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normalizer2impl.cpp (111045B)
      1 // © 2016 and later: Unicode, Inc. and others.
      2 // License & terms of use: http://www.unicode.org/copyright.html
      3 /*
      4 *******************************************************************************
      5 *
      6 *   Copyright (C) 2009-2014, International Business Machines
      7 *   Corporation and others.  All Rights Reserved.
      8 *
      9 *******************************************************************************
     10 *   file name:  normalizer2impl.cpp
     11 *   encoding:   UTF-8
     12 *   tab size:   8 (not used)
     13 *   indentation:4
     14 *
     15 *   created on: 2009nov22
     16 *   created by: Markus W. Scherer
     17 */
     18 
     19 // #define UCPTRIE_DEBUG
     20 
     21 #include "unicode/utypes.h"
     22 
     23 #if !UCONFIG_NO_NORMALIZATION
     24 
     25 #include "unicode/bytestream.h"
     26 #include "unicode/edits.h"
     27 #include "unicode/normalizer2.h"
     28 #include "unicode/stringoptions.h"
     29 #include "unicode/ucptrie.h"
     30 #include "unicode/udata.h"
     31 #include "unicode/umutablecptrie.h"
     32 #include "unicode/ustring.h"
     33 #include "unicode/utf16.h"
     34 #include "unicode/utf8.h"
     35 #include "bytesinkutil.h"
     36 #include "cmemory.h"
     37 #include "mutex.h"
     38 #include "normalizer2impl.h"
     39 #include "putilimp.h"
     40 #include "uassert.h"
     41 #include "ucptrie_impl.h"
     42 #include "uset_imp.h"
     43 #include "uvector.h"
     44 
     45 U_NAMESPACE_BEGIN
     46 
     47 namespace {
     48 
     49 /**
     50 * UTF-8 lead byte for minNoMaybeCP.
     51 * Can be lower than the actual lead byte for c.
     52 * Typically U+0300 for NFC/NFD, U+00A0 for NFKC/NFKD, U+0041 for NFKC_Casefold.
     53 */
     54 inline uint8_t leadByteForCP(UChar32 c) {
     55    if (c <= 0x7f) {
     56        return static_cast<uint8_t>(c);
     57    } else if (c <= 0x7ff) {
     58        return static_cast<uint8_t>(0xc0 + (c >> 6));
     59    } else {
     60        // Should not occur because ccc(U+0300)!=0.
     61        return 0xe0;
     62    }
     63 }
     64 
     65 /**
     66 * Returns the code point from one single well-formed UTF-8 byte sequence
     67 * between cpStart and cpLimit.
     68 *
     69 * Trie UTF-8 macros do not assemble whole code points (for efficiency).
     70 * When we do need the code point, we call this function.
     71 * We should not need it for normalization-inert data (norm16==0).
     72 * Illegal sequences yield the error value norm16==0 just like real normalization-inert code points.
     73 */
     74 UChar32 codePointFromValidUTF8(const uint8_t *cpStart, const uint8_t *cpLimit) {
     75    // Similar to U8_NEXT_UNSAFE(s, i, c).
     76    U_ASSERT(cpStart < cpLimit);
     77    uint8_t c = *cpStart;
     78    switch(cpLimit-cpStart) {
     79    case 1:
     80        return c;
     81    case 2:
     82        return ((c&0x1f)<<6) | (cpStart[1]&0x3f);
     83    case 3:
     84        // no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (char16_t)
     85        return static_cast<char16_t>((c << 12) | ((cpStart[1] & 0x3f) << 6) | (cpStart[2] & 0x3f));
     86    case 4:
     87        return ((c&7)<<18) | ((cpStart[1]&0x3f)<<12) | ((cpStart[2]&0x3f)<<6) | (cpStart[3]&0x3f);
     88    default:
     89        UPRV_UNREACHABLE_EXIT;  // Should not occur.
     90    }
     91 }
     92 
     93 /**
     94 * Returns the last code point in [start, p[ if it is valid and in U+1000..U+D7FF.
     95 * Otherwise returns a negative value.
     96 */
     97 UChar32 previousHangulOrJamo(const uint8_t *start, const uint8_t *p) {
     98    if ((p - start) >= 3) {
     99        p -= 3;
    100        uint8_t l = *p;
    101        uint8_t t1, t2;
    102        if (0xe1 <= l && l <= 0xed &&
    103                (t1 = static_cast<uint8_t>(p[1] - 0x80)) <= 0x3f &&
    104                (t2 = static_cast<uint8_t>(p[2] - 0x80)) <= 0x3f &&
    105                (l < 0xed || t1 <= 0x1f)) {
    106            return ((l & 0xf) << 12) | (t1 << 6) | t2;
    107        }
    108    }
    109    return U_SENTINEL;
    110 }
    111 
    112 /**
    113 * Returns the offset from the Jamo T base if [src, limit[ starts with a single Jamo T code point.
    114 * Otherwise returns a negative value.
    115 */
    116 int32_t getJamoTMinusBase(const uint8_t *src, const uint8_t *limit) {
    117    // Jamo T: E1 86 A8..E1 87 82
    118    if ((limit - src) >= 3 && *src == 0xe1) {
    119        if (src[1] == 0x86) {
    120            uint8_t t = src[2];
    121            // The first Jamo T is U+11A8 but JAMO_T_BASE is 11A7.
    122            // Offset 0 does not correspond to any conjoining Jamo.
    123            if (0xa8 <= t && t <= 0xbf) {
    124                return t - 0xa7;
    125            }
    126        } else if (src[1] == 0x87) {
    127            uint8_t t = src[2];
    128            if (static_cast<int8_t>(t) <= static_cast<int8_t>(0x82u)) {
    129                return t - (0xa7 - 0x40);
    130            }
    131        }
    132    }
    133    return -1;
    134 }
    135 
    136 void
    137 appendCodePointDelta(const uint8_t *cpStart, const uint8_t *cpLimit, int32_t delta,
    138                     ByteSink &sink, Edits *edits) {
    139    char buffer[U8_MAX_LENGTH];
    140    int32_t length;
    141    int32_t cpLength = static_cast<int32_t>(cpLimit - cpStart);
    142    if (cpLength == 1) {
    143        // The builder makes ASCII map to ASCII.
    144        buffer[0] = static_cast<uint8_t>(*cpStart + delta);
    145        length = 1;
    146    } else {
    147        int32_t trail = *(cpLimit-1) + delta;
    148        if (0x80 <= trail && trail <= 0xbf) {
    149            // The delta only changes the last trail byte.
    150            --cpLimit;
    151            length = 0;
    152            do { buffer[length++] = *cpStart++; } while (cpStart < cpLimit);
    153            buffer[length++] = static_cast<uint8_t>(trail);
    154        } else {
    155            // Decode the code point, add the delta, re-encode.
    156            UChar32 c = codePointFromValidUTF8(cpStart, cpLimit) + delta;
    157            length = 0;
    158            U8_APPEND_UNSAFE(buffer, length, c);
    159        }
    160    }
    161    if (edits != nullptr) {
    162        edits->addReplace(cpLength, length);
    163    }
    164    sink.Append(buffer, length);
    165 }
    166 
    167 }  // namespace
    168 
    169 // ReorderingBuffer -------------------------------------------------------- ***
    170 
    171 ReorderingBuffer::ReorderingBuffer(const Normalizer2Impl &ni, UnicodeString &dest,
    172                                   UErrorCode &errorCode) :
    173        impl(ni), str(dest),
    174        start(str.getBuffer(8)), reorderStart(start), limit(start),
    175        remainingCapacity(str.getCapacity()), lastCC(0) {
    176    if (start == nullptr && U_SUCCESS(errorCode)) {
    177        // getBuffer() already did str.setToBogus()
    178        errorCode = U_MEMORY_ALLOCATION_ERROR;
    179    }
    180 }
    181 
    182 UBool ReorderingBuffer::init(int32_t destCapacity, UErrorCode &errorCode) {
    183    int32_t length=str.length();
    184    start=str.getBuffer(destCapacity);
    185    if(start==nullptr) {
    186        // getBuffer() already did str.setToBogus()
    187        errorCode=U_MEMORY_ALLOCATION_ERROR;
    188        return false;
    189    }
    190    limit=start+length;
    191    remainingCapacity=str.getCapacity()-length;
    192    reorderStart=start;
    193    if(start==limit) {
    194        lastCC=0;
    195    } else {
    196        setIterator();
    197        lastCC=previousCC();
    198        // Set reorderStart after the last code point with cc<=1 if there is one.
    199        if(lastCC>1) {
    200            while(previousCC()>1) {}
    201        }
    202        reorderStart=codePointLimit;
    203    }
    204    return true;
    205 }
    206 
    207 UBool ReorderingBuffer::equals(const char16_t *otherStart, const char16_t *otherLimit) const {
    208    int32_t length = static_cast<int32_t>(limit - start);
    209    return
    210        length == static_cast<int32_t>(otherLimit - otherStart) &&
    211        0==u_memcmp(start, otherStart, length);
    212 }
    213 
    214 UBool ReorderingBuffer::equals(const uint8_t *otherStart, const uint8_t *otherLimit) const {
    215    U_ASSERT((otherLimit - otherStart) <= INT32_MAX);  // ensured by caller
    216    int32_t length = static_cast<int32_t>(limit - start);
    217    int32_t otherLength = static_cast<int32_t>(otherLimit - otherStart);
    218    // For equal strings, UTF-8 is at least as long as UTF-16, and at most three times as long.
    219    if (otherLength < length || (otherLength / 3) > length) {
    220        return false;
    221    }
    222    // Compare valid strings from between normalization boundaries.
    223    // (Invalid sequences are normalization-inert.)
    224    for (int32_t i = 0, j = 0;;) {
    225        if (i >= length) {
    226            return j >= otherLength;
    227        } else if (j >= otherLength) {
    228            return false;
    229        }
    230        // Not at the end of either string yet.
    231        UChar32 c, other;
    232        U16_NEXT_UNSAFE(start, i, c);
    233        U8_NEXT_UNSAFE(otherStart, j, other);
    234        if (c != other) {
    235            return false;
    236        }
    237    }
    238 }
    239 
    240 UBool ReorderingBuffer::appendSupplementary(UChar32 c, uint8_t cc, UErrorCode &errorCode) {
    241    if(remainingCapacity<2 && !resize(2, errorCode)) {
    242        return false;
    243    }
    244    if(lastCC<=cc || cc==0) {
    245        limit[0]=U16_LEAD(c);
    246        limit[1]=U16_TRAIL(c);
    247        limit+=2;
    248        lastCC=cc;
    249        if(cc<=1) {
    250            reorderStart=limit;
    251        }
    252    } else {
    253        insert(c, cc);
    254    }
    255    remainingCapacity-=2;
    256    return true;
    257 }
    258 
    259 UBool ReorderingBuffer::append(const char16_t *s, int32_t length, UBool isNFD,
    260                               uint8_t leadCC, uint8_t trailCC,
    261                               UErrorCode &errorCode) {
    262    if(length==0) {
    263        return true;
    264    }
    265    if(remainingCapacity<length && !resize(length, errorCode)) {
    266        return false;
    267    }
    268    remainingCapacity-=length;
    269    if(lastCC<=leadCC || leadCC==0) {
    270        if(trailCC<=1) {
    271            reorderStart=limit+length;
    272        } else if(leadCC<=1) {
    273            reorderStart=limit+1;  // Ok if not a code point boundary.
    274        }
    275        const char16_t *sLimit=s+length;
    276        do { *limit++=*s++; } while(s!=sLimit);
    277        lastCC=trailCC;
    278    } else {
    279        int32_t i=0;
    280        UChar32 c;
    281        U16_NEXT(s, i, length, c);
    282        insert(c, leadCC);  // insert first code point
    283        while(i<length) {
    284            U16_NEXT(s, i, length, c);
    285            if(i<length) {
    286                if (isNFD) {
    287                    leadCC = Normalizer2Impl::getCCFromYesOrMaybeYes(impl.getRawNorm16(c));
    288                } else {
    289                    leadCC = impl.getCC(impl.getNorm16(c));
    290                }
    291            } else {
    292                leadCC=trailCC;
    293            }
    294            append(c, leadCC, errorCode);
    295        }
    296    }
    297    return true;
    298 }
    299 
    300 UBool ReorderingBuffer::appendZeroCC(UChar32 c, UErrorCode &errorCode) {
    301    int32_t cpLength=U16_LENGTH(c);
    302    if(remainingCapacity<cpLength && !resize(cpLength, errorCode)) {
    303        return false;
    304    }
    305    remainingCapacity-=cpLength;
    306    if(cpLength==1) {
    307        *limit++ = static_cast<char16_t>(c);
    308    } else {
    309        limit[0]=U16_LEAD(c);
    310        limit[1]=U16_TRAIL(c);
    311        limit+=2;
    312    }
    313    lastCC=0;
    314    reorderStart=limit;
    315    return true;
    316 }
    317 
    318 UBool ReorderingBuffer::appendZeroCC(const char16_t *s, const char16_t *sLimit, UErrorCode &errorCode) {
    319    if(s==sLimit) {
    320        return true;
    321    }
    322    int32_t length = static_cast<int32_t>(sLimit - s);
    323    if(remainingCapacity<length && !resize(length, errorCode)) {
    324        return false;
    325    }
    326    u_memcpy(limit, s, length);
    327    limit+=length;
    328    remainingCapacity-=length;
    329    lastCC=0;
    330    reorderStart=limit;
    331    return true;
    332 }
    333 
    334 void ReorderingBuffer::remove() {
    335    reorderStart=limit=start;
    336    remainingCapacity=str.getCapacity();
    337    lastCC=0;
    338 }
    339 
    340 void ReorderingBuffer::removeSuffix(int32_t suffixLength) {
    341    if(suffixLength<(limit-start)) {
    342        limit-=suffixLength;
    343        remainingCapacity+=suffixLength;
    344    } else {
    345        limit=start;
    346        remainingCapacity=str.getCapacity();
    347    }
    348    lastCC=0;
    349    reorderStart=limit;
    350 }
    351 
    352 UBool ReorderingBuffer::resize(int32_t appendLength, UErrorCode &errorCode) {
    353    int32_t reorderStartIndex = static_cast<int32_t>(reorderStart - start);
    354    int32_t length = static_cast<int32_t>(limit - start);
    355    str.releaseBuffer(length);
    356    int32_t newCapacity=length+appendLength;
    357    int32_t doubleCapacity=2*str.getCapacity();
    358    if(newCapacity<doubleCapacity) {
    359        newCapacity=doubleCapacity;
    360    }
    361    if(newCapacity<256) {
    362        newCapacity=256;
    363    }
    364    start=str.getBuffer(newCapacity);
    365    if(start==nullptr) {
    366        // getBuffer() already did str.setToBogus()
    367        errorCode=U_MEMORY_ALLOCATION_ERROR;
    368        return false;
    369    }
    370    reorderStart=start+reorderStartIndex;
    371    limit=start+length;
    372    remainingCapacity=str.getCapacity()-length;
    373    return true;
    374 }
    375 
    376 void ReorderingBuffer::skipPrevious() {
    377    codePointLimit=codePointStart;
    378    char16_t c=*--codePointStart;
    379    if(U16_IS_TRAIL(c) && start<codePointStart && U16_IS_LEAD(*(codePointStart-1))) {
    380        --codePointStart;
    381    }
    382 }
    383 
    384 uint8_t ReorderingBuffer::previousCC() {
    385    codePointLimit=codePointStart;
    386    if(reorderStart>=codePointStart) {
    387        return 0;
    388    }
    389    UChar32 c=*--codePointStart;
    390    char16_t c2;
    391    if(U16_IS_TRAIL(c) && start<codePointStart && U16_IS_LEAD(c2=*(codePointStart-1))) {
    392        --codePointStart;
    393        c=U16_GET_SUPPLEMENTARY(c2, c);
    394    }
    395    return impl.getCCFromYesOrMaybeYesCP(c);
    396 }
    397 
    398 // Inserts c somewhere before the last character.
    399 // Requires 0<cc<lastCC which implies reorderStart<limit.
