and display names</b>
 *
 * <p>A transliterator is designated by a short identifier string or
 * <em>ID</em>.  IDs follow the format <em>source-destination</em>,
 * where <em>source</em> describes the entity being replaced, and
 * <em>destination</em> describes the entity replacing
 * <em>source</em>.  The entities may be the names of scripts,
 * particular sequences of characters, or whatever else it is that the
 * transliterator converts to or from.  For example, a transliterator
 * from Russian to Latin might be named "Russian-Latin".  A
 * transliterator from keyboard escape sequences to Latin-1 characters
 * might be named "KeyboardEscape-Latin1".  By convention, system
 * entity names are in English, with the initial letters of words
 * capitalized; user entity names may follow any format so long as
 * they do not contain dashes.
 *
 * <p>In addition to programmatic IDs, transliterator objects have
 * display names for presentation in user interfaces, returned by
 * {@link #getDisplayName }.
 *
 * <p><b>Factory methods and registration</b>
 *
 * <p>In general, client code should use the factory method
 * {@link #createInstance } to obtain an instance of a
 * transliterator given its ID.  Valid IDs may be enumerated using
 * <code>getAvailableIDs()</code>.  Since transliterators are mutable,
 * multiple calls to {@link #createInstance } with the same ID will
 * return distinct objects.
 *
 * <p>In addition to the system transliterators registered at startup,
 * user transliterators may be registered by calling
 * <code>registerInstance()</code> at run time.  A registered instance
 * acts a template; future calls to {@link #createInstance } with the ID
 * of the registered object return clones of that object.  Thus any
 * object passed to <tt>registerInstance()</tt> must implement
 * <tt>clone()</tt> propertly.  To register a transliterator subclass
 * without instantiating it (until it is needed), users may call
 * {@link #registerFactory }.  In this case, the objects are
 * instantiated by invoking the zero-argument public constructor of
 * the class.
 *
 * <p><b>Subclassing</b>
 *
 * Subclasses must implement the abstract method
 * <code>handleTransliterate()</code>.  <p>Subclasses should override
 * the <code>transliterate()</code> method taking a
 * <code>Replaceable</code> and the <code>transliterate()</code>
 * method taking a <code>String</code> and <code>StringBuffer</code>
 * if the performance of these methods can be improved over the
 * performance obtained by the default implementations in this class.
 *
 * @author Alan Liu
 * @stable ICU 2.0
 */
class U_I18N_API Transliterator : public UObject {

private:

    /**
     * Programmatic name, e.g., "Latin-Arabic".
     */
    UnicodeString ID;

    /**
     * This transliterator's filter.  Any character for which
     * <tt>filter.contains()</tt> returns <tt>false</tt> will not be
     * altered by this transliterator.  If <tt>filter</tt> is
     * <tt>null</tt> then no filtering is applied.
     */
    UnicodeFilter* filter;

    int32_t maximumContextLength;

 public:

    /**
     * A context integer or pointer for a factory function, passed by
     * value.
     * @stable ICU 2.4
     */
    union Token {
        /**
         * This token, interpreted as a 32-bit integer.
         * @stable ICU 2.4
         */
        int32_t integer;
        /**
         * This token, interpreted as a native pointer.
         * @stable ICU 2.4
         */
        void*   pointer;
    };

#ifndef U_HIDE_INTERNAL_API
    /**
     * Return a token containing an integer.
     * @return a token containing an integer.
     * @internal
     */
    inline static Token integerToken(int32_t);

    /**
     * Return a token containing a pointer.
     * @return a token containing a pointer.
     * @internal
     */
    inline static Token pointerToken(void*);
#endif  /* U_HIDE_INTERNAL_API */

    /**
     * A function that creates and returns a Transliterator.  When
     * invoked, it will be passed the ID string that is being
     * instantiated, together with the context pointer that was passed
     * in when the factory function was first registered.  Many
     * factory functions will ignore both parameters, however,
     * functions that are registered to more than one ID may use the
     * ID or the context parameter to parameterize the transliterator
     * they create.
     * @param ID      the string identifier for this transliterator
     * @param context a context pointer that will be stored and
     *                later passed to the factory function when an ID matching
     *                the registration ID is being instantiated with this factory.
     * @stable ICU 2.4
     */
    typedef Transliterator* (U_EXPORT2 *Factory)(const UnicodeString& ID, Token context);

protected:

    /**
     * Default constructor.
     * @param ID the string identifier for this transliterator
     * @param adoptedFilter the filter.  Any character for which
     * <tt>filter.contains()</tt> returns <tt>false</tt> will not be
     * altered by this transliterator.  If <tt>filter</tt> is
     * <tt>null</tt> then no filtering is applied.
     * @stable ICU 2.4
     */
    Transliterator(const UnicodeString& ID, UnicodeFilter* adoptedFilter);

    /**
     * Copy constructor.
     * @stable ICU 2.4
     */
    Transliterator(const Transliterator&);

    /**
     * Assignment operator.
     * @stable ICU 2.4
     */
    Transliterator& operator=(const Transliterator&);

