icuSources/i18n/collationfastlatin.h

   1 /*
   2 *******************************************************************************
   3 * Copyright (C) 2013-2015, International Business Machines
   4 * Corporation and others.  All Rights Reserved.
   5 *******************************************************************************
   6 * collationfastlatin.h
   7 *
   8 * created on: 2013aug09
   9 * created by: Markus W. Scherer
  10 */
  11
  12 #ifndef __COLLATIONFASTLATIN_H__
  13 #define __COLLATIONFASTLATIN_H__
  14
  15 #include "unicode/utypes.h"
  16
  17 #if !UCONFIG_NO_COLLATION
  18
  19 U_NAMESPACE_BEGIN
  20
  21 struct CollationData;
  22 struct CollationSettings;
  23
  24 class U_I18N_API CollationFastLatin /* all static */ {
  25 public:
  26     /**
  27      * Fast Latin format version (one byte 1..FF).
  28      * Must be incremented for any runtime-incompatible changes,
  29      * in particular, for changes to any of the following constants.
  30      *
  31      * When the major version number of the main data format changes,
  32      * we can reset this fast Latin version to 1.
  33      */
  34     static const uint16_t VERSION = 2;
  35
  36     static const int32_t LATIN_MAX = 0x17f;
  37     static const int32_t LATIN_LIMIT = LATIN_MAX + 1;
  38
  39     static const int32_t LATIN_MAX_UTF8_LEAD = 0xc5;  // UTF-8 lead byte of LATIN_MAX
  40
  41     static const int32_t PUNCT_START = 0x2000;
  42     static const int32_t PUNCT_LIMIT = 0x2040;
  43
  44     // excludes U+FFFE & U+FFFF
  45     static const int32_t NUM_FAST_CHARS = LATIN_LIMIT + (PUNCT_LIMIT - PUNCT_START);
  46
  47     // Note on the supported weight ranges:
  48     // Analysis of UCA 6.3 and CLDR 23 non-search tailorings shows that
  49     // the CEs for characters in the above ranges, excluding expansions with length >2,
  50     // excluding contractions of >2 characters, and other restrictions
  51     // (see the builder's getCEsFromCE32()),
  52     // use at most about 150 primary weights,
  53     // where about 94 primary weights are possibly-variable (space/punct/symbol/currency),
  54     // at most 4 secondary before-common weights,
  55     // at most 4 secondary after-common weights,
  56     // at most 16 secondary high weights (in secondary CEs), and
  57     // at most 4 tertiary after-common weights.
  58     // The following ranges are designed to support slightly more weights than that.
  59     // (en_US_POSIX is unusual: It creates about 64 variable + 116 Latin primaries.)
  60
  61     // Digits may use long primaries (preserving more short ones)
  62     // or short primaries (faster) without changing this data structure.
  63     // (If we supported numeric collation, then digits would have to have long primaries
  64     // so that special handling does not affect the fast path.)
  65
  66     static const uint32_t SHORT_PRIMARY_MASK = 0xfc00;  // bits 15..10
  67     static const uint32_t INDEX_MASK = 0x3ff;  // bits 9..0 for expansions & contractions
  68     static const uint32_t SECONDARY_MASK = 0x3e0;  // bits 9..5
  69     static const uint32_t CASE_MASK = 0x18;  // bits 4..3
  70     static const uint32_t LONG_PRIMARY_MASK = 0xfff8;  // bits 15..3
  71     static const uint32_t TERTIARY_MASK = 7;  // bits 2..0
  72     static const uint32_t CASE_AND_TERTIARY_MASK = CASE_MASK | TERTIARY_MASK;
  73
  74     static const uint32_t TWO_SHORT_PRIMARIES_MASK =
  75             (SHORT_PRIMARY_MASK << 16) | SHORT_PRIMARY_MASK;  // 0xfc00fc00
  76     static const uint32_t TWO_LONG_PRIMARIES_MASK =
  77             (LONG_PRIMARY_MASK << 16) | LONG_PRIMARY_MASK;  // 0xfff8fff8
  78     static const uint32_t TWO_SECONDARIES_MASK =
  79             (SECONDARY_MASK << 16) | SECONDARY_MASK;  // 0x3e003e0
  80     static const uint32_t TWO_CASES_MASK =
  81             (CASE_MASK << 16) | CASE_MASK;  // 0x180018
  82     static const uint32_t TWO_TERTIARIES_MASK =
  83             (TERTIARY_MASK << 16) | TERTIARY_MASK;  // 0x70007
  84
  85     /**
  86      * Contraction with one fast Latin character.
