DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Mercurial (31ec81b5d7bb)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827
/*
 ******************************************************************************
 *   Copyright (C) 1996-2012, International Business Machines                 *
 *   Corporation and others.  All Rights Reserved.                            *
 ******************************************************************************
 */

#include "unicode/utypes.h"

#if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION

#include "unicode/unistr.h"
#include "unicode/putil.h"
#include "unicode/usearch.h"

#include "cmemory.h"
#include "unicode/coll.h"
#include "unicode/tblcoll.h"
#include "unicode/coleitr.h"
#include "unicode/ucoleitr.h"

#include "unicode/regex.h"        // TODO: make conditional on regexp being built.

#include "unicode/uniset.h"
#include "unicode/uset.h"
#include "unicode/ustring.h"
#include "hash.h"
#include "uhash.h"
#include "ucol_imp.h"
#include "normalizer2impl.h"

#include "unicode/colldata.h"
#include "unicode/bmsearch.h"

U_NAMESPACE_BEGIN

#define ARRAY_SIZE(array) (sizeof(array)/sizeof(array[0]))
#define NEW_ARRAY(type, count) (type *) uprv_malloc((count) * sizeof(type))
#define DELETE_ARRAY(array) uprv_free((void *) (array))


struct CEI
{
    uint32_t order;
    int32_t  lowOffset;
    int32_t  highOffset;
};

class Target : public UMemory
{
public:
    Target(UCollator *theCollator, const UnicodeString *target, int32_t patternLength, UErrorCode &status);
    ~Target();

    void setTargetString(const UnicodeString *target);

    const CEI *nextCE(int32_t offset);
    const CEI *prevCE(int32_t offset);

    int32_t stringLength();
    UChar charAt(int32_t offset);

    UBool isBreakBoundary(int32_t offset);
    int32_t nextBreakBoundary(int32_t offset);
    int32_t nextSafeBoundary(int32_t offset);

    UBool isIdentical(UnicodeString &pattern, int32_t start, int32_t end);

    void setOffset(int32_t offset);
    void setLast(int32_t last);
    int32_t getOffset();

private:
    CEI *ceb;
    int32_t bufferSize;
    int32_t bufferMin;
    int32_t bufferMax;

    uint32_t strengthMask;
    UCollationStrength strength;
    uint32_t variableTop;
    UBool toShift;
    UCollator *coll;
    const Normalizer2 &nfd;

    const UnicodeString *targetString;
    const UChar *targetBuffer;
    int32_t targetLength;

    UCollationElements *elements;
    UBreakIterator *charBreakIterator;
};

Target::Target(UCollator *theCollator, const UnicodeString *target, int32_t patternLength, UErrorCode &status)
    : bufferSize(0), bufferMin(0), bufferMax(0),
      strengthMask(0), strength(UCOL_PRIMARY), variableTop(0), toShift(FALSE), coll(theCollator),
      nfd(*Normalizer2Factory::getNFDInstance(status)),
      targetString(NULL), targetBuffer(NULL), targetLength(0), elements(NULL), charBreakIterator(NULL)
{
    strength = ucol_getStrength(coll);
    toShift = ucol_getAttribute(coll, UCOL_ALTERNATE_HANDLING, &status) ==  UCOL_SHIFTED;
    variableTop = ucol_getVariableTop(coll, &status);

    // find the largest expansion
    uint8_t maxExpansion = 0;
    for (const uint8_t *expansion = coll->expansionCESize; *expansion != 0; expansion += 1) {
        if (*expansion > maxExpansion) {
            maxExpansion = *expansion;
        }
    }

