1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 *******************************************************************************
5 * Copyright (C) 2013-2015, International Business Machines
6 * Corporation and others.  All Rights Reserved.
7 *******************************************************************************
8 * collationfastlatin.h
9 *
10 * created on: 2013aug09
11 * created by: Markus W. Scherer
12 */
13 
14 #ifndef __COLLATIONFASTLATIN_H__
15 #define __COLLATIONFASTLATIN_H__
16 
17 #include "unicode/utypes.h"
18 
19 #if !UCONFIG_NO_COLLATION
20 
21 U_NAMESPACE_BEGIN
22 
23 struct CollationData;
24 struct CollationSettings;
25 
26 class U_I18N_API CollationFastLatin /* all static */ {
27 public:
28     /**
29      * Fast Latin format version (one byte 1..FF).
30      * Must be incremented for any runtime-incompatible changes,
31      * in particular, for changes to any of the following constants.
32      *
33      * When the major version number of the main data format changes,
34      * we can reset this fast Latin version to 1.
35      */
36     static const uint16_t VERSION = 2;
37 
38     static const int32_t LATIN_MAX = 0x17f;
39     static const int32_t LATIN_LIMIT = LATIN_MAX + 1;
40 
41     static const int32_t LATIN_MAX_UTF8_LEAD = 0xc5;  // UTF-8 lead byte of LATIN_MAX
42 
43     static const int32_t PUNCT_START = 0x2000;
44     static const int32_t PUNCT_LIMIT = 0x2040;
45 
46     // excludes U+FFFE & U+FFFF
47     static const int32_t NUM_FAST_CHARS = LATIN_LIMIT + (PUNCT_LIMIT - PUNCT_START);
48 
49     // Note on the supported weight ranges:
50     // Analysis of UCA 6.3 and CLDR 23 non-search tailorings shows that
51     // the CEs for characters in the above ranges, excluding expansions with length >2,
52     // excluding contractions of >2 characters, and other restrictions
53     // (see the builder's getCEsFromCE32()),
54     // use at most about 150 primary weights,
55     // where about 94 primary weights are possibly-variable (space/punct/symbol/currency),
56     // at most 4 secondary before-common weights,
57     // at most 4 secondary after-common weights,
58     // at most 16 secondary high weights (in secondary CEs), and
59     // at most 4 tertiary after-common weights.
60     // The following ranges are designed to support slightly more weights than that.
61     // (en_US_POSIX is unusual: It creates about 64 variable + 116 Latin primaries.)
62 
63     // Digits may use long primaries (preserving more short ones)
64     // or short primaries (faster) without changing this data structure.
65     // (If we supported numeric collation, then digits would have to have long primaries
66     // so that special handling does not affect the fast path.)
67 
68     static const uint32_t SHORT_PRIMARY_MASK = 0xfc00;  // bits 15..10
69     static const uint32_t INDEX_MASK = 0x3ff;  // bits 9..0 for expansions & contractions
70     static const uint32_t SECONDARY_MASK = 0x3e0;  // bits 9..5
71     static const uint32_t CASE_MASK = 0x18;  // bits 4..3
72     static const uint32_t LONG_PRIMARY_MASK = 0xfff8;  // bits 15..3
73     static const uint32_t TERTIARY_MASK = 7;  // bits 2..0
74     static const uint32_t CASE_AND_TERTIARY_MASK = CASE_MASK | TERTIARY_MASK;
75 
76     static const uint32_t TWO_SHORT_PRIMARIES_MASK =
77             (SHORT_PRIMARY_MASK << 16) | SHORT_PRIMARY_MASK;  // 0xfc00fc00
78     static const uint32_t TWO_LONG_PRIMARIES_MASK =
79             (LONG_PRIMARY_MASK << 16) | LONG_PRIMARY_MASK;  // 0xfff8fff8
80     static const uint32_t TWO_SECONDARIES_MASK =
81             (SECONDARY_MASK << 16) | SECONDARY_MASK;  // 0x3e003e0
82     static const uint32_t TWO_CASES_MASK =
83             (CASE_MASK << 16) | CASE_MASK;  // 0x180018
84     static const uint32_t TWO_TERTIARIES_MASK =
85             (TERTIARY_MASK << 16) | TERTIARY_MASK;  // 0x70007
86 
87     /**
88      * Contraction with one fast Latin character.