    /**
     * Create a transliterator from a basic ID.  This is an ID
     * containing only the forward direction source, target, and
     * variant.
     * @param id a basic ID of the form S-T or S-T/V.
     * @param canon canonical ID to assign to the object, or
     * NULL to leave the ID unchanged
     * @return a newly created Transliterator or null if the ID is
     * invalid.
     * @stable ICU 2.4
     */
    static Transliterator* createBasicInstance(const UnicodeString& id,
                                               const UnicodeString* canon);

    friend class TransliteratorParser; // for parseID()
    friend class TransliteratorIDParser; // for createBasicInstance()
    friend class TransliteratorAlias; // for setID()

public:

    /**
     * Destructor.
     * @stable ICU 2.0
     */
    virtual ~Transliterator();

    /**
     * Implements Cloneable.
     * All subclasses are encouraged to implement this method if it is
     * possible and reasonable to do so.  Subclasses that are to be
     * registered with the system using <tt>registerInstance()</tt>
     * are required to implement this method.  If a subclass does not
     * implement clone() properly and is registered with the system
     * using registerInstance(), then the default clone() implementation
     * will return null, and calls to createInstance() will fail.
     *
     * @return a copy of the object.
     * @see #registerInstance
     * @stable ICU 2.0
     */
    virtual Transliterator* clone() const;

    /**
     * Transliterates a segment of a string, with optional filtering.
     *
     * @param text the string to be transliterated
     * @param start the beginning index, inclusive; <code>0 <= start
     * <= limit</code>.
     * @param limit the ending index, exclusive; <code>start <= limit
     * <= text.length()</code>.
     * @return The new limit index.  The text previously occupying <code>[start,
     * limit)</code> has been transliterated, possibly to a string of a different
     * length, at <code>[start, </code><em>new-limit</em><code>)</code>, where
     * <em>new-limit</em> is the return value. If the input offsets are out of bounds,
     * the returned value is -1 and the input string remains unchanged.
     * @stable ICU 2.0
     */
    virtual int32_t transliterate(Replaceable& text,
                                  int32_t start, int32_t limit) const;

    /**
     * Transliterates an entire string in place. Convenience method.
     * @param text the string to be transliterated
     * @stable ICU 2.0
     */
    virtual void transliterate(Replaceable& text) const;

    /**
     * Transliterates the portion of the text buffer that can be
     * transliterated unambiguosly after new text has been inserted,
     * typically as a result of a keyboard event.  The new text in
     * <code>insertion</code> will be inserted into <code>text</code>
     * at <code>index.limit</code>, advancing
     * <code>index.limit</code> by <code>insertion.length()</code>.
     * Then the transliterator will try to transliterate characters of
     * <code>text</code> between <code>index.cursor</code> and
     * <code>index.limit</code>.  Characters before
     * <code>index.cursor</code> will not be changed.
     *
     * <p>Upon return, values in <code>index</code> will be updated.
     * <code>index.start</code> will be advanced to the first
     * character that future calls to this method will read.
     * <code>index.cursor</code> and <code>index.limit</code> will
     * be adjusted to delimit the range of text that future calls to
     * this method may change.
     *
     * <p>Typical usage of this method begins with an initial call
     * with <code>index.start</code> and <code>index.limit</code>
     * set to indicate the portion of <code>text</code> to be
     * transliterated, and <code>index.cursor == index.start</code>.
     * Thereafter, <code>index</code> can be used without
     * modification in future calls, provided that all changes to
     * <code>text</code> are made via this method.
     *
     * <p>This method assumes that future calls may be made that will
     * insert new text into the buffer.  As a result, it only performs
     * unambiguous transliterations.  After the last call to this
     * method, there may be untransliterated text that is waiting for
     * more input to resolve an ambiguity.  In order to perform these
     * pending transliterations, clients should call {@link
     * #finishTransliteration } after the last call to this
     * method has been made.
     *
     * @param text the buffer holding transliterated and untransliterated text
     * @param index an array of three integers.
     *
     * <ul><li><code>index.start</code>: the beginning index,
     * inclusive; <code>0 <= index.start <= index.limit</code>.
     *
     * <li><code>index.limit</code>: the ending index, exclusive;
     * <code>index.start <= index.limit <= text.length()</code>.
     * <code>insertion</code> is inserted at
     * <code>index.limit</code>.
     *
     * <li><code>index.cursor</code>: the next character to be
     * considered for transliteration; <code>index.start <=
     * index.cursor <= index.limit</code>.  Characters before
     * <code>index.cursor</code> will not be changed by future calls
     * to this method.</ul>
     *
     * @param insertion text to be inserted and possibly
     * transliterated into the translation buffer at
     * <code>index.limit</code>.  If <code>null</code> then no text
     * is inserted.
     * @param status    Output param to filled in with a success or an error.
     * @see #handleTransliterate
     * @exception IllegalArgumentException if <code>index</code>
     * is invalid
     * @see UTransPosition
     * @stable ICU 2.0
     */
    virtual void transliterate(Replaceable& text, UTransPosition& index,
                               const UnicodeString& insertion,
                               UErrorCode& status) const;