    // room for an extra character on each end, plus 4 for safety
    bufferSize = patternLength + (2 * maxExpansion) + 4;

    ceb = NEW_ARRAY(CEI, bufferSize);

    if (ceb == NULL) {
        status = U_MEMORY_ALLOCATION_ERROR;
        return;
    }

    if (target != NULL) {
        setTargetString(target);
    }

    switch (strength)
    {
    default:
        strengthMask |= UCOL_TERTIARYORDERMASK;
        /* fall through */

    case UCOL_SECONDARY:
        strengthMask |= UCOL_SECONDARYORDERMASK;
        /* fall through */

    case UCOL_PRIMARY:
        strengthMask |= UCOL_PRIMARYORDERMASK;
    }
}

Target::~Target()
{
    ubrk_close(charBreakIterator);
    ucol_closeElements(elements);

    DELETE_ARRAY(ceb);
}

void Target::setTargetString(const UnicodeString *target)
{
    if (charBreakIterator != NULL) {
        ubrk_close(charBreakIterator);
        ucol_closeElements(elements);
    }

    targetString = target;

    if (targetString != NULL) {
        UErrorCode status = U_ZERO_ERROR;

        targetBuffer = targetString->getBuffer();
        targetLength = targetString->length();

        elements = ucol_openElements(coll, target->getBuffer(), target->length(), &status);
        ucol_forceHanImplicit(elements, &status);

        charBreakIterator = ubrk_open(UBRK_CHARACTER, ucol_getLocaleByType(coll, ULOC_VALID_LOCALE, &status),
                                      targetBuffer, targetLength, &status);
    } else {
        targetBuffer = NULL;
        targetLength = 0;
    }
}

const CEI *Target::nextCE(int32_t offset)
{
    UErrorCode status = U_ZERO_ERROR;
    int32_t low = -1, high = -1;
    uint32_t order;
    UBool cont = FALSE;

    if (offset >= bufferMin && offset < bufferMax) {
        return &ceb[offset];
    }

    if (bufferMax >= bufferSize || offset != bufferMax) {
        return NULL;
    }

    do {
        low   = ucol_getOffset(elements);
        order = ucol_next(elements, &status);
        high  = ucol_getOffset(elements);

        if (order == (uint32_t)UCOL_NULLORDER) {
          //high = low = -1;
            break;
        }

        cont = isContinuation(order);
        order &= strengthMask;

        if (toShift && variableTop > order && (order & UCOL_PRIMARYORDERMASK) != 0) {
            if (strength >= UCOL_QUATERNARY) {
                order &= UCOL_PRIMARYORDERMASK;
            } else {
                order = UCOL_IGNORABLE;
            }
        }
    } while (order == UCOL_IGNORABLE);

    if (cont) {
        order |= UCOL_CONTINUATION_MARKER;
    }

    ceb[offset].order = order;
    ceb[offset].lowOffset = low;
    ceb[offset].highOffset = high;

    bufferMax += 1;

    return &ceb[offset];
}

const CEI *Target::prevCE(int32_t offset)
{
    UErrorCode status = U_ZERO_ERROR;
    int32_t low = -1, high = -1;
    uint32_t order;
    UBool cont = FALSE;

    if (offset >= bufferMin && offset < bufferMax) {
        return &ceb[offset];
    }

    if (bufferMax >= bufferSize || offset != bufferMax) {
        return NULL;
    }

    do {
        high  = ucol_getOffset(elements);
        order = ucol_previous(elements, &status);
        low   = ucol_getOffset(elements);

        if (order == (uint32_t)UCOL_NULLORDER) {
            break;
        }

        cont = isContinuation(order);
        order &= strengthMask;

        if (toShift && variableTop > order && (order & UCOL_PRIMARYORDERMASK) != 0) {
            if (strength >= UCOL_QUATERNARY) {
                order &= UCOL_PRIMARYORDERMASK;
            } else {
                order = UCOL_IGNORABLE;
            }
        }
    } while (order == UCOL_IGNORABLE);

    bufferMax += 1;

    if (cont) {
        order |= UCOL_CONTINUATION_MARKER;
    }

    ceb[offset].order       = order;
    ceb[offset].lowOffset   = low;
    ceb[offset].highOffset = high;

    return &ceb[offset];
}

int32_t Target::stringLength()
{
    if (targetString != NULL) {
        return targetLength;
    }