89      * Use INDEX_MASK to find the start of the contraction list after the fixed table.
90      * The first entry contains the default mapping.
91      * Otherwise use CONTR_CHAR_MASK for the contraction character index
92      * (in ascending order).
93      * Use CONTR_LENGTH_SHIFT for the length of the entry
94      * (1=BAIL_OUT, 2=one CE, 3=two CEs).
95      *
96      * Also, U+0000 maps to a contraction entry, so that the fast path need not
97      * check for NUL termination.
98      * It usually maps to a contraction list with only the completely ignorable default value.
99      */
100     static const uint32_t CONTRACTION = 0x400;
101     /**
102      * An expansion encodes two CEs.
103      * Use INDEX_MASK to find the pair of CEs after the fixed table.
104      *
105      * The higher a mini CE value, the easier it is to process.
106      * For expansions and higher, no context needs to be considered.
107      */
108     static const uint32_t EXPANSION = 0x800;
109     /**
110      * Encodes one CE with a long/low mini primary (there are 128).
111      * All potentially-variable primaries must be in this range,
112      * to make the short-primary path as fast as possible.
113      */
114     static const uint32_t MIN_LONG = 0xc00;
115     static const uint32_t LONG_INC = 8;
116     static const uint32_t MAX_LONG = 0xff8;
117     /**
118      * Encodes one CE with a short/high primary (there are 60),
119      * plus a secondary CE if the secondary weight is high.
120      * Fast handling: At least all letter primaries should be in this range.
121      */
122     static const uint32_t MIN_SHORT = 0x1000;
123     static const uint32_t SHORT_INC = 0x400;
124     /** The highest primary weight is reserved for U+FFFF. */
125     static const uint32_t MAX_SHORT = SHORT_PRIMARY_MASK;
126 
127     static const uint32_t MIN_SEC_BEFORE = 0;  // must add SEC_OFFSET
128     static const uint32_t SEC_INC = 0x20;
129     static const uint32_t MAX_SEC_BEFORE = MIN_SEC_BEFORE + 4 * SEC_INC;  // 5 before common
130     static const uint32_t COMMON_SEC = MAX_SEC_BEFORE + SEC_INC;
131     static const uint32_t MIN_SEC_AFTER = COMMON_SEC + SEC_INC;
132     static const uint32_t MAX_SEC_AFTER = MIN_SEC_AFTER + 5 * SEC_INC;  // 6 after common
133     static const uint32_t MIN_SEC_HIGH = MAX_SEC_AFTER + SEC_INC;  // 20 high secondaries
134     static const uint32_t MAX_SEC_HIGH = SECONDARY_MASK;
135 
136     /**
137      * Lookup: Add this offset to secondary weights, except for completely ignorable CEs.
138      * Must be greater than any special value, e.g., MERGE_WEIGHT.
139      * The exact value is not relevant for the format version.
140      */
141     static const uint32_t SEC_OFFSET = SEC_INC;
142     static const uint32_t COMMON_SEC_PLUS_OFFSET = COMMON_SEC + SEC_OFFSET;
143 
144     static const uint32_t TWO_SEC_OFFSETS =
145             (SEC_OFFSET << 16) | SEC_OFFSET;  // 0x200020
146     static const uint32_t TWO_COMMON_SEC_PLUS_OFFSET =
147             (COMMON_SEC_PLUS_OFFSET << 16) | COMMON_SEC_PLUS_OFFSET;
148 
149     static const uint32_t LOWER_CASE = 8;  // case bits include this offset
150     static const uint32_t TWO_LOWER_CASES = (LOWER_CASE << 16) | LOWER_CASE;  // 0x80008
151 
152     static const uint32_t COMMON_TER = 0;  // must add TER_OFFSET
153     static const uint32_t MAX_TER_AFTER = 7;  // 7 after common
154 
155     /**
156      * Lookup: Add this offset to tertiary weights, except for completely ignorable CEs.