    /**
     * Transliterates the portion of the text buffer that can be
     * transliterated unambiguosly after a new character has been
     * inserted, typically as a result of a keyboard event.  This is a
     * convenience method.
     * @param text the buffer holding transliterated and
     * untransliterated text
     * @param index an array of three integers.
     * @param insertion text to be inserted and possibly
     * transliterated into the translation buffer at
     * <code>index.limit</code>.
     * @param status    Output param to filled in with a success or an error.
     * @see #transliterate(Replaceable&, UTransPosition&, const UnicodeString&, UErrorCode&) const
     * @stable ICU 2.0
     */
    virtual void transliterate(Replaceable& text, UTransPosition& index,
                               UChar32 insertion,
                               UErrorCode& status) const;

    /**
     * Transliterates the portion of the text buffer that can be
     * transliterated unambiguosly.  This is a convenience method; see
     * {@link
     * #transliterate(Replaceable&, UTransPosition&, const UnicodeString&, UErrorCode&) const }
     * for details.
     * @param text the buffer holding transliterated and
     * untransliterated text
     * @param index an array of three integers.  See {@link #transliterate(Replaceable&, UTransPosition&, const UnicodeString*, UErrorCode&) const }.
     * @param status    Output param to filled in with a success or an error.
     * @see #transliterate(Replaceable, int[], String)
     * @stable ICU 2.0
     */
    virtual void transliterate(Replaceable& text, UTransPosition& index,
                               UErrorCode& status) const;

    /**
     * Finishes any pending transliterations that were waiting for
     * more characters.  Clients should call this method as the last
     * call after a sequence of one or more calls to
     * <code>transliterate()</code>.
     * @param text the buffer holding transliterated and
     * untransliterated text.
     * @param index the array of indices previously passed to {@link
     * #transliterate }
     * @stable ICU 2.0
     */
    virtual void finishTransliteration(Replaceable& text,
                                       UTransPosition& index) const;

private:

    /**
     * This internal method does incremental transliteration.  If the
     * 'insertion' is non-null then we append it to 'text' before
     * proceeding.  This method calls through to the pure virtual
     * framework method handleTransliterate() to do the actual
     * work.
     * @param text the buffer holding transliterated and
     * untransliterated text
     * @param index an array of three integers.  See {@link
     * #transliterate(Replaceable, int[], String)}.
     * @param insertion text to be inserted and possibly
     * transliterated into the translation buffer at
     * <code>index.limit</code>.
     * @param status    Output param to filled in with a success or an error.
     */
    void _transliterate(Replaceable& text,
                        UTransPosition& index,
                        const UnicodeString* insertion,
                        UErrorCode &status) const;

protected:

    /**
     * Abstract method that concrete subclasses define to implement
     * their transliteration algorithm.  This method handles both
     * incremental and non-incremental transliteration.  Let
     * <code>originalStart</code> refer to the value of
     * <code>pos.start</code> upon entry.
     *
     * <ul>
     *  <li>If <code>incremental</code> is false, then this method
     *  should transliterate all characters between
     *  <code>pos.start</code> and <code>pos.limit</code>. Upon return
     *  <code>pos.start</code> must == <code> pos.limit</code>.</li>
     *
     *  <li>If <code>incremental</code> is true, then this method
     *  should transliterate all characters between
     *  <code>pos.start</code> and <code>pos.limit</code> that can be
     *  unambiguously transliterated, regardless of future insertions
     *  of text at <code>pos.limit</code>.  Upon return,
     *  <code>pos.start</code> should be in the range
     *  [<code>originalStart</code>, <code>pos.limit</code>).
     *  <code>pos.start</code> should be positioned such that
     *  characters [<code>originalStart</code>, <code>
     *  pos.start</code>) will not be changed in the future by this
     *  transliterator and characters [<code>pos.start</code>,
     *  <code>pos.limit</code>) are unchanged.</li>
     * </ul>
     *
     * <p>Implementations of this method should also obey the
     * following invariants:</p>
     *
     * <ul>
     *  <li> <code>pos.limit</code> and <code>pos.contextLimit</code>
     *  should be updated to reflect changes in length of the text
     *  between <code>pos.start</code> and <code>pos.limit</code>. The
     *  difference <code> pos.contextLimit - pos.limit</code> should
     *  not change.</li>
     *
     *  <li><code>pos.contextStart</code> should not change.</li>
     *
     *  <li>Upon return, neither <code>pos.start</code> nor
     *  <code>pos.limit</code> should be less than
     *  <code>originalStart</code>.</li>
     *
     *  <li>Text before <code>originalStart</code> and text after
     *  <code>pos.limit</code> should not change.</li>
     *
     *  <li>Text before <code>pos.contextStart</code> and text after
     *  <code> pos.contextLimit</code> should be ignored.</li>
     * </ul>
     *
     * <p>Subclasses may safely assume that all characters in
     * [<code>pos.start</code>, <code>pos.limit</code>) are filtered.
     * In other words, the filter has already been applied by the time
     * this method is called.  See
     * <code>filteredTransliterate()</code>.
     *
     * <p>This method is <b>not</b> for public consumption.  Calling
     * this method directly will transliterate
     * [<code>pos.start</code>, <code>pos.limit</code>) without
     * applying the filter. End user code should call <code>
     * transliterate()</code> instead of this method. Subclass code
     * and wrapping transliterators should call
     * <code>filteredTransliterate()</code> instead of this method.<p>
     *
     * @param text the buffer holding transliterated and
     * untransliterated text
     *
     * @param pos the indices indicating the start, limit, context
     * start, and context limit of the text.
     *
     * @param incremental if true, assume more text may be inserted at
     * <code>pos.limit</code> and act accordingly.  Otherwise,
     * transliterate all text between <code>pos.start</code> and
     * <code>pos.limit</code> and move <code>pos.start</code> up to
     * <code>pos.limit</code>.
     *
     * @see #transliterate
     * @stable ICU 2.4
     */
    virtual void handleTransliterate(Replaceable& text,
                                     UTransPosition& pos,
                                     UBool incremental) const = 0;

