The Tor Browser: intl/icu/source/common/ucase.cpp@129ffea94266 (annotated)

intl/icu/source/common/ucase.cpp@129ffea94266 (annotated)

intl/icu/source/common/ucase.cpp

Sat, 03 Jan 2015 20:18:00 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Sat, 03 Jan 2015 20:18:00 +0100
branch: TOR_BUG_3246
changeset 7: 129ffea94266
permissions: -rw-r--r--

Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.

 /*
 *******************************************************************************
 *
 *   Copyright (C) 2004-2012, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 *******************************************************************************
 *   file name:  ucase.cpp
 *   encoding:   US-ASCII
 *   tab size:   8 (not used)
 *   indentation:4
 *
 *   created on: 2004aug30
 *   created by: Markus W. Scherer
 *
 *   Low-level Unicode character/string case mapping code.
 *   Much code moved here (and modified) from uchar.c.
 */
 #include "unicode/utypes.h"
 #include "unicode/unistr.h"
 #include "unicode/uset.h"
 #include "unicode/udata.h" /* UDataInfo */
 #include "unicode/utf16.h"
 #include "ucmndata.h" /* DataHeader */
 #include "udatamem.h"
 #include "umutex.h"
 #include "uassert.h"
 #include "cmemory.h"
 #include "utrie2.h"
 #include "ucase.h"
 #include "ucln_cmn.h"
 struct UCaseProps {
     UDataMemory *mem;
     const int32_t *indexes;
     const uint16_t *exceptions;
     const uint16_t *unfold;
     UTrie2 trie;
     uint8_t formatVersion[4];
 };
 /* ucase_props_data.h is machine-generated by gencase --csource */
 #define INCLUDED_FROM_UCASE_CPP
 #include "ucase_props_data.h"
 /* UCaseProps singleton ----------------------------------------------------- */
 U_CAPI const UCaseProps * U_EXPORT2
 ucase_getSingleton() {
     return &ucase_props_singleton;
 }
 /* set of property starts for UnicodeSet ------------------------------------ */
 static UBool U_CALLCONV
 _enumPropertyStartsRange(const void *context, UChar32 start, UChar32 /*end*/, uint32_t /*value*/) {
     /* add the start code point to the USet */
     const USetAdder *sa=(const USetAdder *)context;
     sa->add(sa->set, start);
     return TRUE;
 }
 U_CFUNC void U_EXPORT2
 ucase_addPropertyStarts(const UCaseProps *csp, const USetAdder *sa, UErrorCode *pErrorCode) {
     if(U_FAILURE(*pErrorCode)) {
         return;
     }
     /* add the start code point of each same-value range of the trie */
     utrie2_enum(&csp->trie, NULL, _enumPropertyStartsRange, sa);
     /* add code points with hardcoded properties, plus the ones following them */
     /* (none right now, see comment below) */
     /*
      * Omit code points with hardcoded specialcasing properties
      * because we do not build property UnicodeSets for them right now.
      */
 }
 /* data access primitives --------------------------------------------------- */
 #define GET_EXCEPTIONS(csp, props) ((csp)->exceptions+((props)>>UCASE_EXC_SHIFT))
 #define PROPS_HAS_EXCEPTION(props) ((props)&UCASE_EXCEPTION)
 /* number of bits in an 8-bit integer value */
 static const uint8_t flagsOffset[256]={
 , 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
 , 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
 , 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
 , 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
 , 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
 , 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
 , 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
 , 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
 , 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
 , 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
 , 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
 , 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
 , 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
 , 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
 , 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
 , 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
 };
 #define HAS_SLOT(flags, idx) ((flags)&(1<<(idx)))
 #define SLOT_OFFSET(flags, idx) flagsOffset[(flags)&((1<<(idx))-1)]
 /*
  * Get the value of an optional-value slot where HAS_SLOT(excWord, idx).
  *
  * @param excWord (in) initial exceptions word
  * @param idx (in) desired slot index
  * @param pExc16 (in/out) const uint16_t * after excWord=*pExc16++;
  *               moved to the last uint16_t of the value, use +1 for beginning of next slot
  * @param value (out) int32_t or uint32_t output if hasSlot, otherwise not modified
  */
 #define GET_SLOT_VALUE(excWord, idx, pExc16, value) \
     if(((excWord)&UCASE_EXC_DOUBLE_SLOTS)==0) { \
         (pExc16)+=SLOT_OFFSET(excWord, idx); \
         (value)=*pExc16; \
     } else { \
         (pExc16)+=2*SLOT_OFFSET(excWord, idx); \
         (value)=*pExc16++; \
         (value)=((value)<<16)|*pExc16; \
     }
 /* simple case mappings ----------------------------------------------------- */
 U_CAPI UChar32 U_EXPORT2
 ucase_tolower(const UCaseProps *csp, UChar32 c) {
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         if(UCASE_GET_TYPE(props)>=UCASE_UPPER) {
             c+=UCASE_GET_DELTA(props);
         }
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(csp, props);
         uint16_t excWord=*pe++;
         if(HAS_SLOT(excWord, UCASE_EXC_LOWER)) {
             GET_SLOT_VALUE(excWord, UCASE_EXC_LOWER, pe, c);
         }
     }
     return c;
 }
 U_CAPI UChar32 U_EXPORT2
 ucase_toupper(const UCaseProps *csp, UChar32 c) {
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         if(UCASE_GET_TYPE(props)==UCASE_LOWER) {
             c+=UCASE_GET_DELTA(props);
         }
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(csp, props);
         uint16_t excWord=*pe++;
         if(HAS_SLOT(excWord, UCASE_EXC_UPPER)) {
             GET_SLOT_VALUE(excWord, UCASE_EXC_UPPER, pe, c);
         }
     }
     return c;
 }
 U_CAPI UChar32 U_EXPORT2
 ucase_totitle(const UCaseProps *csp, UChar32 c) {
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         if(UCASE_GET_TYPE(props)==UCASE_LOWER) {
             c+=UCASE_GET_DELTA(props);
         }
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(csp, props);
         uint16_t excWord=*pe++;
         int32_t idx;
         if(HAS_SLOT(excWord, UCASE_EXC_TITLE)) {
             idx=UCASE_EXC_TITLE;
         } else if(HAS_SLOT(excWord, UCASE_EXC_UPPER)) {
             idx=UCASE_EXC_UPPER;
         } else {
             return c;
         }
         GET_SLOT_VALUE(excWord, idx, pe, c);
     }
     return c;
 }
 static const UChar iDot[2] = { 0x69, 0x307 };
 static const UChar jDot[2] = { 0x6a, 0x307 };
 static const UChar iOgonekDot[3] = { 0x12f, 0x307 };
 static const UChar iDotGrave[3] = { 0x69, 0x307, 0x300 };
 static const UChar iDotAcute[3] = { 0x69, 0x307, 0x301 };
 static const UChar iDotTilde[3] = { 0x69, 0x307, 0x303 };
 U_CFUNC void U_EXPORT2
 ucase_addCaseClosure(const UCaseProps *csp, UChar32 c, const USetAdder *sa) {
     uint16_t props;
     /*
      * Hardcode the case closure of i and its relatives and ignore the
      * data file data for these characters.