157      * Must be greater than any special value, e.g., MERGE_WEIGHT.
158      * Must be greater than case bits as well, so that with combined case+tertiary weights
159      * plus the offset the tertiary bits does not spill over into the case bits.
160      * The exact value is not relevant for the format version.
161      */
162     static const uint32_t TER_OFFSET = SEC_OFFSET;
163     static const uint32_t COMMON_TER_PLUS_OFFSET = COMMON_TER + TER_OFFSET;
164 
165     static const uint32_t TWO_TER_OFFSETS = (TER_OFFSET << 16) | TER_OFFSET;
166     static const uint32_t TWO_COMMON_TER_PLUS_OFFSET =
167             (COMMON_TER_PLUS_OFFSET << 16) | COMMON_TER_PLUS_OFFSET;
168 
169     static const uint32_t MERGE_WEIGHT = 3;
170     static const uint32_t EOS = 2;  // end of string
171     static const uint32_t BAIL_OUT = 1;
172 
173     /**
174      * Contraction result first word bits 8..0 contain the
175      * second contraction character, as a char index 0..NUM_FAST_CHARS-1.
176      * Each contraction list is terminated with a word containing CONTR_CHAR_MASK.
177      */
178     static const uint32_t CONTR_CHAR_MASK = 0x1ff;
179     /**
180      * Contraction result first word bits 10..9 contain the result length:
181      * 1=bail out, 2=one mini CE, 3=two mini CEs
182      */
183     static const uint32_t CONTR_LENGTH_SHIFT = 9;
184 
185     /**
186      * Comparison return value when the regular comparison must be used.
187      * The exact value is not relevant for the format version.
188      */
189     static const int32_t BAIL_OUT_RESULT = -2;
190 
getCharIndex(UChar c)191     static inline int32_t getCharIndex(UChar c) {
192         if(c <= LATIN_MAX) {
193             return c;
194         } else if(PUNCT_START <= c && c < PUNCT_LIMIT) {
195             return c - (PUNCT_START - LATIN_LIMIT);
196         } else {
197             // Not a fast Latin character.
198             // Note: U+FFFE & U+FFFF are forbidden in tailorings
199             // and thus do not occur in any contractions.
200             return -1;
201         }
202     }
203 
204     /**
205      * Computes the options value for the compare functions
206      * and writes the precomputed primary weights.
207      * Returns -1 if the Latin fastpath is not supported for the data and settings.
208      * The capacity must be LATIN_LIMIT.
209      */
210     static int32_t getOptions(const CollationData *data, const CollationSettings &settings,
211                               uint16_t *primaries, int32_t capacity);
212 
213     static int32_t compareUTF16(const uint16_t *table, const uint16_t *primaries, int32_t options,
214                                 const UChar *left, int32_t leftLength,
215                                 const UChar *right, int32_t rightLength);
216 
217     static int32_t compareUTF8(const uint16_t *table, const uint16_t *primaries, int32_t options,
218                                const uint8_t *left, int32_t leftLength,
219                                const uint8_t *right, int32_t rightLength);
220 
221 private:
222     static uint32_t lookup(const uint16_t *table, UChar32 c);
223     static uint32_t lookupUTF8(const uint16_t *table, UChar32 c,
224                                const uint8_t *s8, int32_t &sIndex, int32_t sLength);
225     static uint32_t lookupUTF8Unsafe(const uint16_t *table, UChar32 c,
226                                      const uint8_t *s8, int32_t &sIndex);
227 
228     static uint32_t nextPair(const uint16_t *table, UChar32 c, uint32_t ce,
229                              const UChar *s16, const uint8_t *s8, int32_t &sIndex, int32_t &sLength);
230 
getPrimaries(uint32_t variableTop,uint32_t pair)231     static inline uint32_t getPrimaries(uint32_t variableTop, uint32_t pair) {
232         uint32_t ce = pair & 0xffff;
233         if(ce >= MIN_SHORT) { return pair & TWO_SHORT_PRIMARIES_MASK; }
234         if(ce > variableTop) { return pair & TWO_LONG_PRIMARIES_MASK; }
235         if(ce >= MIN_LONG) { return 0; }  // variable
236         return pair;  // special mini CE
237     }
getSecondariesFromOneShortCE(uint32_t ce)238     static inline uint32_t getSecondariesFromOneShortCE(uint32_t ce) {
239         ce &= SECONDARY_MASK;
240         if(ce < MIN_SEC_HIGH) {
241             return ce + SEC_OFFSET;
242         } else {
243             return ((ce + SEC_OFFSET) << 16) | COMMON_SEC_PLUS_OFFSET;
244         }
245     }
246     static uint32_t getSecondaries(uint32_t variableTop, uint32_t pair);
247     static uint32_t getCases(uint32_t variableTop, UBool strengthIsPrimary, uint32_t pair);
248     static uint32_t getTertiaries(uint32_t variableTop, UBool withCaseBits, uint32_t pair);
249     static uint32_t getQuaternaries(uint32_t variableTop, uint32_t pair);
250 
251 private:
252     CollationFastLatin();  // no constructor
253 };
254 
255 /*
256  * Format of the CollationFastLatin data table.
