1/*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.  Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26/*
27 *
28 * (C) Copyright IBM Corp. 1998-2007 - All Rights Reserved
29 *
30 * This file is a modification of the ICU file IndicReordering.cpp
31 * by Jens Herden and Javier Sola for Khmer language
32 *
33 */
34
35#include "LETypes.h"
36#include "OpenTypeTables.h"
37#include "KhmerReordering.h"
38#include "LEGlyphStorage.h"
39
40
41U_NAMESPACE_BEGIN
42
43// Characters that get referred to by name...
44enum
45{
46    C_SIGN_ZWNJ     = 0x200C,
47    C_SIGN_ZWJ      = 0x200D,
48    C_DOTTED_CIRCLE = 0x25CC,
49    C_RO            = 0x179A,
50    C_VOWEL_AA      = 0x17B6,
51    C_SIGN_NIKAHIT  = 0x17C6,
52    C_VOWEL_E       = 0x17C1,
53    C_COENG         = 0x17D2
54};
55
56
57enum
58{
59    // simple classes, they are used in the statetable (in this file) to control the length of a syllable
60    // they are also used to know where a character should be placed (location in reference to the base character)
61    // and also to know if a character, when independtly displayed, should be displayed with a dotted-circle to
62    // indicate error in syllable construction
63    _xx = KhmerClassTable::CC_RESERVED,
64    _sa = KhmerClassTable::CC_SIGN_ABOVE | KhmerClassTable::CF_DOTTED_CIRCLE | KhmerClassTable::CF_POS_ABOVE,
65    _sp = KhmerClassTable::CC_SIGN_AFTER | KhmerClassTable::CF_DOTTED_CIRCLE| KhmerClassTable::CF_POS_AFTER,
66    _c1 = KhmerClassTable::CC_CONSONANT | KhmerClassTable::CF_CONSONANT,
67    _c2 = KhmerClassTable::CC_CONSONANT2 | KhmerClassTable::CF_CONSONANT,
68    _c3 = KhmerClassTable::CC_CONSONANT3 | KhmerClassTable::CF_CONSONANT,
69    _rb = KhmerClassTable::CC_ROBAT | KhmerClassTable::CF_POS_ABOVE | KhmerClassTable::CF_DOTTED_CIRCLE,
70    _cs = KhmerClassTable::CC_CONSONANT_SHIFTER | KhmerClassTable::CF_DOTTED_CIRCLE | KhmerClassTable::CF_SHIFTER,
71    _dl = KhmerClassTable::CC_DEPENDENT_VOWEL | KhmerClassTable::CF_POS_BEFORE | KhmerClassTable::CF_DOTTED_CIRCLE,
72    _db = KhmerClassTable::CC_DEPENDENT_VOWEL | KhmerClassTable::CF_POS_BELOW | KhmerClassTable::CF_DOTTED_CIRCLE,
73    _da = KhmerClassTable::CC_DEPENDENT_VOWEL | KhmerClassTable::CF_POS_ABOVE | KhmerClassTable::CF_DOTTED_CIRCLE | KhmerClassTable::CF_ABOVE_VOWEL,
74    _dr = KhmerClassTable::CC_DEPENDENT_VOWEL | KhmerClassTable::CF_POS_AFTER | KhmerClassTable::CF_DOTTED_CIRCLE,
75    _co = KhmerClassTable::CC_COENG | KhmerClassTable::CF_COENG | KhmerClassTable::CF_DOTTED_CIRCLE,
76
77    // split vowel
78    _va = _da | KhmerClassTable::CF_SPLIT_VOWEL,
79    _vr = _dr | KhmerClassTable::CF_SPLIT_VOWEL
80};
81
82
83// Character class tables
84// _xx character does not combine into syllable, such as numbers, puntuation marks, non-Khmer signs...
