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* Copyright (C) 2009-2011, International Business Machines
* Corporation and others. All Rights Reserved.
* file name: normalizer2impl.h
* encoding: US-ASCII
* tab size: 8 (not used)
* indentation:4
* created on: 2009nov22
* created by: Markus W. Scherer
#include "unicode/utypes.h"
#include "unicode/normalizer2.h"
#include "unicode/udata.h"
#include "unicode/unistr.h"
#include "unicode/unorm.h"
#include "mutex.h"
#include "uset_imp.h"
#include "utrie2.h"
struct CanonIterData;
class Hangul {
/* Korean Hangul and Jamo constants */
enum {
JAMO_L_BASE=0x1100, /* "lead" jamo */
JAMO_V_BASE=0x1161, /* "vowel" jamo */
JAMO_T_BASE=0x11a7, /* "trail" jamo */
static inline UBool isHangul(UChar32 c) {
static inline UBool
isHangulWithoutJamoT(UChar c) {
return c<HANGUL_COUNT && c%JAMO_T_COUNT==0;
static inline UBool isJamoL(UChar32 c) {
return (uint32_t)(c-JAMO_L_BASE)<JAMO_L_COUNT;
static inline UBool isJamoV(UChar32 c) {
return (uint32_t)(c-JAMO_V_BASE)<JAMO_V_COUNT;
* Decomposes c, which must be a Hangul syllable, into buffer
* and returns the length of the decomposition (2 or 3).
static inline int32_t decompose(UChar32 c, UChar buffer[3]) {
UChar32 c2=c%JAMO_T_COUNT;
if(c2==0) {
return 2;
} else {
return 3;
Hangul(); // no instantiation
class Normalizer2Impl;
class ReorderingBuffer : public UMemory {
ReorderingBuffer(const Normalizer2Impl &ni, UnicodeString &dest) :
impl(ni), str(dest),
start(NULL), reorderStart(NULL), limit(NULL),
remainingCapacity(0), lastCC(0) {}
~ReorderingBuffer() {
if(start!=NULL) {
UBool init(int32_t destCapacity, UErrorCode &errorCode);
UBool isEmpty() const { return start==limit; }
int32_t length() const { return (int32_t)(limit-start); }
UChar *getStart() { return start; }
UChar *getLimit() { return limit; }
uint8_t getLastCC() const { return lastCC; }
UBool equals(const UChar *start, const UChar *limit) const;
// For Hangul composition, replacing the Leading consonant Jamo with the syllable.
void setLastChar(UChar c) {
UBool append(UChar32 c, uint8_t cc, UErrorCode &errorCode) {
return (c<=0xffff) ?
appendBMP((UChar)c, cc, errorCode) :
appendSupplementary(c, cc, errorCode);
// s must be in NFD, otherwise change the implementation.
UBool append(const UChar *s, int32_t length,
uint8_t leadCC, uint8_t trailCC,
UErrorCode &errorCode);
UBool appendBMP(UChar c, uint8_t cc, UErrorCode &errorCode) {
if(remainingCapacity==0 && !resize(1, errorCode)) {
return FALSE;
if(lastCC<=cc || cc==0) {
if(cc<=1) {
} else {
insert(c, cc);
return TRUE;
UBool appendZeroCC(UChar32 c, UErrorCode &errorCode);
UBool appendZeroCC(const UChar *s, const UChar *sLimit, UErrorCode &errorCode);
void remove();
void removeSuffix(int32_t suffixLength);
void setReorderingLimit(UChar *newLimit) {
void copyReorderableSuffixTo(UnicodeString &s) const {
s.setTo(reorderStart, (int32_t)(limit-reorderStart));
* TODO: Revisit whether it makes sense to track reorderStart.
* It is set to after the last known character with cc<=1,
* which stops previousCC() before it reads that character and looks up its cc.
* previousCC() is normally only called from insert().
* In other words, reorderStart speeds up the insertion of a combining mark
* into a multi-combining mark sequence where it does not belong at the end.
* This might not be worth the trouble.
* On the other hand, it's not a huge amount of trouble.
* We probably need it for UNORM_SIMPLE_APPEND.
