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      1 /*
      2  ******************************************************************************
      3  * Copyright (C) 1996-2010, International Business Machines Corporation and
      4  * others. All Rights Reserved.
      5  ******************************************************************************
      6  */
      7 
      8 /**
      9  * File tblcoll.cpp
     10  *
     11  * Created by: Helena Shih
     12  *
     13  * Modification History:
     14  *
     15  *  Date        Name        Description
     16  *  2/5/97      aliu        Added streamIn and streamOut methods.  Added
     17  *                          constructor which reads RuleBasedCollator object from
     18  *                          a binary file.  Added writeToFile method which streams
     19  *                          RuleBasedCollator out to a binary file.  The streamIn
     20  *                          and streamOut methods use istream and ostream objects
     21  *                          in binary mode.
     22  *  2/11/97     aliu        Moved declarations out of for loop initializer.
     23  *                          Added Mac compatibility #ifdef for ios::nocreate.
     24  *  2/12/97     aliu        Modified to use TableCollationData sub-object to
     25  *                          hold invariant data.
     26  *  2/13/97     aliu        Moved several methods into this class from Collation.
     27  *                          Added a private RuleBasedCollator(Locale&) constructor,
     28  *                          to be used by Collator::getInstance().  General
     29  *                          clean up.  Made use of UErrorCode variables consistent.
     30  *  2/20/97     helena      Added clone, operator==, operator!=, operator=, and copy
     31  *                          constructor and getDynamicClassID.
     32  *  3/5/97      aliu        Changed compaction cycle to improve performance.  We
     33  *                          use the maximum allowable value which is kBlockCount.
     34  *                          Modified getRules() to load rules dynamically.  Changed
     35  *                          constructFromFile() call to accomodate this (added
     36  *                          parameter to specify whether binary loading is to
     37  *                          take place).
     38  * 05/06/97     helena      Added memory allocation error check.
     39  *  6/20/97     helena      Java class name change.
     40  *  6/23/97     helena      Adding comments to make code more readable.
     41  * 09/03/97     helena      Added createCollationKeyValues().
     42  * 06/26/98     erm         Changes for CollationKeys using byte arrays.
     43  * 08/10/98     erm         Synched with 1.2 version of RuleBasedCollator.java
     44  * 04/23/99     stephen     Removed EDecompositionMode, merged with
     45  *                          Normalizer::EMode
     46  * 06/14/99     stephen     Removed kResourceBundleSuffix
     47  * 06/22/99     stephen     Fixed logic in constructFromFile() since .ctx
     48  *                          files are no longer used.
     49  * 11/02/99     helena      Collator performance enhancements.  Special case
     50  *                          for NO_OP situations.
     51  * 11/17/99     srl         More performance enhancements. Inlined some internal functions.
     52  * 12/15/99     aliu        Update to support Thai collation.  Move NormalizerIterator
     53  *                          to implementation file.
