/*

 *******************************************************************************

 *

 *   Copyright (C) 2001-2004, International Business Machines

 *   Corporation and others.  All Rights Reserved.

 *

 *******************************************************************************

 *   file name:  unormimp.h

 *   encoding:   US-ASCII

 *   tab size:   8 (not used)

 *   indentation:4

 *

 *   created on: 2001may25

 *   created by: Markus W. Scherer

 */

 #ifndef __UNORMIMP_H__

 #define __UNORMIMP_H__

 #include "unicode/utypes.h"

 #if !UCONFIG_NO_NORMALIZATION

 #ifdef XP_CPLUSPLUS

 #include "unicode/uniset.h"

 #endif

 #include "unicode/uiter.h"

 #include "unicode/unorm.h"

 #include "unicode/uset.h"

 #include "utrie.h"

 #include "ustr_imp.h"

 #include "udataswp.h"

 /*

  * This new implementation of the normalization code loads its data from

  * unorm.icu, which is generated with the gennorm tool.

  * The format of that file is described at the end of this file.

  */

 /* norm32 value constants */

 enum {

     /* quick check flags 0..3 set mean "no" for their forms */

     _NORM_QC_NFC=0x11,          /* no|maybe */

     _NORM_QC_NFKC=0x22,         /* no|maybe */

     _NORM_QC_NFD=4,             /* no */

     _NORM_QC_NFKD=8,            /* no */

     _NORM_QC_ANY_NO=0xf,

     /* quick check flags 4..5 mean "maybe" for their forms; test flags>=_NORM_QC_MAYBE */

     _NORM_QC_MAYBE=0x10,

     _NORM_QC_ANY_MAYBE=0x30,

     _NORM_QC_MASK=0x3f,

     _NORM_COMBINES_FWD=0x40,

     _NORM_COMBINES_BACK=0x80,

     _NORM_COMBINES_ANY=0xc0,

     _NORM_CC_SHIFT=8,           /* UnicodeData.txt combining class in bits 15..8 */

     _NORM_CC_MASK=0xff00,

     _NORM_EXTRA_SHIFT=16,               /* 16 bits for the index to UChars and other extra data */

     _NORM_EXTRA_INDEX_TOP=0xfc00,       /* start of surrogate specials after shift */

     _NORM_EXTRA_SURROGATE_MASK=0x3ff,

     _NORM_EXTRA_SURROGATE_TOP=0x3f0,    /* hangul etc. */

     _NORM_EXTRA_HANGUL=_NORM_EXTRA_SURROGATE_TOP,

     _NORM_EXTRA_JAMO_L,

     _NORM_EXTRA_JAMO_V,

     _NORM_EXTRA_JAMO_T

 };

 /* norm32 value constants using >16 bits */

 #define _NORM_MIN_SPECIAL       0xfc000000

 #define _NORM_SURROGATES_TOP    0xfff00000

 #define _NORM_MIN_HANGUL        0xfff00000

 #define _NORM_MIN_JAMO_V        0xfff20000

 #define _NORM_JAMO_V_TOP        0xfff30000

 /* value constants for auxTrie */

 enum {

     _NORM_AUX_COMP_EX_SHIFT=10,

     _NORM_AUX_UNSAFE_SHIFT=11,

     _NORM_AUX_NFC_SKIPPABLE_F_SHIFT=12

 };

 #define _NORM_AUX_MAX_FNC           ((int32_t)1<<_NORM_AUX_COMP_EX_SHIFT)

 #define _NORM_AUX_FNC_MASK          (uint32_t)(_NORM_AUX_MAX_FNC-1)

 #define _NORM_AUX_COMP_EX_MASK      ((uint32_t)1<<_NORM_AUX_COMP_EX_SHIFT)

 #define _NORM_AUX_UNSAFE_MASK       ((uint32_t)1<<_NORM_AUX_UNSAFE_SHIFT)

 #define _NORM_AUX_NFC_SKIP_F_MASK   ((uint32_t)1<<_NORM_AUX_NFC_SKIPPABLE_F_SHIFT)

