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1/*
2** 2007 May 6
3**
4** The author disclaims copyright to this source code. In place of
5** a legal notice, here is a blessing:
6**
7** May you do good and not evil.
8** May you find forgiveness for yourself and forgive others.
9** May you share freely, never taking more than you give.
10**
11*************************************************************************
12** $Id: icu.c,v 1.6 2007/06/22 15:21:16 danielk1977 Exp $
13**
14** This file implements an integration between the ICU library
15** ("International Components for Unicode", an open-source library
16** for handling unicode data) and SQLite. The integration uses
17** ICU to provide the following to SQLite:
18**
19** * An implementation of the SQL regexp() function (and hence REGEXP
20** operator) using the ICU uregex_XX() APIs.
21**
22** * Implementations of the SQL scalar upper() and lower() functions
23** for case mapping.
24**
25** * Integration of ICU and SQLite collation seqences.
26**
27** * An implementation of the LIKE operator that uses ICU to
28** provide case-independent matching.
29*/
30
31#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ICU)
32
33/* Include ICU headers */
34#include <unicode/utypes.h>
35#include <unicode/uregex.h>
36#include <unicode/ustring.h>
37#include <unicode/ucol.h>
38
39#include <assert.h>
40
41#ifndef SQLITE_CORE
42 #include "sqlite3ext.h"
43 SQLITE_EXTENSION_INIT1
44#else
45 #include "sqlite3.h"
46#endif
47
48/*
49** Maximum length (in bytes) of the pattern in a LIKE or GLOB
50** operator.
51*/
52#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
53# define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000
54#endif
55
56/*
57** Version of sqlite3_free() that is always a function, never a macro.
58*/
59static void xFree(void *p){
60 sqlite3_free(p);
61}
62
63/*
64** Compare two UTF-8 strings for equality where the first string is
65** a "LIKE" expression. Return true (1) if they are the same and
66** false (0) if they are different.
67*/
68static int icuLikeCompare(
69 const uint8_t *zPattern, /* LIKE pattern */
70 const uint8_t *zString, /* The UTF-8 string to compare against */
71 const UChar32 uEsc /* The escape character */
72){
73 static const int MATCH_ONE = (UChar32)'_';
74 static const int MATCH_ALL = (UChar32)'%';
75
76 int iPattern = 0; /* Current byte index in zPattern */
77 int iString = 0; /* Current byte index in zString */
78
79 int prevEscape = 0; /* True if the previous character was uEsc */
80
81 while( zPattern[iPattern]!=0 ){
82
83 /* Read (and consume) the next character from the input pattern. */
84 UChar32 uPattern;
85 U8_NEXT_UNSAFE(zPattern, iPattern, uPattern);
86 assert(uPattern!=0);
87
88 /* There are now 4 possibilities:
89 **
90 ** 1. uPattern is an unescaped match-all character "%",
91 ** 2. uPattern is an unescaped match-one character "_",
92 ** 3. uPattern is an unescaped escape character, or
93 ** 4. uPattern is to be handled as an ordinary character
94 */
95 if( !prevEscape && uPattern==MATCH_ALL ){
96 /* Case 1. */
97 uint8_t c;
98
99 /* Skip any MATCH_ALL or MATCH_ONE characters that follow a
100 ** MATCH_ALL. For each MATCH_ONE, skip one character in the
101 ** test string.
102 */
103 while( (c=zPattern[iPattern]) == MATCH_ALL || c == MATCH_ONE ){
104 if( c==MATCH_ONE ){
105 if( zString[iString]==0 ) return 0;
106 U8_FWD_1_UNSAFE(zString, iString);
107 }
108 iPattern++;
109 }
110
111 if( zPattern[iPattern]==0 ) return 1;
112
113 while( zString[iString] ){
114 if( icuLikeCompare(&zPattern[iPattern], &zString[iString], uEsc) ){
115 return 1;
116 }
117 U8_FWD_1_UNSAFE(zString, iString);
118 }
119 return 0;
120
121 }else if( !prevEscape && uPattern==MATCH_ONE ){
122 /* Case 2. */
123 if( zString[iString]==0 ) return 0;
124 U8_FWD_1_UNSAFE(zString, iString);
125
126 }else if( !prevEscape && uPattern==uEsc){
127 /* Case 3. */
128 prevEscape = 1;
129
130 }else{
131 /* Case 4. */
132 UChar32 uString;
133 U8_NEXT_UNSAFE(zString, iString, uString);
134 uString = u_foldCase(uString, U_FOLD_CASE_DEFAULT);
135 uPattern = u_foldCase(uPattern, U_FOLD_CASE_DEFAULT);
136 if( uString!=uPattern ){
137 return 0;
138 }
139 prevEscape = 0;
140 }
141 }
142
143 return zString[iString]==0;
144}
145
146/*
147** Implementation of the like() SQL function. This function implements
148** the build-in LIKE operator. The first argument to the function is the
149** pattern and the second argument is the string. So, the SQL statements:
150**
151** A LIKE B
152**
153** is implemented as like(B, A). If there is an escape character E,
154**
155** A LIKE B ESCAPE E
156**
157** is mapped to like(B, A, E).