     54  * 01/29/01     synwee      Modified into a C++ wrapper calling C APIs (ucol.h)
     55  */
     56 
     57 #include "unicode/utypeinfo.h"  // for 'typeid' to work
     58 
     59 #include "unicode/utypes.h"
     60 
     61 #if !UCONFIG_NO_COLLATION
     62 
     63 #include "unicode/tblcoll.h"
     64 #include "unicode/coleitr.h"
     65 #include "unicode/ures.h"
     66 #include "unicode/uset.h"
     67 #include "ucol_imp.h"
     68 #include "uresimp.h"
     69 #include "uhash.h"
     70 #include "cmemory.h"
     71 #include "cstring.h"
     72 #include "putilimp.h"
     73 
     74 /* public RuleBasedCollator constructor ---------------------------------- */
     75 
     76 U_NAMESPACE_BEGIN
     77 
     78 /**
     79 * Copy constructor, aliasing, not write-through
     80 */
     81 RuleBasedCollator::RuleBasedCollator(const RuleBasedCollator& that)
     82 : Collator(that)
     83 , dataIsOwned(FALSE)
     84 , isWriteThroughAlias(FALSE)
     85 , ucollator(NULL)
     86 {
     87     RuleBasedCollator::operator=(that);
     88 }
     89 
     90 RuleBasedCollator::RuleBasedCollator(const UnicodeString& rules,
     91                                      UErrorCode& status) :
     92 dataIsOwned(FALSE)
     93 {
     94     construct(rules,
     95         UCOL_DEFAULT_STRENGTH,
     96         UCOL_DEFAULT,
     97         status);
     98 }
     99 
    100 RuleBasedCollator::RuleBasedCollator(const UnicodeString& rules,
    101                                      ECollationStrength collationStrength,
    102                                      UErrorCode& status) : dataIsOwned(FALSE)
    103 {
    104     construct(rules,
    105         getUCollationStrength(collationStrength),
    106         UCOL_DEFAULT,
    107         status);
    108 }
    109 
    110 RuleBasedCollator::RuleBasedCollator(const UnicodeString& rules,
    111                                      UColAttributeValue decompositionMode,
    112                                      UErrorCode& status) :
    113 dataIsOwned(FALSE)
    114 {
    115     construct(rules,
    116         UCOL_DEFAULT_STRENGTH,
    117         decompositionMode,
    118         status);
    119 }
    120 
    121 RuleBasedCollator::RuleBasedCollator(const UnicodeString& rules,
    122                                      ECollationStrength collationStrength,
    123                                      UColAttributeValue decompositionMode,
    124                                      UErrorCode& status) : dataIsOwned(FALSE)
    125 {
    126     construct(rules,
    127         getUCollationStrength(collationStrength),
    128         decompositionMode,
    129         status);
    130 }
    131 RuleBasedCollator::RuleBasedCollator(const uint8_t *bin, int32_t length,
    132                     const RuleBasedCollator *base,
    133                     UErrorCode &status) :
    134 dataIsOwned(TRUE),
    135 isWriteThroughAlias(FALSE)
    136 {
    137   ucollator = ucol_openBinary(bin, length, base->ucollator, &status);
    138 }
    139 
    140 void
    141 RuleBasedCollator::setRuleStringFromCollator()
    142 {
    143     int32_t length;
    144     const UChar *r = ucol_getRules(ucollator, &length);
    145 
    146     if (r && length > 0) {
    147         // alias the rules string
    148         urulestring.setTo(TRUE, r, length);
    149     }
    150     else {
    151         urulestring.truncate(0); // Clear string.
    152     }
    153 }
    154 
    155 // not aliasing, not write-through
    156 void
    157 RuleBasedCollator::construct(const UnicodeString& rules,
    158                              UColAttributeValue collationStrength,
    159                              UColAttributeValue decompositionMode,
    160                              UErrorCode& status)
    161 {
    162     ucollator = ucol_openRules(rules.getBuffer(), rules.length(),
    163         decompositionMode, collationStrength,
    164         NULL, &status);
    165 
    166     dataIsOwned = TRUE; // since we own a collator now, we need to get rid of it
    167     isWriteThroughAlias = FALSE;
    168 
    169     if(ucollator == NULL) {
    170         if(U_SUCCESS(status)) {
    171             status = U_MEMORY_ALLOCATION_ERROR;