      * The Turkic dotless i and dotted I with their case mapping conditions
      * and case folding option make the related characters behave specially.
      * This code matches their closure behavior to their case folding behavior.
      */
     switch(c) {
     case 0x49:
         /* regular i and I are in one equivalence class */
         sa->add(sa->set, 0x69);
         return;
     case 0x69:
         sa->add(sa->set, 0x49);
         return;
     case 0x130:
         /* dotted I is in a class with <0069 0307> (for canonical equivalence with <0049 0307>) */
         sa->addString(sa->set, iDot, 2);
         return;
     case 0x131:
         /* dotless i is in a class by itself */
         return;
     default:
         /* otherwise use the data file data */
         break;
     }
     props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         if(UCASE_GET_TYPE(props)!=UCASE_NONE) {
             /* add the one simple case mapping, no matter what type it is */
             int32_t delta=UCASE_GET_DELTA(props);
             if(delta!=0) {
                 sa->add(sa->set, c+delta);
             }
         }
     } else {
         /*
          * c has exceptions, so there may be multiple simple and/or
          * full case mappings. Add them all.
          */
         const uint16_t *pe0, *pe=GET_EXCEPTIONS(csp, props);
         const UChar *closure;
         uint16_t excWord=*pe++;
         int32_t idx, closureLength, fullLength, length;
         pe0=pe;
         /* add all simple case mappings */
         for(idx=UCASE_EXC_LOWER; idx<=UCASE_EXC_TITLE; ++idx) {
             if(HAS_SLOT(excWord, idx)) {
                 pe=pe0;
                 GET_SLOT_VALUE(excWord, idx, pe, c);
                 sa->add(sa->set, c);
             }
         }
         /* get the closure string pointer & length */
         if(HAS_SLOT(excWord, UCASE_EXC_CLOSURE)) {
             pe=pe0;
             GET_SLOT_VALUE(excWord, UCASE_EXC_CLOSURE, pe, closureLength);
             closureLength&=UCASE_CLOSURE_MAX_LENGTH; /* higher bits are reserved */
             closure=(const UChar *)pe+1; /* behind this slot, unless there are full case mappings */
         } else {
             closureLength=0;
             closure=NULL;
         }
         /* add the full case folding */
         if(HAS_SLOT(excWord, UCASE_EXC_FULL_MAPPINGS)) {
             pe=pe0;
             GET_SLOT_VALUE(excWord, UCASE_EXC_FULL_MAPPINGS, pe, fullLength);
             /* start of full case mapping strings */
             ++pe;
             fullLength&=0xffff; /* bits 16 and higher are reserved */
             /* skip the lowercase result string */
             pe+=fullLength&UCASE_FULL_LOWER;
             fullLength>>=4;
             /* add the full case folding string */
             length=fullLength&0xf;
             if(length!=0) {
                 sa->addString(sa->set, (const UChar *)pe, length);
                 pe+=length;
             }
             /* skip the uppercase and titlecase strings */
             fullLength>>=4;
             pe+=fullLength&0xf;
             fullLength>>=4;
             pe+=fullLength;
             closure=(const UChar *)pe; /* behind full case mappings */
         }
         /* add each code point in the closure string */
         for(idx=0; idx<closureLength;) {
             U16_NEXT_UNSAFE(closure, idx, c);
             sa->add(sa->set, c);
         }
     }
 }
 /*
  * compare s, which has a length, with t, which has a maximum length or is NUL-terminated
  * must be length>0 and max>0 and length<=max
  */
 static inline int32_t
 strcmpMax(const UChar *s, int32_t length, const UChar *t, int32_t max) {
     int32_t c1, c2;
     max-=length; /* we require length<=max, so no need to decrement max in the loop */
     do {
         c1=*s++;
         c2=*t++;
         if(c2==0) {
             return 1; /* reached the end of t but not of s */
         }
         c1-=c2;
         if(c1!=0) {
             return c1; /* return difference result */
         }
     } while(--length>0);
     /* ends with length==0 */
     if(max==0 || *t==0) {
         return 0; /* equal to length of both strings */
     } else {
         return -max; /* return lengh difference */
     }
 }
 U_CFUNC UBool U_EXPORT2
 ucase_addStringCaseClosure(const UCaseProps *csp, const UChar *s, int32_t length, const USetAdder *sa) {
     int32_t i, start, limit, result, unfoldRows, unfoldRowWidth, unfoldStringWidth;
     if(csp->unfold==NULL || s==NULL) {
         return FALSE; /* no reverse case folding data, or no string */
     }
     if(length<=1) {
         /* the string is too short to find any match */
         /*
          * more precise would be:
          * if(!u_strHasMoreChar32Than(s, length, 1))
          * but this does not make much practical difference because
          * a single supplementary code point would just not be found
          */
         return FALSE;
     }
     const uint16_t *unfold=csp->unfold;
     unfoldRows=unfold[UCASE_UNFOLD_ROWS];
     unfoldRowWidth=unfold[UCASE_UNFOLD_ROW_WIDTH];
     unfoldStringWidth=unfold[UCASE_UNFOLD_STRING_WIDTH];
     unfold+=unfoldRowWidth;
     if(length>unfoldStringWidth) {
         /* the string is too long to find any match */
         return FALSE;
     }
     /* do a binary search for the string */
     start=0;
     limit=unfoldRows;
     while(start<limit) {
         i=(start+limit)/2;
         const UChar *p=reinterpret_cast<const UChar *>(unfold+(i*unfoldRowWidth));
         result=strcmpMax(s, length, p, unfoldStringWidth);
         if(result==0) {
             /* found the string: add each code point, and its case closure */
             UChar32 c;
             for(i=unfoldStringWidth; i<unfoldRowWidth && p[i]!=0;) {
                 U16_NEXT_UNSAFE(p, i, c);
                 sa->add(sa->set, c);
                 ucase_addCaseClosure(csp, c, sa);
             }
             return TRUE;
         } else if(result<0) {
             limit=i;
         } else /* result>0 */ {
             start=i+1;
         }
     }
     return FALSE; /* string not found */
 }
 U_NAMESPACE_BEGIN
 FullCaseFoldingIterator::FullCaseFoldingIterator()
         : unfold(reinterpret_cast<const UChar *>(ucase_props_singleton.unfold)),
           unfoldRows(unfold[UCASE_UNFOLD_ROWS]),
           unfoldRowWidth(unfold[UCASE_UNFOLD_ROW_WIDTH]),
           unfoldStringWidth(unfold[UCASE_UNFOLD_STRING_WIDTH]),
           currentRow(0),
           rowCpIndex(unfoldStringWidth) {
     unfold+=unfoldRowWidth;
 }
 UChar32
 FullCaseFoldingIterator::next(UnicodeString &full) {
     // Advance past the last-delivered code point.
