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+/*
+** 2007 May 6
+**
+** The author disclaims copyright to this source code. In place of
+** a legal notice, here is a blessing:
+**
+** May you do good and not evil.
+** May you find forgiveness for yourself and forgive others.
+** May you share freely, never taking more than you give.
+**
+*************************************************************************
+** $Id: icu.c,v 1.7 2007/12/13 21:54:11 drh Exp $
+**
+** This file implements an integration between the ICU library
+** ("International Components for Unicode", an open-source library
+** for handling unicode data) and SQLite. The integration uses
+** ICU to provide the following to SQLite:
+**
+** * An implementation of the SQL regexp() function (and hence REGEXP
+** operator) using the ICU uregex_XX() APIs.
+**
+** * Implementations of the SQL scalar upper() and lower() functions
+** for case mapping.
+**
+** * Integration of ICU and SQLite collation seqences.
+**
+** * An implementation of the LIKE operator that uses ICU to
+** provide case-independent matching.
+*/
+
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_ICU)
+
+/* Include ICU headers */
+#include <unicode/utypes.h>
+#include <unicode/uregex.h>
+#include <unicode/ustring.h>
+#include <unicode/ucol.h>
+
+#include <assert.h>
+
+#ifndef SQLITE_CORE
+ #include "sqlite3ext.h"
+ SQLITE_EXTENSION_INIT1
+#else
+ #include "sqlite3.h"
+#endif
+
+/*
+** Maximum length (in bytes) of the pattern in a LIKE or GLOB
+** operator.
+*/
+#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
+# define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000
+#endif
+
+/*
+** Version of sqlite3_free() that is always a function, never a macro.
+*/
+static void xFree(void *p){
+ sqlite3_free(p);
+}
+
+/*
+** Compare two UTF-8 strings for equality where the first string is
+** a "LIKE" expression. Return true (1) if they are the same and
+** false (0) if they are different.
+*/
+static int icuLikeCompare(
+ const uint8_t *zPattern, /* LIKE pattern */
+ const uint8_t *zString, /* The UTF-8 string to compare against */
+ const UChar32 uEsc /* The escape character */
+){
+ static const int MATCH_ONE = (UChar32)'_';
+ static const int MATCH_ALL = (UChar32)'%';
+
+ int iPattern = 0; /* Current byte index in zPattern */
+ int iString = 0; /* Current byte index in zString */
+
+ int prevEscape = 0; /* True if the previous character was uEsc */
+
+ while( zPattern[iPattern]!=0 ){
+
+ /* Read (and consume) the next character from the input pattern. */
+ UChar32 uPattern;
+ U8_NEXT_UNSAFE(zPattern, iPattern, uPattern);
+ assert(uPattern!=0);
+
+ /* There are now 4 possibilities:
+ **
+ ** 1. uPattern is an unescaped match-all character "%",
+ ** 2. uPattern is an unescaped match-one character "_",
+ ** 3. uPattern is an unescaped escape character, or
+ ** 4. uPattern is to be handled as an ordinary character
+ */
+ if( !prevEscape && uPattern==MATCH_ALL ){
+ /* Case 1. */
+ uint8_t c;
+
+ /* Skip any MATCH_ALL or MATCH_ONE characters that follow a
+ ** MATCH_ALL. For each MATCH_ONE, skip one character in the
+ ** test string.
+ */
+ while( (c=zPattern[iPattern]) == MATCH_ALL || c == MATCH_ONE ){
+ if( c==MATCH_ONE ){
+ if( zString[iString]==0 ) return 0;
+ U8_FWD_1_UNSAFE(zString, iString);
+ }
+ iPattern++;
+ }
+
+ if( zPattern[iPattern]==0 ) return 1;
+
+ while( zString[iString] ){
+ if( icuLikeCompare(&zPattern[iPattern], &zString[iString], uEsc) ){
+ return 1;
+ }
+ U8_FWD_1_UNSAFE(zString, iString);
+ }
+ return 0;
+
+ }else if( !prevEscape && uPattern==MATCH_ONE ){
+ /* Case 2. */
+ if( zString[iString]==0 ) return 0;
+ U8_FWD_1_UNSAFE(zString, iString);
+
+ }else if( !prevEscape && uPattern==uEsc){
+ /* Case 3. */
+ prevEscape = 1;
+
+ }else{
+ /* Case 4. */
+ UChar32 uString;
+ U8_NEXT_UNSAFE(zString, iString, uString);
+ uString = u_foldCase(uString, U_FOLD_CASE_DEFAULT);
+ uPattern = u_foldCase(uPattern, U_FOLD_CASE_DEFAULT);
+ if( uString!=uPattern ){
+ return 0;
+ }
+ prevEscape = 0;
+ }
+ }
+
+ return zString[iString]==0;
+}
+
+/*
+** Implementation of the like() SQL function. This function implements
+** the build-in LIKE operator. The first argument to the function is the
+** pattern and the second argument is the string. So, the SQL statements:
+**
+** A LIKE B
+**
+** is implemented as like(B, A). If there is an escape character E,
+**
+** A LIKE B ESCAPE E
+**
+** is mapped to like(B, A, E).