    172         }
    173         return; // Failure
    174     }
    175 
    176     setRuleStringFromCollator();
    177 }
    178 
    179 /* RuleBasedCollator public destructor ----------------------------------- */
    180 
    181 RuleBasedCollator::~RuleBasedCollator()
    182 {
    183     if (dataIsOwned)
    184     {
    185         ucol_close(ucollator);
    186     }
    187     ucollator = 0;
    188 }
    189 
    190 /* RuleBaseCollator public methods --------------------------------------- */
    191 
    192 UBool RuleBasedCollator::operator==(const Collator& that) const
    193 {
    194   /* only checks for address equals here */
    195   if (Collator::operator==(that))
    196     return TRUE;
    197 
    198   if (typeid(*this) != typeid(that))
    199     return FALSE;  /* not the same class */
    200 
    201   RuleBasedCollator& thatAlias = (RuleBasedCollator&)that;
    202 
    203   // weiv: use C function, commented code below is wrong
    204   return ucol_equals(this->ucollator, thatAlias.ucollator);
    205   /*
    206   synwee : orginal code does not check for data compatibility
    207   */
    208   /*
    209   if (ucollator != thatAlias.ucollator)
    210     return FALSE;
    211 
    212   return TRUE;
    213   */
    214 }
    215 
    216 UBool RuleBasedCollator::operator!=(const Collator& other) const
    217 {
    218     return !(*this == other);
    219 }
    220 
    221 // aliasing, not write-through
    222 RuleBasedCollator& RuleBasedCollator::operator=(const RuleBasedCollator& that)
    223 {
    224     if (this != &that)
    225     {
    226         if (dataIsOwned)
    227         {
    228             ucol_close(ucollator);
    229         }
    230 
    231         urulestring.truncate(0); // empty the rule string
    232         dataIsOwned = TRUE;
    233         isWriteThroughAlias = FALSE;
    234 
    235         UErrorCode intStatus = U_ZERO_ERROR;
    236         int32_t buffersize = U_COL_SAFECLONE_BUFFERSIZE;
    237         ucollator = ucol_safeClone(that.ucollator, NULL, &buffersize,
    238                                         &intStatus);
    239         if (U_SUCCESS(intStatus)) {
    240             setRuleStringFromCollator();
    241         }
    242     }
    243     return *this;
    244 }
    245 
    246 // aliasing, not write-through
    247 Collator* RuleBasedCollator::clone() const
    248 {
    249     return new RuleBasedCollator(*this);
    250 }
    251 
    252 CollationElementIterator* RuleBasedCollator::createCollationElementIterator
    253                                            (const UnicodeString& source) const
    254 {
    255     UErrorCode status = U_ZERO_ERROR;
    256     CollationElementIterator *result = new CollationElementIterator(source, this,
    257                                                                     status);
    258     if (U_FAILURE(status)) {
    259         delete result;
    260         return NULL;
    261     }
    262 
    263     return result;
    264 }
    265 
    266 /**
    267 * Create a CollationElementIterator object that will iterate over the
    268 * elements in a string, using the collation rules defined in this
    269 * RuleBasedCollator
    270 */
    271 CollationElementIterator* RuleBasedCollator::createCollationElementIterator
    272                                        (const CharacterIterator& source) const
    273 {
    274     UErrorCode status = U_ZERO_ERROR;
    275     CollationElementIterator *result = new CollationElementIterator(source, this,
    276                                                                     status);
    277 
    278     if (U_FAILURE(status)) {
    279         delete result;
    280         return NULL;
    281     }
    282 
    283     return result;
    284 }
    285 
    286 /**
    287 * Return a string representation of this collator's rules. The string can
    288 * later be passed to the constructor that takes a UnicodeString argument,
    289 * which will construct a collator that's functionally identical to this one.
    290 * You can also allow users to edit the string in order to change the collation
    291 * data, or you can print it out for inspection, or whatever.