158*/
159static void icuLikeFunc(
160 sqlite3_context *context,
161 int argc,
162 sqlite3_value **argv
163){
164 const unsigned char *zA = sqlite3_value_text(argv[0]);
165 const unsigned char *zB = sqlite3_value_text(argv[1]);
166 UChar32 uEsc = 0;
167
168 /* Limit the length of the LIKE or GLOB pattern to avoid problems
169 ** of deep recursion and N*N behavior in patternCompare().
170 */
171 if( sqlite3_value_bytes(argv[0])>SQLITE_MAX_LIKE_PATTERN_LENGTH ){
172 sqlite3_result_error(context, "LIKE or GLOB pattern too complex", -1);
173 return;
174 }
175
176
177 if( argc==3 ){
178 /* The escape character string must consist of a single UTF-8 character.
179 ** Otherwise, return an error.
180 */
181 int nE= sqlite3_value_bytes(argv[2]);
182 const unsigned char *zE = sqlite3_value_text(argv[2]);
183 int i = 0;
184 if( zE==0 ) return;
185 U8_NEXT(zE, i, nE, uEsc);
186 if( i!=nE){
187 sqlite3_result_error(context,
188 "ESCAPE expression must be a single character", -1);
189 return;
190 }
191 }
192
193 if( zA && zB ){
194 sqlite3_result_int(context, icuLikeCompare(zA, zB, uEsc));
195 }
196}
197
198/*
199** This function is called when an ICU function called from within
200** the implementation of an SQL scalar function returns an error.
201**
202** The scalar function context passed as the first argument is
203** loaded with an error message based on the following two args.
204*/
205static void icuFunctionError(
206 sqlite3_context *pCtx, /* SQLite scalar function context */
207 const char *zName, /* Name of ICU function that failed */
208 UErrorCode e /* Error code returned by ICU function */
209){
210 char zBuf[128];
211 sqlite3_snprintf(128, zBuf, "ICU error: %s(): %s", zName, u_errorName(e));
212 zBuf[127] = '\0';
213 sqlite3_result_error(pCtx, zBuf, -1);
214}
215
216/*
217** Function to delete compiled regexp objects. Registered as
218** a destructor function with sqlite3_set_auxdata().
219*/
220static void icuRegexpDelete(void *p){
221 URegularExpression *pExpr = (URegularExpression *)p;
222 uregex_close(pExpr);
223}
224
225/*
226** Implementation of SQLite REGEXP operator. This scalar function takes
227** two arguments. The first is a regular expression pattern to compile
228** the second is a string to match against that pattern. If either
229** argument is an SQL NULL, then NULL Is returned. Otherwise, the result
230** is 1 if the string matches the pattern, or 0 otherwise.
231**
232** SQLite maps the regexp() function to the regexp() operator such
233** that the following two are equivalent:
234**
235** zString REGEXP zPattern
236** regexp(zPattern, zString)
237**
238** Uses the following ICU regexp APIs:
239**
240** uregex_open()
241** uregex_matches()
242** uregex_close()
243*/
244static void icuRegexpFunc(sqlite3_context *p, int nArg, sqlite3_value **apArg){
245 UErrorCode status = U_ZERO_ERROR;
246 URegularExpression *pExpr;
247 UBool res;
248 const UChar *zString = sqlite3_value_text16(apArg[1]);
249
250 /* If the left hand side of the regexp operator is NULL,
251 ** then the result is also NULL.