UBool appendSupplementary(UChar32 c, uint8_t cc, UErrorCode &errorCode);
void insert(UChar32 c, uint8_t cc);
static void writeCodePoint(UChar *p, UChar32 c) {
if(c<=0xffff) {
} else {
UBool resize(int32_t appendLength, UErrorCode &errorCode);
const Normalizer2Impl &impl;
UnicodeString &str;
UChar *start, *reorderStart, *limit;
int32_t remainingCapacity;
uint8_t lastCC;
// private backward iterator
void setIterator() { codePointStart=limit; }
void skipPrevious(); // Requires start<codePointStart.
uint8_t previousCC(); // Returns 0 if there is no previous character.
UChar *codePointStart, *codePointLimit;
class U_COMMON_API Normalizer2Impl : public UMemory {
Normalizer2Impl() : memory(NULL), normTrie(NULL) {
void load(const char *packageName, const char *name, UErrorCode &errorCode);
void addPropertyStarts(const USetAdder *sa, UErrorCode &errorCode) const;
void addCanonIterPropertyStarts(const USetAdder *sa, UErrorCode &errorCode) const;
// low-level properties ------------------------------------------------ ***
const UTrie2 *getNormTrie() const { return normTrie; }
const UTrie2 *getFCDTrie(UErrorCode &errorCode) const ;
UBool ensureCanonIterData(UErrorCode &errorCode) const;
uint16_t getNorm16(UChar32 c) const { return UTRIE2_GET16(normTrie, c); }
UNormalizationCheckResult getCompQuickCheck(uint16_t norm16) const {
if(norm16<minNoNo || MIN_YES_YES_WITH_CC<=norm16) {
return UNORM_YES;
} else if(minMaybeYes<=norm16) {
} else {
return UNORM_NO;
UBool isCompNo(uint16_t norm16) const { return minNoNo<=norm16 && norm16<minMaybeYes; }
UBool isDecompYes(uint16_t norm16) const { return norm16<minYesNo || minMaybeYes<=norm16; }
uint8_t getCC(uint16_t norm16) const {
if(norm16>=MIN_NORMAL_MAYBE_YES) {
return (uint8_t)norm16;
if(norm16<minNoNo || limitNoNo<=norm16) {
return 0;
return getCCFromNoNo(norm16);
static uint8_t getCCFromYesOrMaybe(uint16_t norm16) {
return norm16>=MIN_NORMAL_MAYBE_YES ? (uint8_t)norm16 : 0;
uint16_t getFCD16(UChar32 c) const { return UTRIE2_GET16(fcdTrie(), c); }
uint16_t getFCD16FromSingleLead(UChar c) const {
return UTRIE2_GET16_FROM_U16_SINGLE_LEAD(fcdTrie(), c);
uint16_t getFCD16FromSupplementary(UChar32 c) const {
return UTRIE2_GET16_FROM_SUPP(fcdTrie(), c);
uint16_t getFCD16FromSurrogatePair(UChar c, UChar c2) const {
return getFCD16FromSupplementary(U16_GET_SUPPLEMENTARY(c, c2));
void setFCD16FromNorm16(UChar32 start, UChar32 end, uint16_t norm16,
UTrie2 *newFCDTrie, UErrorCode &errorCode) const;
void makeCanonIterDataFromNorm16(UChar32 start, UChar32 end, uint16_t norm16,
CanonIterData &newData, UErrorCode &errorCode) const;
* Get the decomposition for one code point.
* @param c code point
* @param buffer out-only buffer for algorithmic decompositions
* @param length out-only, takes the length of the decomposition, if any
* @return pointer to the decomposition, or NULL if none
const UChar *getDecomposition(UChar32 c, UChar buffer[4], int32_t &length) const;
UBool isCanonSegmentStarter(UChar32 c) const;
UBool getCanonStartSet(UChar32 c, UnicodeSet &set) const;
enum {
enum {
enum {
// Byte offsets from the start of the data, after the generic header.
// Code point thresholds for quick check codes.
// Norm16 value thresholds for quick check combinations and types of extra data.