85// _sa Sign placed above the base
86// _sp Sign placed after the base
87// _c1 Consonant of type 1 or independent vowel (independent vowels behave as type 1 consonants)
88// _c2 Consonant of type 2 (only RO)
89// _c3 Consonant of type 3
90// _rb Khmer sign robat u17CC. combining mark for subscript consonants
91// _cd Consonant-shifter
92// _dl Dependent vowel placed before the base (left of the base)
93// _db Dependent vowel placed below the base
94// _da Dependent vowel placed above the base
95// _dr Dependent vowel placed behind the base (right of the base)
96// _co Khmer combining mark COENG u17D2, combines with the consonant or independent vowel following
97//     it to create a subscript consonant or independent vowel
98// _va Khmer split vowel in wich the first part is before the base and the second one above the base
99// _vr Khmer split vowel in wich the first part is before the base and the second one behind (right of) the base
100
101static const KhmerClassTable::CharClass khmerCharClasses[] =
102{
103    _c1, _c1, _c1, _c3, _c1, _c1, _c1, _c1, _c3, _c1, _c1, _c1, _c1, _c3, _c1, _c1, // 1780 - 178F
104    _c1, _c1, _c1, _c1, _c3, _c1, _c1, _c1, _c1, _c3, _c2, _c1, _c1, _c1, _c3, _c3, // 1790 - 179F
105    _c1, _c3, _c1, _c1, _c1, _c1, _c1, _c1, _c1, _c1, _c1, _c1, _c1, _c1, _c1, _c1, // 17A0 - 17AF
106    _c1, _c1, _c1, _c1, _dr, _dr, _dr, _da, _da, _da, _da, _db, _db, _db, _va, _vr, // 17B0 - 17BF
107    _vr, _dl, _dl, _dl, _vr, _vr, _sa, _sp, _sp, _cs, _cs, _sa, _rb, _sa, _sa, _sa, // 17C0 - 17CF
108    _sa, _sa, _co, _sa, _xx, _xx, _xx, _xx, _xx, _xx, _xx, _xx, _xx, _sa, _xx, _xx, // 17D0 - 17DF
109};
110
111
112//
113// Khmer Class Tables
114//
115
116//
117// The range of characters defined in the above table is defined here. FOr Khmer 1780 to 17DF
118// Even if the Khmer range is bigger, all other characters are not combinable, and therefore treated
119// as _xx
120static const KhmerClassTable khmerClassTable = {0x1780, 0x17df, khmerCharClasses};
121
122
123// Below we define how a character in the input string is either in the khmerCharClasses table
124// (in which case we get its type back), a ZWJ or ZWNJ (two characters that may appear
125// within the syllable, but are not in the table) we also get their type back, or an unknown object
126// in which case we get _xx (CC_RESERVED) back
127KhmerClassTable::CharClass KhmerClassTable::getCharClass(LEUnicode ch) const
128{
129
130    if (ch == C_SIGN_ZWJ) {
131        return CC_ZERO_WIDTH_J_MARK;
132    }
133
134    if (ch == C_SIGN_ZWNJ) {
135        return CC_ZERO_WIDTH_NJ_MARK;
136    }
137
138    if (ch < firstChar || ch > lastChar) {
139        return CC_RESERVED;
140    }
141
142    return classTable[ch - firstChar];
143}
144
145const KhmerClassTable *KhmerClassTable::getKhmerClassTable()
146{
147    return &khmerClassTable;
148}
149
150
151
152class KhmerReorderingOutput : public UMemory {
153private:
154    le_int32 fSyllableCount;
155    le_int32 fOutIndex;
156    LEUnicode *fOutChars;
157
158    LEGlyphStorage &fGlyphStorage;
159
160
161public:
162    KhmerReorderingOutput(LEUnicode *outChars, LEGlyphStorage &glyphStorage)
163        : fSyllableCount(0), fOutIndex(0), fOutChars(outChars), fGlyphStorage(glyphStorage)
164    {
165        // nothing else to do...
166    }
167
168    ~KhmerReorderingOutput()
169    {
170        // nothing to do here...