     const UChar *p=unfold+(currentRow*unfoldRowWidth);
     if(rowCpIndex>=unfoldRowWidth || p[rowCpIndex]==0) {
         ++currentRow;
         p+=unfoldRowWidth;
         rowCpIndex=unfoldStringWidth;
     }
     if(currentRow>=unfoldRows) { return U_SENTINEL; }
     // Set "full" to the NUL-terminated string in the first unfold column.
     int32_t length=unfoldStringWidth;
     while(length>0 && p[length-1]==0) { --length; }
     full.setTo(FALSE, p, length);
     // Return the code point.
     UChar32 c;
     U16_NEXT_UNSAFE(p, rowCpIndex, c);
     return c;
 }
 U_NAMESPACE_END
 /** @return UCASE_NONE, UCASE_LOWER, UCASE_UPPER, UCASE_TITLE */
 U_CAPI int32_t U_EXPORT2
 ucase_getType(const UCaseProps *csp, UChar32 c) {
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     return UCASE_GET_TYPE(props);
 }
 /** @return same as ucase_getType() and set bit 2 if c is case-ignorable */
 U_CAPI int32_t U_EXPORT2
 ucase_getTypeOrIgnorable(const UCaseProps *csp, UChar32 c) {
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     return UCASE_GET_TYPE_AND_IGNORABLE(props);
 }
 /** @return UCASE_NO_DOT, UCASE_SOFT_DOTTED, UCASE_ABOVE, UCASE_OTHER_ACCENT */
 static inline int32_t
 getDotType(const UCaseProps *csp, UChar32 c) {
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         return props&UCASE_DOT_MASK;
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(csp, props);
         return (*pe>>UCASE_EXC_DOT_SHIFT)&UCASE_DOT_MASK;
     }
 }
 U_CAPI UBool U_EXPORT2
 ucase_isSoftDotted(const UCaseProps *csp, UChar32 c) {
     return (UBool)(getDotType(csp, c)==UCASE_SOFT_DOTTED);
 }
 U_CAPI UBool U_EXPORT2
 ucase_isCaseSensitive(const UCaseProps *csp, UChar32 c) {
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     return (UBool)((props&UCASE_SENSITIVE)!=0);
 }
 /* string casing ------------------------------------------------------------ */
 /*
  * These internal functions form the core of string case mappings.
  * They map single code points to result code points or strings and take
  * all necessary conditions (context, locale ID, options) into account.
  *
  * They do not iterate over the source or write to the destination
  * so that the same functions are useful for non-standard string storage,
  * such as in a Replaceable (for Transliterator) or UTF-8/32 strings etc.
  * For the same reason, the "surrounding text" context is passed in as a
  * UCaseContextIterator which does not make any assumptions about
  * the underlying storage.
  *
  * This section contains helper functions that check for conditions
  * in the input text surrounding the current code point
  * according to SpecialCasing.txt.
  *
  * Each helper function gets the index
  * - after the current code point if it looks at following text
  * - before the current code point if it looks at preceding text
  *
  * Unicode 3.2 UAX 21 "Case Mappings" defines the conditions as follows:
  *
  * Final_Sigma
  *   C is preceded by a sequence consisting of
  *     a cased letter and a case-ignorable sequence,
  *   and C is not followed by a sequence consisting of
  *     an ignorable sequence and then a cased letter.
  *
  * More_Above
  *   C is followed by one or more characters of combining class 230 (ABOVE)
  *   in the combining character sequence.
  *
  * After_Soft_Dotted
  *   The last preceding character with combining class of zero before C
  *   was Soft_Dotted,
  *   and there is no intervening combining character class 230 (ABOVE).
  *
  * Before_Dot
  *   C is followed by combining dot above (U+0307).
  *   Any sequence of characters with a combining class that is neither 0 nor 230
  *   may intervene between the current character and the combining dot above.
  *
  * The erratum from 2002-10-31 adds the condition
  *
  * After_I
  *   The last preceding base character was an uppercase I, and there is no
  *   intervening combining character class 230 (ABOVE).
  *
  *   (See Jitterbug 2344 and the comments on After_I below.)
  *
  * Helper definitions in Unicode 3.2 UAX 21:
  *
  * D1. A character C is defined to be cased
  *     if it meets any of the following criteria:
  *
  *   - The general category of C is Titlecase Letter (Lt)
  *   - In [CoreProps], C has one of the properties Uppercase, or Lowercase
  *   - Given D = NFD(C), then it is not the case that:
  *     D = UCD_lower(D) = UCD_upper(D) = UCD_title(D)
  *     (This third criterium does not add any characters to the list
  *      for Unicode 3.2. Ignored.)