+*/
+static void icuLikeFunc(
+ sqlite3_context *context,
+ int argc,
+ sqlite3_value **argv
+){
+ const unsigned char *zA = sqlite3_value_text(argv[0]);
+ const unsigned char *zB = sqlite3_value_text(argv[1]);
+ UChar32 uEsc = 0;
+
+ /* Limit the length of the LIKE or GLOB pattern to avoid problems
+ ** of deep recursion and N*N behavior in patternCompare().
+ */
+ if( sqlite3_value_bytes(argv[0])>SQLITE_MAX_LIKE_PATTERN_LENGTH ){
+ sqlite3_result_error(context, "LIKE or GLOB pattern too complex", -1);
+ return;
+ }
+
+
+ if( argc==3 ){
+ /* The escape character string must consist of a single UTF-8 character.
+ ** Otherwise, return an error.
+ */
+ int nE= sqlite3_value_bytes(argv[2]);
+ const unsigned char *zE = sqlite3_value_text(argv[2]);
+ int i = 0;
+ if( zE==0 ) return;
+ U8_NEXT(zE, i, nE, uEsc);
+ if( i!=nE){
+ sqlite3_result_error(context,
+ "ESCAPE expression must be a single character", -1);
+ return;
+ }
+ }
+
+ if( zA && zB ){
+ sqlite3_result_int(context, icuLikeCompare(zA, zB, uEsc));
+ }
+}
+
+/*
+** This function is called when an ICU function called from within
+** the implementation of an SQL scalar function returns an error.
+**
+** The scalar function context passed as the first argument is
+** loaded with an error message based on the following two args.
+*/
+static void icuFunctionError(
+ sqlite3_context *pCtx, /* SQLite scalar function context */
+ const char *zName, /* Name of ICU function that failed */
+ UErrorCode e /* Error code returned by ICU function */
+){
+ char zBuf[128];
+ sqlite3_snprintf(128, zBuf, "ICU error: %s(): %s", zName, u_errorName(e));
+ zBuf[127] = '\0';
+ sqlite3_result_error(pCtx, zBuf, -1);
+}
+
+/*
+** Function to delete compiled regexp objects. Registered as
+** a destructor function with sqlite3_set_auxdata().
+*/
+static void icuRegexpDelete(void *p){
+ URegularExpression *pExpr = (URegularExpression *)p;
+ uregex_close(pExpr);
+}
+
+/*
+** Implementation of SQLite REGEXP operator. This scalar function takes
+** two arguments. The first is a regular expression pattern to compile
+** the second is a string to match against that pattern. If either
+** argument is an SQL NULL, then NULL Is returned. Otherwise, the result
+** is 1 if the string matches the pattern, or 0 otherwise.
+**
+** SQLite maps the regexp() function to the regexp() operator such
+** that the following two are equivalent:
+**
+** zString REGEXP zPattern
+** regexp(zPattern, zString)
+**
+** Uses the following ICU regexp APIs:
+**
+** uregex_open()
+** uregex_matches()
+** uregex_close()
+*/
+static void icuRegexpFunc(sqlite3_context *p, int nArg, sqlite3_value **apArg){
+ UErrorCode status = U_ZERO_ERROR;
+ URegularExpression *pExpr;
+ UBool res;
+ const UChar *zString = sqlite3_value_text16(apArg[1]);
+
+ (void)nArg; /* Unused parameter */
+
+ /* If the left hand side of the regexp operator is NULL,
+ ** then the result is also NULL.