    return 0;
}

UChar Target::charAt(int32_t offset)
{
    if (targetString != NULL) {
        return targetBuffer[offset];
    }

    return 0x0000;
}

void Target::setOffset(int32_t offset)
{
    UErrorCode status = U_ZERO_ERROR;

    bufferMin = 0;
    bufferMax = 0;

    ucol_setOffset(elements, offset, &status);
}

void Target::setLast(int32_t last)
{
    UErrorCode status = U_ZERO_ERROR;

    bufferMin = 0;
    bufferMax = 1;

    ceb[0].order      = (uint32_t)UCOL_NULLORDER;
    ceb[0].lowOffset  = last;
    ceb[0].highOffset = last;

    ucol_setOffset(elements, last, &status);
}

int32_t Target::getOffset()
{
    return ucol_getOffset(elements);
}

UBool Target::isBreakBoundary(int32_t offset)
{
    return ubrk_isBoundary(charBreakIterator, offset);
}

int32_t Target::nextBreakBoundary(int32_t offset)
{
    return ubrk_following(charBreakIterator, offset);
}

int32_t Target::nextSafeBoundary(int32_t offset)
{
    while (offset < targetLength) {
      //UChar ch = charAt(offset);
        UChar ch = targetBuffer[offset];

        if (U_IS_LEAD(ch) || ! ucol_unsafeCP(ch, coll)) {
            return offset;
        }

        offset += 1;
    }

    return targetLength;
}

UBool Target::isIdentical(UnicodeString &pattern, int32_t start, int32_t end)
{
    if (strength < UCOL_IDENTICAL) {
        return TRUE;
    }

    // Note: We could use Normalizer::compare() or similar, but for short strings
    // which may not be in FCD it might be faster to just NFD them.
    UErrorCode status = U_ZERO_ERROR;
    UnicodeString t2, p2;
    nfd.normalize(UnicodeString(FALSE, targetBuffer + start, end - start), t2, status);
    nfd.normalize(pattern, p2, status);
    // return FALSE if NFD failed
    return U_SUCCESS(status) && t2 == p2;
}

#define HASH_TABLE_SIZE 257

class BadCharacterTable : public UMemory
{
public:
    BadCharacterTable(CEList &patternCEs, CollData *data, UErrorCode &status);
    ~BadCharacterTable();

    int32_t operator[](uint32_t ce) const;
    int32_t getMaxSkip() const;
    int32_t minLengthInChars(int32_t index);

private:
    static int32_t hash(uint32_t ce);

    int32_t maxSkip;
    int32_t badCharacterTable[HASH_TABLE_SIZE];

    int32_t *minLengthCache;
};

BadCharacterTable::BadCharacterTable(CEList &patternCEs, CollData *data, UErrorCode &status)
    : minLengthCache(NULL)
{
    int32_t plen = patternCEs.size();

    // **** need a better way to deal with this ****
    if (U_FAILURE(status) || plen == 0) {
        return;
    }

    int32_t *history = NEW_ARRAY(int32_t, plen);

    if (history == NULL) {
        status = U_MEMORY_ALLOCATION_ERROR;
        return;
    }

    for (int32_t i = 0; i < plen; i += 1) {
        history[i] = -1;
    }

    minLengthCache = NEW_ARRAY(int32_t, plen + 1);

    if (minLengthCache == NULL) {
        DELETE_ARRAY(history);
        status = U_MEMORY_ALLOCATION_ERROR;
        return;
    }

    maxSkip = minLengthCache[0] = data->minLengthInChars(&patternCEs, 0, history);

    for(int32_t j = 0; j < HASH_TABLE_SIZE; j += 1) {
        badCharacterTable[j] = maxSkip;
    }

    for(int32_t p = 1; p < plen; p += 1) {
        minLengthCache[p] = data->minLengthInChars(&patternCEs, p, history);