enum {
enum {
COMP_1_TRAIL_SHIFT=9, // 10-1 for the "triple" bit
// higher-level functionality ------------------------------------------ ***
const UChar *decompose(const UChar *src, const UChar *limit,
ReorderingBuffer *buffer, UErrorCode &errorCode) const;
void decomposeAndAppend(const UChar *src, const UChar *limit,
UBool doDecompose,
UnicodeString &safeMiddle,
ReorderingBuffer &buffer,
UErrorCode &errorCode) const;
UBool compose(const UChar *src, const UChar *limit,
UBool onlyContiguous,
UBool doCompose,
ReorderingBuffer &buffer,
UErrorCode &errorCode) const;
const UChar *composeQuickCheck(const UChar *src, const UChar *limit,
UBool onlyContiguous,
UNormalizationCheckResult *pQCResult) const;
void composeAndAppend(const UChar *src, const UChar *limit,
UBool doCompose,
UBool onlyContiguous,
UnicodeString &safeMiddle,
ReorderingBuffer &buffer,
UErrorCode &errorCode) const;
const UChar *makeFCD(const UChar *src, const UChar *limit,
ReorderingBuffer *buffer, UErrorCode &errorCode) const;
void makeFCDAndAppend(const UChar *src, const UChar *limit,
UBool doMakeFCD,
UnicodeString &safeMiddle,
ReorderingBuffer &buffer,
UErrorCode &errorCode) const;
UBool hasDecompBoundary(UChar32 c, UBool before) const;
UBool isDecompInert(UChar32 c) const { return isDecompYesAndZeroCC(getNorm16(c)); }
UBool hasCompBoundaryBefore(UChar32 c) const {
return c<minCompNoMaybeCP || hasCompBoundaryBefore(c, getNorm16(c));
UBool hasCompBoundaryAfter(UChar32 c, UBool onlyContiguous, UBool testInert) const;
UBool hasFCDBoundaryBefore(UChar32 c) const { return c<MIN_CCC_LCCC_CP || getFCD16(c)<=0xff; }
UBool hasFCDBoundaryAfter(UChar32 c) const {
uint16_t fcd16=getFCD16(c);
return fcd16<=1 || (fcd16&0xff)==0;
UBool isFCDInert(UChar32 c) const { return getFCD16(c)<=1; }
static UBool U_CALLCONV
isAcceptable(void *context, const char *type, const char *name, const UDataInfo *pInfo);
UBool isMaybe(uint16_t norm16) const { return minMaybeYes<=norm16 && norm16<=JAMO_VT; }
UBool isMaybeOrNonZeroCC(uint16_t norm16) const { return norm16>=minMaybeYes; }
static UBool isInert(uint16_t norm16) { return norm16==0; }
// static UBool isJamoL(uint16_t norm16) const { return norm16==1; }
static UBool isJamoVT(uint16_t norm16) { return norm16==JAMO_VT; }
UBool isHangul(uint16_t norm16) const { return norm16==minYesNo; }
UBool isCompYesAndZeroCC(uint16_t norm16) const { return norm16<minNoNo; }
// UBool isCompYes(uint16_t norm16) const {
// return norm16>=MIN_YES_YES_WITH_CC || norm16<minNoNo;
// }
// UBool isCompYesOrMaybe(uint16_t norm16) const {
// return norm16<minNoNo || minMaybeYes<=norm16;
// }
// UBool hasZeroCCFromDecompYes(uint16_t norm16) const {
// return norm16<=MIN_NORMAL_MAYBE_YES || norm16==JAMO_VT;
// }
UBool isDecompYesAndZeroCC(uint16_t norm16) const {
return norm16<minYesNo ||
norm16==JAMO_VT ||
(minMaybeYes<=norm16 && norm16<=MIN_NORMAL_MAYBE_YES);
* A little faster and simpler than isDecompYesAndZeroCC() but does not include
* the MaybeYes which combine-forward and have ccc=0.
* (Standard Unicode 5.2 normalization does not have such characters.)
UBool isMostDecompYesAndZeroCC(uint16_t norm16) const {
return norm16<minYesNo || norm16==MIN_NORMAL_MAYBE_YES || norm16==JAMO_VT;
UBool isDecompNoAlgorithmic(uint16_t norm16) const { return norm16>=limitNoNo; }
// For use with isCompYes().
// Perhaps the compiler can combine the two tests for MIN_YES_YES_WITH_CC.
// static uint8_t getCCFromYes(uint16_t norm16) {
// return norm16>=MIN_YES_YES_WITH_CC ? (uint8_t)norm16 : 0;
// }
uint8_t getCCFromNoNo(uint16_t norm16) const {
const uint16_t *mapping=getMapping(norm16);
return (uint8_t)mapping[1];
} else {
return 0;
// requires that the [cpStart..cpLimit[ character passes isCompYesAndZeroCC()
uint8_t getTrailCCFromCompYesAndZeroCC(const UChar *cpStart, const UChar *cpLimit) const;
// Requires algorithmic-NoNo.