    400 void ReorderingBuffer::insert(UChar32 c, uint8_t cc) {
    401    for(setIterator(), skipPrevious(); previousCC()>cc;) {}
    402    // insert c at codePointLimit, after the character with prevCC<=cc
    403    char16_t *q=limit;
    404    char16_t *r=limit+=U16_LENGTH(c);
    405    do {
    406        *--r=*--q;
    407    } while(codePointLimit!=q);
    408    writeCodePoint(q, c);
    409    if(cc<=1) {
    410        reorderStart=r;
    411    }
    412 }
    413 
    414 // Normalizer2Impl --------------------------------------------------------- ***
    415 
    416 struct CanonIterData : public UMemory {
    417    CanonIterData(UErrorCode &errorCode);
    418    ~CanonIterData();
    419    void addToStartSet(UChar32 origin, UChar32 decompLead, UErrorCode &errorCode);
    420    UMutableCPTrie *mutableTrie;
    421    UCPTrie *trie;
    422    UVector canonStartSets;  // contains UnicodeSet *
    423 };
    424 
    425 Normalizer2Impl::~Normalizer2Impl() {
    426    delete fCanonIterData;
    427 }
    428 
    429 void
    430 Normalizer2Impl::init(const int32_t *inIndexes, const UCPTrie *inTrie,
    431                      const uint16_t *inExtraData, const uint8_t *inSmallFCD) {
    432    minDecompNoCP = static_cast<char16_t>(inIndexes[IX_MIN_DECOMP_NO_CP]);
    433    minCompNoMaybeCP = static_cast<char16_t>(inIndexes[IX_MIN_COMP_NO_MAYBE_CP]);
    434    minLcccCP = static_cast<char16_t>(inIndexes[IX_MIN_LCCC_CP]);
    435 
    436    minYesNo = static_cast<uint16_t>(inIndexes[IX_MIN_YES_NO]);
    437    minYesNoMappingsOnly = static_cast<uint16_t>(inIndexes[IX_MIN_YES_NO_MAPPINGS_ONLY]);
    438    minNoNo = static_cast<uint16_t>(inIndexes[IX_MIN_NO_NO]);
    439    minNoNoCompBoundaryBefore = static_cast<uint16_t>(inIndexes[IX_MIN_NO_NO_COMP_BOUNDARY_BEFORE]);
    440    minNoNoCompNoMaybeCC = static_cast<uint16_t>(inIndexes[IX_MIN_NO_NO_COMP_NO_MAYBE_CC]);
    441    minNoNoEmpty = static_cast<uint16_t>(inIndexes[IX_MIN_NO_NO_EMPTY]);
    442    limitNoNo = static_cast<uint16_t>(inIndexes[IX_LIMIT_NO_NO]);
    443    minMaybeNo = static_cast<uint16_t>(inIndexes[IX_MIN_MAYBE_NO]);
    444    minMaybeNoCombinesFwd = static_cast<uint16_t>(inIndexes[IX_MIN_MAYBE_NO_COMBINES_FWD]);
    445    minMaybeYes = static_cast<uint16_t>(inIndexes[IX_MIN_MAYBE_YES]);
    446    U_ASSERT((minMaybeNo & 7) == 0);  // 8-aligned for noNoDelta bit fields
    447    centerNoNoDelta = (minMaybeNo >> DELTA_SHIFT) - MAX_DELTA - 1;
    448 
    449    normTrie=inTrie;
    450    extraData=inExtraData;
    451    smallFCD=inSmallFCD;
    452 }
    453 
    454 U_CDECL_BEGIN
    455 
    456 static uint32_t U_CALLCONV
    457 segmentStarterMapper(const void * /*context*/, uint32_t value) {
    458    return value&CANON_NOT_SEGMENT_STARTER;
    459 }
    460 
    461 U_CDECL_END
    462 
    463 void
    464 Normalizer2Impl::addLcccChars(UnicodeSet &set) const {
    465    UChar32 start = 0, end;
    466    uint32_t norm16;
    467    while ((end = ucptrie_getRange(normTrie, start, UCPMAP_RANGE_FIXED_LEAD_SURROGATES, INERT,
    468                                   nullptr, nullptr, &norm16)) >= 0) {
    469        if (norm16 > Normalizer2Impl::MIN_NORMAL_MAYBE_YES &&
    470                norm16 != Normalizer2Impl::JAMO_VT) {
    471            set.add(start, end);
    472        } else if (minNoNoCompNoMaybeCC <= norm16 && norm16 < limitNoNo) {
    473            uint16_t fcd16 = getFCD16(start);
    474            if (fcd16 > 0xff) { set.add(start, end); }
    475        }
    476        start = end + 1;
    477    }
    478 }
    479 
    480 void
    481 Normalizer2Impl::addPropertyStarts(const USetAdder *sa, UErrorCode & /*errorCode*/) const {
    482    // Add the start code point of each same-value range of the trie.
    483    UChar32 start = 0, end;
    484    uint32_t value;
    485    while ((end = ucptrie_getRange(normTrie, start, UCPMAP_RANGE_FIXED_LEAD_SURROGATES, INERT,
    486                                   nullptr, nullptr, &value)) >= 0) {
    487        sa->add(sa->set, start);
    488        if (start != end && isAlgorithmicNoNo(static_cast<uint16_t>(value)) &&
    489                (value & Normalizer2Impl::DELTA_TCCC_MASK) > Normalizer2Impl::DELTA_TCCC_1) {
    490            // Range of code points with same-norm16-value algorithmic decompositions.
    491            // They might have different non-zero FCD16 values.
    492            uint16_t prevFCD16 = getFCD16(start);
    493            while (++start <= end) {
    494                uint16_t fcd16 = getFCD16(start);
    495                if (fcd16 != prevFCD16) {
    496                    sa->add(sa->set, start);
    497                    prevFCD16 = fcd16;
    498                }
    499            }
    500        }
    501        start = end + 1;
    502    }
    503 
    504    /* add Hangul LV syllables and LV+1 because of skippables */
    505    for(char16_t c=Hangul::HANGUL_BASE; c<Hangul::HANGUL_LIMIT; c+=Hangul::JAMO_T_COUNT) {
    506        sa->add(sa->set, c);
    507        sa->add(sa->set, c+1);
    508    }
    509    sa->add(sa->set, Hangul::HANGUL_LIMIT); /* add Hangul+1 to continue with other properties */
    510 }
    511 
    512 void
    513 Normalizer2Impl::addCanonIterPropertyStarts(const USetAdder *sa, UErrorCode &errorCode) const {
    514    // Add the start code point of each same-value range of the canonical iterator data trie.
    515    if (!ensureCanonIterData(errorCode)) { return; }
    516    // Currently only used for the SEGMENT_STARTER property.
    517    UChar32 start = 0, end;
    518    uint32_t value;
    519    while ((end = ucptrie_getRange(fCanonIterData->trie, start, UCPMAP_RANGE_NORMAL, 0,
    520                                   segmentStarterMapper, nullptr, &value)) >= 0) {
    521        sa->add(sa->set, start);
    522        start = end + 1;
    523    }
    524 }
    525 
    526 const char16_t *
    527 Normalizer2Impl::copyLowPrefixFromNulTerminated(const char16_t *src,
    528                                                UChar32 minNeedDataCP,
    529                                                ReorderingBuffer *buffer,
    530                                                UErrorCode &errorCode) const {
    531    // Make some effort to support NUL-terminated strings reasonably.
    532    // Take the part of the fast quick check loop that does not look up
    533    // data and check the first part of the string.
    534    // After this prefix, determine the string length to simplify the rest
    535    // of the code.
    536    const char16_t *prevSrc=src;
    537    char16_t c;
    538    while((c=*src++)<minNeedDataCP && c!=0) {}
    539    // Back out the last character for full processing.
    540    // Copy this prefix.
    541    if(--src!=prevSrc) {
    542        if(buffer!=nullptr) {
    543            buffer->appendZeroCC(prevSrc, src, errorCode);
    544        }
    545    }
    546    return src;
    547 }
    548 
    549 UnicodeString &
    550 Normalizer2Impl::decompose(const UnicodeString &src, UnicodeString &dest,
    551                           UErrorCode &errorCode) const {
    552    if(U_FAILURE(errorCode)) {
    553        dest.setToBogus();
    554        return dest;
    555    }
    556    const char16_t *sArray=src.getBuffer();
    557    if(&dest==&src || sArray==nullptr) {
    558        errorCode=U_ILLEGAL_ARGUMENT_ERROR;
    559        dest.setToBogus();
    560        return dest;
    561    }
    562    decompose(sArray, sArray+src.length(), dest, src.length(), errorCode);
    563    return dest;
    564 }
    565 
    566 void
    567 Normalizer2Impl::decompose(const char16_t *src, const char16_t *limit,
    568                           UnicodeString &dest,
    569                           int32_t destLengthEstimate,
    570                           UErrorCode &errorCode) const {
    571    if(destLengthEstimate<0 && limit!=nullptr) {
    572        destLengthEstimate = static_cast<int32_t>(limit - src);
    573    }
    574    dest.remove();
    575    ReorderingBuffer buffer(*this, dest);
    576    if(buffer.init(destLengthEstimate, errorCode)) {
    577        decompose(src, limit, &buffer, errorCode);
    578    }
    579 }
    580 
    581 // Dual functionality:
    582 // buffer!=nullptr: normalize
    583 // buffer==nullptr: isNormalized/spanQuickCheckYes
    584 const char16_t *
    585 Normalizer2Impl::decompose(const char16_t *src, const char16_t *limit,
    586                           ReorderingBuffer *buffer,
    587                           UErrorCode &errorCode) const {
    588    UChar32 minNoCP=minDecompNoCP;
    589    if(limit==nullptr) {
    590        src=copyLowPrefixFromNulTerminated(src, minNoCP, buffer, errorCode);
    591        if(U_FAILURE(errorCode)) {
    592            return src;
    593        }
    594        limit=u_strchr(src, 0);
    595    }
    596 
    597    const char16_t *prevSrc;
    598    UChar32 c=0;
    599    uint16_t norm16=0;
    600 
    601    // only for quick check
    602    const char16_t *prevBoundary=src;
    603    uint8_t prevCC=0;
    604 
    605    for(;;) {
    606        // count code units below the minimum or with irrelevant data for the quick check
    607        for(prevSrc=src; src!=limit;) {
    608            if( (c=*src)<minNoCP ||
    609                isMostDecompYesAndZeroCC(norm16=UCPTRIE_FAST_BMP_GET(normTrie, UCPTRIE_16, c))
    610            ) {
    611                ++src;
    612            } else if(!U16_IS_LEAD(c)) {
    613                break;
    614            } else {
    615                char16_t c2;
    616                if((src+1)!=limit && U16_IS_TRAIL(c2=src[1])) {
    617                    c=U16_GET_SUPPLEMENTARY(c, c2);
    618                    norm16=UCPTRIE_FAST_SUPP_GET(normTrie, UCPTRIE_16, c);
    619                    if(isMostDecompYesAndZeroCC(norm16)) {
    620                        src+=2;
    621                    } else {
    622                        break;
    623                    }
    624                } else {
    625                    ++src;  // unpaired lead surrogate: inert
    626                }
    627            }
    628        }
    629        // copy these code units all at once
    630        if(src!=prevSrc) {
    631            if(buffer!=nullptr) {
    632                if(!buffer->appendZeroCC(prevSrc, src, errorCode)) {
    633                    break;
    634                }
    635            } else {
    636                prevCC=0;
    637                prevBoundary=src;
    638            }
    639        }
    640        if(src==limit) {
    641            break;
    642        }
    643 
    644        // Check one above-minimum, relevant code point.
    645        src+=U16_LENGTH(c);
    646        if(buffer!=nullptr) {
    647            if(!decompose(c, norm16, *buffer, errorCode)) {
    648                break;
    649            }
    650        } else {
    651            if(isDecompYes(norm16)) {
    652                uint8_t cc=getCCFromYesOrMaybeYes(norm16);
    653                if(prevCC<=cc || cc==0) {
    654                    prevCC=cc;
    655                    if(cc<=1) {
    656                        prevBoundary=src;
    657                    }
    658                    continue;
    659                }
    660            }
    661            return prevBoundary;  // "no" or cc out of order
    662        }
    663    }
    664    return src;
    665 }
    666 
    667 // Decompose a short piece of text which is likely to contain characters that
    668 // fail the quick check loop and/or where the quick check loop's overhead
    669 // is unlikely to be amortized.
    670 // Called by the compose() and makeFCD() implementations.
    671 const char16_t *
    672 Normalizer2Impl::decomposeShort(const char16_t *src, const char16_t *limit,
    673                                UBool stopAtCompBoundary, UBool onlyContiguous,
    674                                ReorderingBuffer &buffer, UErrorCode &errorCode) const {
    675    if (U_FAILURE(errorCode)) {
    676        return nullptr;
    677    }
    678    while(src<limit) {
    679        if (stopAtCompBoundary && *src < minCompNoMaybeCP) {
    680            return src;
    681        }
    682        const char16_t *prevSrc = src;
    683        UChar32 c;
    684        uint16_t norm16;
    685        UCPTRIE_FAST_U16_NEXT(normTrie, UCPTRIE_16, src, limit, c, norm16);
    686        if (stopAtCompBoundary && norm16HasCompBoundaryBefore(norm16)) {
    687            return prevSrc;
    688        }
    689        if(!decompose(c, norm16, buffer, errorCode)) {
    690            return nullptr;
    691        }
    692        if (stopAtCompBoundary && norm16HasCompBoundaryAfter(norm16, onlyContiguous)) {
    693            return src;
    694        }
    695    }
    696    return src;
    697 }
    698 
    699 UBool Normalizer2Impl::decompose(UChar32 c, uint16_t norm16,
    700                                 ReorderingBuffer &buffer,
    701                                 UErrorCode &errorCode) const {
    702    // get the decomposition and the lead and trail cc's
    703    if (norm16 >= limitNoNo) {
    704        if (isMaybeYesOrNonZeroCC(norm16)) {
    705            return buffer.append(c, getCCFromYesOrMaybeYes(norm16), errorCode);
    706        } else if (norm16 < minMaybeNo) {
    707            // Maps to an isCompYesAndZeroCC.
    708            c=mapAlgorithmic(c, norm16);
    709            norm16=getRawNorm16(c);
    710        }
    711    }
    712    if (norm16 < minYesNo) {
    713        // c does not decompose
    714        return buffer.append(c, 0, errorCode);
    715    } else if(isHangulLV(norm16) || isHangulLVT(norm16)) {
    716        // Hangul syllable: decompose algorithmically
    717        char16_t jamos[3];
    718        return buffer.appendZeroCC(jamos, jamos+Hangul::decompose(c, jamos), errorCode);
    719    }
    720    // c decomposes, get everything from the variable-length extra data
    721    const uint16_t *mapping=getData(norm16);
    722    uint16_t firstUnit=*mapping;
    723    int32_t length=firstUnit&MAPPING_LENGTH_MASK;
    724    uint8_t leadCC, trailCC;
    725    trailCC = static_cast<uint8_t>(firstUnit >> 8);
    726    if(firstUnit&MAPPING_HAS_CCC_LCCC_WORD) {
    727        leadCC = static_cast<uint8_t>(*(mapping - 1) >> 8);
    728    } else {
    729        leadCC=0;
    730    }
    731    return buffer.append(reinterpret_cast<const char16_t*>(mapping) + 1, length, true, leadCC, trailCC, errorCode);
    732 }
    733 
    734 // Dual functionality:
    735 // sink != nullptr: normalize
    736 // sink == nullptr: isNormalized/spanQuickCheckYes
    737 const uint8_t *
    738 Normalizer2Impl::decomposeUTF8(uint32_t options,
    739                               const uint8_t *src, const uint8_t *limit,
    740                               ByteSink *sink, Edits *edits, UErrorCode &errorCode) const {
    741    U_ASSERT(limit != nullptr);
    742    UnicodeString s16;
    743    uint8_t minNoLead = leadByteForCP(minDecompNoCP);
    744 
    745    const uint8_t *prevBoundary = src;
    746    // only for quick check
    747    uint8_t prevCC = 0;
    748 
    749    for (;;) {
    750        // Fast path: Scan over a sequence of characters below the minimum "no" code point,
    751        // or with (decompYes && ccc==0) properties.