171    }
172
173    void reset()
174    {
175        fSyllableCount += 1;
176    }
177
178    void writeChar(LEUnicode ch, le_uint32 charIndex, FeatureMask charFeatures)
179    {
180        LEErrorCode success = LE_NO_ERROR;
181
182        fOutChars[fOutIndex] = ch;
183
184        fGlyphStorage.setCharIndex(fOutIndex, charIndex, success);
185        fGlyphStorage.setAuxData(fOutIndex, charFeatures | (fSyllableCount & LE_GLYPH_GROUP_MASK), success);
186
187        fOutIndex += 1;
188    }
189
190    le_int32 getOutputIndex()
191    {
192        return fOutIndex;
193    }
194};
195
196
197#define blwfFeatureTag LE_BLWF_FEATURE_TAG
198#define pstfFeatureTag LE_PSTF_FEATURE_TAG
199#define presFeatureTag LE_PRES_FEATURE_TAG
200#define blwsFeatureTag LE_BLWS_FEATURE_TAG
201#define abvsFeatureTag LE_ABVS_FEATURE_TAG
202#define pstsFeatureTag LE_PSTS_FEATURE_TAG
203
204#define blwmFeatureTag LE_BLWM_FEATURE_TAG
205#define abvmFeatureTag LE_ABVM_FEATURE_TAG
206#define distFeatureTag LE_DIST_FEATURE_TAG
207
208#define prefFeatureTag LE_PREF_FEATURE_TAG
209#define abvfFeatureTag LE_ABVF_FEATURE_TAG
210#define cligFeatureTag LE_CLIG_FEATURE_TAG
211#define mkmkFeatureTag LE_MKMK_FEATURE_TAG
212
213#define prefFeatureMask 0x80000000UL
214#define blwfFeatureMask 0x40000000UL
215#define abvfFeatureMask 0x20000000UL
216#define pstfFeatureMask 0x10000000UL
217#define presFeatureMask 0x08000000UL
218#define blwsFeatureMask 0x04000000UL
219#define abvsFeatureMask 0x02000000UL
220#define pstsFeatureMask 0x01000000UL
221#define cligFeatureMask 0x00800000UL
222#define distFeatureMask 0x00400000UL
223#define blwmFeatureMask 0x00200000UL
224#define abvmFeatureMask 0x00100000UL
225#define mkmkFeatureMask 0x00080000UL
226
227#define tagPref    (prefFeatureMask | presFeatureMask | cligFeatureMask | distFeatureMask)
228#define tagAbvf    (abvfFeatureMask | abvsFeatureMask | cligFeatureMask | distFeatureMask | abvmFeatureMask | mkmkFeatureMask)
229#define tagPstf    (blwfFeatureMask | blwsFeatureMask | prefFeatureMask | presFeatureMask | pstfFeatureMask | pstsFeatureMask | cligFeatureMask | distFeatureMask | blwmFeatureMask)
230#define tagBlwf    (blwfFeatureMask | blwsFeatureMask | cligFeatureMask | distFeatureMask | blwmFeatureMask | mkmkFeatureMask)
231#define tagDefault (prefFeatureMask | blwfFeatureMask | presFeatureMask | blwsFeatureMask | cligFeatureMask | distFeatureMask | abvmFeatureMask | blwmFeatureMask | mkmkFeatureMask)
232
233
234
235// These are in the order in which the features need to be applied
236// for correct processing
237static const FeatureMap featureMap[] =
238{
239    // Shaping features
240    {prefFeatureTag, prefFeatureMask},
241    {blwfFeatureTag, blwfFeatureMask},
242    {abvfFeatureTag, abvfFeatureMask},
243    {pstfFeatureTag, pstfFeatureMask},
244    {presFeatureTag, presFeatureMask},
245    {blwsFeatureTag, blwsFeatureMask},
246    {abvsFeatureTag, abvsFeatureMask},
247    {pstsFeatureTag, pstsFeatureMask},
248    {cligFeatureTag, cligFeatureMask},
249
250    // Positioning features
251    {distFeatureTag, distFeatureMask},
252    {blwmFeatureTag, blwmFeatureMask},
253    {abvmFeatureTag, abvmFeatureMask},
254    {mkmkFeatureTag, mkmkFeatureMask},
255};
256
257static const le_int32 featureMapCount = LE_ARRAY_SIZE(featureMap);
258
259// The stateTable is used to calculate the end (the length) of a well
260// formed Khmer Syllable.
261//
262// Each horizontal line is ordered exactly the same way as the values in KhmerClassTable
263// CharClassValues in KhmerReordering.h This coincidence of values allows the
264// follow up of the table.