 /* canonStartSets[0..31] contains indexes for what is in the array */

 enum {

     _NORM_SET_INDEX_CANON_SETS_LENGTH,      /* number of uint16_t in canonical starter sets */

     _NORM_SET_INDEX_CANON_BMP_TABLE_LENGTH, /* number of uint16_t in the BMP search table (contains pairs) */

     _NORM_SET_INDEX_CANON_SUPP_TABLE_LENGTH,/* number of uint16_t in the supplementary search table (contains triplets) */

     /* from formatVersion 2.3: */

     _NORM_SET_INDEX_NX_CJK_COMPAT_OFFSET,   /* uint16_t offset from canonStartSets[0] to the

                                                exclusion set for CJK compatibility characters */

     _NORM_SET_INDEX_NX_UNICODE32_OFFSET,    /* uint16_t offset from canonStartSets[0] to the

                                                exclusion set for Unicode 3.2 characters */

     _NORM_SET_INDEX_NX_RESERVED_OFFSET,     /* uint16_t offset from canonStartSets[0] to the

                                                end of the previous exclusion set */

     _NORM_SET_INDEX_TOP=32                  /* changing this requires a new formatVersion */

 };

 /* more constants for canonical starter sets */

 /* 14 bit indexes to canonical USerializedSets */

 #define _NORM_MAX_CANON_SETS            0x4000

 /* single-code point BMP sets are encoded directly in the search table except if result=0x4000..0x7fff */

 #define _NORM_CANON_SET_BMP_MASK        0xc000

 #define _NORM_CANON_SET_BMP_IS_INDEX    0x4000

 /* indexes[] value names */

 enum {

     _NORM_INDEX_TRIE_SIZE,              /* number of bytes in normalization trie */

     _NORM_INDEX_UCHAR_COUNT,            /* number of UChars in extra data */

     _NORM_INDEX_COMBINE_DATA_COUNT,     /* number of uint16_t words for combining data */

     _NORM_INDEX_COMBINE_FWD_COUNT,      /* number of code points that combine forward */

     _NORM_INDEX_COMBINE_BOTH_COUNT,     /* number of code points that combine forward and backward */

     _NORM_INDEX_COMBINE_BACK_COUNT,     /* number of code points that combine backward */

     _NORM_INDEX_MIN_NFC_NO_MAYBE,       /* first code point with quick check NFC NO/MAYBE */

     _NORM_INDEX_MIN_NFKC_NO_MAYBE,      /* first code point with quick check NFKC NO/MAYBE */

     _NORM_INDEX_MIN_NFD_NO_MAYBE,       /* first code point with quick check NFD NO/MAYBE */

     _NORM_INDEX_MIN_NFKD_NO_MAYBE,      /* first code point with quick check NFKD NO/MAYBE */

     _NORM_INDEX_FCD_TRIE_SIZE,          /* number of bytes in FCD trie */

     _NORM_INDEX_AUX_TRIE_SIZE,          /* number of bytes in the auxiliary trie */

     _NORM_INDEX_CANON_SET_COUNT,        /* number of uint16_t in the array of serialized USet */

     _NORM_INDEX_TOP=32                  /* changing this requires a new formatVersion */

 };

 enum {

     /* FCD check: everything below this code point is known to have a 0 lead combining class */

     _NORM_MIN_WITH_LEAD_CC=0x300

 };

 enum {

     /**

      * Bit 7 of the length byte for a decomposition string in extra data is

      * a flag indicating whether the decomposition string is

      * preceded by a 16-bit word with the leading and trailing cc

      * of the decomposition (like for A-umlaut);

      * if not, then both cc's are zero (like for compatibility ideographs).

      */

     _NORM_DECOMP_FLAG_LENGTH_HAS_CC=0x80,

     /**

      * Bits 6..0 of the length byte contain the actual length.