        // Make sure this entry is not bigger than the previous one.
        // Otherwise, we might skip too far in some cases.
        if (minLengthCache[p] < 0 || minLengthCache[p] > minLengthCache[p - 1]) {
            minLengthCache[p] = minLengthCache[p - 1];
        }
    }

    minLengthCache[plen] = 0;

    for(int32_t p = 0; p < plen - 1; p += 1) {
        badCharacterTable[hash(patternCEs[p])] = minLengthCache[p + 1];
    }

    DELETE_ARRAY(history);
}

BadCharacterTable::~BadCharacterTable()
{
    DELETE_ARRAY(minLengthCache);
}

int32_t BadCharacterTable::operator[](uint32_t ce) const
{
    return badCharacterTable[hash(ce)];
}

int32_t BadCharacterTable::getMaxSkip() const
{
    return maxSkip;
}

int32_t BadCharacterTable::minLengthInChars(int32_t index)
{
    return minLengthCache[index];
}

int32_t BadCharacterTable::hash(uint32_t ce)
{
    return UCOL_PRIMARYORDER(ce) % HASH_TABLE_SIZE;
}

class GoodSuffixTable : public UMemory
{
public:
    GoodSuffixTable(CEList &patternCEs, BadCharacterTable &badCharacterTable, UErrorCode &status);
    ~GoodSuffixTable();

    int32_t operator[](int32_t offset) const;

private:
    int32_t *goodSuffixTable;
};

GoodSuffixTable::GoodSuffixTable(CEList &patternCEs, BadCharacterTable &badCharacterTable, UErrorCode &status)
    : goodSuffixTable(NULL)
{
    int32_t patlen = patternCEs.size();

    // **** need a better way to deal with this ****
    if (U_FAILURE(status) || patlen <= 0) {
        return;
    }

    int32_t *suff  = NEW_ARRAY(int32_t, patlen);
    int32_t start = patlen - 1, end = - 1;
    int32_t maxSkip = badCharacterTable.getMaxSkip();

    if (suff == NULL) {
        status = U_MEMORY_ALLOCATION_ERROR;
        return;
    }

    // initialze suff
    suff[patlen - 1] = patlen;

    for (int32_t i = patlen - 2; i >= 0; i -= 1) {
        // (i > start) means we're inside the last suffix match we found
        // ((patlen - 1) - end) is how far the end of that match is from end of pattern
        // (i - start) is how far we are from start of that match
        // (i + (patlen - 1) - end) is index of same character at end of pattern
        // so if any suffix match at that character doesn't extend beyond the last match,
        // it's the suffix for this character as well
        if (i > start && suff[i + patlen - 1 - end] < i - start) {
            suff[i] = suff[i + patlen - 1 - end];
        } else {
            start = end = i;

            int32_t s = patlen;

            while (start >= 0 && patternCEs[start] == patternCEs[--s]) {
                start -= 1;
            }

            suff[i] = end - start;
        }
    }

    // now build goodSuffixTable
    goodSuffixTable  = NEW_ARRAY(int32_t, patlen);

    if (goodSuffixTable == NULL) {
        DELETE_ARRAY(suff);
        status = U_MEMORY_ALLOCATION_ERROR;
        return;
    }


    // initialize entries to minLengthInChars of the pattern
    for (int32_t i = 0; i < patlen; i += 1) {
        goodSuffixTable[i] = maxSkip;
    }

    int32_t prefix = 0;

    for (int32_t i = patlen - /*1*/ 2; i >= 0; i -= 1) {
        if (suff[i] == i + 1) {
            // this matching suffix is a prefix of the pattern
            int32_t prefixSkip = badCharacterTable.minLengthInChars(i + 1);

            // for any mis-match before this suffix, we should skip
            // so that the front of the pattern (i.e. the prefix)
            // lines up with the front of the suffix.
            // (patlen - 1 - i) is the start of the suffix
            while (prefix < patlen - 1 - i) {
                // value of maxSkip means never set...
                if (goodSuffixTable[prefix] == maxSkip) {
                    goodSuffixTable[prefix] = prefixSkip;
                }

                prefix += 1;
            }
        }
    }

    for (int32_t i = 0; i < patlen - 1; i += 1) {
        goodSuffixTable[patlen - 1 - suff[i]] = badCharacterTable.minLengthInChars(i + 1);
    }