    752        const uint8_t *fastStart = src;
    753        const uint8_t *prevSrc;
    754        uint16_t norm16 = 0;
    755 
    756        for (;;) {
    757            if (src == limit) {
    758                if (prevBoundary != limit && sink != nullptr) {
    759                    ByteSinkUtil::appendUnchanged(prevBoundary, limit,
    760                                                  *sink, options, edits, errorCode);
    761                }
    762                return src;
    763            }
    764            if (*src < minNoLead) {
    765                ++src;
    766            } else {
    767                prevSrc = src;
    768                UCPTRIE_FAST_U8_NEXT(normTrie, UCPTRIE_16, src, limit, norm16);
    769                if (!isMostDecompYesAndZeroCC(norm16)) {
    770                    break;
    771                }
    772            }
    773        }
    774        // isMostDecompYesAndZeroCC(norm16) is false, that is, norm16>=minYesNo,
    775        // and the current character at [prevSrc..src[ is not a common case with cc=0
    776        // (MIN_NORMAL_MAYBE_YES or JAMO_VT).
    777        // It could still be a maybeYes with cc=0.
    778        if (prevSrc != fastStart) {
    779            // The fast path looped over yes/0 characters before the current one.
    780            if (sink != nullptr &&
    781                    !ByteSinkUtil::appendUnchanged(prevBoundary, prevSrc,
    782                                                   *sink, options, edits, errorCode)) {
    783                break;
    784            }
    785            prevBoundary = prevSrc;
    786            prevCC = 0;
    787        }
    788 
    789        // Medium-fast path: Quick check.
    790        if (isMaybeYesOrNonZeroCC(norm16)) {
    791            // Does not decompose.
    792            uint8_t cc = getCCFromYesOrMaybeYes(norm16);
    793            if (prevCC <= cc || cc == 0) {
    794                prevCC = cc;
    795                if (cc <= 1) {
    796                    if (sink != nullptr &&
    797                            !ByteSinkUtil::appendUnchanged(prevBoundary, src,
    798                                                           *sink, options, edits, errorCode)) {
    799                        break;
    800                    }
    801                    prevBoundary = src;
    802                }
    803                continue;
    804            }
    805        }
    806        if (sink == nullptr) {
    807            return prevBoundary;  // quick check: "no" or cc out of order
    808        }
    809 
    810        // Slow path
    811        // Decompose up to and including the current character.
    812        if (prevBoundary != prevSrc && norm16HasDecompBoundaryBefore(norm16)) {
    813            if (!ByteSinkUtil::appendUnchanged(prevBoundary, prevSrc,
    814                                               *sink, options, edits, errorCode)) {
    815                break;
    816            }
    817            prevBoundary = prevSrc;
    818        }
    819        ReorderingBuffer buffer(*this, s16, errorCode);
    820        if (U_FAILURE(errorCode)) {
    821            break;
    822        }
    823        decomposeShort(prevBoundary, src, STOP_AT_LIMIT, false /* onlyContiguous */,
    824                       buffer, errorCode);
    825        // Decompose until the next boundary.
    826        if (buffer.getLastCC() > 1) {
    827            src = decomposeShort(src, limit, STOP_AT_DECOMP_BOUNDARY, false /* onlyContiguous */,
    828                                 buffer, errorCode);
    829        }
    830        if (U_FAILURE(errorCode)) {
    831            break;
    832        }
    833        if ((src - prevSrc) > INT32_MAX) {  // guard before buffer.equals()
    834            errorCode = U_INDEX_OUTOFBOUNDS_ERROR;
    835            break;
    836        }
    837        // We already know there was a change if the original character decomposed;
    838        // otherwise compare.
    839        if (isMaybeYesOrNonZeroCC(norm16) && buffer.equals(prevBoundary, src)) {
    840            if (!ByteSinkUtil::appendUnchanged(prevBoundary, src,
    841                                               *sink, options, edits, errorCode)) {
    842                break;
    843            }
    844        } else {
    845            if (!ByteSinkUtil::appendChange(prevBoundary, src, buffer.getStart(), buffer.length(),
    846                                            *sink, edits, errorCode)) {
    847                break;
    848            }
    849        }
    850        prevBoundary = src;
    851        prevCC = 0;
    852    }
    853    return src;
    854 }
    855 
    856 const uint8_t *
    857 Normalizer2Impl::decomposeShort(const uint8_t *src, const uint8_t *limit,
    858                                StopAt stopAt, UBool onlyContiguous,
    859                                ReorderingBuffer &buffer, UErrorCode &errorCode) const {
    860    if (U_FAILURE(errorCode)) {
    861        return nullptr;
    862    }
    863    while (src < limit) {
    864        const uint8_t *prevSrc = src;
    865        uint16_t norm16;
    866        UCPTRIE_FAST_U8_NEXT(normTrie, UCPTRIE_16, src, limit, norm16);
    867        // Get the decomposition and the lead and trail cc's.
    868        UChar32 c = U_SENTINEL;
    869        if (norm16 >= limitNoNo) {
    870            if (isMaybeYesOrNonZeroCC(norm16)) {
    871                // No comp boundaries around this character.
    872                uint8_t cc = getCCFromYesOrMaybeYes(norm16);
    873                if (cc == 0 && stopAt == STOP_AT_DECOMP_BOUNDARY) {
    874                    return prevSrc;
    875                }
    876                c = codePointFromValidUTF8(prevSrc, src);
    877                if (!buffer.append(c, cc, errorCode)) {
    878                    return nullptr;
    879                }
    880                if (stopAt == STOP_AT_DECOMP_BOUNDARY && buffer.getLastCC() <= 1) {
    881                    return src;
    882                }
    883                continue;
    884            } else if (norm16 < minMaybeNo) {
    885                // Maps to an isCompYesAndZeroCC.
    886                if (stopAt != STOP_AT_LIMIT) {
    887                    return prevSrc;
    888                }
    889                c = codePointFromValidUTF8(prevSrc, src);
    890                c = mapAlgorithmic(c, norm16);
    891                norm16 = getRawNorm16(c);
    892            }
    893        } else if (stopAt != STOP_AT_LIMIT && norm16 < minNoNoCompNoMaybeCC) {
    894            return prevSrc;
    895        }
    896        // norm16!=INERT guarantees that [prevSrc, src[ is valid UTF-8.
    897        // We do not see invalid UTF-8 here because
    898        // its norm16==INERT is normalization-inert,
    899        // so it gets copied unchanged in the fast path,
    900        // and we stop the slow path where invalid UTF-8 begins.
    901        // c >= 0 is the result of an algorithmic mapping.
    902        U_ASSERT(c >= 0 || norm16 != INERT);
    903        if (norm16 < minYesNo) {
    904            if (c < 0) {
    905                c = codePointFromValidUTF8(prevSrc, src);
    906            }
    907            // does not decompose
    908            if (!buffer.append(c, 0, errorCode)) {
    909                return nullptr;
    910            }
    911        } else if (isHangulLV(norm16) || isHangulLVT(norm16)) {
    912            // Hangul syllable: decompose algorithmically
    913            if (c < 0) {
    914                c = codePointFromValidUTF8(prevSrc, src);
    915            }
    916            char16_t jamos[3];
    917            if (!buffer.appendZeroCC(jamos, jamos+Hangul::decompose(c, jamos), errorCode)) {
    918                return nullptr;
    919            }
    920        } else {
    921            // The character decomposes, get everything from the variable-length extra data.
    922            const uint16_t *mapping = getData(norm16);
    923            uint16_t firstUnit = *mapping;
    924            int32_t length = firstUnit & MAPPING_LENGTH_MASK;
    925            uint8_t trailCC = static_cast<uint8_t>(firstUnit >> 8);
    926            uint8_t leadCC;
    927            if (firstUnit & MAPPING_HAS_CCC_LCCC_WORD) {
    928                leadCC = static_cast<uint8_t>(*(mapping - 1) >> 8);
    929            } else {
    930                leadCC = 0;
    931            }
    932            if (leadCC == 0 && stopAt == STOP_AT_DECOMP_BOUNDARY) {
    933                return prevSrc;
    934            }
    935            if (!buffer.append(reinterpret_cast<const char16_t*>(mapping) + 1, length, true, leadCC, trailCC, errorCode)) {
    936                return nullptr;
    937            }
    938        }
    939        if ((stopAt == STOP_AT_COMP_BOUNDARY && norm16HasCompBoundaryAfter(norm16, onlyContiguous)) ||
    940                (stopAt == STOP_AT_DECOMP_BOUNDARY && buffer.getLastCC() <= 1)) {
    941            return src;
    942        }
    943    }
    944    return src;
    945 }
    946 
    947 const char16_t *
    948 Normalizer2Impl::getDecomposition(UChar32 c, char16_t buffer[4], int32_t &length) const {
    949    uint16_t norm16;
    950    if(c<minDecompNoCP || isMaybeYesOrNonZeroCC(norm16=getNorm16(c))) {
    951        // c does not decompose
    952        return nullptr;
    953    }
    954    const char16_t *decomp = nullptr;
    955    if(isDecompNoAlgorithmic(norm16)) {
    956        // Maps to an isCompYesAndZeroCC.
    957        c=mapAlgorithmic(c, norm16);
    958        decomp=buffer;
    959        length=0;
    960        U16_APPEND_UNSAFE(buffer, length, c);
    961        // The mapping might decompose further.
    962        norm16 = getRawNorm16(c);
    963    }
    964    if (norm16 < minYesNo) {
    965        return decomp;
    966    } else if(isHangulLV(norm16) || isHangulLVT(norm16)) {
    967        // Hangul syllable: decompose algorithmically
    968        length=Hangul::decompose(c, buffer);
    969        return buffer;
    970    }
    971    // c decomposes, get everything from the variable-length extra data
    972    const uint16_t *mapping=getData(norm16);
    973    length=*mapping&MAPPING_LENGTH_MASK;
    974    return reinterpret_cast<const char16_t*>(mapping) + 1;
    975 }
    976 
    977 // The capacity of the buffer must be 30=MAPPING_LENGTH_MASK-1
    978 // so that a raw mapping fits that consists of one unit ("rm0")
    979 // plus all but the first two code units of the normal mapping.
    980 // The maximum length of a normal mapping is 31=MAPPING_LENGTH_MASK.
    981 const char16_t *
    982 Normalizer2Impl::getRawDecomposition(UChar32 c, char16_t buffer[30], int32_t &length) const {
    983    uint16_t norm16;
    984    if(c<minDecompNoCP || isDecompYes(norm16=getNorm16(c))) {
    985        // c does not decompose
    986        return nullptr;
    987    } else if(isHangulLV(norm16) || isHangulLVT(norm16)) {
    988        // Hangul syllable: decompose algorithmically
    989        Hangul::getRawDecomposition(c, buffer);
    990        length=2;
    991        return buffer;
    992    } else if(isDecompNoAlgorithmic(norm16)) {
    993        c=mapAlgorithmic(c, norm16);
    994        length=0;
    995        U16_APPEND_UNSAFE(buffer, length, c);
    996        return buffer;
    997    }
    998    // c decomposes, get everything from the variable-length extra data
    999    const uint16_t *mapping=getData(norm16);
   1000    uint16_t firstUnit=*mapping;
   1001    int32_t mLength=firstUnit&MAPPING_LENGTH_MASK;  // length of normal mapping
   1002    if(firstUnit&MAPPING_HAS_RAW_MAPPING) {
   1003        // Read the raw mapping from before the firstUnit and before the optional ccc/lccc word.
   1004        // Bit 7=MAPPING_HAS_CCC_LCCC_WORD
   1005        const uint16_t *rawMapping=mapping-((firstUnit>>7)&1)-1;
   1006        uint16_t rm0=*rawMapping;
   1007        if(rm0<=MAPPING_LENGTH_MASK) {
   1008            length=rm0;
   1009            return reinterpret_cast<const char16_t*>(rawMapping) - rm0;
   1010        } else {
   1011            // Copy the normal mapping and replace its first two code units with rm0.
   1012            buffer[0] = static_cast<char16_t>(rm0);
   1013            u_memcpy(buffer + 1, reinterpret_cast<const char16_t*>(mapping) + 1 + 2, mLength - 2);
   1014            length=mLength-1;
   1015            return buffer;
   1016        }
   1017    } else {
   1018        length=mLength;
   1019        return reinterpret_cast<const char16_t*>(mapping) + 1;
   1020    }
   1021 }
   1022 
   1023 void Normalizer2Impl::decomposeAndAppend(const char16_t *src, const char16_t *limit,
   1024                                         UBool doDecompose,
   1025                                         UnicodeString &safeMiddle,
   1026                                         ReorderingBuffer &buffer,
   1027                                         UErrorCode &errorCode) const {
   1028    buffer.copyReorderableSuffixTo(safeMiddle);
   1029    if(doDecompose) {
   1030        decompose(src, limit, &buffer, errorCode);
   1031        return;
   1032    }
   1033    // Just merge the strings at the boundary.
   1034    bool isFirst = true;
   1035    uint8_t firstCC = 0, prevCC = 0, cc;
   1036    const char16_t *p = src;
   1037    while (p != limit) {
   1038        const char16_t *codePointStart = p;
   1039        UChar32 c;
   1040        uint16_t norm16;
   1041        UCPTRIE_FAST_U16_NEXT(normTrie, UCPTRIE_16, p, limit, c, norm16);
   1042        if ((cc = getCC(norm16)) == 0) {
   1043            p = codePointStart;
   1044            break;
   1045        }
   1046        if (isFirst) {
   1047            firstCC = cc;
   1048            isFirst = false;
   1049        }
   1050        prevCC = cc;
   1051    }
   1052    if(limit==nullptr) {  // appendZeroCC() needs limit!=nullptr
   1053        limit=u_strchr(p, 0);
   1054    }
   1055 
   1056    if (buffer.append(src, static_cast<int32_t>(p - src), false, firstCC, prevCC, errorCode)) {
   1057        buffer.appendZeroCC(p, limit, errorCode);
   1058    }
   1059 }
   1060 
   1061 UBool Normalizer2Impl::hasDecompBoundaryBefore(UChar32 c) const {
   1062    return c < minLcccCP || (c <= 0xffff && !singleLeadMightHaveNonZeroFCD16(c)) ||
   1063        norm16HasDecompBoundaryBefore(getNorm16(c));
   1064 }
   1065 
   1066 UBool Normalizer2Impl::norm16HasDecompBoundaryBefore(uint16_t norm16) const {
   1067    if (norm16 < minNoNoCompNoMaybeCC) {
   1068        return true;
   1069    }
   1070    if (norm16 >= limitNoNo) {
   1071        return norm16 <= MIN_NORMAL_MAYBE_YES || norm16 == JAMO_VT;
   1072    }
   1073    // c decomposes, get everything from the variable-length extra data
   1074    const uint16_t *mapping=getDataForYesOrNo(norm16);
   1075    uint16_t firstUnit=*mapping;
   1076    // true if leadCC==0 (hasFCDBoundaryBefore())
   1077    return (firstUnit&MAPPING_HAS_CCC_LCCC_WORD)==0 || (*(mapping-1)&0xff00)==0;
   1078 }
   1079 
   1080 UBool Normalizer2Impl::hasDecompBoundaryAfter(UChar32 c) const {
   1081    if (c < minDecompNoCP) {
   1082        return true;
   1083    }
   1084    if (c <= 0xffff && !singleLeadMightHaveNonZeroFCD16(c)) {
   1085        return true;
   1086    }
   1087    return norm16HasDecompBoundaryAfter(getNorm16(c));
   1088 }
   1089 
   1090 UBool Normalizer2Impl::norm16HasDecompBoundaryAfter(uint16_t norm16) const {
   1091    if(norm16 <= minYesNo || isHangulLVT(norm16)) {
   1092        return true;
   1093    }
   1094    if (norm16 >= limitNoNo) {
   1095        if (isMaybeYesOrNonZeroCC(norm16)) {
   1096            return norm16 <= MIN_NORMAL_MAYBE_YES || norm16 == JAMO_VT;
   1097        } else if (norm16 < minMaybeNo) {
   1098            // Maps to an isCompYesAndZeroCC.
   1099            return (norm16 & DELTA_TCCC_MASK) <= DELTA_TCCC_1;
   1100        }
   1101    }
   1102    // c decomposes, get everything from the variable-length extra data
   1103    const uint16_t *mapping=getData(norm16);
   1104    uint16_t firstUnit=*mapping;
   1105    // decomp after-boundary: same as hasFCDBoundaryAfter(),
   1106    // fcd16<=1 || trailCC==0
   1107    if(firstUnit>0x1ff) {
   1108        return false;  // trailCC>1
   1109    }
   1110    if(firstUnit<=0xff) {
   1111        return true;  // trailCC==0
   1112    }
   1113    // if(trailCC==1) test leadCC==0, same as checking for before-boundary
   1114    // true if leadCC==0 (hasFCDBoundaryBefore())
   1115    return (firstUnit&MAPPING_HAS_CCC_LCCC_WORD)==0 || (*(mapping-1)&0xff00)==0;
   1116 }
   1117 
   1118 /*
   1119 * Finds the recomposition result for
   1120 * a forward-combining "lead" character,
   1121 * specified with a pointer to its compositions list,
   1122 * and a backward-combining "trail" character.