      */

     _NORM_DECOMP_LENGTH_MASK=0x7f

 };

 #endif /* #if !UCONFIG_NO_NORMALIZATION */

 /* Korean Hangul and Jamo constants */

 enum {

     JAMO_L_BASE=0x1100,     /* "lead" jamo */

     JAMO_V_BASE=0x1161,     /* "vowel" jamo */

     JAMO_T_BASE=0x11a7,     /* "trail" jamo */

     HANGUL_BASE=0xac00,

     JAMO_L_COUNT=19,

     JAMO_V_COUNT=21,

     JAMO_T_COUNT=28,

     HANGUL_COUNT=JAMO_L_COUNT*JAMO_V_COUNT*JAMO_T_COUNT

 };

 #if !UCONFIG_NO_NORMALIZATION

 /* Constants for options flags for normalization. @draft ICU 2.6 */

 enum {

     /** Options bit 0, do not decompose Hangul syllables. @draft ICU 2.6 */

     UNORM_NX_HANGUL=1,

     /** Options bit 1, do not decompose CJK compatibility characters. @draft ICU 2.6 */

     UNORM_NX_CJK_COMPAT=2,

     /**

      * Options bit 8, use buggy recomposition described in

      * Unicode Public Review Issue #29

      * at http://www.unicode.org/review/resolved-pri.html#pri29

      *

      * Used in IDNA implementation according to strict interpretation

      * of IDNA definition based on Unicode 3.2 which predates PRI #29.

      */

     UNORM_BEFORE_PRI_29=0x100

 };

 /**

  * Is the normalizer data loaded?

  * This is used internally before other internal normalizer functions

  * are called.

  * It saves this check in each of many normalization calls that

  * are made for, e.g., collation.

  *

  * @param pErrorCode as usual

  * @return boolean value for whether the normalization data is loaded

  *

  * @internal

  */

 U_CAPI UBool U_EXPORT2

 unorm_haveData(UErrorCode *pErrorCode);

 /**

  * Internal API for normalizing.

  * Does not check for bad input.

  * @internal

  */

 U_CAPI int32_t U_EXPORT2

 unorm_internalNormalize(UChar *dest, int32_t destCapacity,

                         const UChar *src, int32_t srcLength,

                         UNormalizationMode mode, int32_t options,

                         UErrorCode *pErrorCode);

 #ifdef XP_CPLUSPLUS

 /**

  * Internal API for normalizing.

  * Does not check for bad input.

  * Requires _haveData() to be true.

  * @internal

  */

 U_CFUNC int32_t

 unorm_internalNormalizeWithNX(UChar *dest, int32_t destCapacity,

                               const UChar *src, int32_t srcLength,

                               UNormalizationMode mode, int32_t options, const UnicodeSet *nx,

                               UErrorCode *pErrorCode);

 #endif

 /**

  * internal API, used by normlzr.cpp

  * @internal

  */

 U_CAPI int32_t U_EXPORT2

 unorm_decompose(UChar *dest, int32_t destCapacity,

                 const UChar *src, int32_t srcLength,

                 UBool compat, int32_t options,

                 UErrorCode *pErrorCode);

 /**

  * internal API, used by normlzr.cpp

  * @internal

  */

 U_CAPI int32_t U_EXPORT2

 unorm_compose(UChar *dest, int32_t destCapacity,

               const UChar *src, int32_t srcLength,

               UBool compat, int32_t options,

               UErrorCode *pErrorCode);

 #ifdef XP_CPLUSPLUS

 /**

  * internal API, used by unormcmp.cpp

  * @internal

  */

 U_CFUNC UNormalizationCheckResult

 unorm_internalQuickCheck(const UChar *src,

                          int32_t srcLength,

                          UNormalizationMode mode,

                          UBool allowMaybe,

                          const UnicodeSet *nx,

                          UErrorCode *pErrorCode);

 #endif

 #endif /* #if !UCONFIG_NO_NORMALIZATION */

 /**

  * Internal option for unorm_cmpEquivFold() for decomposing.

  * If not set, just do strcasecmp().

  * @internal

  */

 #define _COMPARE_EQUIV 0x80000

 #ifndef U_COMPARE_IGNORE_CASE

 /* see also unorm.h */

 /**

  * Option bit for unorm_compare:

  * Perform case-insensitive comparison.