252 */
253 if( !zString ){
254 return;
255 }
256
257 pExpr = sqlite3_get_auxdata(p, 0);
258 if( !pExpr ){
259 const UChar *zPattern = sqlite3_value_text16(apArg[0]);
260 if( !zPattern ){
261 return;
262 }
263 pExpr = uregex_open(zPattern, -1, 0, 0, &status);
264
265 if( U_SUCCESS(status) ){
266 sqlite3_set_auxdata(p, 0, pExpr, icuRegexpDelete);
267 }else{
268 assert(!pExpr);
269 icuFunctionError(p, "uregex_open", status);
270 return;
271 }
272 }
273
274 /* Configure the text that the regular expression operates on. */
275 uregex_setText(pExpr, zString, -1, &status);
276 if( !U_SUCCESS(status) ){
277 icuFunctionError(p, "uregex_setText", status);
278 return;
279 }
280
281 /* Attempt the match */
282 res = uregex_matches(pExpr, 0, &status);
283 if( !U_SUCCESS(status) ){
284 icuFunctionError(p, "uregex_matches", status);
285 return;
286 }
287
288 /* Set the text that the regular expression operates on to a NULL
289 ** pointer. This is not really necessary, but it is tidier than
290 ** leaving the regular expression object configured with an invalid
291 ** pointer after this function returns.
292 */
293 uregex_setText(pExpr, 0, 0, &status);
294
295 /* Return 1 or 0. */
296 sqlite3_result_int(p, res ? 1 : 0);
297}
298
299/*
300** Implementations of scalar functions for case mapping - upper() and
301** lower(). Function upper() converts it's input to upper-case (ABC).
302** Function lower() converts to lower-case (abc).
303**
304** ICU provides two types of case mapping, "general" case mapping and
305** "language specific". Refer to ICU documentation for the differences
306** between the two.
307**
308** To utilise "general" case mapping, the upper() or lower() scalar
309** functions are invoked with one argument:
310**
311** upper('ABC') -> 'abc'
312** lower('abc') -> 'ABC'
313**
314** To access ICU "language specific" case mapping, upper() or lower()
315** should be invoked with two arguments. The second argument is the name
316** of the locale to use. Passing an empty string ("") or SQL NULL value
317** as the second argument is the same as invoking the 1 argument version
318** of upper() or lower().
319**
320** lower('I', 'en_us') -> 'i'
321** lower('I', 'tr_tr') -> 'ı' (small dotless i)
322**
323** http://www.icu-project.org/userguide/posix.html#case_mappings
324*/
325static void icuCaseFunc16(sqlite3_context *p, int nArg, sqlite3_value **apArg){
326 const UChar *zInput;
327 UChar *zOutput;
328 int nInput;
329 int nOutput;
330
331 UErrorCode status = U_ZERO_ERROR;
332 const char *zLocale = 0;
333
334 assert(nArg==1 || nArg==2);
335 if( nArg==2 ){
336 zLocale = (const char *)sqlite3_value_text(apArg[1]);
337 }
338
339 zInput = sqlite3_value_text16(apArg[0]);
340 if( !zInput ){
341 return;
342 }
343 nInput = sqlite3_value_bytes16(apArg[0]);
344
345 nOutput = nInput * 2 + 2;
346 zOutput = sqlite3_malloc(nOutput);
347 if( !zOutput ){
348 return;
349 }
350
351 if( sqlite3_user_data(p) ){
352 u_strToUpper(zOutput, nOutput/2, zInput, nInput/2, zLocale, &status);
353 }else{
354 u_strToLower(zOutput, nOutput/2, zInput, nInput/2, zLocale, &status);
355 }
356
357 if( !U_SUCCESS(status) ){
358 icuFunctionError(p, "u_strToLower()/u_strToUpper", status);
359 return;
360 }
361
362 sqlite3_result_text16(p, zOutput, -1, xFree);
363}
364
365/*
366** Collation sequence destructor function. The pCtx argument points to
367** a UCollator structure previously allocated using ucol_open().
368*/
369static void icuCollationDel(void *pCtx){
370 UCollator *p = (UCollator *)pCtx;
371 ucol_close(p);
372}
373
374/*
375** Collation sequence comparison function. The pCtx argument points to
376** a UCollator structure previously allocated using ucol_open().