265//
266// Each line corresponds to a state, which does not necessarily need to be a type
267// of component... for example, state 2 is a base, with is always a first character
268// in the syllable, but the state could be produced a consonant of any type when
269// it is the first character that is analysed (in ground state).
270//
271// Differentiating 3 types of consonants is necessary in order to
272// forbid the use of certain combinations, such as having a second
273// coeng after a coeng RO,
274// The inexistent possibility of having a type 3 after another type 3 is permitted,
275// eliminating it would very much complicate the table, and it does not create typing
276// problems, as the case above.
277//
278// The table is quite complex, in order to limit the number of coeng consonants
279// to 2 (by means of the table).
280//
281// There a peculiarity, as far as Unicode is concerned:
282// - The consonant-shifter is considered in two possible different
283//   locations, the one considered in Unicode 3.0 and the one considered in
284//   Unicode 4.0. (there is a backwards compatibility problem in this standard).
285
286
287// xx    independent character, such as a number, punctuation sign or non-khmer char
288//
289// c1    Khmer consonant of type 1 or an independent vowel
290//       that is, a letter in which the subscript for is only under the
291//       base, not taking any space to the right or to the left
292//
293// c2    Khmer consonant of type 2, the coeng form takes space under
294//       and to the left of the base (only RO is of this type)
295//
296// c3    Khmer consonant of type 3. Its subscript form takes space under
297//       and to the right of the base.
298//
299// cs    Khmer consonant shifter
300//
301// rb    Khmer robat
302//
303// co    coeng character (u17D2)
304//
305// dv    dependent vowel (including split vowels, they are treated in the same way).
306//       even if dv is not defined above, the component that is really tested for is
307//       KhmerClassTable::CC_DEPENDENT_VOWEL, which is common to all dependent vowels
308//
309// zwj   Zero Width joiner
310//
311// zwnj  Zero width non joiner
312//
313// sa    above sign
314//
315// sp    post sign
316//
317// there are lines with equal content but for an easier understanding
318// (and maybe change in the future) we did not join them
319//
320static const le_int8 khmerStateTable[][KhmerClassTable::CC_COUNT] =
321{
322
323//   xx  c1  c2  c3 zwnj cs  rb  co  dv  sa  sp zwj
324    { 1,  2,  2,  2,  1,  1,  1,  6,  1,  1,  1,  2}, //  0 - ground state
325    {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1}, //  1 - exit state (or sign to the right of the syllable)
326    {-1, -1, -1, -1,  3,  4,  5,  6, 16, 17,  1, -1}, //  2 - Base consonant
327    {-1, -1, -1, -1, -1,  4, -1, -1, 16, -1, -1, -1}, //  3 - First ZWNJ before a register shifter
328                                                      //      It can only be followed by a shifter or a vowel
329    {-1, -1, -1, -1, 15, -1, -1,  6, 16, 17,  1, 14}, //  4 - First register shifter
330    {-1, -1, -1, -1, -1, -1, -1, -1, 20, -1,  1, -1}, //  5 - Robat
331    {-1,  7,  8,  9, -1, -1, -1, -1, -1, -1, -1, -1}, //  6 - First Coeng
332    {-1, -1, -1, -1, 12, 13, -1, 10, 16, 17,  1, 14}, //  7 - First consonant of type 1 after coeng
333    {-1, -1, -1, -1, 12, 13, -1, -1, 16, 17,  1, 14}, //  8 - First consonant of type 2 after coeng
334    {-1, -1, -1, -1, 12, 13, -1, 10, 16, 17,  1, 14}, //  9 - First consonant or type 3 after ceong
335    {-1, 11, 11, 11, -1, -1, -1, -1, -1, -1, -1, -1}, // 10 - Second Coeng (no register shifter before)
336    {-1, -1, -1, -1, 15, -1, -1, -1, 16, 17,  1, 14}, // 11 - Second coeng consonant (or ind. vowel) no register shifter before
337    {-1, -1, -1, -1, -1, 13, -1, -1, 16, -1, -1, -1}, // 12 - Second ZWNJ before a register shifter
338    {-1, -1, -1, -1, 15, -1, -1, -1, 16, 17,  1, 14}, // 13 - Second register shifter
339    {-1, -1, -1, -1, -1, -1, -1, -1, 16, -1, -1, -1}, // 14 - ZWJ before vowel
340    {-1, -1, -1, -1, -1, -1, -1, -1, 16, -1, -1, -1}, // 15 - ZWNJ before vowel
341    {-1, -1, -1, -1, -1, -1, -1, -1, -1, 17,  1, 18}, // 16 - dependent vowel
342    {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  1, 18}, // 17 - sign above
343    {-1, -1, -1, -1, -1, -1, -1, 19, -1, -1, -1, -1}, // 18 - ZWJ after vowel
344    {-1,  1, -1,  1, -1, -1, -1, -1, -1, -1, -1, -1}, // 19 - Third coeng
345    {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  1, -1}, // 20 - dependent vowel after a Robat
346
347};
348
349
350const FeatureMap *KhmerReordering::getFeatureMap(le_int32 &count)
351{
352    count = featureMapCount;
353
354    return featureMap;
355}
356
357
358// Given an input string of characters and a location in which to start looking
359// calculate, using the state table, which one is the last character of the syllable
360// that starts in the starting position.