  * @draft ICU 2.2

  */

 #define U_COMPARE_IGNORE_CASE       0x10000

 #endif

 /**

  * Internal option for unorm_cmpEquivFold() for strncmp style.

  * If set, checks for both string length and terminating NUL.

  * @internal

  */

 #define _STRNCMP_STYLE 0x1000

 #if !UCONFIG_NO_NORMALIZATION

 /**

  * Internal API to get the 16-bit FCD value (lccc + tccc) for c,

  * for u_getIntPropertyValue().

  * @internal

  */

 U_CAPI uint16_t U_EXPORT2

 unorm_getFCD16FromCodePoint(UChar32 c);

 /**

  * 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.

  * @internal

  */

 U_CAPI const uint16_t * U_EXPORT2

 unorm_getFCDTrie(UErrorCode *pErrorCode);

 #ifdef XP_CPLUSPLUS

 U_NAMESPACE_BEGIN

 /**

  * 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 instead of combining classes the value

  * is used in unorm_getFCD16FromSurrogatePair() to get the real value

  * of the supplementary code point.

  *

  * @internal

  */

 inline uint16_t

 unorm_getFCD16(const uint16_t *fcdTrieIndex, UChar c) {

     return

         fcdTrieIndex[

             (fcdTrieIndex[

                 c>>UTRIE_SHIFT

             ]<<UTRIE_INDEX_SHIFT)+

             (c&UTRIE_MASK)

         ];

 }

 /**

  * Internal API, used by collation code.

  * Get the FCD value for a supplementary code point, with

  * bits 15..8   lead combining class

  * bits  7..0   trail combining class

  *

  * @param fcd16  The FCD value for the lead surrogate, not 0.

  * @param c2     The trail surrogate code unit.

  *

  * @internal

  */

 inline uint16_t

 unorm_getFCD16FromSurrogatePair(const uint16_t *fcdTrieIndex, uint16_t fcd16, UChar c2) {

     return

         fcdTrieIndex[

             (fcdTrieIndex[

                 (int32_t)fcd16+((c2&0x3ff)>>UTRIE_SHIFT)

             ]<<UTRIE_INDEX_SHIFT)+

             (c2&UTRIE_MASK)

         ];

 }

 U_NAMESPACE_END

 #endif

 /**

  * internal API, used by StringPrep

  * @internal

  */

 U_CAPI void U_EXPORT2

 unorm_getUnicodeVersion(UVersionInfo *versionInfo, UErrorCode *pErrorCode);

 /**

  * Get the canonical decomposition for one code point.

  * Requires unorm_haveData() and buffer!=NULL and pLength!=NULL.

  * @param c code point

  * @param buffer out-only buffer for algorithmic decompositions of Hangul

  * @param length out-only, takes the length of the decomposition, if any

  * @return pointer to decomposition, or 0 if none

  * @internal

  */

 U_CFUNC const UChar *

 unorm_getCanonicalDecomposition(UChar32 c, UChar buffer[4], int32_t *pLength);

 /**

  * internal API, used by the canonical iterator

  * TODO Consider using signature similar to unorm_getCanonicalDecomposition()

  * for more efficiency

  * @internal

  */

 U_CAPI int32_t U_EXPORT2

 unorm_getDecomposition(UChar32 c, UBool compat,

                        UChar *dest, int32_t destCapacity);

 /**

  * internal API, used by uprops.cpp

  * @internal

  */

 U_CAPI UBool U_EXPORT2

 unorm_internalIsFullCompositionExclusion(UChar32 c);

 /**

  * Internal API, used by enumeration of canonically equivalent strings

  * @internal

  */

 U_CAPI UBool U_EXPORT2

 unorm_isCanonSafeStart(UChar32 c);

 /**

  * Internal API, used by enumeration of canonically equivalent strings

  * @internal

  */

 U_CAPI UBool U_EXPORT2

 unorm_getCanonStartSet(UChar32 c, USerializedSet *fillSet);

 /**

  * Is c an NF<mode>-skippable code point? See unormimp.h.