377*/
378static int icuCollationColl(
379 void *pCtx,
380 int nLeft,
381 const void *zLeft,
382 int nRight,
383 const void *zRight
384){
385 UCollationResult res;
386 UCollator *p = (UCollator *)pCtx;
387 res = ucol_strcoll(p, (UChar *)zLeft, nLeft/2, (UChar *)zRight, nRight/2);
388 switch( res ){
389 case UCOL_LESS: return -1;
390 case UCOL_GREATER: return +1;
391 case UCOL_EQUAL: return 0;
392 }
393 assert(!"Unexpected return value from ucol_strcoll()");
394 return 0;
395}
396
397/*
398** Implementation of the scalar function icu_load_collation().
399**
400** This scalar function is used to add ICU collation based collation
401** types to an SQLite database connection. It is intended to be called
402** as follows:
403**
404** SELECT icu_load_collation(<locale>, <collation-name>);
405**
406** Where <locale> is a string containing an ICU locale identifier (i.e.
407** "en_AU", "tr_TR" etc.) and <collation-name> is the name of the
408** collation sequence to create.
409*/
410static void icuLoadCollation(
411 sqlite3_context *p,
412 int nArg,
413 sqlite3_value **apArg
414){
415 sqlite3 *db = (sqlite3 *)sqlite3_user_data(p);
416 UErrorCode status = U_ZERO_ERROR;
417 const char *zLocale; /* Locale identifier - (eg. "jp_JP") */
418 const char *zName; /* SQL Collation sequence name (eg. "japanese") */
419 UCollator *pUCollator; /* ICU library collation object */
420 int rc; /* Return code from sqlite3_create_collation_x() */
421
422 assert(nArg==2);
423 zLocale = (const char *)sqlite3_value_text(apArg[0]);
424 zName = (const char *)sqlite3_value_text(apArg[1]);
425
426 if( !zLocale || !zName ){
427 return;
428 }
429
430 pUCollator = ucol_open(zLocale, &status);
431 if( !U_SUCCESS(status) ){
432 icuFunctionError(p, "ucol_open", status);
433 return;
434 }
435 assert(p);
436
437 rc = sqlite3_create_collation_v2(db, zName, SQLITE_UTF16, (void *)pUCollator,
438 icuCollationColl, icuCollationDel
439 );
440 if( rc!=SQLITE_OK ){
441 ucol_close(pUCollator);
442 sqlite3_result_error(p, "Error registering collation function", -1);
443 }
444}
445
446/*
447** Register the ICU extension functions with database db.
448*/
449int sqlite3IcuInit(sqlite3 *db){
450 struct IcuScalar {
451 const char *zName; /* Function name */
452 int nArg; /* Number of arguments */
453 int enc; /* Optimal text encoding */
454 void *pContext; /* sqlite3_user_data() context */
455 void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
456 } scalars[] = {
457 {"regexp",-1, SQLITE_ANY, 0, icuRegexpFunc},
458
459 {"lower", 1, SQLITE_UTF16, 0, icuCaseFunc16},
460 {"lower", 2, SQLITE_UTF16, 0, icuCaseFunc16},
461 {"upper", 1, SQLITE_UTF16, (void*)1, icuCaseFunc16},
462 {"upper", 2, SQLITE_UTF16, (void*)1, icuCaseFunc16},
463
464 {"lower", 1, SQLITE_UTF8, 0, icuCaseFunc16},
465 {"lower", 2, SQLITE_UTF8, 0, icuCaseFunc16},
466 {"upper", 1, SQLITE_UTF8, (void*)1, icuCaseFunc16},
467 {"upper", 2, SQLITE_UTF8, (void*)1, icuCaseFunc16},
468
469 {"like", 2, SQLITE_UTF8, 0, icuLikeFunc},
470 {"like", 3, SQLITE_UTF8, 0, icuLikeFunc},
471
472 {"icu_load_collation", 2, SQLITE_UTF8, (void*)db, icuLoadCollation},
473 };
474
475 int rc = SQLITE_OK;
476 int i;
477
478 for(i=0; rc==SQLITE_OK && i<(sizeof(scalars)/sizeof(struct IcuScalar)); i++){
479 struct IcuScalar *p = &scalars[i];
480 rc = sqlite3_create_function(
481 db, p->zName, p->nArg, p->enc, p->pContext, p->xFunc, 0, 0
482 );
483 }
484
485 return rc;
486}
487
488#if !SQLITE_CORE
489int sqlite3_extension_init(
490 sqlite3 *db,
491 char **pzErrMsg,
492 const sqlite3_api_routines *pApi
493){
494 SQLITE_EXTENSION_INIT2(pApi)
495 return sqlite3IcuInit(db);
496}
497#endif
498
499#endif