361le_int32 KhmerReordering::findSyllable(const KhmerClassTable *classTable, const LEUnicode *chars, le_int32 prev, le_int32 charCount)
362{
363    le_int32 cursor = prev;
364    le_int8 state = 0;
365
366    while (cursor < charCount) {
367        KhmerClassTable::CharClass charClass = (classTable->getCharClass(chars[cursor]) & KhmerClassTable::CF_CLASS_MASK);
368
369        state = khmerStateTable[state][charClass];
370
371        if (state < 0) {
372            break;
373        }
374
375        cursor += 1;
376    }
377
378    return cursor;
379}
380
381
382// This is the real reordering function as applied to the Khmer language
383
384le_int32 KhmerReordering::reorder(const LEUnicode *chars, le_int32 charCount, le_int32 /*scriptCode*/,
385                                  LEUnicode *outChars, LEGlyphStorage &glyphStorage)
386{
387    const KhmerClassTable *classTable = KhmerClassTable::getKhmerClassTable();
388
389    KhmerReorderingOutput output(outChars, glyphStorage);
390    KhmerClassTable::CharClass charClass;
391    le_int32 i, prev = 0, coengRo;
392
393
394    // This loop only exits when we reach the end of a run, which may contain
395    // several syllables.
396    while (prev < charCount) {
397        le_int32 syllable = findSyllable(classTable, chars, prev, charCount);
398
399        output.reset();
400
401        // write a pre vowel or the pre part of a split vowel first
402        // and look out for coeng + ro. RO is the only vowel of type 2, and
403        // therefore the only one that requires saving space before the base.
404        coengRo = -1;  // There is no Coeng Ro, if found this value will change
405        for (i = prev; i < syllable; i += 1) {
406            charClass = classTable->getCharClass(chars[i]);
407
408            // if a split vowel, write the pre part. In Khmer the pre part
409            // is the same for all split vowels, same glyph as pre vowel C_VOWEL_E
410            if (charClass & KhmerClassTable::CF_SPLIT_VOWEL) {
411                output.writeChar(C_VOWEL_E, i, tagPref);
412                break; // there can be only one vowel
413            }
414
415            // if a vowel with pos before write it out
416            if (charClass & KhmerClassTable::CF_POS_BEFORE) {
417                output.writeChar(chars[i], i, tagPref);
418                break; // there can be only one vowel
419            }
420
421            // look for coeng + ro and remember position
422            // works because coeng + ro is always in front of a vowel (if there is a vowel)
423            // and because CC_CONSONANT2 is enough to identify it, as it is the only consonant
424            // with this flag
425            if ( (charClass & KhmerClassTable::CF_COENG) && (i + 1 < syllable) &&
426                 ( (classTable->getCharClass(chars[i + 1]) & KhmerClassTable::CF_CLASS_MASK) == KhmerClassTable::CC_CONSONANT2) )
427            {
428                    coengRo = i;
429            }
430        }
431
432        // write coeng + ro if found
433        if (coengRo > -1) {
434            output.writeChar(C_COENG, coengRo, tagPref);
435            output.writeChar(C_RO, coengRo + 1, tagPref);
436        }
437
438        // shall we add a dotted circle?