  87      * Use INDEX_MASK to find the start of the contraction list after the fixed table.
  88      * The first entry contains the default mapping.
  89      * Otherwise use CONTR_CHAR_MASK for the contraction character index
  90      * (in ascending order).
  91      * Use CONTR_LENGTH_SHIFT for the length of the entry
  92      * (1=BAIL_OUT, 2=one CE, 3=two CEs).
  93      *
  94      * Also, U+0000 maps to a contraction entry, so that the fast path need not
  95      * check for NUL termination.
  96      * It usually maps to a contraction list with only the completely ignorable default value.
  97      */
  98     static const uint32_t CONTRACTION = 0x400;
  99     /**
 100      * An expansion encodes two CEs.
 101      * Use INDEX_MASK to find the pair of CEs after the fixed table.
 102      *
 103      * The higher a mini CE value, the easier it is to process.
 104      * For expansions and higher, no context needs to be considered.
 105      */
 106     static const uint32_t EXPANSION = 0x800;
 107     /**
 108      * Encodes one CE with a long/low mini primary (there are 128).
 109      * All potentially-variable primaries must be in this range,
 110      * to make the short-primary path as fast as possible.
 111      */
 112     static const uint32_t MIN_LONG = 0xc00;
 113     static const uint32_t LONG_INC = 8;
 114     static const uint32_t MAX_LONG = 0xff8;
 115     /**
 116      * Encodes one CE with a short/high primary (there are 60),
 117      * plus a secondary CE if the secondary weight is high.
 118      * Fast handling: At least all letter primaries should be in this range.
 119      */
 120     static const uint32_t MIN_SHORT = 0x1000;
 121     static const uint32_t SHORT_INC = 0x400;
 122     /** The highest primary weight is reserved for U+FFFF. */
 123     static const uint32_t MAX_SHORT = SHORT_PRIMARY_MASK;
 124
 125     static const uint32_t MIN_SEC_BEFORE = 0;  // must add SEC_OFFSET
 126     static const uint32_t SEC_INC = 0x20;
 127     static const uint32_t MAX_SEC_BEFORE = MIN_SEC_BEFORE + 4 * SEC_INC;  // 5 before common
 128     static const uint32_t COMMON_SEC = MAX_SEC_BEFORE + SEC_INC;
 129     static const uint32_t MIN_SEC_AFTER = COMMON_SEC + SEC_INC;
 130     static const uint32_t MAX_SEC_AFTER = MIN_SEC_AFTER + 5 * SEC_INC;  // 6 after common
 131     static const uint32_t MIN_SEC_HIGH = MAX_SEC_AFTER + SEC_INC;  // 20 high secondaries
 132     static const uint32_t MAX_SEC_HIGH = SECONDARY_MASK;
 133
 134     /**
 135      * Lookup: Add this offset to secondary weights, except for completely ignorable CEs.
 136      * Must be greater than any special value, e.g., MERGE_WEIGHT.
 137      * The exact value is not relevant for the format version.
 138      */
 139     static const uint32_t SEC_OFFSET = SEC_INC;
 140     static const uint32_t COMMON_SEC_PLUS_OFFSET = COMMON_SEC + SEC_OFFSET;
 141
 142     static const uint32_t TWO_SEC_OFFSETS =
 143             (SEC_OFFSET << 16) | SEC_OFFSET;  // 0x200020
 144     static const uint32_t TWO_COMMON_SEC_PLUS_OFFSET =
 145             (COMMON_SEC_PLUS_OFFSET << 16) | COMMON_SEC_PLUS_OFFSET;
 146
 147     static const uint32_t LOWER_CASE = 8;  // case bits include this offset
 148     static const uint32_t TWO_LOWER_CASES = (LOWER_CASE << 16) | LOWER_CASE;  // 0x80008
 149
 150     static const uint32_t COMMON_TER = 0;  // must add TER_OFFSET
 151     static const uint32_t MAX_TER_AFTER = 7;  // 7 after common
 152
 153     /**
 154      * Lookup: Add this offset to tertiary weights, except for completely ignorable CEs.