  * @internal

  */

 U_CAPI UBool U_EXPORT2

 unorm_isNFSkippable(UChar32 c, UNormalizationMode mode);

 #ifdef XP_CPLUSPLUS

 /**

  * Get normalization exclusion set for the options.

  * Requires unorm_haveData().

  * @internal

  */

 U_CFUNC const UnicodeSet *

 unorm_getNX(int32_t options, UErrorCode *pErrorCode);

 #endif

 /**

  * Enumerate each normalization data trie and add the

  * start of each range of same properties to the set.

  * @internal

  */

 U_CAPI void U_EXPORT2

 unorm_addPropertyStarts(const USetAdder *sa, UErrorCode *pErrorCode);

 /**

  * Swap unorm.icu. See udataswp.h.

  * @internal

  */

 U_CAPI int32_t U_EXPORT2

 unorm_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_CAPI UNormalizationCheckResult U_EXPORT2

 unorm_getQuickCheck(UChar32 c, UNormalizationMode mode);

 /**

  * Description of the format of unorm.icu version 2.3.

  *

  * Main change from version 1 to version 2:

  * Use of new, common UTrie instead of normalization-specific tries.

  * Change to version 2.1: add third/auxiliary trie with associated data.

  * Change to version 2.2: add skippable (f) flag data (_NORM_AUX_NFC_SKIP_F_MASK).

  * Change to version 2.3: add serialized sets for normalization exclusions

  *                        stored inside canonStartSets[]

  *

  * For more details of how to use the data structures see the code

  * in unorm.cpp (runtime normalization code) and

  * in gennorm.c and gennorm/store.c (build-time data generation).

  *

  * For the serialized format of UTrie see utrie.c/UTrieHeader.

  *

  * - Overall partition

  *

  * unorm.dat customarily begins with a UDataInfo structure, see udata.h and .c.

  * After that there are the following structures:

  *

  * int32_t indexes[_NORM_INDEX_TOP];            -- _NORM_INDEX_TOP=32, see enum in this file

  *

  * UTrie normTrie;                              -- size in bytes=indexes[_NORM_INDEX_TRIE_SIZE]

  * 

  * uint16_t extraData[extraDataTop];            -- extraDataTop=indexes[_NORM_INDEX_UCHAR_COUNT]

  *                                                 extraData[0] contains the number of units for

  *                                                 FC_NFKC_Closure (formatVersion>=2.1)

  *

  * uint16_t combiningTable[combiningTableTop];  -- combiningTableTop=indexes[_NORM_INDEX_COMBINE_DATA_COUNT]

  *                                                 combiningTableTop may include one 16-bit padding unit

  *                                                 to make sure that fcdTrie is 32-bit-aligned

  *

  * UTrie fcdTrie;                               -- size in bytes=indexes[_NORM_INDEX_FCD_TRIE_SIZE]

  *

  * UTrie auxTrie;                               -- size in bytes=indexes[_NORM_INDEX_AUX_TRIE_SIZE]

  *

  * uint16_t canonStartSets[canonStartSetsTop]   -- canonStartSetsTop=indexes[_NORM_INDEX_CANON_SET_COUNT]

  *                                                 serialized USets and binary search tables, see below

  *

  *

  * The indexes array contains lengths and sizes of the following arrays and structures

  * as well as the following values:

  *  indexes[_NORM_INDEX_COMBINE_FWD_COUNT]=combineFwdTop

  *      -- one more than the highest combining index computed for forward-only-combining characters

  *  indexes[_NORM_INDEX_COMBINE_BOTH_COUNT]=combineBothTop-combineFwdTop

  *      -- number of combining indexes computed for both-ways-combining characters

  *  indexes[_NORM_INDEX_COMBINE_BACK_COUNT]=combineBackTop-combineBothTop

  *      -- number of combining indexes computed for backward-only-combining characters

  *

  *  indexes[_NORM_INDEX_MIN_NF*_NO_MAYBE] (where *={ C, D, KC, KD })

  *      -- first code point with a quick check NF* value of NO/MAYBE

  *

  *

  * - Tries

  *

  * The main structures are two UTrie tables ("compact arrays"),

  * each with one index array and one data array.