public:
    /**
     * Transliterate a substring of text, as specified by index, taking filters
     * into account.  This method is for subclasses that need to delegate to
     * another transliterator, such as CompoundTransliterator.
     * @param text the text to be transliterated
     * @param index the position indices
     * @param incremental if TRUE, then assume more characters may be inserted
     * at index.limit, and postpone processing to accomodate future incoming
     * characters
     * @stable ICU 2.4
     */
    virtual void filteredTransliterate(Replaceable& text,
                                       UTransPosition& index,
                                       UBool incremental) const;

private:

    /**
     * Top-level transliteration method, handling filtering, incremental and
     * non-incremental transliteration, and rollback.  All transliteration
     * public API methods eventually call this method with a rollback argument
     * of TRUE.  Other entities may call this method but rollback should be
     * FALSE.
     *
     * <p>If this transliterator has a filter, break up the input text into runs
     * of unfiltered characters.  Pass each run to
     * subclass.handleTransliterate().
     *
     * <p>In incremental mode, if rollback is TRUE, perform a special
     * incremental procedure in which several passes are made over the input
     * text, adding one character at a time, and committing successful
     * transliterations as they occur.  Unsuccessful transliterations are rolled
     * back and retried with additional characters to give correct results.
     *
     * @param text the text to be transliterated
     * @param index the position indices
     * @param incremental if TRUE, then assume more characters may be inserted
     * at index.limit, and postpone processing to accomodate future incoming
     * characters
     * @param rollback if TRUE and if incremental is TRUE, then perform special
     * incremental processing, as described above, and undo partial
     * transliterations where necessary.  If incremental is FALSE then this
     * parameter is ignored.
     */
    virtual void filteredTransliterate(Replaceable& text,
                                       UTransPosition& index,
                                       UBool incremental,
                                       UBool rollback) const;

public:

    /**
     * Returns the length of the longest context required by this transliterator.
     * This is <em>preceding</em> context.  The default implementation supplied
     * by <code>Transliterator</code> returns zero; subclasses
     * that use preceding context should override this method to return the
     * correct value.  For example, if a transliterator translates "ddd" (where
     * d is any digit) to "555" when preceded by "(ddd)", then the preceding
     * context length is 5, the length of "(ddd)".
     *
     * @return The maximum number of preceding context characters this
     * transliterator needs to examine
     * @stable ICU 2.0
     */
    int32_t getMaximumContextLength(void) const;

protected:

    /**
     * Method for subclasses to use to set the maximum context length.
     * @param maxContextLength the new value to be set.
     * @see #getMaximumContextLength
     * @stable ICU 2.4
     */
    void setMaximumContextLength(int32_t maxContextLength);

public:

    /**
     * Returns a programmatic identifier for this transliterator.
     * If this identifier is passed to <code>createInstance()</code>, it
     * will return this object, if it has been registered.
     * @return a programmatic identifier for this transliterator.
     * @see #registerInstance
     * @see #registerFactory
     * @see #getAvailableIDs
     * @stable ICU 2.0
     */
    virtual const UnicodeString& getID(void) const;

    /**
     * Returns a name for this transliterator that is appropriate for
     * display to the user in the default locale.  See {@link
     * #getDisplayName } for details.
     * @param ID     the string identifier for this transliterator
     * @param result Output param to receive the display name
     * @return       A reference to 'result'.
     * @stable ICU 2.0
     */
    static UnicodeString& U_EXPORT2 getDisplayName(const UnicodeString& ID,
                                         UnicodeString& result);

    /**
     * Returns a name for this transliterator that is appropriate for
     * display to the user in the given locale.  This name is taken
     * from the locale resource data in the standard manner of the
     * <code>java.text</code> package.
     *
     * <p>If no localized names exist in the system resource bundles,
     * a name is synthesized using a localized
     * <code>MessageFormat</code> pattern from the resource data.  The
     * arguments to this pattern are an integer followed by one or two
     * strings.  The integer is the number of strings, either 1 or 2.
     * The strings are formed by splitting the ID for this
     * transliterator at the first '-'.  If there is no '-', then the
     * entire ID forms the only string.
     * @param ID       the string identifier for this transliterator
     * @param inLocale the Locale in which the display name should be
     *                 localized.
     * @param result   Output param to receive the display name
     * @return         A reference to 'result'.
     * @stable ICU 2.0
     */
    static UnicodeString& U_EXPORT2 getDisplayName(const UnicodeString& ID,
                                         const Locale& inLocale,
                                         UnicodeString& result);