 155      * Must be greater than any special value, e.g., MERGE_WEIGHT.
 156      * Must be greater than case bits as well, so that with combined case+tertiary weights
 157      * plus the offset the tertiary bits does not spill over into the case bits.
 158      * The exact value is not relevant for the format version.
 159      */
 160     static const uint32_t TER_OFFSET = SEC_OFFSET;
 161     static const uint32_t COMMON_TER_PLUS_OFFSET = COMMON_TER + TER_OFFSET;
 162
 163     static const uint32_t TWO_TER_OFFSETS = (TER_OFFSET << 16) | TER_OFFSET;
 164     static const uint32_t TWO_COMMON_TER_PLUS_OFFSET =
 165             (COMMON_TER_PLUS_OFFSET << 16) | COMMON_TER_PLUS_OFFSET;
 166
 167     static const uint32_t MERGE_WEIGHT = 3;
 168     static const uint32_t EOS = 2;  // end of string
 169     static const uint32_t BAIL_OUT = 1;
 170
 171     /**
 172      * Contraction result first word bits 8..0 contain the
 173      * second contraction character, as a char index 0..NUM_FAST_CHARS-1.
 174      * Each contraction list is terminated with a word containing CONTR_CHAR_MASK.
 175      */
 176     static const uint32_t CONTR_CHAR_MASK = 0x1ff;
 177     /**
 178      * Contraction result first word bits 10..9 contain the result length:
 179      * 1=bail out, 2=one mini CE, 3=two mini CEs
 180      */
 181     static const uint32_t CONTR_LENGTH_SHIFT = 9;
 182
 183     /**
 184      * Comparison return value when the regular comparison must be used.
 185      * The exact value is not relevant for the format version.
 186      */
 187     static const int32_t BAIL_OUT_RESULT = -2;
 188
 189     static inline int32_t getCharIndex(UChar c) {
 190         if(c <= LATIN_MAX) {
 191             return c;
 192         } else if(PUNCT_START <= c && c < PUNCT_LIMIT) {
 193             return c - (PUNCT_START - LATIN_LIMIT);
 194         } else {
 195             // Not a fast Latin character.
 196             // Note: U+FFFE & U+FFFF are forbidden in tailorings
 197             // and thus do not occur in any contractions.
 198             return -1;
 199         }
 200     }
 201
 202     /**
 203      * Computes the options value for the compare functions
 204      * and writes the precomputed primary weights.
 205      * Returns -1 if the Latin fastpath is not supported for the data and settings.
 206      * The capacity must be LATIN_LIMIT.
 207      */
 208     static int32_t getOptions(const CollationData *data, const CollationSettings &settings,
 209                               uint16_t *primaries, int32_t capacity);
 210
 211     static int32_t compareUTF16(const uint16_t *table, const uint16_t *primaries, int32_t options,
 212                                 const UChar *left, int32_t leftLength,
 213                                 const UChar *right, int32_t rightLength);
 214
 215     static int32_t compareUTF8(const uint16_t *table, const uint16_t *primaries, int32_t options,
 216                                const uint8_t *left, int32_t leftLength,
 217                                const uint8_t *right, int32_t rightLength);
 218
 219 private:
 220     static uint32_t lookup(const uint16_t *table, UChar32 c);
 221     static uint32_t lookupUTF8(const uint16_t *table, UChar32 c,
 222                                const uint8_t *s8, int32_t &sIndex, int32_t sLength);
 223     static uint32_t lookupUTF8Unsafe(const uint16_t *table, UChar32 c,
 224                                      const uint8_t *s8, int32_t &sIndex);
 225
 226     static uint32_t nextPair(const uint16_t *table, UChar32 c, uint32_t ce,
 227                              const UChar *s16, const uint8_t *s8, int32_t &sIndex, int32_t &sLength);
 228
 229     static inline uint32_t getPrimaries(uint32_t variableTop, uint32_t pair) {
 230         uint32_t ce = pair & 0xffff;
 231         if(ce >= MIN_SHORT) { return pair & TWO_SHORT_PRIMARIES_MASK; }
 232         if(ce > variableTop) { return pair & TWO_LONG_PRIMARIES_MASK; }
 233         if(ce >= MIN_LONG) { return 0; }  // variable
 234         return pair;  // special mini CE
 235     }
 236     static inline uint32_t getSecondariesFromOneShortCE(uint32_t ce) {
 237         ce &= SECONDARY_MASK;
 238         if(ce < MIN_SEC_HIGH) {
 239             return ce + SEC_OFFSET;
 240         } else {
 241             return ((ce + SEC_OFFSET) << 16) | COMMON_SEC_PLUS_OFFSET;
 242         }
 243     }
 244     static uint32_t getSecondaries(uint32_t variableTop, uint32_t pair);
 245     static uint32_t getCases(uint32_t variableTop, UBool strengthIsPrimary, uint32_t pair);
 246     static uint32_t getTertiaries(uint32_t variableTop, UBool withCaseBits, uint32_t pair);
 247     static uint32_t getQuaternaries(uint32_t variableTop, uint32_t pair);
 248
 249 private:
 250     CollationFastLatin();  // no constructor
 251 };
 252
 253 /*
 254  * Format of the CollationFastLatin data table.