  * See utrie.h and utrie.c.

  *

  *

  * - Tries in unorm.dat

  *

  * The first trie (normTrie above)

  * provides data for the NF* quick checks and normalization.

  * The second trie (fcdTrie above) provides data just for FCD checks.

  *

  *

  * - norm32 data words from the first trie

  *

  * The norm32Table contains one 32-bit word "norm32" per code point.

  * It contains the following bit fields:

  * 31..16   extra data index, _NORM_EXTRA_SHIFT is used to shift this field down

  *          if this index is <_NORM_EXTRA_INDEX_TOP then it is an index into

  *              extraData[] where variable-length normalization data for this

  *              code point is found

  *          if this index is <_NORM_EXTRA_INDEX_TOP+_NORM_EXTRA_SURROGATE_TOP

  *              then this is a norm32 for a leading surrogate, and the index

  *              value is used together with the following trailing surrogate

  *              code unit in the second trie access

  *          if this index is >=_NORM_EXTRA_INDEX_TOP+_NORM_EXTRA_SURROGATE_TOP

  *              then this is a norm32 for a "special" character,

  *              i.e., the character is a Hangul syllable or a Jamo

  *              see _NORM_EXTRA_HANGUL etc.

  *          generally, instead of extracting this index from the norm32 and

  *              comparing it with the above constants,

  *              the normalization code compares the entire norm32 value

  *              with _NORM_MIN_SPECIAL, _NORM_SURROGATES_TOP, _NORM_MIN_HANGUL etc.

  *

  * 15..8    combining class (cc) according to UnicodeData.txt

  *

  *  7..6    _NORM_COMBINES_ANY flags, used in composition to see if a character

  *              combines with any following or preceding character(s)

  *              at all

  *     7    _NORM_COMBINES_BACK

  *     6    _NORM_COMBINES_FWD

  *

  *  5..0    quick check flags, set for "no" or "maybe", with separate flags for

  *              each normalization form

  *              the higher bits are "maybe" flags; for NF*D there are no such flags

  *              the lower bits are "no" flags for all forms, in the same order

  *              as the "maybe" flags,

  *              which is (MSB to LSB): NFKD NFD NFKC NFC

  *  5..4    _NORM_QC_ANY_MAYBE

  *  3..0    _NORM_QC_ANY_NO

  *              see further related constants

  *

  *

  * - Extra data per code point

  *

  * "Extra data" is referenced by the index in norm32.

  * It is variable-length data. It is only present, and only those parts

  * of it are, as needed for a given character.

  * The norm32 extra data index is added to the beginning of extraData[]

  * to get to a vector of 16-bit words with data at the following offsets:

  *

  * [-1]     Combining index for composition.

  *              Stored only if norm32&_NORM_COMBINES_ANY .

  * [0]      Lengths of the canonical and compatibility decomposition strings.

  *              Stored only if there are decompositions, i.e.,

  *              if norm32&(_NORM_QC_NFD|_NORM_QC_NFKD)

  *          High byte: length of NFKD, or 0 if none

  *          Low byte: length of NFD, or 0 if none

  *          Each length byte also has another flag:

  *              Bit 7 of a length byte is set if there are non-zero

  *              combining classes (cc's) associated with the respective

  *              decomposition. If this flag is set, then the decomposition

  *              is preceded by a 16-bit word that contains the

  *              leading and trailing cc's.

  *              Bits 6..0 of a length byte are the length of the

  *              decomposition string, not counting the cc word.

  * [1..n]   NFD

  * [n+1..]  NFKD

  *

  * Each of the two decompositions consists of up to two parts:

  * - The 16-bit words with the leading and trailing cc's.

  *   This is only stored if bit 7 of the corresponding length byte

  *   is set. In this case, at least one of the cc's is not zero.