    /**
     * Returns the filter used by this transliterator, or <tt>NULL</tt>
     * if this transliterator uses no filter.
     * @return the filter used by this transliterator, or <tt>NULL</tt>
     *         if this transliterator uses no filter.
     * @stable ICU 2.0
     */
    const UnicodeFilter* getFilter(void) const;

    /**
     * Returns the filter used by this transliterator, or <tt>NULL</tt> if this
     * transliterator uses no filter.  The caller must eventually delete the
     * result.  After this call, this transliterator's filter is set to
     * <tt>NULL</tt>.
     * @return the filter used by this transliterator, or <tt>NULL</tt> if this
     *         transliterator uses no filter.
     * @stable ICU 2.4
     */
    UnicodeFilter* orphanFilter(void);

    /**
     * Changes the filter used by this transliterator.  If the filter
     * is set to <tt>null</tt> then no filtering will occur.
     *
     * <p>Callers must take care if a transliterator is in use by
     * multiple threads.  The filter should not be changed by one
     * thread while another thread may be transliterating.
     * @param adoptedFilter the new filter to be adopted.
     * @stable ICU 2.0
     */
    void adoptFilter(UnicodeFilter* adoptedFilter);

    /**
     * Returns this transliterator's inverse.  See the class
     * documentation for details.  This implementation simply inverts
     * the two entities in the ID and attempts to retrieve the
     * resulting transliterator.  That is, if <code>getID()</code>
     * returns "A-B", then this method will return the result of
     * <code>createInstance("B-A")</code>, or <code>null</code> if that
     * call fails.
     *
     * <p>Subclasses with knowledge of their inverse may wish to
     * override this method.
     *
     * @param status Output param to filled in with a success or an error.
     * @return a transliterator that is an inverse, not necessarily
     * exact, of this transliterator, or <code>null</code> if no such
     * transliterator is registered.
     * @see #registerInstance
     * @stable ICU 2.0
     */
    Transliterator* createInverse(UErrorCode& status) const;

    /**
     * Returns a <code>Transliterator</code> object given its ID.
     * The ID must be either a system transliterator ID or a ID registered
     * using <code>registerInstance()</code>.
     *
     * @param ID a valid ID, as enumerated by <code>getAvailableIDs()</code>
     * @param dir        either FORWARD or REVERSE.
     * @param parseError Struct to recieve information on position
     *                   of error if an error is encountered
     * @param status     Output param to filled in with a success or an error.
     * @return A <code>Transliterator</code> object with the given ID
     * @see #registerInstance
     * @see #getAvailableIDs
     * @see #getID
     * @stable ICU 2.0
     */
    static Transliterator* U_EXPORT2 createInstance(const UnicodeString& ID,
                                          UTransDirection dir,
                                          UParseError& parseError,
                                          UErrorCode& status);

    /**
     * Returns a <code>Transliterator</code> object given its ID.
     * The ID must be either a system transliterator ID or a ID registered
     * using <code>registerInstance()</code>.
     * @param ID a valid ID, as enumerated by <code>getAvailableIDs()</code>
     * @param dir        either FORWARD or REVERSE.
     * @param status     Output param to filled in with a success or an error.
     * @return A <code>Transliterator</code> object with the given ID
     * @stable ICU 2.0
     */
    static Transliterator* U_EXPORT2 createInstance(const UnicodeString& ID,
                                          UTransDirection dir,
                                          UErrorCode& status);

    /**
     * Returns a <code>Transliterator</code> object constructed from
     * the given rule string.  This will be a RuleBasedTransliterator,
     * if the rule string contains only rules, or a
     * CompoundTransliterator, if it contains ID blocks, or a
     * NullTransliterator, if it contains ID blocks which parse as
     * empty for the given direction.
     * @param ID            the id for the transliterator.
     * @param rules         rules, separated by ';'
     * @param dir           either FORWARD or REVERSE.
     * @param parseError    Struct to recieve information on position
     *                      of error if an error is encountered
     * @param status        Output param set to success/failure code.
     * @stable ICU 2.0
     */
    static Transliterator* U_EXPORT2 createFromRules(const UnicodeString& ID,
                                           const UnicodeString& rules,
                                           UTransDirection dir,
                                           UParseError& parseError,
                                           UErrorCode& status);

    /**
     * Create a rule string that can be passed to createFromRules()
     * to recreate this transliterator.
     * @param result the string to receive the rules.  Previous
     * contents will be deleted.
     * @param escapeUnprintable if TRUE then convert unprintable
     * character to their hex escape representations, \\uxxxx or
     * \\Uxxxxxxxx.  Unprintable characters are those other than
     * U+000A, U+0020..U+007E.
     * @stable ICU 2.0
     */
    virtual UnicodeString& toRules(UnicodeString& result,
                                   UBool escapeUnprintable) const;