   1123 *
   1124 * If the lead and trail characters combine, then this function returns
   1125 * the following "compositeAndFwd" value:
   1126 * Bits 21..1  composite character
   1127 * Bit      0  set if the composite is a forward-combining starter
   1128 * otherwise it returns -1.
   1129 *
   1130 * The compositions list has (trail, compositeAndFwd) pair entries,
   1131 * encoded as either pairs or triples of 16-bit units.
   1132 * The last entry has the high bit of its first unit set.
   1133 *
   1134 * The list is sorted by ascending trail characters (there are no duplicates).
   1135 * A linear search is used.
   1136 *
   1137 * See normalizer2impl.h for a more detailed description
   1138 * of the compositions list format.
   1139 */
   1140 int32_t Normalizer2Impl::combine(const uint16_t *list, UChar32 trail) {
   1141    uint16_t key1, firstUnit;
   1142    if(trail<COMP_1_TRAIL_LIMIT) {
   1143        // trail character is 0..33FF
   1144        // result entry may have 2 or 3 units
   1145        key1 = static_cast<uint16_t>(trail << 1);
   1146        while(key1>(firstUnit=*list)) {
   1147            list+=2+(firstUnit&COMP_1_TRIPLE);
   1148        }
   1149        if(key1==(firstUnit&COMP_1_TRAIL_MASK)) {
   1150            if(firstUnit&COMP_1_TRIPLE) {
   1151                return (static_cast<int32_t>(list[1]) << 16) | list[2];
   1152            } else {
   1153                return list[1];
   1154            }
   1155        }
   1156    } else {
   1157        // trail character is 3400..10FFFF
   1158        // result entry has 3 units
   1159        key1 = static_cast<uint16_t>(COMP_1_TRAIL_LIMIT +
   1160                        (((trail>>COMP_1_TRAIL_SHIFT))&
   1161                          ~COMP_1_TRIPLE));
   1162        uint16_t key2 = static_cast<uint16_t>(trail << COMP_2_TRAIL_SHIFT);
   1163        uint16_t secondUnit;
   1164        for(;;) {
   1165            if(key1>(firstUnit=*list)) {
   1166                list+=2+(firstUnit&COMP_1_TRIPLE);
   1167            } else if(key1==(firstUnit&COMP_1_TRAIL_MASK)) {
   1168                if(key2>(secondUnit=list[1])) {
   1169                    if(firstUnit&COMP_1_LAST_TUPLE) {
   1170                        break;
   1171                    } else {
   1172                        list+=3;
   1173                    }
   1174                } else if(key2==(secondUnit&COMP_2_TRAIL_MASK)) {
   1175                    return (static_cast<int32_t>(secondUnit & ~COMP_2_TRAIL_MASK) << 16) | list[2];
   1176                } else {
   1177                    break;
   1178                }
   1179            } else {
   1180                break;
   1181            }
   1182        }
   1183    }
   1184    return -1;
   1185 }
   1186 
   1187 /**
   1188  * @param list some character's compositions list
   1189  * @param set recursively receives the composites from these compositions
   1190  */
   1191 void Normalizer2Impl::addComposites(const uint16_t *list, UnicodeSet &set) const {
   1192    uint16_t firstUnit;
   1193    int32_t compositeAndFwd;
   1194    do {
   1195        firstUnit=*list;
   1196        if((firstUnit&COMP_1_TRIPLE)==0) {
   1197            compositeAndFwd=list[1];
   1198            list+=2;
   1199        } else {
   1200            compositeAndFwd = ((static_cast<int32_t>(list[1]) & ~COMP_2_TRAIL_MASK) << 16) | list[2];
   1201            list+=3;
   1202        }
   1203        UChar32 composite=compositeAndFwd>>1;
   1204        if((compositeAndFwd&1)!=0) {
   1205            addComposites(getCompositionsListForComposite(getRawNorm16(composite)), set);
   1206        }
   1207        set.add(composite);
   1208    } while((firstUnit&COMP_1_LAST_TUPLE)==0);
   1209 }
   1210 
   1211 /*
   1212 * Recomposes the buffer text starting at recomposeStartIndex
   1213 * (which is in NFD - decomposed and canonically ordered),
   1214 * and truncates the buffer contents.
   1215 *
   1216 * Note that recomposition never lengthens the text:
   1217 * Any character consists of either one or two code units;
   1218 * a composition may contain at most one more code unit than the original starter,
   1219 * while the combining mark that is removed has at least one code unit.
   1220 */
   1221 void Normalizer2Impl::recompose(ReorderingBuffer &buffer, int32_t recomposeStartIndex,
   1222                                UBool onlyContiguous) const {
   1223    char16_t *p=buffer.getStart()+recomposeStartIndex;
   1224    char16_t *limit=buffer.getLimit();
   1225    if(p==limit) {
   1226        return;
   1227    }
   1228 
   1229    char16_t *starter, *pRemove, *q, *r;
   1230    const uint16_t *compositionsList;
   1231    UChar32 c, compositeAndFwd;
   1232    uint16_t norm16;
   1233    uint8_t cc, prevCC;
   1234    UBool starterIsSupplementary;
   1235 
   1236    // Some of the following variables are not used until we have a forward-combining starter
   1237    // and are only initialized now to avoid compiler warnings.
   1238    compositionsList=nullptr;  // used as indicator for whether we have a forward-combining starter
   1239    starter=nullptr;
   1240    starterIsSupplementary=false;
   1241    prevCC=0;
   1242 
   1243    for(;;) {
   1244        UCPTRIE_FAST_U16_NEXT(normTrie, UCPTRIE_16, p, limit, c, norm16);
   1245        cc=getCCFromYesOrMaybeYes(norm16);
   1246        if( // this character combines backward and
   1247            isMaybe(norm16) &&
   1248            // we have seen a starter that combines forward and
   1249            compositionsList!=nullptr &&
   1250            // the backward-combining character is not blocked
   1251            (prevCC<cc || prevCC==0)
   1252        ) {
   1253            if(isJamoVT(norm16)) {
   1254                // c is a Jamo V/T, see if we can compose it with the previous character.
   1255                if(c<Hangul::JAMO_T_BASE) {
   1256                    // c is a Jamo Vowel, compose with previous Jamo L and following Jamo T.
   1257                    char16_t prev = static_cast<char16_t>(*starter - Hangul::JAMO_L_BASE);
   1258                    if(prev<Hangul::JAMO_L_COUNT) {
   1259                        pRemove=p-1;
   1260                        char16_t syllable = static_cast<char16_t>(
   1261                            Hangul::HANGUL_BASE +
   1262                             (prev*Hangul::JAMO_V_COUNT+(c-Hangul::JAMO_V_BASE))*
   1263                             Hangul::JAMO_T_COUNT);
   1264                        char16_t t;
   1265                        if (p != limit && (t = static_cast<char16_t>(*p - Hangul::JAMO_T_BASE)) < Hangul::JAMO_T_COUNT) {
   1266                            ++p;
   1267                            syllable+=t;  // The next character was a Jamo T.
   1268                        }
   1269                        *starter=syllable;
   1270                        // remove the Jamo V/T
   1271                        q=pRemove;
   1272                        r=p;
   1273                        while(r<limit) {
   1274                            *q++=*r++;
   1275                        }
   1276                        limit=q;
   1277                        p=pRemove;
   1278                    }
   1279                }
   1280                /*
   1281                 * No "else" for Jamo T:
   1282                 * Since the input is in NFD, there are no Hangul LV syllables that
   1283                 * a Jamo T could combine with.
   1284                 * All Jamo Ts are combined above when handling Jamo Vs.
   1285                 */
   1286                if(p==limit) {
   1287                    break;
   1288                }
   1289                compositionsList=nullptr;
   1290                continue;
   1291            } else if((compositeAndFwd=combine(compositionsList, c))>=0) {
   1292                // The starter and the combining mark (c) do combine.
   1293                UChar32 composite=compositeAndFwd>>1;
   1294 
   1295                // Replace the starter with the composite, remove the combining mark.
   1296                pRemove=p-U16_LENGTH(c);  // pRemove & p: start & limit of the combining mark
   1297                if(starterIsSupplementary) {
   1298                    if(U_IS_SUPPLEMENTARY(composite)) {
   1299                        // both are supplementary
   1300                        starter[0]=U16_LEAD(composite);
   1301                        starter[1]=U16_TRAIL(composite);
   1302                    } else {
   1303                        *starter = static_cast<char16_t>(composite);
   1304                        // The composite is shorter than the starter,
   1305                        // move the intermediate characters forward one.
   1306                        starterIsSupplementary=false;
   1307                        q=starter+1;
   1308                        r=q+1;
   1309                        while(r<pRemove) {
   1310                            *q++=*r++;
   1311                        }
   1312                        --pRemove;
   1313                    }
   1314                } else if(U_IS_SUPPLEMENTARY(composite)) {
   1315                    // The composite is longer than the starter,
   1316                    // move the intermediate characters back one.
   1317                    starterIsSupplementary=true;
   1318                    ++starter;  // temporarily increment for the loop boundary
   1319                    q=pRemove;
   1320                    r=++pRemove;
   1321                    while(starter<q) {
   1322                        *--r=*--q;
   1323                    }
   1324                    *starter=U16_TRAIL(composite);
   1325                    *--starter=U16_LEAD(composite);  // undo the temporary increment
   1326                } else {
   1327                    // both are on the BMP
   1328                    *starter = static_cast<char16_t>(composite);
   1329                }
   1330 
   1331                /* remove the combining mark by moving the following text over it */
   1332                if(pRemove<p) {
   1333                    q=pRemove;
   1334                    r=p;
   1335                    while(r<limit) {
   1336                        *q++=*r++;
   1337                    }
   1338                    limit=q;
   1339                    p=pRemove;
   1340                }
   1341                // Keep prevCC because we removed the combining mark.
   1342 
   1343                if(p==limit) {
   1344                    break;
   1345                }
   1346                // Is the composite a starter that combines forward?
   1347                if(compositeAndFwd&1) {
   1348                    compositionsList=
   1349                        getCompositionsListForComposite(getRawNorm16(composite));
   1350                } else {
   1351                    compositionsList=nullptr;
   1352                }
   1353 
   1354                // We combined; continue with looking for compositions.
   1355                continue;
   1356            }
   1357        }
   1358 
   1359        // no combination this time
   1360        prevCC=cc;
   1361        if(p==limit) {
   1362            break;
   1363        }
   1364 
   1365        // If c did not combine, then check if it is a starter.
   1366        if(cc==0) {
   1367            // Found a new starter.
   1368            if((compositionsList=getCompositionsListForDecompYes(norm16))!=nullptr) {
   1369                // It may combine with something, prepare for it.
   1370                if(U_IS_BMP(c)) {
   1371                    starterIsSupplementary=false;
   1372                    starter=p-1;
   1373                } else {
   1374                    starterIsSupplementary=true;
   1375                    starter=p-2;
   1376                }
   1377            }
   1378        } else if(onlyContiguous) {
   1379            // FCC: no discontiguous compositions; any intervening character blocks.
   1380            compositionsList=nullptr;
   1381        }
   1382    }
   1383    buffer.setReorderingLimit(limit);
   1384 }
   1385 
   1386 UChar32
   1387 Normalizer2Impl::composePair(UChar32 a, UChar32 b) const {
   1388    uint16_t norm16=getNorm16(a);  // maps an out-of-range 'a' to inert norm16
   1389    const uint16_t *list;
   1390    if(isInert(norm16)) {
   1391        return U_SENTINEL;
   1392    } else if(norm16<minYesNoMappingsOnly) {
   1393        // a combines forward.
   1394        if(isJamoL(norm16)) {
   1395            if (b < Hangul::JAMO_V_BASE) {
   1396                return U_SENTINEL;
   1397            }
   1398            b-=Hangul::JAMO_V_BASE;
   1399            if(b<Hangul::JAMO_V_COUNT) {
   1400                return
   1401                    (Hangul::HANGUL_BASE+
   1402                     ((a-Hangul::JAMO_L_BASE)*Hangul::JAMO_V_COUNT+b)*
   1403                     Hangul::JAMO_T_COUNT);
   1404            } else {
   1405                return U_SENTINEL;
   1406            }
   1407        } else if(isHangulLV(norm16)) {
   1408            if (b <= Hangul::JAMO_T_BASE) {
   1409               return U_SENTINEL;
   1410            }
   1411            b-=Hangul::JAMO_T_BASE;
   1412            if(b<Hangul::JAMO_T_COUNT) {  // not b==0!
   1413                return a+b;
   1414            } else {
   1415                return U_SENTINEL;
   1416            }
   1417        } else {
   1418            // 'a' has a compositions list in extraData
   1419            list=getDataForYesOrNo(norm16);
   1420            if(norm16>minYesNo) {  // composite 'a' has both mapping & compositions list
   1421                list+=  // mapping pointer
   1422                    1+  // +1 to skip the first unit with the mapping length
   1423                    (*list&MAPPING_LENGTH_MASK);  // + mapping length
   1424            }
   1425        }
   1426    } else if(norm16<minMaybeNoCombinesFwd || MIN_NORMAL_MAYBE_YES<=norm16) {
   1427        return U_SENTINEL;
   1428    } else {
   1429        list=getDataForMaybe(norm16);
   1430        if(norm16<minMaybeYes) {  // composite 'a' has both mapping & compositions list
   1431            list+=  // mapping pointer
   1432                1+  // +1 to skip the first unit with the mapping length
   1433                (*list&MAPPING_LENGTH_MASK);  // + mapping length
   1434        }
   1435    }
   1436    if(b<0 || 0x10ffff<b) {  // combine(list, b) requires a valid code point b
   1437        return U_SENTINEL;
   1438    }
   1439 #if U_SIGNED_RIGHT_SHIFT_IS_ARITHMETIC
   1440    return combine(list, b)>>1;
   1441 #else
   1442    int32_t compositeAndFwd=combine(list, b);
   1443    return compositeAndFwd>=0 ? compositeAndFwd>>1 : U_SENTINEL;
   1444 #endif
   1445 }
   1446 
   1447 // Very similar to composeQuickCheck(): Make the same changes in both places if relevant.
   1448 // doCompose: normalize
   1449 // !doCompose: isNormalized (buffer must be empty and initialized)
   1450 UBool
   1451 Normalizer2Impl::compose(const char16_t *src, const char16_t *limit,
   1452                         UBool onlyContiguous,
   1453                         UBool doCompose,
   1454                         ReorderingBuffer &buffer,
   1455                         UErrorCode &errorCode) const {
   1456    const char16_t *prevBoundary=src;
   1457    UChar32 minNoMaybeCP=minCompNoMaybeCP;
   1458    if(limit==nullptr) {
   1459        src=copyLowPrefixFromNulTerminated(src, minNoMaybeCP,
   1460                                           doCompose ? &buffer : nullptr,
   1461                                           errorCode);
   1462        if(U_FAILURE(errorCode)) {
   1463            return false;
   1464        }
   1465        limit=u_strchr(src, 0);
   1466        if (prevBoundary != src) {
   1467            if (hasCompBoundaryAfter(*(src-1), onlyContiguous)) {
   1468                prevBoundary = src;
   1469            } else {
   1470                buffer.removeSuffix(1);
   1471                prevBoundary = --src;
   1472            }
   1473        }
   1474    }
   1475 
   1476    for (;;) {
   1477        // Fast path: Scan over a sequence of characters below the minimum "no or maybe" code point,
   1478        // or with (compYes && ccc==0) properties.