  *   High byte: leading cc==cc of the first code point in the decomposition string

  *   Low byte: trailing cc==cc of the last code point in the decomposition string

  * - The decomposition string in UTF-16, with length code units.

  *

  *

  * - Combining indexes and combiningTable[]

  *

  * Combining indexes are stored at the [-1] offset of the extra data

  * if the character combines forward or backward with any other characters.

  * They are used for (re)composition in NF*C.

  * Values of combining indexes are arranged according to whether a character

  * combines forward, backward, or both ways:

  *    forward-only < both ways < backward-only

  *

  * The index values for forward-only and both-ways combining characters

  * are indexes into the combiningTable[].

  * The index values for backward-only combining characters are simply

  * incremented from the preceding index values to be unique.

  *

  * In the combiningTable[], a variable-length list

  * of variable-length (back-index, code point) pair entries is stored

  * for each forward-combining character.

  *

  * These back-indexes are the combining indexes of both-ways or backward-only

  * combining characters that the forward-combining character combines with.

  *

  * Each list is sorted in ascending order of back-indexes.

  * Each list is terminated with the last back-index having bit 15 set.

  *

  * Each pair (back-index, code point) takes up either 2 or 3

  * 16-bit words.

  * The first word of a list entry is the back-index, with its bit 15 set if

  * this is the last pair in the list.

  *

  * The second word contains flags in bits 15..13 that determine

  * if there is a third word and how the combined character is encoded:

  * 15   set if there is a third word in this list entry

  * 14   set if the result is a supplementary character

  * 13   set if the result itself combines forward

  *

  * According to these bits 15..14 of the second word,

  * the result character is encoded as follows:

  * 00 or 01 The result is <=0x1fff and stored in bits 12..0 of

  *          the second word.

  * 10       The result is 0x2000..0xffff and stored in the third word.

  *          Bits 12..0 of the second word are not used.

  * 11       The result is a supplementary character.

  *          Bits 9..0 of the leading surrogate are in bits 9..0 of

  *          the second word.

  *          Add 0xd800 to these bits to get the complete surrogate.

  *          Bits 12..10 of the second word are not used.

  *          The trailing surrogate is stored in the third word.

  *

  *

  * - FCD trie

  *

  * The FCD trie is very simple.

  * It is a folded trie with 16-bit data words.

  * In each word, the high byte contains the leading cc of the character,

  * and the low byte contains the trailing cc of the character.

  * These cc's are the cc's of the first and last code points in the

  * canonical decomposition of the character.

  *

  * Since all 16 bits are used for cc's, lead surrogates must be tested

  * by checking the code unit instead of the trie data.

  * This is done only if the 16-bit data word is not zero.

  * If the code unit is a leading surrogate and the data word is not zero,

  * then instead of cc's it contains the offset for the second trie lookup.

  *

  *

  * - Auxiliary trie and data

  *

  * The auxiliary 16-bit trie contains data for additional properties.

  * Bits

  * 15..13   reserved

  *     12   not NFC_Skippable (f) (formatVersion>=2.2)

  *     11   flag: not a safe starter for canonical closure

  *     10   composition exclusion

  *  9.. 0   index into extraData[] to FC_NFKC_Closure string

  *          (not for lead surrogate),

  *          or lead surrogate offset (for lead surrogate, if 9..0 not zero)

  *

  * - FC_NFKC_Closure strings in extraData[]

  *

  * Strings are either stored as a single code unit or as the length

  * followed by that many units.

  *   const UChar *s=extraData+(index from auxTrie data bits 9..0);

  *   int32_t length;

  *   if(*s<0xff00) {

  *     // s points to the single-unit string

  *     length=1;

  *   } else {

  *     length=*s&0xff;

  *     ++s;

  *   }

  *

  * Conditions for "NF* Skippable" from Mark Davis' com.ibm.text.UCD.NFSkippable:

  * (used in NormalizerTransliterator)

  *

  * A skippable character is

  * a) unassigned, or ALL of the following:

  * b) of combining class 0.

  * c) not decomposed by this normalization form.