  *
  * D2. A character C is defined to be case-ignorable
  *     if it meets either of the following criteria:
  *
  *   - The general category of C is
  *     Nonspacing Mark (Mn), or Enclosing Mark (Me), or Format Control (Cf), or
  *     Letter Modifier (Lm), or Symbol Modifier (Sk)
  *   - C is one of the following characters
  *     U+0027 APOSTROPHE
  *     U+00AD SOFT HYPHEN (SHY)
  *     U+2019 RIGHT SINGLE QUOTATION MARK
  *            (the preferred character for apostrophe)
  *
  * D3. A case-ignorable sequence is a sequence of
  *     zero or more case-ignorable characters.
  */
 #define is_a(c) ((c)=='a' || (c)=='A')
 #define is_d(c) ((c)=='d' || (c)=='D')
 #define is_e(c) ((c)=='e' || (c)=='E')
 #define is_i(c) ((c)=='i' || (c)=='I')
 #define is_l(c) ((c)=='l' || (c)=='L')
 #define is_n(c) ((c)=='n' || (c)=='N')
 #define is_r(c) ((c)=='r' || (c)=='R')
 #define is_t(c) ((c)=='t' || (c)=='T')
 #define is_u(c) ((c)=='u' || (c)=='U')
 #define is_z(c) ((c)=='z' || (c)=='Z')
 /* separator? */
 #define is_sep(c) ((c)=='_' || (c)=='-' || (c)==0)
 /**
  * Requires non-NULL locale ID but otherwise does the equivalent of
  * checking for language codes as if uloc_getLanguage() were called:
  * Accepts both 2- and 3-letter codes and accepts case variants.
  */
 U_CFUNC int32_t
 ucase_getCaseLocale(const char *locale, int32_t *locCache) {
     int32_t result;
     char c;
     if(locCache!=NULL && (result=*locCache)!=UCASE_LOC_UNKNOWN) {
         return result;
     }
     result=UCASE_LOC_ROOT;
     /*
      * This function used to use uloc_getLanguage(), but the current code
      * removes the dependency of this low-level code on uloc implementation code
      * and is faster because not the whole locale ID has to be
      * examined and copied/transformed.
      *
      * Because this code does not want to depend on uloc, the caller must
      * pass in a non-NULL locale, i.e., may need to call uloc_getDefault().
      */
     c=*locale++;
     if(is_t(c)) {
         /* tr or tur? */
         c=*locale++;
         if(is_u(c)) {
             c=*locale++;
         }
         if(is_r(c)) {
             c=*locale;
             if(is_sep(c)) {
                 result=UCASE_LOC_TURKISH;
             }
         }
     } else if(is_a(c)) {
         /* az or aze? */
         c=*locale++;
         if(is_z(c)) {
             c=*locale++;
             if(is_e(c)) {
                 c=*locale;
             }
             if(is_sep(c)) {
                 result=UCASE_LOC_TURKISH;
             }
         }
     } else if(is_l(c)) {
         /* lt or lit? */
         c=*locale++;
         if(is_i(c)) {
             c=*locale++;
         }
         if(is_t(c)) {
             c=*locale;
             if(is_sep(c)) {
                 result=UCASE_LOC_LITHUANIAN;
             }
         }
     } else if(is_n(c)) {
         /* nl or nld? */
         c=*locale++;
         if(is_l(c)) {
             c=*locale++;
             if(is_d(c)) {
                 c=*locale;
             }
             if(is_sep(c)) {
                 result=UCASE_LOC_DUTCH;
             }
         }
     }
     if(locCache!=NULL) {
         *locCache=result;
     }
     return result;
 }
 /*
  * Is followed by
  *   {case-ignorable}* cased
  * ?
  * (dir determines looking forward/backward)
  * If a character is case-ignorable, it is skipped regardless of whether
  * it is also cased or not.
  */
 static UBool
 isFollowedByCasedLetter(const UCaseProps *csp, UCaseContextIterator *iter, void *context, int8_t dir) {
     UChar32 c;
     if(iter==NULL) {
         return FALSE;
     }
     for(/* dir!=0 sets direction */; (c=iter(context, dir))>=0; dir=0) {
         int32_t type=ucase_getTypeOrIgnorable(csp, c);
         if(type&4) {
             /* case-ignorable, continue with the loop */
         } else if(type!=UCASE_NONE) {
             return TRUE; /* followed by cased letter */
         } else {
             return FALSE; /* uncased and not case-ignorable */
         }
     }
     return FALSE; /* not followed by cased letter */
 }
 /* Is preceded by Soft_Dotted character with no intervening cc=230 ? */
 static UBool
 isPrecededBySoftDotted(const UCaseProps *csp, UCaseContextIterator *iter, void *context) {
     UChar32 c;
     int32_t dotType;
     int8_t dir;
     if(iter==NULL) {
         return FALSE;
     }
     for(dir=-1; (c=iter(context, dir))>=0; dir=0) {
         dotType=getDotType(csp, c);
         if(dotType==UCASE_SOFT_DOTTED) {
             return TRUE; /* preceded by TYPE_i */
         } else if(dotType!=UCASE_OTHER_ACCENT) {
             return FALSE; /* preceded by different base character (not TYPE_i), or intervening cc==230 */
         }
     }
     return FALSE; /* not preceded by TYPE_i */
 }
 /*
  * See Jitterbug 2344:
  * The condition After_I for Turkic-lowercasing of U+0307 combining dot above
  * is checked in ICU 2.0, 2.1, 2.6 but was not in 2.2 & 2.4 because
  * we made those releases compatible with Unicode 3.2 which had not fixed
  * a related bug in SpecialCasing.txt.
  *
  * From the Jitterbug 2344 text:
  * ... this bug is listed as a Unicode erratum
  * from 2002-10-31 at http://www.unicode.org/uni2errata/UnicodeErrata.html
  * <quote>
  * There are two errors in SpecialCasing.txt.