439        // If in the position in which the base should be (first char in the string) there is
440        // a character that has the Dotted circle flag (a character that cannot be a base)
441        // then write a dotted circle
442        if (classTable->getCharClass(chars[prev]) & KhmerClassTable::CF_DOTTED_CIRCLE) {
443            output.writeChar(C_DOTTED_CIRCLE, prev, tagDefault);
444        }
445
446        // copy what is left to the output, skipping before vowels and coeng Ro if they are present
447        for (i = prev; i < syllable; i += 1) {
448            charClass = classTable->getCharClass(chars[i]);
449
450            // skip a before vowel, it was already processed
451            if (charClass & KhmerClassTable::CF_POS_BEFORE) {
452                continue;
453            }
454
455            // skip coeng + ro, it was already processed
456            if (i == coengRo) {
457                i += 1;
458                continue;
459            }
460
461            switch (charClass & KhmerClassTable::CF_POS_MASK) {
462                case KhmerClassTable::CF_POS_ABOVE :
463                    output.writeChar(chars[i], i, tagAbvf);
464                    break;
465
466                case KhmerClassTable::CF_POS_AFTER :
467                    output.writeChar(chars[i], i, tagPstf);
468                    break;
469
470                case KhmerClassTable::CF_POS_BELOW :
471                    output.writeChar(chars[i], i, tagBlwf);
472                    break;
473
474                default:
475                    // assign the correct flags to a coeng consonant
476                    // Consonants of type 3 are taged as Post forms and those type 1 as below forms
477                    if ( (charClass & KhmerClassTable::CF_COENG) && i + 1 < syllable ) {
478                        if ( (classTable->getCharClass(chars[i + 1]) & KhmerClassTable::CF_CLASS_MASK)
479                              == KhmerClassTable::CC_CONSONANT3) {
480                            output.writeChar(chars[i], i, tagPstf);
481                            i += 1;
482                            output.writeChar(chars[i], i, tagPstf);
483                        }
484                        else {
485                            output.writeChar(chars[i], i, tagBlwf);
486                            i += 1;
487                            output.writeChar(chars[i], i, tagBlwf);
488                        }
489                        break;
490                    }
491                    // if a shifter is followed by an above vowel change the shifter to below form,
492                    // an above vowel can have two possible positions i + 1 or i + 3
493                    // (position i+1 corresponds to unicode 3, position i+3 to Unicode 4)
494                    // and there is an extra rule for C_VOWEL_AA + C_SIGN_NIKAHIT also for two
495                    // different positions, right after the shifter or after a vowel (Unicode 4)
496                    if ( (charClass & KhmerClassTable::CF_SHIFTER) && (i + 1 < syllable) ) {
497                        if ((classTable->getCharClass(chars[i + 1]) & KhmerClassTable::CF_ABOVE_VOWEL)
498                            || (i + 2 < syllable
499                                && ( (classTable->getCharClass(chars[i + 1]) & KhmerClassTable::CF_CLASS_MASK) == C_VOWEL_AA)
500                                && ( (classTable->getCharClass(chars[i + 2]) & KhmerClassTable::CF_CLASS_MASK) == C_SIGN_NIKAHIT))
501                            || (i + 3 < syllable && (classTable->getCharClass(chars[i + 3]) & KhmerClassTable::CF_ABOVE_VOWEL))
502                            || (i + 4 < syllable
503                                && ( (classTable->getCharClass(chars[i + 3]) & KhmerClassTable::CF_CLASS_MASK) == C_VOWEL_AA)
504                                && ( (classTable->getCharClass(chars[i + 4]) & KhmerClassTable::CF_CLASS_MASK) == C_SIGN_NIKAHIT) ) )
505                        {
506                            output.writeChar(chars[i], i, tagBlwf);
507                            break;
508                        }
509
510                    }
511                    // default - any other characters
512                    output.writeChar(chars[i], i, tagDefault);
513                    break;
514            } // switch
515        } // for
516
517        prev = syllable; // move the pointer to the start of next syllable
518    }
519
520    return output.getOutputIndex();
521}
522
523
524U_NAMESPACE_END
525