    292 */
    293 const UnicodeString& RuleBasedCollator::getRules() const
    294 {
    295     return urulestring;
    296 }
    297 
    298 void RuleBasedCollator::getRules(UColRuleOption delta, UnicodeString &buffer)
    299 {
    300     int32_t rulesize = ucol_getRulesEx(ucollator, delta, NULL, -1);
    301 
    302     if (rulesize > 0) {
    303         UChar *rules = (UChar*) uprv_malloc( sizeof(UChar) * (rulesize) );
    304         if(rules != NULL) {
    305             ucol_getRulesEx(ucollator, delta, rules, rulesize);
    306             buffer.setTo(rules, rulesize);
    307             uprv_free(rules);
    308         } else { // couldn't allocate
    309             buffer.remove();
    310         }
    311     }
    312     else {
    313         buffer.remove();
    314     }
    315 }
    316 
    317 UnicodeSet *
    318 RuleBasedCollator::getTailoredSet(UErrorCode &status) const
    319 {
    320     if(U_FAILURE(status)) {
    321         return NULL;
    322     }
    323     return (UnicodeSet *)ucol_getTailoredSet(this->ucollator, &status);
    324 }
    325 
    326 
    327 void RuleBasedCollator::getVersion(UVersionInfo versionInfo) const
    328 {
    329     if (versionInfo!=NULL){
    330         ucol_getVersion(ucollator, versionInfo);
    331     }
    332 }
    333 
    334 Collator::EComparisonResult RuleBasedCollator::compare(
    335                                                const UnicodeString& source,
    336                                                const UnicodeString& target,
    337                                                int32_t length) const
    338 {
    339     UErrorCode status = U_ZERO_ERROR;
    340     return getEComparisonResult(compare(source.getBuffer(), uprv_min(length,source.length()), target.getBuffer(), uprv_min(length,target.length()), status));
    341 }
    342 
    343 UCollationResult RuleBasedCollator::compare(
    344                                                const UnicodeString& source,
    345                                                const UnicodeString& target,
    346                                                int32_t length,
    347                                                UErrorCode &status) const
    348 {
    349     return compare(source.getBuffer(), uprv_min(length,source.length()), target.getBuffer(), uprv_min(length,target.length()), status);
    350 }
    351 
    352 Collator::EComparisonResult RuleBasedCollator::compare(const UChar* source,
    353                                                        int32_t sourceLength,
    354                                                        const UChar* target,
    355                                                        int32_t targetLength)
    356                                                        const
    357 {
    358     return  getEComparisonResult(ucol_strcoll(ucollator, source, sourceLength,
    359                                                          target, targetLength));
    360 }
    361 
    362 UCollationResult RuleBasedCollator::compare(const UChar* source,
    363                                                        int32_t sourceLength,
    364                                                        const UChar* target,
    365                                                        int32_t targetLength,
    366                                                        UErrorCode &status) const
    367 {
    368     if(U_SUCCESS(status)) {
    369         return  ucol_strcoll(ucollator, source, sourceLength, target, targetLength);
    370     } else {
    371         return UCOL_EQUAL;
    372     }
    373 }
    374 
    375 /**
    376 * Compare two strings using this collator
    377 */
    378 Collator::EComparisonResult RuleBasedCollator::compare(
    379                                              const UnicodeString& source,
    380                                              const UnicodeString& target) const
    381 {
    382     return getEComparisonResult(ucol_strcoll(ucollator, source.getBuffer(), source.length(),
    383                                                         target.getBuffer(), target.length()));
    384 }
    385 
    386 UCollationResult RuleBasedCollator::compare(
    387                                              const UnicodeString& source,
    388                                              const UnicodeString& target,
    389                                              UErrorCode &status) const
    390 {
    391     if(U_SUCCESS(status)) {
    392         return ucol_strcoll(ucollator, source.getBuffer(), source.length(),
    393                                        target.getBuffer(), target.length());
    394     } else {
    395         return UCOL_EQUAL;
    396     }
    397 }
    398 
    399 UCollationResult RuleBasedCollator::compare(UCharIterator &sIter,
    400                                             UCharIterator &tIter,
    401                                             UErrorCode &status) const {
    402     if(U_SUCCESS(status)) {
    403         return ucol_strcollIter(ucollator, &sIter, &tIter, &status);
    404     } else {
    405         return UCOL_EQUAL;
    406     }
    407 }
    408 
    409 /**
    410 * Retrieve a collation key for the specified string. The key can be compared
    411 * with other collation keys using a bitwise comparison (e.g. memcmp) to find
    412 * the ordering of their respective source strings. This is handy when doing a
    413 * sort, where each sort key must be compared many times.
    414 *
    415 * The basic algorithm here is to find all of the collation elements for each
    416 * character in the source string, convert them to an ASCII representation, and
    417 * put them into the collation key.  But it's trickier than that. Each
    418 * collation element in a string has three components: primary ('A' vs 'B'),
    419 * secondary ('u' vs '\u00FC'), and tertiary ('A' vs 'a'), and a primary difference
    420 * at the end of a string takes precedence over a secondary or tertiary
    421 * difference earlier in the string.