UChar32 mapAlgorithmic(UChar32 c, uint16_t norm16) const {
return c+norm16-(minMaybeYes-MAX_DELTA-1);
// Requires minYesNo<norm16<limitNoNo.
const uint16_t *getMapping(uint16_t norm16) const { return extraData+norm16; }
const uint16_t *getCompositionsListForDecompYes(uint16_t norm16) const {
if(norm16==0 || MIN_NORMAL_MAYBE_YES<=norm16) {
return NULL;
} else if(norm16<minMaybeYes) {
return extraData+norm16; // for yesYes; if Jamo L: harmless empty list
} else {
return maybeYesCompositions+norm16-minMaybeYes;
const uint16_t *getCompositionsListForComposite(uint16_t norm16) const {
const uint16_t *list=extraData+norm16; // composite has both mapping & compositions list
return list+ // mapping pointer
1+ // +1 to skip the first unit with the mapping lenth
(*list&MAPPING_LENGTH_MASK)+ // + mapping length
((*list>>7)&1); // +1 if MAPPING_HAS_CCC_LCCC_WORD
* @param c code point must have compositions
* @return compositions list pointer
const uint16_t *getCompositionsList(uint16_t norm16) const {
return isDecompYes(norm16) ?
getCompositionsListForDecompYes(norm16) :
const UChar *copyLowPrefixFromNulTerminated(const UChar *src,
UChar32 minNeedDataCP,
ReorderingBuffer *buffer,
UErrorCode &errorCode) const;
UBool decomposeShort(const UChar *src, const UChar *limit,
ReorderingBuffer &buffer, UErrorCode &errorCode) const;
UBool decompose(UChar32 c, uint16_t norm16,
ReorderingBuffer &buffer, UErrorCode &errorCode) const;
static int32_t combine(const uint16_t *list, UChar32 trail);
void addComposites(const uint16_t *list, UnicodeSet &set) const;
void recompose(ReorderingBuffer &buffer, int32_t recomposeStartIndex,
UBool onlyContiguous) const;
UBool hasCompBoundaryBefore(UChar32 c, uint16_t norm16) const;
const UChar *findPreviousCompBoundary(const UChar *start, const UChar *p) const;
const UChar *findNextCompBoundary(const UChar *p, const UChar *limit) const;
const UTrie2 *fcdTrie() const { return (const UTrie2 *)fcdTrieSingleton.fInstance; }
const UChar *findPreviousFCDBoundary(const UChar *start, const UChar *p) const;
const UChar *findNextFCDBoundary(const UChar *p, const UChar *limit) const;
int32_t getCanonValue(UChar32 c) const;
const UnicodeSet &getCanonStartSet(int32_t n) const;
UDataMemory *memory;
UVersionInfo dataVersion;
// Code point thresholds for quick check codes.
UChar32 minDecompNoCP;
UChar32 minCompNoMaybeCP;
// Norm16 value thresholds for quick check combinations and types of extra data.
uint16_t minYesNo;
uint16_t minNoNo;
uint16_t limitNoNo;
uint16_t minMaybeYes;
UTrie2 *normTrie;
const uint16_t *maybeYesCompositions;
const uint16_t *extraData; // mappings and/or compositions for yesYes, yesNo & noNo characters
SimpleSingleton fcdTrieSingleton;
SimpleSingleton canonIterDataSingleton;
// bits in canonIterData
#define CANON_NOT_SEGMENT_STARTER 0x80000000
#define CANON_HAS_COMPOSITIONS 0x40000000
#define CANON_HAS_SET 0x200000
#define CANON_VALUE_MASK 0x1fffff
* ICU-internal shortcut for quick access to standard Unicode normalization.
class U_COMMON_API Normalizer2Factory {
static const Normalizer2 *getNFCInstance(UErrorCode &errorCode);
static const Normalizer2 *getNFDInstance(UErrorCode &errorCode);
static const Normalizer2 *getFCDInstance(UErrorCode &errorCode);
static const Normalizer2 *getFCCInstance(UErrorCode &errorCode);
static const Normalizer2 *getNFKCInstance(UErrorCode &errorCode);
static const Normalizer2 *getNFKDInstance(UErrorCode &errorCode);
static const Normalizer2 *getNFKC_CFInstance(UErrorCode &errorCode);
static const Normalizer2 *getNoopInstance(UErrorCode &errorCode);
static const Normalizer2 *getInstance(UNormalizationMode mode, UErrorCode &errorCode);
static const Normalizer2Impl *getNFCImpl(UErrorCode &errorCode);
static const Normalizer2Impl *getNFKCImpl(UErrorCode &errorCode);
static const Normalizer2Impl *getNFKC_CFImpl(UErrorCode &errorCode);
// Get the Impl instance of the Normalizer2.
