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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 
getCharIndex(UChar c)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 
getPrimaries(uint32_t variableTop,uint32_t pair)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     }
getSecondariesFromOneShortCE(uint32_t ce)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__
318