    /**
     * Return the number of elements that make up this transliterator.
     * For example, if the transliterator "NFD;Jamo-Latin;Latin-Greek"
     * were created, the return value of this method would be 3.
     *
     * <p>If this transliterator is not composed of other
     * transliterators, then this method returns 1.
     * @return the number of transliterators that compose this
     * transliterator, or 1 if this transliterator is not composed of
     * multiple transliterators
     * @stable ICU 3.0
     */
    int32_t countElements() const;

    /**
     * Return an element that makes up this transliterator.  For
     * example, if the transliterator "NFD;Jamo-Latin;Latin-Greek"
     * were created, the return value of this method would be one
     * of the three transliterator objects that make up that
     * transliterator: [NFD, Jamo-Latin, Latin-Greek].
     *
     * <p>If this transliterator is not composed of other
     * transliterators, then this method will return a reference to
     * this transliterator when given the index 0.
     * @param index a value from 0..countElements()-1 indicating the
     * transliterator to return
     * @param ec input-output error code
     * @return one of the transliterators that makes up this
     * transliterator, if this transliterator is made up of multiple
     * transliterators, otherwise a reference to this object if given
     * an index of 0
     * @stable ICU 3.0
     */
    const Transliterator& getElement(int32_t index, UErrorCode& ec) const;

    /**
     * Returns the set of all characters that may be modified in the
     * input text by this Transliterator.  This incorporates this
     * object's current filter; if the filter is changed, the return
     * value of this function will change.  The default implementation
     * returns an empty set.  Some subclasses may override {@link
     * #handleGetSourceSet } to return a more precise result.  The
     * return result is approximate in any case and is intended for
     * use by tests, tools, or utilities.
     * @param result receives result set; previous contents lost
     * @return a reference to result
     * @see #getTargetSet
     * @see #handleGetSourceSet
     * @stable ICU 2.4
     */
    UnicodeSet& getSourceSet(UnicodeSet& result) const;

    /**
     * Framework method that returns the set of all characters that
     * may be modified in the input text by this Transliterator,
     * ignoring the effect of this object's filter.  The base class
     * implementation returns the empty set.  Subclasses that wish to
     * implement this should override this method.
     * @return the set of characters that this transliterator may
     * modify.  The set may be modified, so subclasses should return a
     * newly-created object.
     * @param result receives result set; previous contents lost
     * @see #getSourceSet
     * @see #getTargetSet
     * @stable ICU 2.4
     */
    virtual void handleGetSourceSet(UnicodeSet& result) const;

    /**
     * Returns the set of all characters that may be generated as
     * replacement text by this transliterator.  The default
     * implementation returns the empty set.  Some subclasses may
     * override this method to return a more precise result.  The
     * return result is approximate in any case and is intended for
     * use by tests, tools, or utilities requiring such
     * meta-information.
     * @param result receives result set; previous contents lost
     * @return a reference to result
     * @see #getTargetSet
     * @stable ICU 2.4
     */
    virtual UnicodeSet& getTargetSet(UnicodeSet& result) const;

public:

    /**
     * Registers a factory function that creates transliterators of
     * a given ID.
     *
     * Because ICU may choose to cache Transliterators internally, this must
     * be called at application startup, prior to any calls to
     * Transliterator::createXXX to avoid undefined behavior.
     *
     * @param id the ID being registered
     * @param factory a function pointer that will be copied and
     * called later when the given ID is passed to createInstance()
     * @param context a context pointer that will be stored and
     * later passed to the factory function when an ID matching
     * the registration ID is being instantiated with this factory.
     * @stable ICU 2.0
     */
    static void U_EXPORT2 registerFactory(const UnicodeString& id,
                                Factory factory,
                                Token context);

    /**
     * Registers an instance <tt>obj</tt> of a subclass of
     * <code>Transliterator</code> with the system.  When
     * <tt>createInstance()</tt> is called with an ID string that is
     * equal to <tt>obj->getID()</tt>, then <tt>obj->clone()</tt> is
     * returned.
     *
     * After this call the Transliterator class owns the adoptedObj
     * and will delete it.
     *
     * Because ICU may choose to cache Transliterators internally, this must
     * be called at application startup, prior to any calls to
     * Transliterator::createXXX to avoid undefined behavior.
     *
     * @param adoptedObj an instance of subclass of
     * <code>Transliterator</code> that defines <tt>clone()</tt>
     * @see #createInstance
     * @see #registerFactory
     * @see #unregister
     * @stable ICU 2.0
     */
    static void U_EXPORT2 registerInstance(Transliterator* adoptedObj);

    /**
     * Registers an ID string as an alias of another ID string.
     * That is, after calling this function, <tt>createInstance(aliasID)</tt>
     * will return the same thing as <tt>createInstance(realID)</tt>.
     * This is generally used to create shorter, more mnemonic aliases
     * for long compound IDs.
     *
     * @param aliasID The new ID being registered.
     * @param realID The ID that the new ID is to be an alias for.
     * This can be a compound ID and can include filters and should
     * refer to transliterators that have already been registered with
     * the framework, although this isn't checked.
     * @stable ICU 3.6
     */
     static void U_EXPORT2 registerAlias(const UnicodeString& aliasID,
                                         const UnicodeString& realID);

protected:

#ifndef U_HIDE_INTERNAL_API
    /**
     * @param id the ID being registered
     * @param factory a function pointer that will be copied and
     * called later when the given ID is passed to createInstance()
     * @param context a context pointer that will be stored and
     * later passed to the factory function when an ID matching
     * the registration ID is being instantiated with this factory.
     * @internal
     */
    static void _registerFactory(const UnicodeString& id,
                                 Factory factory,
                                 Token context);

    /**
     * @internal
     */
    static void _registerInstance(Transliterator* adoptedObj);

    /**
     * @internal
     */
    static void _registerAlias(const UnicodeString& aliasID, const UnicodeString& realID);

    /**
     * Register two targets as being inverses of one another.  For
     * example, calling registerSpecialInverse("NFC", "NFD", true) causes
     * Transliterator to form the following inverse relationships:
     *
     * <pre>NFC => NFD
     * Any-NFC => Any-NFD
     * NFD => NFC
     * Any-NFD => Any-NFC</pre>
     *
     * (Without the special inverse registration, the inverse of NFC
     * would be NFC-Any.)  Note that NFD is shorthand for Any-NFD, but
     * that the presence or absence of "Any-" is preserved.
     *
     * <p>The relationship is symmetrical; registering (a, b) is
     * equivalent to registering (b, a).
     *
     * <p>The relevant IDs must still be registered separately as
     * factories or classes.
     *
     * <p>Only the targets are specified.  Special inverses always
     * have the form Any-Target1 <=> Any-Target2.  The target should
     * have canonical casing (the casing desired to be produced when
     * an inverse is formed) and should contain no whitespace or other
     * extraneous characters.
     *
     * @param target the target against which to register the inverse
     * @param inverseTarget the inverse of target, that is
     * Any-target.getInverse() => Any-inverseTarget
     * @param bidirectional if true, register the reverse relation
     * as well, that is, Any-inverseTarget.getInverse() => Any-target
     * @internal
     */
    static void _registerSpecialInverse(const UnicodeString& target,
                                        const UnicodeString& inverseTarget,
                                        UBool bidirectional);
#endif  /* U_HIDE_INTERNAL_API */

public:

    /**
     * Unregisters a transliterator or class.  This may be either
     * a system transliterator or a user transliterator or class.
     * Any attempt to construct an unregistered transliterator based
     * on its ID will fail.
     *
     * Because ICU may choose to cache Transliterators internally, this should
     * be called during application shutdown, after all calls to
     * Transliterator::createXXX to avoid undefined behavior.
     *
     * @param ID the ID of the transliterator or class
     * @return the <code>Object</code> that was registered with
     * <code>ID</code>, or <code>null</code> if none was
     * @see #registerInstance
     * @see #registerFactory
     * @stable ICU 2.0
     */
    static void U_EXPORT2 unregister(const UnicodeString& ID);

public:

    /**
     * Return a StringEnumeration over the IDs available at the time of the
     * call, including user-registered IDs.
     * @param ec input-output error code
     * @return a newly-created StringEnumeration over the transliterators
     * available at the time of the call. The caller should delete this object
     * when done using it.
     * @stable ICU 3.0
     */
    static StringEnumeration* U_EXPORT2 getAvailableIDs(UErrorCode& ec);

    /**
     * Return the number of registered source specifiers.
     * @return the number of registered source specifiers.
     * @stable ICU 2.0
     */
    static int32_t U_EXPORT2 countAvailableSources(void);

    /**
     * Return a registered source specifier.
     * @param index which specifier to return, from 0 to n-1, where
     * n = countAvailableSources()
     * @param result fill-in paramter to receive the source specifier.
     * If index is out of range, result will be empty.
     * @return reference to result
     * @stable ICU 2.0
     */
    static UnicodeString& U_EXPORT2 getAvailableSource(int32_t index,
                                             UnicodeString& result);

    /**
     * Return the number of registered target specifiers for a given
     * source specifier.
     * @param source the given source specifier.
     * @return the number of registered target specifiers for a given
     *         source specifier.
     * @stable ICU 2.0
     */
    static int32_t U_EXPORT2 countAvailableTargets(const UnicodeString& source);

    /**
     * Return a registered target specifier for a given source.
     * @param index which specifier to return, from 0 to n-1, where
     * n = countAvailableTargets(source)
     * @param source the source specifier
     * @param result fill-in paramter to receive the target specifier.
     * If source is invalid or if index is out of range, result will
     * be empty.
     * @return reference to result
     * @stable ICU 2.0
     */
    static UnicodeString& U_EXPORT2 getAvailableTarget(int32_t index,
                                             const UnicodeString& source,
                                             UnicodeString& result);

    /**
     * Return the number of registered variant specifiers for a given
     * source-target pair.
     * @param source    the source specifiers.
     * @param target    the target specifiers.
     * @stable ICU 2.0
     */
    static int32_t U_EXPORT2 countAvailableVariants(const UnicodeString& source,
                                          const UnicodeString& target);