    422 *
    423 * To account for this, we put all of the primary orders at the beginning of
    424 * the string, followed by the secondary and tertiary orders. Each set of
    425 * orders is terminated by nulls so that a key for a string which is a initial
    426 * substring of another key will compare less without any special case.
    427 *
    428 * Here's a hypothetical example, with the collation element represented as a
    429 * three-digit number, one digit for primary, one for secondary, etc.
    430 *
    431 * String:              A     a     B    \u00C9
    432 * Collation Elements: 101   100   201  511
    433 * Collation Key:      1125<null>0001<null>1011<null>
    434 *
    435 * To make things even trickier, secondary differences (accent marks) are
    436 * compared starting at the *end* of the string in languages with French
    437 * secondary ordering. But when comparing the accent marks on a single base
    438 * character, they are compared from the beginning. To handle this, we reverse
    439 * all of the accents that belong to each base character, then we reverse the
    440 * entire string of secondary orderings at the end.
    441 */
    442 CollationKey& RuleBasedCollator::getCollationKey(
    443                                                   const UnicodeString& source,
    444                                                   CollationKey& sortkey,
    445                                                   UErrorCode& status) const
    446 {
    447     return getCollationKey(source.getBuffer(), source.length(), sortkey, status);
    448 }
    449 
    450 CollationKey& RuleBasedCollator::getCollationKey(const UChar* source,
    451                                                     int32_t sourceLen,
    452                                                     CollationKey& sortkey,
    453                                                     UErrorCode& status) const
    454 {
    455     if (U_FAILURE(status))
    456     {
    457         return sortkey.setToBogus();
    458     }
    459 
    460     if ((!source) || (sourceLen == 0)) {
    461         return sortkey.reset();
    462     }
    463 
    464     uint8_t *result;
    465     int32_t resultLen = ucol_getSortKeyWithAllocation(ucollator,
    466                                                       source, sourceLen,
    467                                                       &result,
    468                                                       &status);
    469     sortkey.adopt(result, resultLen);
    470     return sortkey;
    471 }
    472 
    473 /**
    474  * Return the maximum length of any expansion sequences that end with the
    475  * specified comparison order.
    476  * @param order a collation order returned by previous or next.
    477  * @return the maximum length of any expansion seuences ending with the
    478  *         specified order or 1 if collation order does not occur at the end of any
    479  *         expansion sequence.
    480  * @see CollationElementIterator#getMaxExpansion
    481  */
    482 int32_t RuleBasedCollator::getMaxExpansion(int32_t order) const
    483 {
    484     uint8_t result;
    485     UCOL_GETMAXEXPANSION(ucollator, (uint32_t)order, result);
    486     return result;
    487 }
    488 
    489 uint8_t* RuleBasedCollator::cloneRuleData(int32_t &length,
    490                                               UErrorCode &status)
    491 {
    492     return ucol_cloneRuleData(ucollator, &length, &status);
    493 }
    494 
    495 
    496 int32_t RuleBasedCollator::cloneBinary(uint8_t *buffer, int32_t capacity, UErrorCode &status)
    497 {
    498   return ucol_cloneBinary(ucollator, buffer, capacity, &status);
    499 }
    500 
    501 void RuleBasedCollator::setAttribute(UColAttribute attr,
    502                                      UColAttributeValue value,
    503                                      UErrorCode &status)
    504 {
    505     if (U_FAILURE(status))
    506         return;
    507     checkOwned();
    508     ucol_setAttribute(ucollator, attr, value, &status);