    DELETE_ARRAY(suff);
}

GoodSuffixTable::~GoodSuffixTable()
{
    DELETE_ARRAY(goodSuffixTable);
}

int32_t GoodSuffixTable::operator[](int32_t offset) const
{
    return goodSuffixTable[offset];
}

UOBJECT_DEFINE_RTTI_IMPLEMENTATION(BoyerMooreSearch)


UBool BoyerMooreSearch::empty()
{
    return patCEs->size() <= 0;
}

CollData *BoyerMooreSearch::getData()
{
    return data;
}

CEList *BoyerMooreSearch::getPatternCEs()
{
    return patCEs;
}

BadCharacterTable *BoyerMooreSearch::getBadCharacterTable()
{
    return badCharacterTable;
}

GoodSuffixTable *BoyerMooreSearch::getGoodSuffixTable()
{
    return goodSuffixTable;
}

BoyerMooreSearch::BoyerMooreSearch(CollData *theData, const UnicodeString &patternString, const UnicodeString *targetString,
                                   UErrorCode &status)
    : data(theData), patCEs(NULL), badCharacterTable(NULL), goodSuffixTable(NULL), pattern(patternString), target(NULL)
{

    if (U_FAILURE(status)) {
        return;
    }

    UCollator *collator = data->getCollator();

    patCEs = new CEList(collator, patternString, status);

    if (patCEs == NULL || U_FAILURE(status)) {
        return;
    }

    badCharacterTable = new BadCharacterTable(*patCEs, data, status);

    if (badCharacterTable == NULL || U_FAILURE(status)) {
        return;
    }

    goodSuffixTable = new GoodSuffixTable(*patCEs, *badCharacterTable, status);

    if (targetString != NULL) {
        target = new Target(collator, targetString, patCEs->size(), status);
    }
}

BoyerMooreSearch::~BoyerMooreSearch()
{
    delete target;
    delete goodSuffixTable;
    delete badCharacterTable;
    delete patCEs;
}

void BoyerMooreSearch::setTargetString(const UnicodeString *targetString, UErrorCode &status)
{
    if (U_FAILURE(status)) {
        return;
    }

    if (target == NULL) {
        target = new Target(data->getCollator(), targetString, patCEs->size(), status);
    } else {
        target->setTargetString(targetString);
    }
}

// **** main flow of this code from Laura Werner's "Unicode Text Searching in Java" paper. ****
/*
 * TODO:
 *  * deal with trailing (and leading?) ignorables.
 *  * Adding BoyerMooreSearch object slowed it down. How can we speed it up?
 */
UBool BoyerMooreSearch::search(int32_t offset, int32_t &start, int32_t &end)
{
    /*UCollator *coll =*/ data->getCollator();
    int32_t plen = patCEs->size();
    int32_t tlen = target->stringLength();
    int32_t maxSkip = badCharacterTable->getMaxSkip();
    int32_t tOffset = offset + maxSkip;

    if (plen <= 0) {
        // Searching for a zero length pattern always fails.
        start = end = -1;
        return FALSE;
    }

    while (tOffset <= tlen) {
        int32_t pIndex = plen - 1;
        int32_t tIndex = 0;
        int32_t lIndex = 0;

        if (tOffset < tlen) {
            // **** we really want to skip ahead enough to  ****
            // **** be sure we get at least 1 non-ignorable ****
            // **** CE after the end of the pattern.        ****
            int32_t next = target->nextSafeBoundary(tOffset + 1);

            target->setOffset(next);

            for (lIndex = 0; ; lIndex += 1) {
                const CEI *cei = target->prevCE(lIndex);
                int32_t low = cei->lowOffset;
                int32_t high = cei->highOffset;

                if (high == 0 || (low < high && low <= tOffset)) {
                    if (low < tOffset) {
                        while (lIndex >= 0 && target->prevCE(lIndex)->highOffset == high) {
                            lIndex -= 1;
                        }