    /**
     * Return a registered variant specifier for a given source-target
     * pair.
     * @param index which specifier to return, from 0 to n-1, where
     * n = countAvailableVariants(source, target)
     * @param source the source specifier
     * @param target the target specifier
     * @param result fill-in paramter to receive the variant
     * specifier.  If source is invalid or if target is invalid or if
     * index is out of range, result will be empty.
     * @return reference to result
     * @stable ICU 2.0
     */
    static UnicodeString& U_EXPORT2 getAvailableVariant(int32_t index,
                                              const UnicodeString& source,
                                              const UnicodeString& target,
                                              UnicodeString& result);

protected:

#ifndef U_HIDE_INTERNAL_API
    /**
     * Non-mutexed internal method
     * @internal
     */
    static int32_t _countAvailableSources(void);

    /**
     * Non-mutexed internal method
     * @internal
     */
    static UnicodeString& _getAvailableSource(int32_t index,
                                              UnicodeString& result);

    /**
     * Non-mutexed internal method
     * @internal
     */
    static int32_t _countAvailableTargets(const UnicodeString& source);

    /**
     * Non-mutexed internal method
     * @internal
     */
    static UnicodeString& _getAvailableTarget(int32_t index,
                                              const UnicodeString& source,
                                              UnicodeString& result);

    /**
     * Non-mutexed internal method
     * @internal
     */
    static int32_t _countAvailableVariants(const UnicodeString& source,
                                           const UnicodeString& target);

    /**
     * Non-mutexed internal method
     * @internal
     */
    static UnicodeString& _getAvailableVariant(int32_t index,
                                               const UnicodeString& source,
                                               const UnicodeString& target,
                                               UnicodeString& result);
#endif  /* U_HIDE_INTERNAL_API */

protected:

    /**
     * Set the ID of this transliterators.  Subclasses shouldn't do
     * this, unless the underlying script behavior has changed.
     * @param id the new id t to be set.
     * @stable ICU 2.4
     */
    void setID(const UnicodeString& id);

public:

    /**
     * Return the class ID for this class.  This is useful only for
     * comparing to a return value from getDynamicClassID().
     * Note that Transliterator is an abstract base class, and therefor
     * no fully constructed object will  have a dynamic
     * UCLassID that equals the UClassID returned from
     * TRansliterator::getStaticClassID().
     * @return       The class ID for class Transliterator.
     * @stable ICU 2.0
     */
    static UClassID U_EXPORT2 getStaticClassID(void);

    /**
     * Returns a unique class ID <b>polymorphically</b>.  This method
     * is to implement a simple version of RTTI, since not all C++
     * compilers support genuine RTTI.  Polymorphic operator==() and
     * clone() methods call this method.
     *
     * <p>Concrete subclasses of Transliterator must use the
     *    UOBJECT_DEFINE_RTTI_IMPLEMENTATION macro from
     *    uobject.h to provide the RTTI functions.
     *
     * @return The class ID for this object. All objects of a given
     * class have the same class ID.  Objects of other classes have
     * different class IDs.
     * @stable ICU 2.0
     */
    virtual UClassID getDynamicClassID(void) const = 0;

private:
    static UBool initializeRegistry(UErrorCode &status);

public:
#ifndef U_HIDE_OBSOLETE_API
    /**
     * Return the number of IDs currently registered with the system.
     * To retrieve the actual IDs, call getAvailableID(i) with
     * i from 0 to countAvailableIDs() - 1.
     * @return the number of IDs currently registered with the system.
     * @obsolete ICU 3.4 use getAvailableIDs() instead
     */
    static int32_t U_EXPORT2 countAvailableIDs(void);

    /**
     * Return the index-th available ID.  index must be between 0
     * and countAvailableIDs() - 1, inclusive.  If index is out of
     * range, the result of getAvailableID(0) is returned.
     * @param index the given ID index.
     * @return      the index-th available ID.  index must be between 0
     *              and countAvailableIDs() - 1, inclusive.  If index is out of
     *              range, the result of getAvailableID(0) is returned.
     * @obsolete ICU 3.4 use getAvailableIDs() instead; this function
     * is not thread safe, since it returns a reference to storage that
     * may become invalid if another thread calls unregister
     */
    static const UnicodeString& U_EXPORT2 getAvailableID(int32_t index);
#endif  /* U_HIDE_OBSOLETE_API */
};

inline int32_t Transliterator::getMaximumContextLength(void) const {
    return maximumContextLength;
}

inline void Transliterator::setID(const UnicodeString& id) {
    ID = id;
    // NUL-terminate the ID string, which is a non-aliased copy.
    ID.append((UChar)0);
    ID.truncate(ID.length()-1);
}

#ifndef U_HIDE_INTERNAL_API
inline Transliterator::Token Transliterator::integerToken(int32_t i) {
    Token t;
    t.integer = i;
    return t;
}

inline Transliterator::Token Transliterator::pointerToken(void* p) {
    Token t;
    t.pointer = p;
    return t;
}
#endif  /* U_HIDE_INTERNAL_API */

U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_TRANSLITERATION */

#endif