    509 }
    510 
    511 UColAttributeValue RuleBasedCollator::getAttribute(UColAttribute attr,
    512                                                       UErrorCode &status)
    513 {
    514     if (U_FAILURE(status))
    515         return UCOL_DEFAULT;
    516     return ucol_getAttribute(ucollator, attr, &status);
    517 }
    518 
    519 uint32_t RuleBasedCollator::setVariableTop(const UChar *varTop, int32_t len, UErrorCode &status) {
    520     checkOwned();
    521     return ucol_setVariableTop(ucollator, varTop, len, &status);
    522 }
    523 
    524 uint32_t RuleBasedCollator::setVariableTop(const UnicodeString varTop, UErrorCode &status) {
    525     checkOwned();
    526     return ucol_setVariableTop(ucollator, varTop.getBuffer(), varTop.length(), &status);
    527 }
    528 
    529 void RuleBasedCollator::setVariableTop(const uint32_t varTop, UErrorCode &status) {
    530     checkOwned();
    531     ucol_restoreVariableTop(ucollator, varTop, &status);
    532 }
    533 
    534 uint32_t RuleBasedCollator::getVariableTop(UErrorCode &status) const {
    535   return ucol_getVariableTop(ucollator, &status);
    536 }
    537 
    538 Collator* RuleBasedCollator::safeClone(void)
    539 {
    540     UErrorCode intStatus = U_ZERO_ERROR;
    541     int32_t buffersize = U_COL_SAFECLONE_BUFFERSIZE;
    542     UCollator *ucol = ucol_safeClone(ucollator, NULL, &buffersize,
    543                                     &intStatus);
    544     if (U_FAILURE(intStatus)) {
    545         return NULL;
    546     }
    547 
    548     RuleBasedCollator *result = new RuleBasedCollator();
    549     // Null pointer check
    550     if (result != NULL) {
    551 	    result->ucollator = ucol;
    552 	    result->dataIsOwned = TRUE;
    553 	    result->isWriteThroughAlias = FALSE;
    554 	    setRuleStringFromCollator();
    555     }
    556 
    557     return result;
    558 }
    559 
    560 
    561 int32_t RuleBasedCollator::getSortKey(const UnicodeString& source,
    562                                          uint8_t *result, int32_t resultLength)
    563                                          const
    564 {
    565     return ucol_getSortKey(ucollator, source.getBuffer(), source.length(), result, resultLength);
    566 }
    567 
    568 int32_t RuleBasedCollator::getSortKey(const UChar *source,
    569                                          int32_t sourceLength, uint8_t *result,
    570                                          int32_t resultLength) const
    571 {
    572     return ucol_getSortKey(ucollator, source, sourceLength, result, resultLength);
    573 }
    574 
    575 Collator::ECollationStrength RuleBasedCollator::getStrength(void) const
    576 {
    577     UErrorCode intStatus = U_ZERO_ERROR;
    578     return getECollationStrength(ucol_getAttribute(ucollator, UCOL_STRENGTH,
    579                                 &intStatus));
    580 }
    581 
    582 void RuleBasedCollator::setStrength(ECollationStrength newStrength)
    583 {
    584     checkOwned();
    585     UErrorCode intStatus = U_ZERO_ERROR;
    586     UCollationStrength strength = getUCollationStrength(newStrength);
    587     ucol_setAttribute(ucollator, UCOL_STRENGTH, strength, &intStatus);
    588 }
    589 
    590 int32_t RuleBasedCollator::getReorderCodes(int32_t *dest,
    591                                           int32_t destCapacity,
    592                                           UErrorCode& status) const
    593 {
    594     return ucol_getReorderCodes(ucollator, dest, destCapacity, &status);
    595 }
    596 
    597 void RuleBasedCollator::setReorderCodes(const int32_t *reorderCodes,
    598                                        int32_t reorderCodesLength,
    599                                        UErrorCode& status)
    600 {
    601     ucol_setReorderCodes(ucollator, reorderCodes, reorderCodesLength, &status);
    602 }
    603 
    604 
    605 /**
    606 * Create a hash code for this collation. Just hash the main rule table -- that
    607 * should be good enough for almost any use.