  * AND if NFC or NFKC,

  * d) can never compose with a previous character.

  * e) can never compose with a following character.

  * f) can never change if another character is added.

  *    Example: a-breve might satisfy all but f, but if you

  *    add an ogonek it changes to a-ogonek + breve

  *

  * a)..e) must be tested from norm32.

  * Since f) is more complicated, the (not-)NFC_Skippable flag (f) is built

  * into the auxiliary trie.

  * The same bit is used for NFC and NFKC; (c) differs for them.

  * As usual, we build the "not skippable" flags so that unassigned

  * code points get a 0 bit.

  * This bit is only valid after (a)..(e) test FALSE; test NFD_NO before (f) as well.

  * Test Hangul LV syllables entirely in code.

  *

  *

  * - structure inside canonStartSets[]

  *

  * This array maps from code points c to sets of code points (USerializedSet).

  * The result sets are the code points whose canonical decompositions start

  * with c.

  *

  * canonStartSets[] contains the following sub-arrays:

  *

  * indexes[_NORM_SET_INDEX_TOP]

  *   - contains lengths of sub-arrays etc.

  *

  * startSets[indexes[_NORM_SET_INDEX_CANON_SETS_LENGTH]-_NORM_SET_INDEX_TOP]

  *   - contains serialized sets (USerializedSet) of canonical starters for

  *     enumerating canonically equivalent strings

  *     indexes[_NORM_SET_INDEX_CANON_SETS_LENGTH] includes _NORM_SET_INDEX_TOP

  *     for details about the structure see uset.c

  *

  * bmpTable[indexes[_NORM_SET_INDEX_CANON_BMP_TABLE_LENGTH]]

  *   - a sorted search table for BMP code points whose results are

  *     either indexes to USerializedSets or single code points for

  *     single-code point sets;

  *     each entry is a pair of { code point, result } with result=(binary) yy xxxxxx xxxxxxxx

  *     if yy==01 then there is a USerializedSet at canonStartSets+x

  *     else build a USerializedSet with result as the single code point

  *

  * suppTable[indexes[_NORM_SET_INDEX_CANON_SUPP_TABLE_LENGTH]]

  *   - a sorted search table for supplementary code points whose results are

  *     either indexes to USerializedSets or single code points for

  *     single-code point sets;

  *     each entry is a triplet of { high16(cp), low16(cp), result }

  *     each code point's high-word may contain extra data in bits 15..5:

  *     if the high word has bit 15 set, then build a set with a single code point

  *     which is (((high16(cp)&0x1f00)<<8)|result;

  *     else there is a USerializedSet at canonStartSets+result

  *

  * FormatVersion 2.3 adds 2 serialized sets for normalization exclusions.

  * They are stored in the data file so that the runtime normalization code need

  * not depend on other properties and their data and implementation files.

  * The _NORM_SET_INDEX_NX_..._OFFSET offsets in the canonStartSets index table

  * give the location for each set.

  * There is no set stored for UNORM_NX_HANGUL because it's trivial to create

  * without using properties.

  *

  * Set contents:

  *

  * _NORM_SET_INDEX_NX_CJK_COMPAT_OFFSET (for UNORM_NX_CJK_COMPAT)

  *     [[:Ideographic:]&[:NFD_QC=No:]]

  *     =[CJK Ideographs]&[has canonical decomposition]

  *

  * _NORM_SET_INDEX_NX_UNICODE32_OFFSET (for UNORM_UNICODE_3_2)

  *     [:^Age=3.2:]

  *     =set with all code points that were not designated by the specified Unicode version

  *

  * _NORM_SET_INDEX_NX_RESERVED_OFFSET

  *     This is an offset that points to where the next, future set would start.

  *     Currently it indicates where the previous set ends, and thus its length.

  *     The name for this enum constant may in the future be applied to different

  *     index slots. In order to get the limit of a set, use its index slot and

  *     the immediately following one regardless of that one's enum name.

  */

 #endif /* #if !UCONFIG_NO_NORMALIZATION */

 #endif