   1479        const char16_t *prevSrc;
   1480        UChar32 c = 0;
   1481        uint16_t norm16 = 0;
   1482        for (;;) {
   1483            if (src == limit) {
   1484                if (prevBoundary != limit && doCompose) {
   1485                    buffer.appendZeroCC(prevBoundary, limit, errorCode);
   1486                }
   1487                return true;
   1488            }
   1489            if( (c=*src)<minNoMaybeCP ||
   1490                isCompYesAndZeroCC(norm16=UCPTRIE_FAST_BMP_GET(normTrie, UCPTRIE_16, c))
   1491            ) {
   1492                ++src;
   1493            } else {
   1494                prevSrc = src++;
   1495                if(!U16_IS_LEAD(c)) {
   1496                    break;
   1497                } else {
   1498                    char16_t c2;
   1499                    if(src!=limit && U16_IS_TRAIL(c2=*src)) {
   1500                        ++src;
   1501                        c=U16_GET_SUPPLEMENTARY(c, c2);
   1502                        norm16=UCPTRIE_FAST_SUPP_GET(normTrie, UCPTRIE_16, c);
   1503                        if(!isCompYesAndZeroCC(norm16)) {
   1504                            break;
   1505                        }
   1506                    }
   1507                }
   1508            }
   1509        }
   1510        // isCompYesAndZeroCC(norm16) is false, that is, norm16>=minNoNo.
   1511        // The current character is either a "noNo" (has a mapping)
   1512        // or a "maybeYes" / "maybeNo" (combines backward)
   1513        // or a "yesYes" with ccc!=0.
   1514        // It is not a Hangul syllable or Jamo L because those have "yes" properties.
   1515 
   1516        // Medium-fast path: Handle cases that do not require full decomposition and recomposition.
   1517        if (norm16 < minMaybeNo) {  // minNoNo <= norm16 < minMaybeNo
   1518            if (!doCompose) {
   1519                return false;
   1520            }
   1521            // Fast path for mapping a character that is immediately surrounded by boundaries.
   1522            // In this case, we need not decompose around the current character.
   1523            if (isDecompNoAlgorithmic(norm16)) {
   1524                // Maps to a single isCompYesAndZeroCC character
   1525                // which also implies hasCompBoundaryBefore.
   1526                if (norm16HasCompBoundaryAfter(norm16, onlyContiguous) ||
   1527                        hasCompBoundaryBefore(src, limit)) {
   1528                    if (prevBoundary != prevSrc && !buffer.appendZeroCC(prevBoundary, prevSrc, errorCode)) {
   1529                        break;
   1530                    }
   1531                    if(!buffer.append(mapAlgorithmic(c, norm16), 0, errorCode)) {
   1532                        break;
   1533                    }
   1534                    prevBoundary = src;
   1535                    continue;
   1536                }
   1537            } else if (norm16 < minNoNoCompBoundaryBefore) {
   1538                // The mapping is comp-normalized which also implies hasCompBoundaryBefore.
   1539                if (norm16HasCompBoundaryAfter(norm16, onlyContiguous) ||
   1540                        hasCompBoundaryBefore(src, limit)) {
   1541                    if (prevBoundary != prevSrc && !buffer.appendZeroCC(prevBoundary, prevSrc, errorCode)) {
   1542                        break;
   1543                    }
   1544                    const char16_t *mapping = reinterpret_cast<const char16_t *>(getDataForYesOrNo(norm16));
   1545                    int32_t length = *mapping++ & MAPPING_LENGTH_MASK;
   1546                    if(!buffer.appendZeroCC(mapping, mapping + length, errorCode)) {
   1547                        break;
   1548                    }
   1549                    prevBoundary = src;
   1550                    continue;
   1551                }
   1552            } else if (norm16 >= minNoNoEmpty) {
   1553                // The current character maps to nothing.
   1554                // Simply omit it from the output if there is a boundary before _or_ after it.
   1555                // The character itself implies no boundaries.
   1556                if (hasCompBoundaryBefore(src, limit) ||
   1557                        hasCompBoundaryAfter(prevBoundary, prevSrc, onlyContiguous)) {
   1558                    if (prevBoundary != prevSrc && !buffer.appendZeroCC(prevBoundary, prevSrc, errorCode)) {
   1559                        break;
   1560                    }
   1561                    prevBoundary = src;
   1562                    continue;
   1563                }
   1564            }
   1565            // Other "noNo" type, or need to examine more text around this character:
   1566            // Fall through to the slow path.
   1567        } else if (isJamoVT(norm16) && prevBoundary != prevSrc) {
   1568            char16_t prev=*(prevSrc-1);
   1569            if(c<Hangul::JAMO_T_BASE) {
   1570                // The current character is a Jamo Vowel,
   1571                // compose with previous Jamo L and following Jamo T.
   1572                char16_t l = static_cast<char16_t>(prev - Hangul::JAMO_L_BASE);
   1573                if(l<Hangul::JAMO_L_COUNT) {
   1574                    if (!doCompose) {
   1575                        return false;
   1576                    }
   1577                    int32_t t;
   1578                    if (src != limit &&
   1579                            0 < (t = (static_cast<int32_t>(*src) - Hangul::JAMO_T_BASE)) &&
   1580                            t < Hangul::JAMO_T_COUNT) {
   1581                        // The next character is a Jamo T.
   1582                        ++src;
   1583                    } else if (hasCompBoundaryBefore(src, limit)) {
   1584                        // No Jamo T follows, not even via decomposition.
   1585                        t = 0;
   1586                    } else {
   1587                        t = -1;
   1588                    }
   1589                    if (t >= 0) {
   1590                        UChar32 syllable = Hangul::HANGUL_BASE +
   1591                            (l*Hangul::JAMO_V_COUNT + (c-Hangul::JAMO_V_BASE)) *
   1592                            Hangul::JAMO_T_COUNT + t;
   1593                        --prevSrc;  // Replace the Jamo L as well.
   1594                        if (prevBoundary != prevSrc && !buffer.appendZeroCC(prevBoundary, prevSrc, errorCode)) {
   1595                            break;
   1596                        }
   1597                        if (!buffer.appendBMP(static_cast<char16_t>(syllable), 0, errorCode)) {
   1598                            break;
   1599                        }
   1600                        prevBoundary = src;
   1601                        continue;
   1602                    }
   1603                    // If we see L+V+x where x!=T then we drop to the slow path,
   1604                    // decompose and recompose.
   1605                    // This is to deal with NFKC finding normal L and V but a
   1606                    // compatibility variant of a T.
   1607                    // We need to either fully compose that combination here
   1608                    // (which would complicate the code and may not work with strange custom data)
   1609                    // or use the slow path.
   1610                }
   1611            } else if (Hangul::isHangulLV(prev)) {
   1612                // The current character is a Jamo Trailing consonant,
   1613                // compose with previous Hangul LV that does not contain a Jamo T.
   1614                if (!doCompose) {
   1615                    return false;
   1616                }
   1617                UChar32 syllable = prev + c - Hangul::JAMO_T_BASE;
   1618                --prevSrc;  // Replace the Hangul LV as well.
   1619                if (prevBoundary != prevSrc && !buffer.appendZeroCC(prevBoundary, prevSrc, errorCode)) {
   1620                    break;
   1621                }
   1622                if (!buffer.appendBMP(static_cast<char16_t>(syllable), 0, errorCode)) {
   1623                    break;
   1624                }
   1625                prevBoundary = src;
   1626                continue;
   1627            }
   1628            // No matching context, or may need to decompose surrounding text first:
   1629            // Fall through to the slow path.
   1630        } else if (norm16 > JAMO_VT) {  // norm16 >= MIN_YES_YES_WITH_CC
   1631            // One or more combining marks that do not combine-back:
   1632            // Check for canonical order, copy unchanged if ok and
   1633            // if followed by a character with a boundary-before.
   1634            uint8_t cc = getCCFromNormalYesOrMaybe(norm16);  // cc!=0
   1635            if (onlyContiguous /* FCC */ && getPreviousTrailCC(prevBoundary, prevSrc) > cc) {
   1636                // Fails FCD test, need to decompose and contiguously recompose.
   1637                if (!doCompose) {
   1638                    return false;
   1639                }
   1640            } else {
   1641                // If !onlyContiguous (not FCC), then we ignore the tccc of
   1642                // the previous character which passed the quick check "yes && ccc==0" test.
   1643                const char16_t *nextSrc;
   1644                uint16_t n16;
   1645                for (;;) {
   1646                    if (src == limit) {
   1647                        if (doCompose) {
   1648                            buffer.appendZeroCC(prevBoundary, limit, errorCode);
   1649                        }
   1650                        return true;
   1651                    }
   1652                    uint8_t prevCC = cc;
   1653                    nextSrc = src;
   1654                    UCPTRIE_FAST_U16_NEXT(normTrie, UCPTRIE_16, nextSrc, limit, c, n16);
   1655                    if (n16 >= MIN_YES_YES_WITH_CC) {
   1656                        cc = getCCFromNormalYesOrMaybe(n16);
   1657                        if (prevCC > cc) {
   1658                            if (!doCompose) {
   1659                                return false;
   1660                            }
   1661                            break;
   1662                        }
   1663                    } else {
   1664                        break;
   1665                    }
   1666                    src = nextSrc;
   1667                }
   1668                // src is after the last in-order combining mark.
   1669                // If there is a boundary here, then we continue with no change.
   1670                if (norm16HasCompBoundaryBefore(n16)) {
   1671                    if (isCompYesAndZeroCC(n16)) {
   1672                        src = nextSrc;
   1673                    }
   1674                    continue;
   1675                }
   1676                // Use the slow path. There is no boundary in [prevSrc, src[.
   1677            }
   1678        }
   1679 
   1680        // Slow path: Find the nearest boundaries around the current character,
   1681        // decompose and recompose.
   1682        if (prevBoundary != prevSrc && !norm16HasCompBoundaryBefore(norm16)) {
   1683            const char16_t *p = prevSrc;
   1684            UCPTRIE_FAST_U16_PREV(normTrie, UCPTRIE_16, prevBoundary, p, c, norm16);
   1685            if (!norm16HasCompBoundaryAfter(norm16, onlyContiguous)) {
   1686                prevSrc = p;
   1687            }
   1688        }
   1689        if (doCompose && prevBoundary != prevSrc && !buffer.appendZeroCC(prevBoundary, prevSrc, errorCode)) {
   1690            break;
   1691        }
   1692        int32_t recomposeStartIndex=buffer.length();
   1693        // We know there is not a boundary here.
   1694        decomposeShort(prevSrc, src, false /* !stopAtCompBoundary */, onlyContiguous,
   1695                       buffer, errorCode);
   1696        // Decompose until the next boundary.
   1697        src = decomposeShort(src, limit, true /* stopAtCompBoundary */, onlyContiguous,
   1698                             buffer, errorCode);
   1699        if (U_FAILURE(errorCode)) {
   1700            break;
   1701        }
   1702        if ((src - prevSrc) > INT32_MAX) {  // guard before buffer.equals()
   1703            errorCode = U_INDEX_OUTOFBOUNDS_ERROR;
   1704            return true;
   1705        }
   1706        recompose(buffer, recomposeStartIndex, onlyContiguous);
   1707        if(!doCompose) {
   1708            if(!buffer.equals(prevSrc, src)) {
   1709                return false;
   1710            }
   1711            buffer.remove();
   1712        }
   1713        prevBoundary=src;
   1714    }
   1715    return true;
   1716 }
   1717 
   1718 // Very similar to compose(): Make the same changes in both places if relevant.
   1719 // pQCResult==nullptr: spanQuickCheckYes
   1720 // pQCResult!=nullptr: quickCheck (*pQCResult must be UNORM_YES)
   1721 const char16_t *
   1722 Normalizer2Impl::composeQuickCheck(const char16_t *src, const char16_t *limit,
   1723                                   UBool onlyContiguous,
   1724                                   UNormalizationCheckResult *pQCResult) const {
   1725    const char16_t *prevBoundary=src;
   1726    UChar32 minNoMaybeCP=minCompNoMaybeCP;
   1727    if(limit==nullptr) {
   1728        UErrorCode errorCode=U_ZERO_ERROR;
   1729        src=copyLowPrefixFromNulTerminated(src, minNoMaybeCP, nullptr, errorCode);
   1730        limit=u_strchr(src, 0);
   1731        if (prevBoundary != src) {
   1732            if (hasCompBoundaryAfter(*(src-1), onlyContiguous)) {
   1733                prevBoundary = src;
   1734            } else {
   1735                prevBoundary = --src;
   1736            }
   1737        }
   1738    }
   1739 
   1740    for(;;) {
   1741        // Fast path: Scan over a sequence of characters below the minimum "no or maybe" code point,
   1742        // or with (compYes && ccc==0) properties.
   1743        const char16_t *prevSrc;
   1744        UChar32 c = 0;
   1745        uint16_t norm16 = 0;
   1746        for (;;) {
   1747            if(src==limit) {
   1748                return src;
   1749            }
   1750            if( (c=*src)<minNoMaybeCP ||
   1751                isCompYesAndZeroCC(norm16=UCPTRIE_FAST_BMP_GET(normTrie, UCPTRIE_16, c))
   1752            ) {
   1753                ++src;
   1754            } else {
   1755                prevSrc = src++;
   1756                if(!U16_IS_LEAD(c)) {
   1757                    break;
   1758                } else {
   1759                    char16_t c2;
   1760                    if(src!=limit && U16_IS_TRAIL(c2=*src)) {
   1761                        ++src;
   1762                        c=U16_GET_SUPPLEMENTARY(c, c2);
   1763                        norm16=UCPTRIE_FAST_SUPP_GET(normTrie, UCPTRIE_16, c);
   1764                        if(!isCompYesAndZeroCC(norm16)) {
   1765                            break;
   1766                        }
   1767                    }
   1768                }
   1769            }
   1770        }
   1771        // isCompYesAndZeroCC(norm16) is false, that is, norm16>=minNoNo.
   1772        // The current character is either a "noNo" (has a mapping)
   1773        // or a "maybeYes" / "maybeNo" (combines backward)
   1774        // or a "yesYes" with ccc!=0.
   1775        // It is not a Hangul syllable or Jamo L because those have "yes" properties.
   1776 
   1777        uint16_t prevNorm16 = INERT;
   1778        if (prevBoundary != prevSrc) {
   1779            if (norm16HasCompBoundaryBefore(norm16)) {
   1780                prevBoundary = prevSrc;
   1781            } else {
   1782                const char16_t *p = prevSrc;
   1783                uint16_t n16;
   1784                UCPTRIE_FAST_U16_PREV(normTrie, UCPTRIE_16, prevBoundary, p, c, n16);
   1785                if (norm16HasCompBoundaryAfter(n16, onlyContiguous)) {
   1786                    prevBoundary = prevSrc;
   1787                } else {
   1788                    prevBoundary = p;
   1789                    prevNorm16 = n16;
   1790                }
   1791            }
   1792        }
   1793 
   1794        if (norm16 >= minMaybeNo) {
   1795            uint16_t fcd16 = getFCD16FromMaybeOrNonZeroCC(norm16);
   1796            uint8_t cc = fcd16 >> 8;
   1797            if (onlyContiguous /* FCC */ && cc != 0 &&
   1798                    getTrailCCFromCompYesAndZeroCC(prevNorm16) > cc) {
   1799                // The [prevBoundary..prevSrc[ character
   1800                // passed the quick check "yes && ccc==0" test
   1801                // but is out of canonical order with the current combining mark.
   1802            } else {
   1803                // If !onlyContiguous (not FCC), then we ignore the tccc of
   1804                // the previous character which passed the quick check "yes && ccc==0" test.
   1805                const char16_t *nextSrc;
   1806                for (;;) {
   1807                    if (norm16 < MIN_YES_YES_WITH_CC) {
   1808                        if (pQCResult != nullptr) {
   1809                            *pQCResult = UNORM_MAYBE;
   1810                        } else {
   1811                            return prevBoundary;
   1812                        }
   1813                    }
   1814                    if (src == limit) {
   1815                        return src;
   1816                    }
   1817                    uint8_t prevCC = fcd16;
   1818                    nextSrc = src;
   1819                    UCPTRIE_FAST_U16_NEXT(normTrie, UCPTRIE_16, nextSrc, limit, c, norm16);
   1820                    if (norm16 >= minMaybeNo) {
   1821                        fcd16 = getFCD16FromMaybeOrNonZeroCC(norm16);
   1822                        cc = fcd16 >> 8;
   1823                        if (!(prevCC <= cc || cc == 0)) {
   1824                            break;
   1825                        }
   1826                    } else {
   1827                        break;
   1828                    }
   1829                    src = nextSrc;
   1830                }
   1831                // src is after the last in-order combining mark.