    608 */
    609 int32_t RuleBasedCollator::hashCode() const
    610 {
    611     int32_t length;
    612     const UChar *rules = ucol_getRules(ucollator, &length);
    613     return uhash_hashUCharsN(rules, length);
    614 }
    615 
    616 /**
    617 * return the locale of this collator
    618 */
    619 const Locale RuleBasedCollator::getLocale(ULocDataLocaleType type, UErrorCode &status) const {
    620     const char *result = ucol_getLocaleByType(ucollator, type, &status);
    621     if(result == NULL) {
    622         Locale res("");
    623         res.setToBogus();
    624         return res;
    625     } else {
    626         return Locale(result);
    627     }
    628 }
    629 
    630 void
    631 RuleBasedCollator::setLocales(const Locale& requestedLocale, const Locale& validLocale, const Locale& actualLocale) {
    632     checkOwned();
    633     char* rloc  = uprv_strdup(requestedLocale.getName());
    634     if (rloc) {
    635         char* vloc = uprv_strdup(validLocale.getName());
    636         if (vloc) {
    637             char* aloc = uprv_strdup(actualLocale.getName());
    638             if (aloc) {
    639                 ucol_setReqValidLocales(ucollator, rloc, vloc, aloc);
    640                 return;
    641             }
    642             uprv_free(vloc);
    643         }
    644         uprv_free(rloc);
    645     }
    646 }
    647 
    648 // RuleBaseCollatorNew private constructor ----------------------------------
    649 
    650 RuleBasedCollator::RuleBasedCollator()
    651   : dataIsOwned(FALSE), isWriteThroughAlias(FALSE), ucollator(NULL)
    652 {
    653 }
    654 
    655 RuleBasedCollator::RuleBasedCollator(const Locale& desiredLocale,
    656                                            UErrorCode& status)
    657  : dataIsOwned(FALSE), isWriteThroughAlias(FALSE), ucollator(NULL)
    658 {
    659     if (U_FAILURE(status))
    660         return;
    661 
    662     /*
    663     Try to load, in order:
    664      1. The desired locale's collation.
    665      2. A fallback of the desired locale.
    666      3. The default locale's collation.
    667      4. A fallback of the default locale.
    668      5. The default collation rules, which contains en_US collation rules.
    669 
    670      To reiterate, we try:
    671      Specific:
    672       language+country+variant
    673       language+country
    674       language
    675      Default:
    676       language+country+variant
    677       language+country
    678       language
    679      Root: (aka DEFAULTRULES)
    680      steps 1-5 are handled by resource bundle fallback mechanism.
    681      however, in a very unprobable situation that no resource bundle
    682      data exists, step 5 is repeated with hardcoded default rules.
    683     */
    684 
    685     setUCollator(desiredLocale, status);
    686 
    687     if (U_FAILURE(status))
    688     {
    689         status = U_ZERO_ERROR;
    690 
    691         setUCollator(kRootLocaleName, status);
    692         if (status == U_ZERO_ERROR) {
    693             status = U_USING_DEFAULT_WARNING;
    694         }
    695     }
    696 
    697     if (U_SUCCESS(status))
    698     {
    699         setRuleStringFromCollator();
    700     }
    701 }
    702 
    703 void
    704 RuleBasedCollator::setUCollator(const char *locale,
    705                                 UErrorCode &status)
    706 {
    707     if (U_FAILURE(status))
    708         return;
    709     if (ucollator && dataIsOwned)
    710         ucol_close(ucollator);
    711     ucollator = ucol_open_internal(locale, &status);
    712     dataIsOwned = TRUE;
    713     isWriteThroughAlias = FALSE;
    714 }
    715 
    716 
    717 void
    718 RuleBasedCollator::checkOwned() {
    719     if (!(dataIsOwned || isWriteThroughAlias)) {
    720         UErrorCode status = U_ZERO_ERROR;
    721         ucollator = ucol_safeClone(ucollator, NULL, NULL, &status);
    722         setRuleStringFromCollator();
    723         dataIsOwned = TRUE;
    724         isWriteThroughAlias = FALSE;
    725     }
    726 }
    727 
    728 UOBJECT_DEFINE_RTTI_IMPLEMENTATION(RuleBasedCollator)
    729 
    730 U_NAMESPACE_END
    731 
    732 #endif /* #if !UCONFIG_NO_COLLATION */
    733