+ */
+ if( !zString ){
+ return;
+ }
+
+ pExpr = sqlite3_get_auxdata(p, 0);
+ if( !pExpr ){
+ const UChar *zPattern = sqlite3_value_text16(apArg[0]);
+ if( !zPattern ){
+ return;
+ }
+ pExpr = uregex_open(zPattern, -1, 0, 0, &status);
+
+ if( U_SUCCESS(status) ){
+ sqlite3_set_auxdata(p, 0, pExpr, icuRegexpDelete);
+ }else{
+ assert(!pExpr);
+ icuFunctionError(p, "uregex_open", status);
+ return;
+ }
+ }
+
+ /* Configure the text that the regular expression operates on. */
+ uregex_setText(pExpr, zString, -1, &status);
+ if( !U_SUCCESS(status) ){
+ icuFunctionError(p, "uregex_setText", status);
+ return;
+ }
+
+ /* Attempt the match */
+ res = uregex_matches(pExpr, 0, &status);
+ if( !U_SUCCESS(status) ){
+ icuFunctionError(p, "uregex_matches", status);
+ return;
+ }
+
+ /* Set the text that the regular expression operates on to a NULL
+ ** pointer. This is not really necessary, but it is tidier than
+ ** leaving the regular expression object configured with an invalid
+ ** pointer after this function returns.
+ */
+ uregex_setText(pExpr, 0, 0, &status);
+
+ /* Return 1 or 0. */
+ sqlite3_result_int(p, res ? 1 : 0);
+}
+
+/*
+** Implementations of scalar functions for case mapping - upper() and
+** lower(). Function upper() converts its input to upper-case (ABC).
+** Function lower() converts to lower-case (abc).
+**
+** ICU provides two types of case mapping, "general" case mapping and
+** "language specific". Refer to ICU documentation for the differences
+** between the two.
+**
+** To utilise "general" case mapping, the upper() or lower() scalar
+** functions are invoked with one argument:
+**
+** upper('ABC') -> 'abc'
+** lower('abc') -> 'ABC'
+**
+** To access ICU "language specific" case mapping, upper() or lower()
+** should be invoked with two arguments. The second argument is the name
+** of the locale to use. Passing an empty string ("") or SQL NULL value
+** as the second argument is the same as invoking the 1 argument version
+** of upper() or lower().
+**
+** lower('I', 'en_us') -> 'i'
+** lower('I', 'tr_tr') -> 'ı' (small dotless i)
+**
+** http://www.icu-project.org/userguide/posix.html#case_mappings
+*/
+static void icuCaseFunc16(sqlite3_context *p, int nArg, sqlite3_value **apArg){
+ const UChar *zInput;
+ UChar *zOutput;
+ int nInput;
+ int nOutput;
+
+ UErrorCode status = U_ZERO_ERROR;
+ const char *zLocale = 0;
+
+ assert(nArg==1 || nArg==2);
+ if( nArg==2 ){
+ zLocale = (const char *)sqlite3_value_text(apArg[1]);
+ }
+
+ zInput = sqlite3_value_text16(apArg[0]);
+ if( !zInput ){
+ return;
+ }
+ nInput = sqlite3_value_bytes16(apArg[0]);
+
+ nOutput = nInput * 2 + 2;
+ zOutput = sqlite3_malloc(nOutput);
+ if( !zOutput ){
+ return;
+ }
+
+ if( sqlite3_user_data(p) ){
+ u_strToUpper(zOutput, nOutput/2, zInput, nInput/2, zLocale, &status);
+ }else{
+ u_strToLower(zOutput, nOutput/2, zInput, nInput/2, zLocale, &status);
+ }
+
+ if( !U_SUCCESS(status) ){
+ icuFunctionError(p, "u_strToLower()/u_strToUpper", status);
+ return;
+ }
+
+ sqlite3_result_text16(p, zOutput, -1, xFree);
+}
+
+/*
+** Collation sequence destructor function. The pCtx argument points to
+** a UCollator structure previously allocated using ucol_open().
+*/
+static void icuCollationDel(void *pCtx){
+ UCollator *p = (UCollator *)pCtx;
+ ucol_close(p);
+}
+
+/*
+** Collation sequence comparison function. The pCtx argument points to
+** a UCollator structure previously allocated using ucol_open().
+*/
+static int icuCollationColl(
+ void *pCtx,
+ int nLeft,
+ const void *zLeft,
+ int nRight,
+ const void *zRight
+){
+ UCollationResult res;
+ UCollator *p = (UCollator *)pCtx;
+ res = ucol_strcoll(p, (UChar *)zLeft, nLeft/2, (UChar *)zRight, nRight/2);
+ switch( res ){
+ case UCOL_LESS: return -1;
+ case UCOL_GREATER: return +1;
+ case UCOL_EQUAL: return 0;
+ }
+ assert(!"Unexpected return value from ucol_strcoll()");
+ return 0;
+}
+
+/*
+** Implementation of the scalar function icu_load_collation().