   1832                if (isCompYesAndZeroCC(norm16)) {
   1833                    prevBoundary = src;
   1834                    src = nextSrc;
   1835                    continue;
   1836                }
   1837            }
   1838        }
   1839        if(pQCResult!=nullptr) {
   1840            *pQCResult=UNORM_NO;
   1841        }
   1842        return prevBoundary;
   1843    }
   1844 }
   1845 
   1846 void Normalizer2Impl::composeAndAppend(const char16_t *src, const char16_t *limit,
   1847                                       UBool doCompose,
   1848                                       UBool onlyContiguous,
   1849                                       UnicodeString &safeMiddle,
   1850                                       ReorderingBuffer &buffer,
   1851                                       UErrorCode &errorCode) const {
   1852    if(!buffer.isEmpty()) {
   1853        const char16_t *firstStarterInSrc=findNextCompBoundary(src, limit, onlyContiguous);
   1854        if(src!=firstStarterInSrc) {
   1855            const char16_t *lastStarterInDest=findPreviousCompBoundary(buffer.getStart(),
   1856                                                                    buffer.getLimit(), onlyContiguous);
   1857            int32_t destSuffixLength = static_cast<int32_t>(buffer.getLimit() - lastStarterInDest);
   1858            UnicodeString middle(lastStarterInDest, destSuffixLength);
   1859            buffer.removeSuffix(destSuffixLength);
   1860            safeMiddle=middle;
   1861            middle.append(src, static_cast<int32_t>(firstStarterInSrc - src));
   1862            const char16_t *middleStart=middle.getBuffer();
   1863            compose(middleStart, middleStart+middle.length(), onlyContiguous,
   1864                    true, buffer, errorCode);
   1865            if(U_FAILURE(errorCode)) {
   1866                return;
   1867            }
   1868            src=firstStarterInSrc;
   1869        }
   1870    }
   1871    if(doCompose) {
   1872        compose(src, limit, onlyContiguous, true, buffer, errorCode);
   1873    } else {
   1874        if(limit==nullptr) {  // appendZeroCC() needs limit!=nullptr
   1875            limit=u_strchr(src, 0);
   1876        }
   1877        buffer.appendZeroCC(src, limit, errorCode);
   1878    }
   1879 }
   1880 
   1881 UBool
   1882 Normalizer2Impl::composeUTF8(uint32_t options, UBool onlyContiguous,
   1883                             const uint8_t *src, const uint8_t *limit,
   1884                             ByteSink *sink, Edits *edits, UErrorCode &errorCode) const {
   1885    U_ASSERT(limit != nullptr);
   1886    UnicodeString s16;
   1887    uint8_t minNoMaybeLead = leadByteForCP(minCompNoMaybeCP);
   1888    const uint8_t *prevBoundary = src;
   1889 
   1890    for (;;) {
   1891        // Fast path: Scan over a sequence of characters below the minimum "no or maybe" code point,
   1892        // or with (compYes && ccc==0) properties.
   1893        const uint8_t *prevSrc;
   1894        uint16_t norm16 = 0;
   1895        for (;;) {
   1896            if (src == limit) {
   1897                if (prevBoundary != limit && sink != nullptr) {
   1898                    ByteSinkUtil::appendUnchanged(prevBoundary, limit,
   1899                                                  *sink, options, edits, errorCode);
   1900                }
   1901                return true;
   1902            }
   1903            if (*src < minNoMaybeLead) {
   1904                ++src;
   1905            } else {
   1906                prevSrc = src;
   1907                UCPTRIE_FAST_U8_NEXT(normTrie, UCPTRIE_16, src, limit, norm16);
   1908                if (!isCompYesAndZeroCC(norm16)) {
   1909                    break;
   1910                }
   1911            }
   1912        }
   1913        // isCompYesAndZeroCC(norm16) is false, that is, norm16>=minNoNo.
   1914        // The current character is either a "noNo" (has a mapping)
   1915        // or a "maybeYes" / "maybeNo" (combines backward)
   1916        // or a "yesYes" with ccc!=0.
   1917        // It is not a Hangul syllable or Jamo L because those have "yes" properties.
   1918 
   1919        // Medium-fast path: Handle cases that do not require full decomposition and recomposition.
   1920        if (norm16 < minMaybeNo) {  // minNoNo <= norm16 < minMaybeNo
   1921            if (sink == nullptr) {
   1922                return false;
   1923            }
   1924            // Fast path for mapping a character that is immediately surrounded by boundaries.
   1925            // In this case, we need not decompose around the current character.
   1926            if (isDecompNoAlgorithmic(norm16)) {
   1927                // Maps to a single isCompYesAndZeroCC character
   1928                // which also implies hasCompBoundaryBefore.
   1929                if (norm16HasCompBoundaryAfter(norm16, onlyContiguous) ||
   1930                        hasCompBoundaryBefore(src, limit)) {
   1931                    if (prevBoundary != prevSrc &&
   1932                            !ByteSinkUtil::appendUnchanged(prevBoundary, prevSrc,
   1933                                                           *sink, options, edits, errorCode)) {
   1934                        break;
   1935                    }
   1936                    appendCodePointDelta(prevSrc, src, getAlgorithmicDelta(norm16), *sink, edits);
   1937                    prevBoundary = src;
   1938                    continue;
   1939                }
   1940            } else if (norm16 < minNoNoCompBoundaryBefore) {
   1941                // The mapping is comp-normalized which also implies hasCompBoundaryBefore.
   1942                if (norm16HasCompBoundaryAfter(norm16, onlyContiguous) ||
   1943                        hasCompBoundaryBefore(src, limit)) {
   1944                    if (prevBoundary != prevSrc &&
   1945                            !ByteSinkUtil::appendUnchanged(prevBoundary, prevSrc,
   1946                                                           *sink, options, edits, errorCode)) {
   1947                        break;
   1948                    }
   1949                    const uint16_t *mapping = getDataForYesOrNo(norm16);
   1950                    int32_t length = *mapping++ & MAPPING_LENGTH_MASK;
   1951                    if (!ByteSinkUtil::appendChange(prevSrc, src, reinterpret_cast<const char16_t*>(mapping), length,
   1952                                                    *sink, edits, errorCode)) {
   1953                        break;
   1954                    }
   1955                    prevBoundary = src;
   1956                    continue;
   1957                }
   1958            } else if (norm16 >= minNoNoEmpty) {
   1959                // The current character maps to nothing.
   1960                // Simply omit it from the output if there is a boundary before _or_ after it.
   1961                // The character itself implies no boundaries.
   1962                if (hasCompBoundaryBefore(src, limit) ||
   1963                        hasCompBoundaryAfter(prevBoundary, prevSrc, onlyContiguous)) {
   1964                    if (prevBoundary != prevSrc &&
   1965                            !ByteSinkUtil::appendUnchanged(prevBoundary, prevSrc,
   1966                                                           *sink, options, edits, errorCode)) {
   1967                        break;
   1968                    }
   1969                    if (edits != nullptr) {
   1970                        edits->addReplace(static_cast<int32_t>(src - prevSrc), 0);
   1971                    }
   1972                    prevBoundary = src;
   1973                    continue;
   1974                }
   1975            }
   1976            // Other "noNo" type, or need to examine more text around this character:
   1977            // Fall through to the slow path.
   1978        } else if (isJamoVT(norm16)) {
   1979            // Jamo L: E1 84 80..92
   1980            // Jamo V: E1 85 A1..B5
   1981            // Jamo T: E1 86 A8..E1 87 82
   1982            U_ASSERT((src - prevSrc) == 3 && *prevSrc == 0xe1);
   1983            UChar32 prev = previousHangulOrJamo(prevBoundary, prevSrc);
   1984            if (prevSrc[1] == 0x85) {
   1985                // The current character is a Jamo Vowel,
   1986                // compose with previous Jamo L and following Jamo T.
   1987                UChar32 l = prev - Hangul::JAMO_L_BASE;
   1988                if (static_cast<uint32_t>(l) < Hangul::JAMO_L_COUNT) {
   1989                    if (sink == nullptr) {
   1990                        return false;
   1991                    }
   1992                    int32_t t = getJamoTMinusBase(src, limit);
   1993                    if (t >= 0) {
   1994                        // The next character is a Jamo T.
   1995                        src += 3;
   1996                    } else if (hasCompBoundaryBefore(src, limit)) {
   1997                        // No Jamo T follows, not even via decomposition.
   1998                        t = 0;
   1999                    }
   2000                    if (t >= 0) {
   2001                        UChar32 syllable = Hangul::HANGUL_BASE +
   2002                            (l*Hangul::JAMO_V_COUNT + (prevSrc[2]-0xa1)) *
   2003                            Hangul::JAMO_T_COUNT + t;
   2004                        prevSrc -= 3;  // Replace the Jamo L as well.
   2005                        if (prevBoundary != prevSrc &&
   2006                                !ByteSinkUtil::appendUnchanged(prevBoundary, prevSrc,
   2007                                                               *sink, options, edits, errorCode)) {
   2008                            break;
   2009                        }
   2010                        ByteSinkUtil::appendCodePoint(prevSrc, src, syllable, *sink, edits);
   2011                        prevBoundary = src;
   2012                        continue;
   2013                    }
   2014                    // If we see L+V+x where x!=T then we drop to the slow path,
   2015                    // decompose and recompose.
   2016                    // This is to deal with NFKC finding normal L and V but a
   2017                    // compatibility variant of a T.
   2018                    // We need to either fully compose that combination here
   2019                    // (which would complicate the code and may not work with strange custom data)
   2020                    // or use the slow path.
   2021                }
   2022            } else if (Hangul::isHangulLV(prev)) {
   2023                // The current character is a Jamo Trailing consonant,
   2024                // compose with previous Hangul LV that does not contain a Jamo T.
   2025                if (sink == nullptr) {
   2026                    return false;
   2027                }
   2028                UChar32 syllable = prev + getJamoTMinusBase(prevSrc, src);
   2029                prevSrc -= 3;  // Replace the Hangul LV as well.
   2030                if (prevBoundary != prevSrc &&
   2031                        !ByteSinkUtil::appendUnchanged(prevBoundary, prevSrc,
   2032                                                       *sink, options, edits, errorCode)) {
   2033                    break;
   2034                }
   2035                ByteSinkUtil::appendCodePoint(prevSrc, src, syllable, *sink, edits);
   2036                prevBoundary = src;
   2037                continue;
   2038            }
   2039            // No matching context, or may need to decompose surrounding text first:
   2040            // Fall through to the slow path.
   2041        } else if (norm16 > JAMO_VT) {  // norm16 >= MIN_YES_YES_WITH_CC
   2042            // One or more combining marks that do not combine-back:
   2043            // Check for canonical order, copy unchanged if ok and
   2044            // if followed by a character with a boundary-before.
   2045            uint8_t cc = getCCFromNormalYesOrMaybe(norm16);  // cc!=0
   2046            if (onlyContiguous /* FCC */ && getPreviousTrailCC(prevBoundary, prevSrc) > cc) {
   2047                // Fails FCD test, need to decompose and contiguously recompose.
   2048                if (sink == nullptr) {
   2049                    return false;
   2050                }
   2051            } else {
   2052                // If !onlyContiguous (not FCC), then we ignore the tccc of
   2053                // the previous character which passed the quick check "yes && ccc==0" test.
   2054                const uint8_t *nextSrc;
   2055                uint16_t n16;
   2056                for (;;) {
   2057                    if (src == limit) {
   2058                        if (sink != nullptr) {
   2059                            ByteSinkUtil::appendUnchanged(prevBoundary, limit,
   2060                                                          *sink, options, edits, errorCode);
   2061                        }
   2062                        return true;
   2063                    }
   2064                    uint8_t prevCC = cc;
   2065                    nextSrc = src;
   2066                    UCPTRIE_FAST_U8_NEXT(normTrie, UCPTRIE_16, nextSrc, limit, n16);
   2067                    if (n16 >= MIN_YES_YES_WITH_CC) {
   2068                        cc = getCCFromNormalYesOrMaybe(n16);
   2069                        if (prevCC > cc) {
   2070                            if (sink == nullptr) {
   2071                                return false;
   2072                            }
   2073                            break;
   2074                        }
   2075                    } else {
   2076                        break;
   2077                    }
   2078                    src = nextSrc;
   2079                }
   2080                // src is after the last in-order combining mark.
   2081                // If there is a boundary here, then we continue with no change.
   2082                if (norm16HasCompBoundaryBefore(n16)) {
   2083                    if (isCompYesAndZeroCC(n16)) {
   2084                        src = nextSrc;
   2085                    }
   2086                    continue;
   2087                }
   2088                // Use the slow path. There is no boundary in [prevSrc, src[.
   2089            }
   2090        }
   2091 
   2092        // Slow path: Find the nearest boundaries around the current character,
   2093        // decompose and recompose.
   2094        if (prevBoundary != prevSrc && !norm16HasCompBoundaryBefore(norm16)) {
   2095            const uint8_t *p = prevSrc;
   2096            UCPTRIE_FAST_U8_PREV(normTrie, UCPTRIE_16, prevBoundary, p, norm16);
   2097            if (!norm16HasCompBoundaryAfter(norm16, onlyContiguous)) {
   2098                prevSrc = p;
   2099            }
   2100        }
   2101        ReorderingBuffer buffer(*this, s16, errorCode);
   2102        if (U_FAILURE(errorCode)) {
   2103            break;
   2104        }
   2105        // We know there is not a boundary here.
   2106        decomposeShort(prevSrc, src, STOP_AT_LIMIT, onlyContiguous,
   2107                       buffer, errorCode);
   2108        // Decompose until the next boundary.
   2109        src = decomposeShort(src, limit, STOP_AT_COMP_BOUNDARY, onlyContiguous,
   2110                             buffer, errorCode);
   2111        if (U_FAILURE(errorCode)) {
   2112            break;
   2113        }
   2114        if ((src - prevSrc) > INT32_MAX) {  // guard before buffer.equals()
   2115            errorCode = U_INDEX_OUTOFBOUNDS_ERROR;
   2116            return true;
   2117        }
   2118        recompose(buffer, 0, onlyContiguous);
   2119        if (!buffer.equals(prevSrc, src)) {
   2120            if (sink == nullptr) {
   2121                return false;
   2122            }
   2123            if (prevBoundary != prevSrc &&
   2124                    !ByteSinkUtil::appendUnchanged(prevBoundary, prevSrc,
   2125                                                   *sink, options, edits, errorCode)) {
   2126                break;
   2127            }
   2128            if (!ByteSinkUtil::appendChange(prevSrc, src, buffer.getStart(), buffer.length(),
   2129                                            *sink, edits, errorCode)) {
   2130                break;
   2131            }
   2132            prevBoundary = src;
   2133        }
   2134    }
   2135    return true;
   2136 }
   2137 
   2138 UBool Normalizer2Impl::hasCompBoundaryBefore(const char16_t *src, const char16_t *limit) const {
   2139    if (src == limit || *src < minCompNoMaybeCP) {
   2140        return true;
   2141    }
   2142    UChar32 c;
   2143    uint16_t norm16;
   2144    UCPTRIE_FAST_U16_NEXT(normTrie, UCPTRIE_16, src, limit, c, norm16);
   2145    return norm16HasCompBoundaryBefore(norm16);
   2146 }
   2147 
   2148 UBool Normalizer2Impl::hasCompBoundaryBefore(const uint8_t *src, const uint8_t *limit) const {
   2149    if (src == limit) {
   2150        return true;
   2151    }
   2152    uint16_t norm16;
   2153    UCPTRIE_FAST_U8_NEXT(normTrie, UCPTRIE_16, src, limit, norm16);
   2154    return norm16HasCompBoundaryBefore(norm16);
   2155 }
   2156 
   2157 UBool Normalizer2Impl::hasCompBoundaryAfter(const char16_t *start, const char16_t *p,
   2158                                            UBool onlyContiguous) const {
   2159    if (start == p) {
   2160        return true;
   2161    }
   2162    UChar32 c;
   2163    uint16_t norm16;
   2164    UCPTRIE_FAST_U16_PREV(normTrie, UCPTRIE_16, start, p, c, norm16);
   2165    return norm16HasCompBoundaryAfter(norm16, onlyContiguous);
   2166 }
   2167 
   2168 UBool Normalizer2Impl::hasCompBoundaryAfter(const uint8_t *start, const uint8_t *p,
   2169                                            UBool onlyContiguous) const {
   2170    if (start == p) {
   2171        return true;
   2172    }
   2173    uint16_t norm16;
   2174    UCPTRIE_FAST_U8_PREV(normTrie, UCPTRIE_16, start, p, norm16);
   2175    return norm16HasCompBoundaryAfter(norm16, onlyContiguous);
   2176 }
   2177 
   2178 const char16_t *Normalizer2Impl::findPreviousCompBoundary(const char16_t *start, const char16_t *p,
   2179                                                       UBool onlyContiguous) const {
   2180    while (p != start) {
   2181        const char16_t *codePointLimit = p;
   2182        UChar32 c;
   2183        uint16_t norm16;
   2184        UCPTRIE_FAST_U16_PREV(normTrie, UCPTRIE_16, start, p, c, norm16);
   2185        if (norm16HasCompBoundaryAfter(norm16, onlyContiguous)) {
   2186            return codePointLimit;
   2187        }
   2188        if (hasCompBoundaryBefore(c, norm16)) {
   2189            return p;
   2190        }
   2191    }
   2192    return p;
   2193 }
   2194 
   2195 const char16_t *Normalizer2Impl::findNextCompBoundary(const char16_t *p, const char16_t *limit,
   2196                                                   UBool onlyContiguous) const {
   2197    while (p != limit) {
   2198        const char16_t *codePointStart = p;
   2199        UChar32 c;
   2200        uint16_t norm16;
   2201        UCPTRIE_FAST_U16_NEXT(normTrie, UCPTRIE_16, p, limit, c, norm16);
   2202        if (hasCompBoundaryBefore(c, norm16)) {
   2203            return codePointStart;
   2204        }
   2205        if (norm16HasCompBoundaryAfter(norm16, onlyContiguous)) {
   2206            return p;
   2207        }
   2208    }
   2209    return p;
   2210 }
   2211 
   2212 uint8_t Normalizer2Impl::getPreviousTrailCC(const char16_t *start, const char16_t *p) const {
   2213    if (start == p) {
   2214        return 0;
   2215    }
   2216    int32_t i = static_cast<int32_t>(p - start);
   2217    UChar32 c;
   2218    U16_PREV(start, 0, i, c);
   2219    return static_cast<uint8_t>(getFCD16(c));
   2220 }
   2221 
   2222 uint8_t Normalizer2Impl::getPreviousTrailCC(const uint8_t *start, const uint8_t *p) const {
   2223    if (start == p) {
   2224        return 0;
   2225    }
   2226    int32_t i = static_cast<int32_t>(p - start);
   2227    UChar32 c;
   2228    U8_PREV(start, 0, i, c);
   2229    return static_cast<uint8_t>(getFCD16(c));
   2230 }
   2231 
   2232 // Note: normalizer2impl.cpp r30982 (2011-nov-27)
   2233 // still had getFCDTrie() which built and cached an FCD trie.
