root/third_party/sqlite/src/ext/icu/icu.c

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DEFINITIONS

This source file includes following definitions.
  1. xFree
  2. icuLikeCompare
  3. icuLikeFunc
  4. icuFunctionError
  5. icuRegexpDelete
  6. icuRegexpFunc
  7. icuCaseFunc16
  8. icuCollationDel
  9. icuCollationColl
  10. icuLoadCollation
  11. sqlite3IcuInit
  12. sqlite3_extension_init

/*
** 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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