257  * CollationFastLatin::VERSION = 2.
258  *
259  * This table contains data for a Latin-text collation fastpath.
260  * The data is stored as an array of uint16_t which contains the following parts.
261  *
262  * uint16_t  -- version & header length
263  *   Bits 15..8: version, must match the VERSION
264  *         7..0: length of the header
265  *
266  * uint16_t varTops[header length - 1]
267  *   Version 2:
268  *   varTops[m] is the highest CollationFastLatin long-primary weight
269  *   of supported maxVariable group m
270  *   (special reorder group space, punct, symbol, currency).
271  *
272  *   Version 1:
273  *   Each of these values maps the variable top lead byte of a supported maxVariable group
274  *   to the highest CollationFastLatin long-primary weight.
275  *   The values are stored in ascending order.
276  *   Bits 15..7: max fast-Latin long-primary weight (bits 11..3 shifted left by 4 bits)
277  *         6..0: regular primary lead byte
278  *
279  * uint16_t miniCEs[0x1c0]
280  *   A mini collation element for each character U+0000..U+017F and U+2000..U+203F.
281  *   Each value encodes one or two mini CEs (two are possible if the first one
282  *   has a short mini primary and the second one is a secondary CE, i.e., primary == 0),
283  *   or points to an expansion or to a contraction table.
284  *   U+0000 always has a contraction entry,
285  *   so that NUL-termination need not be tested in the fastpath.
286  *   If the collation elements for a character or contraction cannot be encoded in this format,
287  *   then the BAIL_OUT value is stored.
288  *   For details see the comments for the class constants.
289  *
290  * uint16_t expansions[variable length];
291  *   Expansion mini CEs contain an offset relative to just after the miniCEs table.
292  *   An expansions contains exactly 2 mini CEs.
293  *
294  * uint16_t contractions[variable length];
295  *   Contraction mini CEs contain an offset relative to just after the miniCEs table.
296  *   It points to a list of tuples which map from a contraction suffix character to a result.
297  *   First uint16_t of each tuple:
298  *     Bits 10..9: Length of the result (1..3), see comments on CONTR_LENGTH_SHIFT.
299  *     Bits  8..0: Contraction character, see comments on CONTR_CHAR_MASK.
300  *   This is followed by 0, 1, or 2 uint16_t according to the length.
301  *   Each list is terminated by an entry with CONTR_CHAR_MASK.
302  *   Each list starts with such an entry which also contains the default result
303  *   for when there is no contraction match.
304  *
305  * -----------------
306  * Changes for version 2 (ICU 55)
307  *
308  * Special reorder groups do not necessarily start on whole primary lead bytes any more.
309  * Therefore, the varTops data has a new format:
310  * Version 1 stored the lead bytes of the highest root primaries for
311  * the maxVariable-supported special reorder groups.
312  * Now the top 16 bits would need to be stored,
313  * and it is simpler to store only the fast-Latin weights.
314  */
315 
316 U_NAMESPACE_END
317 
318 #endif  // !UCONFIG_NO_COLLATION
319 #endif  // __COLLATIONFASTLATIN_H__
320