   2234 // That provided faster access to FCD data than getFCD16FromNormData()
   2235 // but required synchronization and consumed some 10kB of heap memory
   2236 // in any process that uses FCD (e.g., via collation).
   2237 // minDecompNoCP etc. and smallFCD[] are intended to help with any loss of performance,
   2238 // at least for ASCII & CJK.
   2239 
   2240 // Ticket 20907 - The optimizer in MSVC/Visual Studio versions below 16.4 has trouble with this
   2241 // function on Windows ARM64. As a work-around, we disable optimizations for this function.
   2242 // This work-around could/should be removed once the following versions of Visual Studio are no
   2243 // longer supported: All versions of VS2017, and versions of VS2019 below 16.4.
   2244 #if (defined(_MSC_VER) && (defined(_M_ARM64)) && (_MSC_VER < 1924))
   2245 #pragma optimize( "", off )
   2246 #endif
   2247 // Gets the FCD value from the regular normalization data.
   2248 uint16_t Normalizer2Impl::getFCD16FromNormData(UChar32 c) const {
   2249    uint16_t norm16=getNorm16(c);
   2250    if (norm16 >= limitNoNo) {
   2251        if(norm16>=MIN_NORMAL_MAYBE_YES) {
   2252            // combining mark
   2253            norm16=getCCFromNormalYesOrMaybe(norm16);
   2254            return norm16|(norm16<<8);
   2255        } else if(norm16>=minMaybeYes) {
   2256            return 0;
   2257        } else if(norm16<minMaybeNo) {  // isDecompNoAlgorithmic(norm16)
   2258            uint16_t deltaTrailCC = norm16 & DELTA_TCCC_MASK;
   2259            if (deltaTrailCC <= DELTA_TCCC_1) {
   2260                return deltaTrailCC >> OFFSET_SHIFT;
   2261            }
   2262            // Maps to an isCompYesAndZeroCC.
   2263            c=mapAlgorithmic(c, norm16);
   2264            norm16=getRawNorm16(c);
   2265        }
   2266    }
   2267    if(norm16<=minYesNo || isHangulLVT(norm16)) {
   2268        // no decomposition or Hangul syllable, all zeros
   2269        return 0;
   2270    }
   2271    // c decomposes, get everything from the variable-length extra data
   2272    const uint16_t *mapping=getData(norm16);
   2273    uint16_t firstUnit=*mapping;
   2274    norm16=firstUnit>>8;  // tccc
   2275    if(firstUnit&MAPPING_HAS_CCC_LCCC_WORD) {
   2276        norm16|=*(mapping-1)&0xff00;  // lccc
   2277    }
   2278    return norm16;
   2279 }
   2280 #if (defined(_MSC_VER) && (defined(_M_ARM64)) && (_MSC_VER < 1924))
   2281 #pragma optimize( "", on )
   2282 #endif
   2283 
   2284 uint16_t Normalizer2Impl::getFCD16FromMaybeOrNonZeroCC(uint16_t norm16) const {
   2285    U_ASSERT(norm16 >= minMaybeNo);
   2286    if (norm16 >= MIN_NORMAL_MAYBE_YES) {
   2287        // combining mark
   2288        norm16 = getCCFromNormalYesOrMaybe(norm16);
   2289        return norm16 | (norm16<<8);
   2290    } else if (norm16 >= minMaybeYes) {
   2291        return 0;
   2292    }
   2293    // c decomposes, get everything from the variable-length extra data
   2294    const uint16_t *mapping = getDataForMaybe(norm16);
   2295    uint16_t firstUnit = *mapping;
   2296    // maybeNo has lccc = 0
   2297    U_ASSERT((firstUnit & MAPPING_HAS_CCC_LCCC_WORD) == 0 || (*(mapping - 1) & 0xff00) == 0);
   2298    return firstUnit >> 8;  // tccc
   2299 }
   2300 
   2301 // Dual functionality:
   2302 // buffer!=nullptr: normalize
   2303 // buffer==nullptr: isNormalized/quickCheck/spanQuickCheckYes
   2304 const char16_t *
   2305 Normalizer2Impl::makeFCD(const char16_t *src, const char16_t *limit,
   2306                         ReorderingBuffer *buffer,
   2307                         UErrorCode &errorCode) const {
   2308    // Tracks the last FCD-safe boundary, before lccc=0 or after properly-ordered tccc<=1.
   2309    // Similar to the prevBoundary in the compose() implementation.
   2310    const char16_t *prevBoundary=src;
   2311    int32_t prevFCD16=0;
   2312    if(limit==nullptr) {
   2313        src=copyLowPrefixFromNulTerminated(src, minLcccCP, buffer, errorCode);
   2314        if(U_FAILURE(errorCode)) {
   2315            return src;
   2316        }
   2317        if(prevBoundary<src) {
   2318            prevBoundary=src;
   2319            // We know that the previous character's lccc==0.
   2320            // Fetching the fcd16 value was deferred for this below-U+0300 code point.
   2321            prevFCD16=getFCD16(*(src-1));
   2322            if(prevFCD16>1) {
   2323                --prevBoundary;
   2324            }
   2325        }
   2326        limit=u_strchr(src, 0);
   2327    }
   2328 
   2329    // Note: In this function we use buffer->appendZeroCC() because we track
   2330    // the lead and trail combining classes here, rather than leaving it to
   2331    // the ReorderingBuffer.
   2332    // The exception is the call to decomposeShort() which uses the buffer
   2333    // in the normal way.
   2334 
   2335    const char16_t *prevSrc;
   2336    UChar32 c=0;
   2337    uint16_t fcd16=0;
   2338 
   2339    for(;;) {
   2340        // count code units with lccc==0
   2341        for(prevSrc=src; src!=limit;) {
   2342            if((c=*src)<minLcccCP) {
   2343                prevFCD16=~c;
   2344                ++src;
   2345            } else if(!singleLeadMightHaveNonZeroFCD16(c)) {
   2346                prevFCD16=0;
   2347                ++src;
   2348            } else {
   2349                if(U16_IS_LEAD(c)) {
   2350                    char16_t c2;
   2351                    if((src+1)!=limit && U16_IS_TRAIL(c2=src[1])) {
   2352                        c=U16_GET_SUPPLEMENTARY(c, c2);
   2353                    }
   2354                }
   2355                if((fcd16=getFCD16FromNormData(c))<=0xff) {
   2356                    prevFCD16=fcd16;
   2357                    src+=U16_LENGTH(c);
   2358                } else {
   2359                    break;
   2360                }
   2361            }
   2362        }
   2363        // copy these code units all at once
   2364        if(src!=prevSrc) {
   2365            if(buffer!=nullptr && !buffer->appendZeroCC(prevSrc, src, errorCode)) {
   2366                break;
   2367            }
   2368            if(src==limit) {
   2369                break;
   2370            }
   2371            prevBoundary=src;
   2372            // We know that the previous character's lccc==0.
   2373            if(prevFCD16<0) {
   2374                // Fetching the fcd16 value was deferred for this below-minLcccCP code point.
   2375                UChar32 prev=~prevFCD16;
   2376                if(prev<minDecompNoCP) {
   2377                    prevFCD16=0;
   2378                } else {
   2379                    prevFCD16=getFCD16FromNormData(prev);
   2380                    if(prevFCD16>1) {
   2381                        --prevBoundary;
   2382                    }
   2383                }
   2384            } else {
   2385                const char16_t *p=src-1;
   2386                if(U16_IS_TRAIL(*p) && prevSrc<p && U16_IS_LEAD(*(p-1))) {
   2387                    --p;
   2388                    // Need to fetch the previous character's FCD value because
   2389                    // prevFCD16 was just for the trail surrogate code point.
   2390                    prevFCD16=getFCD16FromNormData(U16_GET_SUPPLEMENTARY(p[0], p[1]));
   2391                    // Still known to have lccc==0 because its lead surrogate unit had lccc==0.
   2392                }
   2393                if(prevFCD16>1) {
   2394                    prevBoundary=p;
   2395                }
   2396            }
   2397            // The start of the current character (c).
   2398            prevSrc=src;
   2399        } else if(src==limit) {
   2400            break;
   2401        }
   2402 
   2403        src+=U16_LENGTH(c);
   2404        // The current character (c) at [prevSrc..src[ has a non-zero lead combining class.
   2405        // Check for proper order, and decompose locally if necessary.
   2406        if((prevFCD16&0xff)<=(fcd16>>8)) {
   2407            // proper order: prev tccc <= current lccc
   2408            if((fcd16&0xff)<=1) {
   2409                prevBoundary=src;
   2410            }
   2411            if(buffer!=nullptr && !buffer->appendZeroCC(c, errorCode)) {
   2412                break;
   2413            }
   2414            prevFCD16=fcd16;
   2415            continue;
   2416        } else if(buffer==nullptr) {
   2417            return prevBoundary;  // quick check "no"
   2418        } else {
   2419            /*
   2420             * Back out the part of the source that we copied or appended
   2421             * already but is now going to be decomposed.
   2422             * prevSrc is set to after what was copied/appended.
   2423             */
   2424            buffer->removeSuffix(static_cast<int32_t>(prevSrc - prevBoundary));
   2425            /*
   2426             * Find the part of the source that needs to be decomposed,
   2427             * up to the next safe boundary.
   2428             */
   2429            src=findNextFCDBoundary(src, limit);
   2430            /*
   2431             * The source text does not fulfill the conditions for FCD.
   2432             * Decompose and reorder a limited piece of the text.
   2433             */
   2434            decomposeShort(prevBoundary, src, false, false, *buffer, errorCode);
   2435            if (U_FAILURE(errorCode)) {
   2436                break;
   2437            }
   2438            prevBoundary=src;
   2439            prevFCD16=0;
   2440        }
   2441    }
   2442    return src;
   2443 }
   2444 
   2445 void Normalizer2Impl::makeFCDAndAppend(const char16_t *src, const char16_t *limit,
   2446                                       UBool doMakeFCD,
   2447                                       UnicodeString &safeMiddle,
   2448                                       ReorderingBuffer &buffer,
   2449                                       UErrorCode &errorCode) const {
   2450    if(!buffer.isEmpty()) {
   2451        const char16_t *firstBoundaryInSrc=findNextFCDBoundary(src, limit);
   2452        if(src!=firstBoundaryInSrc) {
   2453            const char16_t *lastBoundaryInDest=findPreviousFCDBoundary(buffer.getStart(),
   2454                                                                    buffer.getLimit());
   2455            int32_t destSuffixLength = static_cast<int32_t>(buffer.getLimit() - lastBoundaryInDest);
   2456            UnicodeString middle(lastBoundaryInDest, destSuffixLength);
   2457            buffer.removeSuffix(destSuffixLength);
   2458            safeMiddle=middle;
   2459            middle.append(src, static_cast<int32_t>(firstBoundaryInSrc - src));
   2460            const char16_t *middleStart=middle.getBuffer();
   2461            makeFCD(middleStart, middleStart+middle.length(), &buffer, errorCode);
   2462            if(U_FAILURE(errorCode)) {
   2463                return;
   2464            }
   2465            src=firstBoundaryInSrc;
   2466        }
   2467    }
   2468    if(doMakeFCD) {
   2469        makeFCD(src, limit, &buffer, errorCode);
   2470    } else {
   2471        if(limit==nullptr) {  // appendZeroCC() needs limit!=nullptr
   2472            limit=u_strchr(src, 0);
   2473        }
   2474        buffer.appendZeroCC(src, limit, errorCode);
   2475    }
   2476 }
   2477 
   2478 const char16_t *Normalizer2Impl::findPreviousFCDBoundary(const char16_t *start, const char16_t *p) const {
   2479    while(start<p) {
   2480        const char16_t *codePointLimit = p;
   2481        UChar32 c;
   2482        uint16_t norm16;
   2483        UCPTRIE_FAST_U16_PREV(normTrie, UCPTRIE_16, start, p, c, norm16);
   2484        if (c < minDecompNoCP || norm16HasDecompBoundaryAfter(norm16)) {
   2485            return codePointLimit;
   2486        }
   2487        if (norm16HasDecompBoundaryBefore(norm16)) {
   2488            return p;
   2489        }
   2490    }
   2491    return p;
   2492 }
   2493 
   2494 const char16_t *Normalizer2Impl::findNextFCDBoundary(const char16_t *p, const char16_t *limit) const {
   2495    while(p<limit) {
   2496        const char16_t *codePointStart=p;
   2497        UChar32 c;
   2498        uint16_t norm16;
   2499        UCPTRIE_FAST_U16_NEXT(normTrie, UCPTRIE_16, p, limit, c, norm16);
   2500        if (c < minLcccCP || norm16HasDecompBoundaryBefore(norm16)) {
   2501            return codePointStart;
   2502        }
   2503        if (norm16HasDecompBoundaryAfter(norm16)) {
   2504            return p;
   2505        }
   2506    }
   2507    return p;
   2508 }
   2509 
   2510 // CanonicalIterator data -------------------------------------------------- ***
   2511 
   2512 CanonIterData::CanonIterData(UErrorCode &errorCode) :
   2513        mutableTrie(umutablecptrie_open(0, 0, &errorCode)), trie(nullptr),
   2514        canonStartSets(uprv_deleteUObject, nullptr, errorCode) {}
   2515 
   2516 CanonIterData::~CanonIterData() {
   2517    umutablecptrie_close(mutableTrie);
   2518    ucptrie_close(trie);
   2519 }
   2520 
   2521 void CanonIterData::addToStartSet(UChar32 origin, UChar32 decompLead, UErrorCode &errorCode) {
   2522    uint32_t canonValue = umutablecptrie_get(mutableTrie, decompLead);
   2523    if((canonValue&(CANON_HAS_SET|CANON_VALUE_MASK))==0 && origin!=0) {
   2524        // origin is the first character whose decomposition starts with
   2525        // the character for which we are setting the value.