  * 1. Missing semicolons on two lines. ... [irrelevant for ICU]
  * 2. An incorrect context definition. Correct as follows:
  * < 0307; ; 0307; 0307; tr After_Soft_Dotted; # COMBINING DOT ABOVE
  * < 0307; ; 0307; 0307; az After_Soft_Dotted; # COMBINING DOT ABOVE
  * ---
  * > 0307; ; 0307; 0307; tr After_I; # COMBINING DOT ABOVE
  * > 0307; ; 0307; 0307; az After_I; # COMBINING DOT ABOVE
  * where the context After_I is defined as:
  * The last preceding base character was an uppercase I, and there is no
  * intervening combining character class 230 (ABOVE).
  * </quote>
  *
  * Note that SpecialCasing.txt even in Unicode 3.2 described the condition as:
  *
  * # When lowercasing, remove dot_above in the sequence I + dot_above, which will turn into i.
  * # This matches the behavior of the canonically equivalent I-dot_above
  *
  * See also the description in this place in older versions of uchar.c (revision 1.100).
  *
  * Markus W. Scherer 2003-feb-15
  */
 /* Is preceded by base character 'I' with no intervening cc=230 ? */
 static UBool
 isPrecededBy_I(const UCaseProps *csp, UCaseContextIterator *iter, void *context) {
     UChar32 c;
     int32_t dotType;
     int8_t dir;
     if(iter==NULL) {
         return FALSE;
     }
     for(dir=-1; (c=iter(context, dir))>=0; dir=0) {
         if(c==0x49) {
             return TRUE; /* preceded by I */
         }
         dotType=getDotType(csp, c);
         if(dotType!=UCASE_OTHER_ACCENT) {
             return FALSE; /* preceded by different base character (not I), or intervening cc==230 */
         }
     }
     return FALSE; /* not preceded by I */
 }
 /* Is followed by one or more cc==230 ? */
 static UBool
 isFollowedByMoreAbove(const UCaseProps *csp, UCaseContextIterator *iter, void *context) {
     UChar32 c;
     int32_t dotType;
     int8_t dir;
     if(iter==NULL) {
         return FALSE;
     }
     for(dir=1; (c=iter(context, dir))>=0; dir=0) {
         dotType=getDotType(csp, c);
         if(dotType==UCASE_ABOVE) {
             return TRUE; /* at least one cc==230 following */
         } else if(dotType!=UCASE_OTHER_ACCENT) {
             return FALSE; /* next base character, no more cc==230 following */
         }
     }
     return FALSE; /* no more cc==230 following */
 }
 /* Is followed by a dot above (without cc==230 in between) ? */
 static UBool
 isFollowedByDotAbove(const UCaseProps *csp, UCaseContextIterator *iter, void *context) {
     UChar32 c;
     int32_t dotType;
     int8_t dir;
     if(iter==NULL) {
         return FALSE;
     }
     for(dir=1; (c=iter(context, dir))>=0; dir=0) {
         if(c==0x307) {
             return TRUE;
         }
         dotType=getDotType(csp, c);
         if(dotType!=UCASE_OTHER_ACCENT) {
             return FALSE; /* next base character or cc==230 in between */
         }
     }
     return FALSE; /* no dot above following */
 }
 U_CAPI int32_t U_EXPORT2
 ucase_toFullLower(const UCaseProps *csp, UChar32 c,
                   UCaseContextIterator *iter, void *context,
                   const UChar **pString,
                   const char *locale, int32_t *locCache)
 {
     UChar32 result=c;
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         if(UCASE_GET_TYPE(props)>=UCASE_UPPER) {
             result=c+UCASE_GET_DELTA(props);
         }
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(csp, props), *pe2;
         uint16_t excWord=*pe++;
         int32_t full;
         pe2=pe;
         if(excWord&UCASE_EXC_CONDITIONAL_SPECIAL) {
             /* use hardcoded conditions and mappings */
             int32_t loc=ucase_getCaseLocale(locale, locCache);
             /*
              * Test for conditional mappings first
              *   (otherwise the unconditional default mappings are always taken),
              * then test for characters that have unconditional mappings in SpecialCasing.txt,
              * then get the UnicodeData.txt mappings.
              */
             if( loc==UCASE_LOC_LITHUANIAN &&
                     /* base characters, find accents above */
                     (((c==0x49 || c==0x4a || c==0x12e) &&
                         isFollowedByMoreAbove(csp, iter, context)) ||
                     /* precomposed with accent above, no need to find one */
                     (c==0xcc || c==0xcd || c==0x128))
             ) {
                 /*
                     # Lithuanian
                     # Lithuanian retains the dot in a lowercase i when followed by accents.
                     # Introduce an explicit dot above when lowercasing capital I's and J's
                     # whenever there are more accents above.
                     # (of the accents used in Lithuanian: grave, acute, tilde above, and ogonek)
 ; 0069 0307; 0049; 0049; lt More_Above; # LATIN CAPITAL LETTER I
 A; 006A 0307; 004A; 004A; lt More_Above; # LATIN CAPITAL LETTER J
 E; 012F 0307; 012E; 012E; lt More_Above; # LATIN CAPITAL LETTER I WITH OGONEK
 CC; 0069 0307 0300; 00CC; 00CC; lt; # LATIN CAPITAL LETTER I WITH GRAVE
 CD; 0069 0307 0301; 00CD; 00CD; lt; # LATIN CAPITAL LETTER I WITH ACUTE
 ; 0069 0307 0303; 0128; 0128; lt; # LATIN CAPITAL LETTER I WITH TILDE
                  */
                 switch(c) {
                 case 0x49:  /* LATIN CAPITAL LETTER I */
                     *pString=iDot;
                     return 2;
                 case 0x4a:  /* LATIN CAPITAL LETTER J */
                     *pString=jDot;
                     return 2;
                 case 0x12e: /* LATIN CAPITAL LETTER I WITH OGONEK */
                     *pString=iOgonekDot;
                     return 2;
                 case 0xcc:  /* LATIN CAPITAL LETTER I WITH GRAVE */
                     *pString=iDotGrave;
                     return 3;
                 case 0xcd:  /* LATIN CAPITAL LETTER I WITH ACUTE */
                     *pString=iDotAcute;
                     return 3;
                 case 0x128: /* LATIN CAPITAL LETTER I WITH TILDE */
                     *pString=iDotTilde;
                     return 3;
                 default:
                     return 0; /* will not occur */
                 }
             /* # Turkish and Azeri */
             } else if(loc==UCASE_LOC_TURKISH && c==0x130) {
                 /*
                     # I and i-dotless; I-dot and i are case pairs in Turkish and Azeri
                     # The following rules handle those cases.
 ; 0069; 0130; 0130; tr # LATIN CAPITAL LETTER I WITH DOT ABOVE
 ; 0069; 0130; 0130; az # LATIN CAPITAL LETTER I WITH DOT ABOVE
                  */
                 return 0x69;
             } else if(loc==UCASE_LOC_TURKISH && c==0x307 && isPrecededBy_I(csp, iter, context)) {
                 /*
                     # When lowercasing, remove dot_above in the sequence I + dot_above, which will turn into i.
                     # This matches the behavior of the canonically equivalent I-dot_above
 ; ; 0307; 0307; tr After_I; # COMBINING DOT ABOVE
 ; ; 0307; 0307; az After_I; # COMBINING DOT ABOVE
                  */
                 return 0; /* remove the dot (continue without output) */
             } else if(loc==UCASE_LOC_TURKISH && c==0x49 && !isFollowedByDotAbove(csp, iter, context)) {
                 /*
                     # When lowercasing, unless an I is before a dot_above, it turns into a dotless i.
 ; 0131; 0049; 0049; tr Not_Before_Dot; # LATIN CAPITAL LETTER I
 ; 0131; 0049; 0049; az Not_Before_Dot; # LATIN CAPITAL LETTER I
                  */
                 return 0x131;
             } else if(c==0x130) {
                 /*
                     # Preserve canonical equivalence for I with dot. Turkic is handled below.
 ; 0069 0307; 0130; 0130; # LATIN CAPITAL LETTER I WITH DOT ABOVE
                  */
                 *pString=iDot;
                 return 2;
             } else if(  c==0x3a3 &&
                         !isFollowedByCasedLetter(csp, iter, context, 1) &&
                         isFollowedByCasedLetter(csp, iter, context, -1) /* -1=preceded */
             ) {
                 /* greek capital sigma maps depending on surrounding cased letters (see SpecialCasing.txt) */
                 /*
                     # Special case for final form of sigma
 A3; 03C2; 03A3; 03A3; Final_Sigma; # GREEK CAPITAL LETTER SIGMA
                  */
                 return 0x3c2; /* greek small final sigma */
             } else {
                 /* no known conditional special case mapping, use a normal mapping */
             }
         } else if(HAS_SLOT(excWord, UCASE_EXC_FULL_MAPPINGS)) {
             GET_SLOT_VALUE(excWord, UCASE_EXC_FULL_MAPPINGS, pe, full);
             full&=UCASE_FULL_LOWER;
             if(full!=0) {
                 /* set the output pointer to the lowercase mapping */
                 *pString=reinterpret_cast<const UChar *>(pe+1);
                 /* return the string length */
                 return full;
             }
         }
         if(HAS_SLOT(excWord, UCASE_EXC_LOWER)) {
             GET_SLOT_VALUE(excWord, UCASE_EXC_LOWER, pe2, result);
         }
     }
     return (result==c) ? ~result : result;
 }
 /* internal */
 static int32_t
 toUpperOrTitle(const UCaseProps *csp, UChar32 c,
                UCaseContextIterator *iter, void *context,
                const UChar **pString,
                const char *locale, int32_t *locCache,
                UBool upperNotTitle) {
     UChar32 result=c;
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         if(UCASE_GET_TYPE(props)==UCASE_LOWER) {
             result=c+UCASE_GET_DELTA(props);
         }
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(csp, props), *pe2;
         uint16_t excWord=*pe++;
         int32_t full, idx;
         pe2=pe;
         if(excWord&UCASE_EXC_CONDITIONAL_SPECIAL) {
             /* use hardcoded conditions and mappings */
             int32_t loc=ucase_getCaseLocale(locale, locCache);
             if(loc==UCASE_LOC_TURKISH && c==0x69) {
                 /*
                     # Turkish and Azeri
                     # I and i-dotless; I-dot and i are case pairs in Turkish and Azeri
                     # The following rules handle those cases.
                     # When uppercasing, i turns into a dotted capital I
 ; 0069; 0130; 0130; tr; # LATIN SMALL LETTER I
 ; 0069; 0130; 0130; az; # LATIN SMALL LETTER I
                 */
                 return 0x130;
             } else if(loc==UCASE_LOC_LITHUANIAN && c==0x307 && isPrecededBySoftDotted(csp, iter, context)) {
                 /*
                     # Lithuanian
                     # Lithuanian retains the dot in a lowercase i when followed by accents.
                     # Remove DOT ABOVE after "i" with upper or titlecase
 ; 0307; ; ; lt After_Soft_Dotted; # COMBINING DOT ABOVE
                  */
                 return 0; /* remove the dot (continue without output) */
             } else {
                 /* no known conditional special case mapping, use a normal mapping */
             }
         } else if(HAS_SLOT(excWord, UCASE_EXC_FULL_MAPPINGS)) {
             GET_SLOT_VALUE(excWord, UCASE_EXC_FULL_MAPPINGS, pe, full);
             /* start of full case mapping strings */
             ++pe;
             /* skip the lowercase and case-folding result strings */
             pe+=full&UCASE_FULL_LOWER;
             full>>=4;
             pe+=full&0xf;
             full>>=4;
             if(upperNotTitle) {
                 full&=0xf;
             } else {
                 /* skip the uppercase result string */
                 pe+=full&0xf;
                 full=(full>>4)&0xf;
             }
             if(full!=0) {
                 /* set the output pointer to the result string */
                 *pString=reinterpret_cast<const UChar *>(pe);
                 /* return the string length */
                 return full;
             }
         }
         if(!upperNotTitle && HAS_SLOT(excWord, UCASE_EXC_TITLE)) {
             idx=UCASE_EXC_TITLE;
         } else if(HAS_SLOT(excWord, UCASE_EXC_UPPER)) {
             /* here, titlecase is same as uppercase */
             idx=UCASE_EXC_UPPER;
         } else {
             return ~c;
         }
         GET_SLOT_VALUE(excWord, idx, pe2, result);
     }
     return (result==c) ? ~result : result;
 }
 U_CAPI int32_t U_EXPORT2
 ucase_toFullUpper(const UCaseProps *csp, UChar32 c,
                   UCaseContextIterator *iter, void *context,
                   const UChar **pString,
                   const char *locale, int32_t *locCache) {
     return toUpperOrTitle(csp, c, iter, context, pString, locale, locCache, TRUE);
 }
 U_CAPI int32_t U_EXPORT2
 ucase_toFullTitle(const UCaseProps *csp, UChar32 c,
                   UCaseContextIterator *iter, void *context,
                   const UChar **pString,
                   const char *locale, int32_t *locCache) {
     return toUpperOrTitle(csp, c, iter, context, pString, locale, locCache, FALSE);
 }
 /* case folding ------------------------------------------------------------- */
 /*
  * Case folding is similar to lowercasing.
