/*
** 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]);
/* 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",-1, 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<(sizeof(scalars)/sizeof(struct IcuScalar)); 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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