   2526        umutablecptrie_set(mutableTrie, decompLead, canonValue|origin, &errorCode);
   2527    } else {
   2528        // origin is not the first character, or it is U+0000.
   2529        UnicodeSet *set;
   2530        if((canonValue&CANON_HAS_SET)==0) {
   2531            LocalPointer<UnicodeSet> lpSet(new UnicodeSet, errorCode);
   2532            set=lpSet.getAlias();
   2533            if(U_FAILURE(errorCode)) {
   2534                return;
   2535            }
   2536            UChar32 firstOrigin = static_cast<UChar32>(canonValue & CANON_VALUE_MASK);
   2537            canonValue = (canonValue & ~CANON_VALUE_MASK) | CANON_HAS_SET | static_cast<uint32_t>(canonStartSets.size());
   2538            umutablecptrie_set(mutableTrie, decompLead, canonValue, &errorCode);
   2539            canonStartSets.adoptElement(lpSet.orphan(), errorCode);
   2540            if (U_FAILURE(errorCode)) {
   2541                return;
   2542            }
   2543            if(firstOrigin!=0) {
   2544                set->add(firstOrigin);
   2545            }
   2546        } else {
   2547            set = static_cast<UnicodeSet*>(canonStartSets[static_cast<int32_t>(canonValue & CANON_VALUE_MASK)]);
   2548        }
   2549        set->add(origin);
   2550    }
   2551 }
   2552 
   2553 // C++ class for friend access to private Normalizer2Impl members.
   2554 class InitCanonIterData {
   2555 public:
   2556    static void doInit(Normalizer2Impl *impl, UErrorCode &errorCode);
   2557 };
   2558 
   2559 U_CDECL_BEGIN
   2560 
   2561 // UInitOnce instantiation function for CanonIterData
   2562 static void U_CALLCONV
   2563 initCanonIterData(Normalizer2Impl *impl, UErrorCode &errorCode) {
   2564    InitCanonIterData::doInit(impl, errorCode);
   2565 }
   2566 
   2567 U_CDECL_END
   2568 
   2569 void InitCanonIterData::doInit(Normalizer2Impl *impl, UErrorCode &errorCode) {
   2570    U_ASSERT(impl->fCanonIterData == nullptr);
   2571    impl->fCanonIterData = new CanonIterData(errorCode);
   2572    if (impl->fCanonIterData == nullptr) {
   2573        errorCode=U_MEMORY_ALLOCATION_ERROR;
   2574    }
   2575    if (U_SUCCESS(errorCode)) {
   2576        UChar32 start = 0, end;
   2577        uint32_t value;
   2578        while ((end = ucptrie_getRange(impl->normTrie, start,
   2579                                       UCPMAP_RANGE_FIXED_LEAD_SURROGATES, Normalizer2Impl::INERT,
   2580                                       nullptr, nullptr, &value)) >= 0) {
   2581            // Call Normalizer2Impl::makeCanonIterDataFromNorm16() for a range of same-norm16 characters.
   2582            if (value != Normalizer2Impl::INERT) {
   2583                impl->makeCanonIterDataFromNorm16(start, end, value, *impl->fCanonIterData, errorCode);
   2584            }
   2585            start = end + 1;
   2586        }
   2587 #ifdef UCPTRIE_DEBUG
   2588        umutablecptrie_setName(impl->fCanonIterData->mutableTrie, "CanonIterData");
   2589 #endif
   2590        impl->fCanonIterData->trie = umutablecptrie_buildImmutable(
   2591            impl->fCanonIterData->mutableTrie, UCPTRIE_TYPE_SMALL, UCPTRIE_VALUE_BITS_32, &errorCode);
   2592        umutablecptrie_close(impl->fCanonIterData->mutableTrie);
   2593        impl->fCanonIterData->mutableTrie = nullptr;
   2594    }
   2595    if (U_FAILURE(errorCode)) {
   2596        delete impl->fCanonIterData;
   2597        impl->fCanonIterData = nullptr;
   2598    }
   2599 }
   2600 
   2601 void Normalizer2Impl::makeCanonIterDataFromNorm16(UChar32 start, UChar32 end, const uint16_t norm16,
   2602                                                  CanonIterData &newData,
   2603                                                  UErrorCode &errorCode) const {
   2604    if(isInert(norm16) ||
   2605            (minYesNo<=norm16 && norm16<minNoNo) ||
   2606            (minMaybeNo<=norm16 && norm16<minMaybeYes)) {
   2607        // Inert, or 2-way mapping (including Hangul syllable).
   2608        // We do not write a canonStartSet for any yesNo/maybeNo character.
   2609        // Composites from 2-way mappings are added at runtime from the
   2610        // starter's compositions list, and the other characters in
   2611        // 2-way mappings get CANON_NOT_SEGMENT_STARTER set because they are
   2612        // "maybe" characters.
   2613        return;
   2614    }
   2615    for(UChar32 c=start; c<=end; ++c) {
   2616        uint32_t oldValue = umutablecptrie_get(newData.mutableTrie, c);
   2617        uint32_t newValue=oldValue;
   2618        if(isMaybeYesOrNonZeroCC(norm16)) {
   2619            // not a segment starter if it occurs in a decomposition or has cc!=0
   2620            newValue|=CANON_NOT_SEGMENT_STARTER;
   2621            if(norm16<MIN_NORMAL_MAYBE_YES) {
   2622                newValue|=CANON_HAS_COMPOSITIONS;
   2623            }
   2624        } else if(norm16<minYesNo) {
   2625            newValue|=CANON_HAS_COMPOSITIONS;
   2626        } else {
   2627            // c has a one-way decomposition
   2628            UChar32 c2=c;
   2629            // Do not modify the whole-range norm16 value.
   2630            uint16_t norm16_2=norm16;
   2631            if (isDecompNoAlgorithmic(norm16_2)) {
   2632                // Maps to an isCompYesAndZeroCC.
   2633                c2 = mapAlgorithmic(c2, norm16_2);
   2634                norm16_2 = getRawNorm16(c2);
   2635                // No compatibility mappings for the CanonicalIterator.
   2636                U_ASSERT(!(isHangulLV(norm16_2) || isHangulLVT(norm16_2)));
   2637            }
   2638            if (norm16_2 > minYesNo) {
   2639                // c decomposes, get everything from the variable-length extra data
   2640                const uint16_t *mapping=getDataForYesOrNo(norm16_2);
   2641                uint16_t firstUnit=*mapping;
   2642                int32_t length=firstUnit&MAPPING_LENGTH_MASK;
   2643                if((firstUnit&MAPPING_HAS_CCC_LCCC_WORD)!=0) {
   2644                    if(c==c2 && (*(mapping-1)&0xff)!=0) {
   2645                        newValue|=CANON_NOT_SEGMENT_STARTER;  // original c has cc!=0
   2646                    }
   2647                }
   2648                // Skip empty mappings (no characters in the decomposition).
   2649                if(length!=0) {
   2650                    ++mapping;  // skip over the firstUnit
   2651                    // add c to first code point's start set
   2652                    int32_t i=0;
   2653                    U16_NEXT_UNSAFE(mapping, i, c2);
   2654                    newData.addToStartSet(c, c2, errorCode);
   2655                    // Set CANON_NOT_SEGMENT_STARTER for each remaining code point of a
   2656                    // one-way mapping. A 2-way mapping is possible here after
   2657                    // intermediate algorithmic mapping.
   2658                    if(norm16_2>=minNoNo) {
   2659                        while(i<length) {
   2660                            U16_NEXT_UNSAFE(mapping, i, c2);
   2661                            uint32_t c2Value = umutablecptrie_get(newData.mutableTrie, c2);
   2662                            if((c2Value&CANON_NOT_SEGMENT_STARTER)==0) {
   2663                                umutablecptrie_set(newData.mutableTrie, c2,
   2664                                                   c2Value|CANON_NOT_SEGMENT_STARTER, &errorCode);
   2665                            }
   2666                        }
   2667                    }
   2668                }
   2669            } else {
   2670                // c decomposed to c2 algorithmically; c has cc==0
   2671                newData.addToStartSet(c, c2, errorCode);
   2672            }
   2673        }
   2674        if(newValue!=oldValue) {
   2675            umutablecptrie_set(newData.mutableTrie, c, newValue, &errorCode);
   2676        }
   2677    }
   2678 }
   2679 
   2680 UBool Normalizer2Impl::ensureCanonIterData(UErrorCode &errorCode) const {
   2681    // Logically const: Synchronized instantiation.
   2682    Normalizer2Impl *me=const_cast<Normalizer2Impl *>(this);
   2683    umtx_initOnce(me->fCanonIterDataInitOnce, &initCanonIterData, me, errorCode);
   2684    return U_SUCCESS(errorCode);
   2685 }
   2686 
   2687 int32_t Normalizer2Impl::getCanonValue(UChar32 c) const {
   2688    return static_cast<int32_t>(ucptrie_get(fCanonIterData->trie, c));
   2689 }
   2690 
   2691 const UnicodeSet &Normalizer2Impl::getCanonStartSet(int32_t n) const {
   2692    return *static_cast<const UnicodeSet*>(fCanonIterData->canonStartSets[n]);
   2693 }
   2694 
   2695 UBool Normalizer2Impl::isCanonSegmentStarter(UChar32 c) const {
   2696    return getCanonValue(c)>=0;
   2697 }
   2698 
   2699 UBool Normalizer2Impl::getCanonStartSet(UChar32 c, UnicodeSet &set) const {
   2700    int32_t canonValue=getCanonValue(c)&~CANON_NOT_SEGMENT_STARTER;
   2701    if(canonValue==0) {
   2702        return false;
   2703    }
   2704    set.clear();
   2705    int32_t value=canonValue&CANON_VALUE_MASK;
   2706    if((canonValue&CANON_HAS_SET)!=0) {
   2707        set.addAll(getCanonStartSet(value));
   2708    } else if(value!=0) {
   2709        set.add(value);
   2710    }
   2711    if((canonValue&CANON_HAS_COMPOSITIONS)!=0) {
   2712        uint16_t norm16=getRawNorm16(c);
   2713        if(norm16==JAMO_L) {
   2714            UChar32 syllable=
   2715                static_cast<UChar32>(Hangul::HANGUL_BASE + (c - Hangul::JAMO_L_BASE) * Hangul::JAMO_VT_COUNT);
   2716            set.add(syllable, syllable+Hangul::JAMO_VT_COUNT-1);
   2717        } else {
   2718            addComposites(getCompositionsList(norm16), set);
   2719        }
   2720    }
   2721    return true;
   2722 }
   2723 
   2724 U_NAMESPACE_END
   2725 
   2726 // Normalizer2 data swapping ----------------------------------------------- ***
   2727 
   2728 U_NAMESPACE_USE
   2729 
   2730 U_CAPI int32_t U_EXPORT2
   2731 unorm2_swap(const UDataSwapper *ds,
   2732            const void *inData, int32_t length, void *outData,
   2733            UErrorCode *pErrorCode) {
   2734    const UDataInfo *pInfo;
   2735    int32_t headerSize;
   2736 
   2737    const uint8_t *inBytes;
   2738    uint8_t *outBytes;
   2739 
   2740    const int32_t *inIndexes;
   2741    int32_t indexes[Normalizer2Impl::IX_TOTAL_SIZE+1];
   2742 
   2743    int32_t i, offset, nextOffset, size;
   2744 
   2745    /* udata_swapDataHeader checks the arguments */
   2746    headerSize=udata_swapDataHeader(ds, inData, length, outData, pErrorCode);
   2747    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
   2748        return 0;
   2749    }
   2750 
   2751    /* check data format and format version */
   2752    pInfo=(const UDataInfo *)((const char *)inData+4);
   2753    uint8_t formatVersion0=pInfo->formatVersion[0];
   2754    if(!(
   2755        pInfo->dataFormat[0]==0x4e &&   /* dataFormat="Nrm2" */
   2756        pInfo->dataFormat[1]==0x72 &&
   2757        pInfo->dataFormat[2]==0x6d &&
   2758        pInfo->dataFormat[3]==0x32 &&
   2759        (1<=formatVersion0 && formatVersion0<=5)
   2760    )) {
   2761        udata_printError(ds, "unorm2_swap(): data format %02x.%02x.%02x.%02x (format version %02x) is not recognized as Normalizer2 data\n",
   2762                         pInfo->dataFormat[0], pInfo->dataFormat[1],
   2763                         pInfo->dataFormat[2], pInfo->dataFormat[3],
   2764                         pInfo->formatVersion[0]);
   2765        *pErrorCode=U_UNSUPPORTED_ERROR;
   2766        return 0;
   2767    }
   2768 
   2769    inBytes=(const uint8_t *)inData+headerSize;
   2770    outBytes=(outData == nullptr) ? nullptr : (uint8_t *)outData+headerSize;
   2771 
   2772    inIndexes=(const int32_t *)inBytes;
   2773    int32_t minIndexesLength;
   2774    if(formatVersion0==1) {
   2775        minIndexesLength=Normalizer2Impl::IX_MIN_MAYBE_YES+1;
   2776    } else if(formatVersion0==2) {
   2777        minIndexesLength=Normalizer2Impl::IX_MIN_YES_NO_MAPPINGS_ONLY+1;
   2778    } else if(formatVersion0<=4) {
   2779        minIndexesLength=Normalizer2Impl::IX_MIN_LCCC_CP+1;
   2780    } else {
   2781        minIndexesLength=Normalizer2Impl::IX_MIN_MAYBE_NO_COMBINES_FWD+1;
   2782    }
   2783 
   2784    if(length>=0) {
   2785        length-=headerSize;
   2786        if(length<minIndexesLength*4) {
   2787            udata_printError(ds, "unorm2_swap(): too few bytes (%d after header) for Normalizer2 data\n",
   2788                             length);
   2789            *pErrorCode=U_INDEX_OUTOFBOUNDS_ERROR;
   2790            return 0;
   2791        }
   2792    }
   2793 
   2794    /* read the first few indexes */
   2795    for(i=0; i<UPRV_LENGTHOF(indexes); ++i) {
   2796        indexes[i]=udata_readInt32(ds, inIndexes[i]);
   2797    }
   2798 
   2799    /* get the total length of the data */
   2800    size=indexes[Normalizer2Impl::IX_TOTAL_SIZE];
   2801 
   2802    if(length>=0) {
   2803        if(length<size) {
   2804            udata_printError(ds, "unorm2_swap(): too few bytes (%d after header) for all of Normalizer2 data\n",
   2805                             length);
   2806            *pErrorCode=U_INDEX_OUTOFBOUNDS_ERROR;
   2807            return 0;
   2808        }
   2809 
   2810        /* copy the data for inaccessible bytes */
   2811        if(inBytes!=outBytes) {
   2812            uprv_memcpy(outBytes, inBytes, size);
   2813        }
   2814 
   2815        offset=0;
   2816 
   2817        /* swap the int32_t indexes[] */
   2818        nextOffset=indexes[Normalizer2Impl::IX_NORM_TRIE_OFFSET];
   2819        ds->swapArray32(ds, inBytes, nextOffset-offset, outBytes, pErrorCode);
   2820        offset=nextOffset;
   2821 
   2822        /* swap the trie */
   2823        nextOffset=indexes[Normalizer2Impl::IX_EXTRA_DATA_OFFSET];
   2824        utrie_swapAnyVersion(ds, inBytes+offset, nextOffset-offset, outBytes+offset, pErrorCode);
   2825        offset=nextOffset;
   2826 
   2827        /* swap the uint16_t extraData[] */
   2828        nextOffset=indexes[Normalizer2Impl::IX_SMALL_FCD_OFFSET];
   2829        ds->swapArray16(ds, inBytes+offset, nextOffset-offset, outBytes+offset, pErrorCode);
   2830        offset=nextOffset;
   2831 
   2832        /* no need to swap the uint8_t smallFCD[] (new in formatVersion 2) */
   2833        nextOffset=indexes[Normalizer2Impl::IX_SMALL_FCD_OFFSET+1];
   2834        offset=nextOffset;
   2835 
   2836        U_ASSERT(offset==size);
   2837    }
   2838 
   2839    return headerSize+size;
   2840 }
   2841 
   2842 #endif  // !UCONFIG_NO_NORMALIZATION
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