  * The result may be a simple mapping, i.e., a single code point, or
  * a full mapping, i.e., a string.
  * If the case folding for a code point is the same as its simple (1:1) lowercase mapping,
  * then only the lowercase mapping is stored.
  *
  * Some special cases are hardcoded because their conditions cannot be
  * parsed and processed from CaseFolding.txt.
  *
  * Unicode 3.2 CaseFolding.txt specifies for its status field:
 # C: common case folding, common mappings shared by both simple and full mappings.
 # F: full case folding, mappings that cause strings to grow in length. Multiple characters are separated by spaces.
 # S: simple case folding, mappings to single characters where different from F.
 # T: special case for uppercase I and dotted uppercase I
 #    - For non-Turkic languages, this mapping is normally not used.
 #    - For Turkic languages (tr, az), this mapping can be used instead of the normal mapping for these characters.
 #
 # Usage:
 #  A. To do a simple case folding, use the mappings with status C + S.
 #  B. To do a full case folding, use the mappings with status C + F.
 #
 #    The mappings with status T can be used or omitted depending on the desired case-folding
 #    behavior. (The default option is to exclude them.)
  * Unicode 3.2 has 'T' mappings as follows:
 ; T; 0131; # LATIN CAPITAL LETTER I
 ; T; 0069; # LATIN CAPITAL LETTER I WITH DOT ABOVE
  * while the default mappings for these code points are:
 ; C; 0069; # LATIN CAPITAL LETTER I
 ; F; 0069 0307; # LATIN CAPITAL LETTER I WITH DOT ABOVE
  * U+0130 has no simple case folding (simple-case-folds to itself).
  */
 /* return the simple case folding mapping for c */
 U_CAPI UChar32 U_EXPORT2
 ucase_fold(const UCaseProps *csp, UChar32 c, uint32_t options) {
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         if(UCASE_GET_TYPE(props)>=UCASE_UPPER) {
             c+=UCASE_GET_DELTA(props);
         }
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(csp, props);
         uint16_t excWord=*pe++;
         int32_t idx;
         if(excWord&UCASE_EXC_CONDITIONAL_FOLD) {
             /* special case folding mappings, hardcoded */
             if((options&_FOLD_CASE_OPTIONS_MASK)==U_FOLD_CASE_DEFAULT) {
                 /* default mappings */
                 if(c==0x49) {
                     /* 0049; C; 0069; # LATIN CAPITAL LETTER I */
                     return 0x69;
                 } else if(c==0x130) {
                     /* no simple case folding for U+0130 */
                     return c;
                 }
             } else {
                 /* Turkic mappings */
                 if(c==0x49) {
                     /* 0049; T; 0131; # LATIN CAPITAL LETTER I */
                     return 0x131;
                 } else if(c==0x130) {
                     /* 0130; T; 0069; # LATIN CAPITAL LETTER I WITH DOT ABOVE */
                     return 0x69;
                 }
             }
         }
         if(HAS_SLOT(excWord, UCASE_EXC_FOLD)) {
             idx=UCASE_EXC_FOLD;
         } else if(HAS_SLOT(excWord, UCASE_EXC_LOWER)) {
             idx=UCASE_EXC_LOWER;
         } else {
             return c;
         }
         GET_SLOT_VALUE(excWord, idx, pe, c);
     }
     return c;
 }
 /*
  * Issue for canonical caseless match (UAX #21):
  * Turkic casefolding (using "T" mappings in CaseFolding.txt) does not preserve
  * canonical equivalence, unlike default-option casefolding.
  * For example, I-grave and I + grave fold to strings that are not canonically
  * equivalent.
  * For more details, see the comment in unorm_compare() in unorm.cpp
  * and the intermediate prototype changes for Jitterbug 2021.
  * (For example, revision 1.104 of uchar.c and 1.4 of CaseFolding.txt.)
  *
  * This did not get fixed because it appears that it is not possible to fix
  * it for uppercase and lowercase characters (I-grave vs. i-grave)
  * together in a way that they still fold to common result strings.