 255  * CollationFastLatin::VERSION = 2.
 256  *
 257  * This table contains data for a Latin-text collation fastpath.
 258  * The data is stored as an array of uint16_t which contains the following parts.
 259  *
 260  * uint16_t  -- version & header length
 261  *   Bits 15..8: version, must match the VERSION
 262  *         7..0: length of the header
 263  *
 264  * uint16_t varTops[header length - 1]
 265  *   Version 2:
 266  *   varTops[m] is the highest CollationFastLatin long-primary weight
 267  *   of supported maxVariable group m
 268  *   (special reorder group space, punct, symbol, currency).
 269  *
 270  *   Version 1:
 271  *   Each of these values maps the variable top lead byte of a supported maxVariable group
 272  *   to the highest CollationFastLatin long-primary weight.
 273  *   The values are stored in ascending order.
 274  *   Bits 15..7: max fast-Latin long-primary weight (bits 11..3 shifted left by 4 bits)
 275  *         6..0: regular primary lead byte
 276  *
 277  * uint16_t miniCEs[0x1c0]
 278  *   A mini collation element for each character U+0000..U+017F and U+2000..U+203F.
 279  *   Each value encodes one or two mini CEs (two are possible if the first one
 280  *   has a short mini primary and the second one is a secondary CE, i.e., primary == 0),
 281  *   or points to an expansion or to a contraction table.
 282  *   U+0000 always has a contraction entry,
 283  *   so that NUL-termination need not be tested in the fastpath.
 284  *   If the collation elements for a character or contraction cannot be encoded in this format,
 285  *   then the BAIL_OUT value is stored.
 286  *   For details see the comments for the class constants.
 287  *
 288  * uint16_t expansions[variable length];
 289  *   Expansion mini CEs contain an offset relative to just after the miniCEs table.
 290  *   An expansions contains exactly 2 mini CEs.
 291  *
 292  * uint16_t contractions[variable length];
 293  *   Contraction mini CEs contain an offset relative to just after the miniCEs table.
 294  *   It points to a list of tuples which map from a contraction suffix character to a result.
 295  *   First uint16_t of each tuple:
 296  *     Bits 10..9: Length of the result (1..3), see comments on CONTR_LENGTH_SHIFT.
 297  *     Bits  8..0: Contraction character, see comments on CONTR_CHAR_MASK.
 298  *   This is followed by 0, 1, or 2 uint16_t according to the length.
 299  *   Each list is terminated by an entry with CONTR_CHAR_MASK.
 300  *   Each list starts with such an entry which also contains the default result
 301  *   for when there is no contraction match.
 302  *
 303  * -----------------
 304  * Changes for version 2 (ICU 55)
 305  *
 306  * Special reorder groups do not necessarily start on whole primary lead bytes any more.
 307  * Therefore, the varTops data has a new format:
 308  * Version 1 stored the lead bytes of the highest root primaries for
 309  * the maxVariable-supported special reorder groups.
 310  * Now the top 16 bits would need to be stored,
 311  * and it is simpler to store only the fast-Latin weights.
 312  */
 313
 314 U_NAMESPACE_END
 315
 316 #endif  // !UCONFIG_NO_COLLATION
 317 #endif  // __COLLATIONFASTLATIN_H__