+**
+** This scalar function is used to add ICU collation based collation
+** types to an SQLite database connection. It is intended to be called
+** as follows:
+**
+** SELECT icu_load_collation(<locale>, <collation-name>);
+**
+** Where <locale> is a string containing an ICU locale identifier (i.e.
+** "en_AU", "tr_TR" etc.) and <collation-name> is the name of the
+** collation sequence to create.
+*/
+static void icuLoadCollation(
+ sqlite3_context *p,
+ int nArg,
+ sqlite3_value **apArg
+){
+ sqlite3 *db = (sqlite3 *)sqlite3_user_data(p);
+ UErrorCode status = U_ZERO_ERROR;
+ const char *zLocale; /* Locale identifier - (eg. "jp_JP") */
+ const char *zName; /* SQL Collation sequence name (eg. "japanese") */
+ UCollator *pUCollator; /* ICU library collation object */
+ int rc; /* Return code from sqlite3_create_collation_x() */
+
+ assert(nArg==2);
+ zLocale = (const char *)sqlite3_value_text(apArg[0]);
+ zName = (const char *)sqlite3_value_text(apArg[1]);
+
+ if( !zLocale || !zName ){
+ return;
+ }
+
+ pUCollator = ucol_open(zLocale, &status);
+ if( !U_SUCCESS(status) ){
+ icuFunctionError(p, "ucol_open", status);
+ return;
+ }
+ assert(p);
+
+ rc = sqlite3_create_collation_v2(db, zName, SQLITE_UTF16, (void *)pUCollator,
+ icuCollationColl, icuCollationDel
+ );
+ if( rc!=SQLITE_OK ){
+ ucol_close(pUCollator);
+ sqlite3_result_error(p, "Error registering collation function", -1);
+ }
+}
+
+/*
+** Register the ICU extension functions with database db.
+*/
+int sqlite3IcuInit(sqlite3 *db){
+ struct IcuScalar {
+ const char *zName; /* Function name */
+ int nArg; /* Number of arguments */
+ int enc; /* Optimal text encoding */
+ void *pContext; /* sqlite3_user_data() context */
+ void (*xFunc)(sqlite3_context*,int,sqlite3_value**);
+ } scalars[] = {
+ {"regexp", 2, SQLITE_ANY, 0, icuRegexpFunc},
+
+ {"lower", 1, SQLITE_UTF16, 0, icuCaseFunc16},
+ {"lower", 2, SQLITE_UTF16, 0, icuCaseFunc16},
+ {"upper", 1, SQLITE_UTF16, (void*)1, icuCaseFunc16},
+ {"upper", 2, SQLITE_UTF16, (void*)1, icuCaseFunc16},
+
+ {"lower", 1, SQLITE_UTF8, 0, icuCaseFunc16},
+ {"lower", 2, SQLITE_UTF8, 0, icuCaseFunc16},
+ {"upper", 1, SQLITE_UTF8, (void*)1, icuCaseFunc16},
+ {"upper", 2, SQLITE_UTF8, (void*)1, icuCaseFunc16},
+
+ {"like", 2, SQLITE_UTF8, 0, icuLikeFunc},
+ {"like", 3, SQLITE_UTF8, 0, icuLikeFunc},
+
+ {"icu_load_collation", 2, SQLITE_UTF8, (void*)db, icuLoadCollation},
+ };
+
+ int rc = SQLITE_OK;
+ int i;
+
+ for(i=0; rc==SQLITE_OK && i<(int)(sizeof(scalars)/sizeof(scalars[0])); i++){
+ struct IcuScalar *p = &scalars[i];
+ rc = sqlite3_create_function(
+ db, p->zName, p->nArg, p->enc, p->pContext, p->xFunc, 0, 0
+ );
+ }
+
+ return rc;
+}
+
+#if !SQLITE_CORE
+int sqlite3_extension_init(
+ sqlite3 *db,
+ char **pzErrMsg,
+ const sqlite3_api_routines *pApi
+){
+ SQLITE_EXTENSION_INIT2(pApi)
+ return sqlite3IcuInit(db);
+}
+#endif
+
+#endif
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