  */
 U_CAPI int32_t U_EXPORT2
 ucase_toFullFolding(const UCaseProps *csp, UChar32 c,
                     const UChar **pString,
                     uint32_t options)
 {
     UChar32 result=c;
     uint16_t props=UTRIE2_GET16(&csp->trie, c);
     if(!PROPS_HAS_EXCEPTION(props)) {
         if(UCASE_GET_TYPE(props)>=UCASE_UPPER) {
             result=c+UCASE_GET_DELTA(props);
         }
     } else {
         const uint16_t *pe=GET_EXCEPTIONS(csp, props), *pe2;
         uint16_t excWord=*pe++;
         int32_t full, idx;
         pe2=pe;
         if(excWord&UCASE_EXC_CONDITIONAL_FOLD) {
             /* use hardcoded conditions and mappings */
             if((options&_FOLD_CASE_OPTIONS_MASK)==U_FOLD_CASE_DEFAULT) {
                 /* default mappings */
                 if(c==0x49) {
                     /* 0049; C; 0069; # LATIN CAPITAL LETTER I */
                     return 0x69;
                 } else if(c==0x130) {
                     /* 0130; F; 0069 0307; # LATIN CAPITAL LETTER I WITH DOT ABOVE */
                     *pString=iDot;
                     return 2;
                 }
             } else {
                 /* Turkic mappings */
                 if(c==0x49) {
                     /* 0049; T; 0131; # LATIN CAPITAL LETTER I */
                     return 0x131;
                 } else if(c==0x130) {
                     /* 0130; T; 0069; # LATIN CAPITAL LETTER I WITH DOT ABOVE */
                     return 0x69;
                 }
             }
         } else if(HAS_SLOT(excWord, UCASE_EXC_FULL_MAPPINGS)) {
             GET_SLOT_VALUE(excWord, UCASE_EXC_FULL_MAPPINGS, pe, full);
             /* start of full case mapping strings */
             ++pe;
             /* skip the lowercase result string */
             pe+=full&UCASE_FULL_LOWER;
             full=(full>>4)&0xf;
             if(full!=0) {
                 /* set the output pointer to the result string */
                 *pString=reinterpret_cast<const UChar *>(pe);
                 /* return the string length */
                 return full;
             }
         }
         if(HAS_SLOT(excWord, UCASE_EXC_FOLD)) {
             idx=UCASE_EXC_FOLD;
         } else if(HAS_SLOT(excWord, UCASE_EXC_LOWER)) {
             idx=UCASE_EXC_LOWER;
         } else {
             return ~c;
         }
         GET_SLOT_VALUE(excWord, idx, pe2, result);
     }
     return (result==c) ? ~result : result;
 }
 /* case mapping properties API ---------------------------------------------- */
 #define GET_CASE_PROPS() &ucase_props_singleton
 /* public API (see uchar.h) */
 U_CAPI UBool U_EXPORT2
 u_isULowercase(UChar32 c) {
     return (UBool)(UCASE_LOWER==ucase_getType(GET_CASE_PROPS(), c));
 }
 U_CAPI UBool U_EXPORT2
 u_isUUppercase(UChar32 c) {
     return (UBool)(UCASE_UPPER==ucase_getType(GET_CASE_PROPS(), c));
 }
 /* Transforms the Unicode character to its lower case equivalent.*/
 U_CAPI UChar32 U_EXPORT2
 u_tolower(UChar32 c) {
     return ucase_tolower(GET_CASE_PROPS(), c);
 }
 /* Transforms the Unicode character to its upper case equivalent.*/
 U_CAPI UChar32 U_EXPORT2
 u_toupper(UChar32 c) {
     return ucase_toupper(GET_CASE_PROPS(), c);
 }
 /* Transforms the Unicode character to its title case equivalent.*/
 U_CAPI UChar32 U_EXPORT2
 u_totitle(UChar32 c) {
     return ucase_totitle(GET_CASE_PROPS(), c);
 }
 /* return the simple case folding mapping for c */
 U_CAPI UChar32 U_EXPORT2
 u_foldCase(UChar32 c, uint32_t options) {
     return ucase_fold(GET_CASE_PROPS(), c, options);
 }
 U_CFUNC int32_t U_EXPORT2
 ucase_hasBinaryProperty(UChar32 c, UProperty which) {
     /* case mapping properties */
     const UChar *resultString;
     int32_t locCache;
     const UCaseProps *csp=GET_CASE_PROPS();
     if(csp==NULL) {
         return FALSE;
     }
     switch(which) {
     case UCHAR_LOWERCASE:
         return (UBool)(UCASE_LOWER==ucase_getType(csp, c));
     case UCHAR_UPPERCASE:
         return (UBool)(UCASE_UPPER==ucase_getType(csp, c));
     case UCHAR_SOFT_DOTTED:
         return ucase_isSoftDotted(csp, c);
     case UCHAR_CASE_SENSITIVE:
         return ucase_isCaseSensitive(csp, c);
     case UCHAR_CASED:
         return (UBool)(UCASE_NONE!=ucase_getType(csp, c));
     case UCHAR_CASE_IGNORABLE:
         return (UBool)(ucase_getTypeOrIgnorable(csp, c)>>2);
     /*
      * Note: The following Changes_When_Xyz are defined as testing whether
      * the NFD form of the input changes when Xyz-case-mapped.
      * However, this simpler implementation of these properties,
      * ignoring NFD, passes the tests.
      * The implementation needs to be changed if the tests start failing.
      * When that happens, optimizations should be used to work with the
      * per-single-code point ucase_toFullXyz() functions unless
      * the NFD form has more than one code point,
      * and the property starts set needs to be the union of the
      * start sets for normalization and case mappings.
      */
     case UCHAR_CHANGES_WHEN_LOWERCASED:
         locCache=UCASE_LOC_ROOT;
         return (UBool)(ucase_toFullLower(csp, c, NULL, NULL, &resultString, "", &locCache)>=0);
     case UCHAR_CHANGES_WHEN_UPPERCASED:
         locCache=UCASE_LOC_ROOT;
         return (UBool)(ucase_toFullUpper(csp, c, NULL, NULL, &resultString, "", &locCache)>=0);
     case UCHAR_CHANGES_WHEN_TITLECASED:
         locCache=UCASE_LOC_ROOT;
         return (UBool)(ucase_toFullTitle(csp, c, NULL, NULL, &resultString, "", &locCache)>=0);
     /* case UCHAR_CHANGES_WHEN_CASEFOLDED: -- in uprops.c */
     case UCHAR_CHANGES_WHEN_CASEMAPPED:
         locCache=UCASE_LOC_ROOT;
         return (UBool)(
             ucase_toFullLower(csp, c, NULL, NULL, &resultString, "", &locCache)>=0 ||
             ucase_toFullUpper(csp, c, NULL, NULL, &resultString, "", &locCache)>=0 ||
             ucase_toFullTitle(csp, c, NULL, NULL, &resultString, "", &locCache)>=0);
     default:
         return FALSE;
     }
 }

The Tor Browser / annotate

intl/icu/source/common/ucase.cpp@129ffea94266 (annotated)

intl/icu/source/common/ucase.cpp