// Must be used only when it is known that norm2 is a Normalizer2WithImpl instance.
static const Normalizer2Impl *getImpl(const Normalizer2 *norm2);
static const UTrie2 *getFCDTrie(UErrorCode &errorCode);
Normalizer2Factory(); // No instantiation.
U_CAPI int32_t U_EXPORT2
unorm2_swap(const UDataSwapper *ds,
const void *inData, int32_t length, void *outData,
UErrorCode *pErrorCode);
* Get the NF*_QC property for a code point, for u_getIntPropertyValue().
* @internal
U_CFUNC UNormalizationCheckResult U_EXPORT2
unorm_getQuickCheck(UChar32 c, UNormalizationMode mode);
* Internal API, used by collation code.
* Get access to the internal FCD trie table to be able to perform
* incremental, per-code unit, FCD checks in collation.
* One pointer is sufficient because the trie index values are offset
* by the index size, so that the same pointer is used to access the trie data.
* Code points at fcdHighStart and above have a zero FCD value.
* @internal
U_CAPI const uint16_t * U_EXPORT2
unorm_getFCDTrieIndex(UChar32 &fcdHighStart, UErrorCode *pErrorCode);
* Internal API, used by collation code.
* Get the FCD value for a code unit, with
* bits 15..8 lead combining class
* bits 7..0 trail combining class
* If c is a lead surrogate and the value is not 0,
* then some of c's associated supplementary code points have a non-zero FCD value.
* @internal
static inline uint16_t
unorm_getFCD16(const uint16_t *fcdTrieIndex, UChar c) {
return fcdTrieIndex[_UTRIE2_INDEX_FROM_U16_SINGLE_LEAD(fcdTrieIndex, c)];
* Internal API, used by collation code.
* Get the FCD value of the next code point (post-increment), with
* bits 15..8 lead combining class
* bits 7..0 trail combining class
* @internal
static inline uint16_t
unorm_nextFCD16(const uint16_t *fcdTrieIndex, UChar32 fcdHighStart,
const UChar *&s, const UChar *limit) {
UChar32 c=*s++;
uint16_t fcd=fcdTrieIndex[_UTRIE2_INDEX_FROM_U16_SINGLE_LEAD(fcdTrieIndex, c)];
if(fcd!=0 && U16_IS_LEAD(c)) {
UChar c2;
if(s!=limit && U16_IS_TRAIL(c2=*s)) {
if(c<fcdHighStart) {
fcd=fcdTrieIndex[_UTRIE2_INDEX_FROM_SUPP(fcdTrieIndex, c)];
} else {
} else /* unpaired lead surrogate */ {
return fcd;
* Internal API, used by collation code.
* Get the FCD value of the previous code point (pre-decrement), with
* bits 15..8 lead combining class
* bits 7..0 trail combining class
* @internal
static inline uint16_t
unorm_prevFCD16(const uint16_t *fcdTrieIndex, UChar32 fcdHighStart,
const UChar *start, const UChar *&s) {
UChar32 c=*--s;
uint16_t fcd;
if(!U16_IS_SURROGATE(c)) {
fcd=fcdTrieIndex[_UTRIE2_INDEX_FROM_U16_SINGLE_LEAD(fcdTrieIndex, c)];
} else {
UChar c2;
if(U16_IS_SURROGATE_TRAIL(c) && s!=start && U16_IS_LEAD(c2=*(s-1))) {
if(c<fcdHighStart) {
fcd=fcdTrieIndex[_UTRIE2_INDEX_FROM_SUPP(fcdTrieIndex, c)];
} else {
} else /* unpaired surrogate */ {
return fcd;
* Format of Normalizer2 .nrm data files.
* Format version 1.0.
* Normalizer2 .nrm data files provide data for the Unicode Normalization algorithms.
* ICU ships with data files for standard Unicode Normalization Forms
* NFC and NFD (nfc.nrm), NFKC and NFKD (nfkc.nrm) and NFKC_Casefold (nfkc_cf.nrm).
* Custom (application-specific) data can be built into additional .nrm files
* with the gennorm2 build tool.
* Normalizer2.getInstance() causes a .nrm file to be loaded, unless it has been
* cached already. Internally, Normalizer2Impl.load() reads the .nrm file.