                        if (high > tOffset) {
                            tOffset = high;
                        }
                    }

                    break;
                }
            }
        } else {
            target->setLast(tOffset);
            lIndex = 0;
        }

        tIndex = ++lIndex;

        // Iterate backward until we hit the beginning of the pattern
        while (pIndex >= 0) {
            uint32_t pce = (*patCEs)[pIndex];
            const CEI *tcei = target->prevCE(tIndex++);


            if (tcei->order != pce) {
                // There is a mismatch at this position.  Decide how far
                // over to shift the pattern, then try again.

                int32_t gsOffset = tOffset + (*goodSuffixTable)[pIndex];
#ifdef EXTRA_CAUTIOUS
                int32_t old = tOffset;
#endif

                tOffset += (*badCharacterTable)[tcei->order] - badCharacterTable->minLengthInChars(pIndex + 1);

                if (gsOffset > tOffset) {
                    tOffset = gsOffset;
                }

#ifdef EXTRA_CAUTIOUS
                // Make sure we don't skip backwards...
                if (tOffset <= old) {
                    tOffset = old + 1;
                }
#endif

                break;
            }

            pIndex -= 1;
        }

        if (pIndex < 0) {
            // We made it back to the beginning of the pattern,
            // which means we matched it all.  Return the location.
            const CEI firstCEI = *target->prevCE(tIndex - 1);
            const CEI lastCEI  = *target->prevCE(lIndex);
            int32_t mStart   = firstCEI.lowOffset;
            int32_t minLimit = lastCEI.lowOffset;
            int32_t maxLimit = lastCEI.highOffset;
            int32_t mLimit;
            UBool found = TRUE;

            target->setOffset(/*tOffset*/maxLimit);

            const CEI nextCEI = *target->nextCE(0);

            if (nextCEI.lowOffset > maxLimit) {
                maxLimit = nextCEI.lowOffset;
            }

            if (nextCEI.lowOffset == nextCEI.highOffset && nextCEI.order != (uint32_t)UCOL_NULLORDER) {
                found = FALSE;
            }

            if (! target->isBreakBoundary(mStart)) {
                found = FALSE;
            }

            if (firstCEI.lowOffset == firstCEI.highOffset) {
                found = FALSE;
            }

            mLimit = maxLimit;
            if (minLimit < maxLimit) {
                // When the last CE's low index is same with its high index, the CE is likely
                // a part of expansion. In this case, the index is located just after the
                // character corresponding to the CEs compared above. If the index is right
                // at the break boundary, move the position to the next boundary will result
                // incorrect match length when there are ignorable characters exist between
                // the position and the next character produces CE(s). See ticket#8482.
                if (minLimit == lastCEI.highOffset && target->isBreakBoundary(minLimit)) {
                    mLimit = minLimit;
                } else {
                    int32_t nbb = target->nextBreakBoundary(minLimit);

                    if (nbb >= lastCEI.highOffset) {
                        mLimit = nbb;
                    }
                }
            }

            if (mLimit > maxLimit) {
                found = FALSE;
            }

            if (! target->isBreakBoundary(mLimit)) {
                found = FALSE;
            }

            if (! target->isIdentical(pattern, mStart, mLimit)) {
                found = FALSE;
            }

            if (found) {
                start = mStart;
                end   = mLimit;

                return TRUE;
            }

            tOffset += (*goodSuffixTable)[0]; // really? Maybe += 1 or += maxSkip?
        }
        // Otherwise, we're here because of a mismatch, so keep going....
    }

    // no match
   start = -1;
   end = -1;
   return FALSE;
}

U_NAMESPACE_END

#endif // #if !UCONFIG_NO_COLLATION