* A .nrm file begins with a standard ICU data file header
* (DataHeader, see ucmndata.h and unicode/udata.h).
* The UDataInfo.dataVersion field usually contains the Unicode version
* for which the data was generated.
* After the header, the file contains the following parts.
* Constants are defined as enum values of the Normalizer2Impl class.
* Many details of the data structures are described in the design doc
* which is at
* int32_t indexes[indexesLength]; -- indexesLength=indexes[IX_NORM_TRIE_OFFSET]/4;
* The first eight indexes are byte offsets in ascending order.
* Each byte offset marks the start of the next part in the data file,
* and the end of the previous one.
* When two consecutive byte offsets are the same, then the corresponding part is empty.
* Byte offsets are offsets from after the header,
* that is, from the beginning of the indexes[].
* Each part starts at an offset with proper alignment for its data.
* If necessary, the previous part may include padding bytes to achieve this alignment.
* minDecompNoCP=indexes[IX_MIN_DECOMP_NO_CP] is the lowest code point
* with a decomposition mapping, that is, with NF*D_QC=No.
* minCompNoMaybeCP=indexes[IX_MIN_COMP_NO_MAYBE_CP] is the lowest code point
* with NF*C_QC=No (has a one-way mapping) or Maybe (combines backward).
* The next four indexes are thresholds of 16-bit trie values for ranges of
* values indicating multiple normalization properties.
* minYesNo=indexes[IX_MIN_YES_NO];
* minNoNo=indexes[IX_MIN_NO_NO];
* limitNoNo=indexes[IX_LIMIT_NO_NO];
* minMaybeYes=indexes[IX_MIN_MAYBE_YES];
* See the normTrie description below and the design doc for details.
* UTrie2 normTrie; -- see utrie2_impl.h and utrie2.h
* The trie holds the main normalization data. Each code point is mapped to a 16-bit value.
* Rather than using independent bits in the value (which would require more than 16 bits),
* information is extracted primarily via range checks.
* For example, a 16-bit value norm16 in the range minYesNo<=norm16<minNoNo
* means that the character has NF*C_QC=Yes and NF*D_QC=No properties,
* which means it has a two-way (round-trip) decomposition mapping.
* Values in the range 2<=norm16<limitNoNo are also directly indexes into the extraData
* pointing to mappings, composition lists, or both.
* Value norm16==0 means that the character is normalization-inert, that is,
* it does not have a mapping, does not participate in composition, has a zero
* canonical combining class, and forms a boundary where text before it and after it
* can be normalized independently.
* For details about how multiple properties are encoded in 16-bit values
* see the design doc.
* Note that the encoding cannot express all combinations of the properties involved;
* it only supports those combinations that are allowed by
* the Unicode Normalization algorithms. Details are in the design doc as well.
* The gennorm2 tool only builds .nrm files for data that conforms to the limitations.
* The trie has a value for each lead surrogate code unit representing the "worst case"
* properties of the 1024 supplementary characters whose UTF-16 form starts with
* the lead surrogate. If all of the 1024 supplementary characters are normalization-inert,
* then their lead surrogate code unit has the trie value 0.
* When the lead surrogate unit's value exceeds the quick check minimum during processing,
* the properties for the full supplementary code point need to be looked up.
* uint16_t maybeYesCompositions[MIN_NORMAL_MAYBE_YES-minMaybeYes];
* uint16_t extraData[];
* There is only one byte offset for the end of these two arrays.
* The split between them is given by the constant and variable mentioned above.
* The maybeYesCompositions array contains composition lists for characters that
* combine both forward (as starters in composition pairs)
* and backward (as trailing characters in composition pairs).
* Such characters do not occur in Unicode 5.2 but are allowed by
* the Unicode Normalization algorithms.
* If there are no such characters, then minMaybeYes==MIN_NORMAL_MAYBE_YES
* and the maybeYesCompositions array is empty.
* If there are such characters, then minMaybeYes is subtracted from their norm16 values
* to get the index into this array.
* The extraData array contains composition lists for "YesYes" characters,
* followed by mappings and optional composition lists for "YesNo" characters,
* followed by only mappings for "NoNo" characters.
* (Referring to pairs of NFC/NFD quick check values.)
* The norm16 values of those characters are directly indexes into the extraData array.
* The data structures for composition lists and mappings are described in the design doc.
#endif /* __NORMALIZER2IMPL_H__ */