func.c

sqlite-3.4.1,嵌入式数据库.是一个功能强大的开源数据库,给学习和研发以及小型公司的发展带来了全所未有的好处.

** This function generates a string of random characters.  Used for
** generating test data.
*/
static void randStr(sqlite3_context *context, int argc, sqlite3_value **argv){
  static const unsigned char zSrc[] = 
     "abcdefghijklmnopqrstuvwxyz"
     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
     "0123456789"
     ".-!,:*^+=_|?/<> ";
  int iMin, iMax, n, r, i;
  unsigned char zBuf[1000];
  if( argc>=1 ){
    iMin = sqlite3_value_int(argv[0]);
    if( iMin<0 ) iMin = 0;
    if( iMin>=sizeof(zBuf) ) iMin = sizeof(zBuf)-1;
  }else{
    iMin = 1;
  }
  if( argc>=2 ){
    iMax = sqlite3_value_int(argv[1]);
    if( iMax<iMin ) iMax = iMin;
    if( iMax>=sizeof(zBuf) ) iMax = sizeof(zBuf)-1;
  }else{
    iMax = 50;
  }
  n = iMin;
  if( iMax>iMin ){
    sqlite3Randomness(sizeof(r), &r);
    r &= 0x7fffffff;
    n += r%(iMax + 1 - iMin);
  }
  assert( n<sizeof(zBuf) );
  sqlite3Randomness(n, zBuf);
  for(i=0; i<n; i++){
    zBuf[i] = zSrc[zBuf[i]%(sizeof(zSrc)-1)];
  }
  zBuf[n] = 0;
  sqlite3_result_text(context, (char*)zBuf, n, SQLITE_TRANSIENT);
}
#endif /* SQLITE_TEST */

#ifdef SQLITE_TEST
/*
** The following two SQL functions are used to test returning a text
** result with a destructor. Function 'test_destructor' takes one argument
** and returns the same argument interpreted as TEXT. A destructor is
** passed with the sqlite3_result_text() call.
**
** SQL function 'test_destructor_count' returns the number of outstanding 
** allocations made by 'test_destructor';
**
** WARNING: Not threadsafe.
*/
static int test_destructor_count_var = 0;
static void destructor(void *p){
  char *zVal = (char *)p;
  assert(zVal);
  zVal--;
  sqliteFree(zVal);
  test_destructor_count_var--;
}
static void test_destructor(
  sqlite3_context *pCtx, 
  int nArg,
  sqlite3_value **argv
){
  char *zVal;
  int len;
  sqlite3 *db = sqlite3_user_data(pCtx);
 
  test_destructor_count_var++;
  assert( nArg==1 );
  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  len = sqlite3ValueBytes(argv[0], ENC(db)); 
  zVal = sqliteMalloc(len+3);
  zVal[len] = 0;
  zVal[len-1] = 0;
  assert( zVal );
  zVal++;
  memcpy(zVal, sqlite3ValueText(argv[0], ENC(db)), len);
  if( ENC(db)==SQLITE_UTF8 ){
    sqlite3_result_text(pCtx, zVal, -1, destructor);
#ifndef SQLITE_OMIT_UTF16
  }else if( ENC(db)==SQLITE_UTF16LE ){
    sqlite3_result_text16le(pCtx, zVal, -1, destructor);
  }else{
    sqlite3_result_text16be(pCtx, zVal, -1, destructor);
#endif /* SQLITE_OMIT_UTF16 */
  }
}
static void test_destructor_count(
  sqlite3_context *pCtx, 
  int nArg,
  sqlite3_value **argv
){
  sqlite3_result_int(pCtx, test_destructor_count_var);
}
#endif /* SQLITE_TEST */

#ifdef SQLITE_TEST
/*
** Routines for testing the sqlite3_get_auxdata() and sqlite3_set_auxdata()
** interface.
**
** The test_auxdata() SQL function attempts to register each of its arguments
** as auxiliary data.  If there are no prior registrations of aux data for
** that argument (meaning the argument is not a constant or this is its first
** call) then the result for that argument is 0.  If there is a prior
** registration, the result for that argument is 1.  The overall result
** is the individual argument results separated by spaces.
*/
static void free_test_auxdata(void *p) {sqliteFree(p);}
static void test_auxdata(
  sqlite3_context *pCtx, 
  int nArg,
  sqlite3_value **argv
){
  int i;
  char *zRet = sqliteMalloc(nArg*2);
  if( !zRet ) return;
  for(i=0; i<nArg; i++){
    char const *z = (char*)sqlite3_value_text(argv[i]);
    if( z ){
      char *zAux = sqlite3_get_auxdata(pCtx, i);
      if( zAux ){
        zRet[i*2] = '1';
        if( strcmp(zAux, z) ){
          sqlite3_result_error(pCtx, "Auxilary data corruption", -1);
          return;
        }
      }else{
        zRet[i*2] = '0';
        zAux = sqliteStrDup(z);
        sqlite3_set_auxdata(pCtx, i, zAux, free_test_auxdata);
      }
      zRet[i*2+1] = ' ';
    }
  }
  sqlite3_result_text(pCtx, zRet, 2*nArg-1, free_test_auxdata);
}
#endif /* SQLITE_TEST */

#ifdef SQLITE_TEST
/*
** A function to test error reporting from user functions. This function
** returns a copy of it's first argument as an error.
*/
static void test_error(
  sqlite3_context *pCtx, 
  int nArg,
  sqlite3_value **argv
){
  sqlite3_result_error(pCtx, (char*)sqlite3_value_text(argv[0]), 0);
}
#endif /* SQLITE_TEST */

/*
** An instance of the following structure holds the context of a
** sum() or avg() aggregate computation.
*/
typedef struct SumCtx SumCtx;
struct SumCtx {
  double rSum;      /* Floating point sum */
  i64 iSum;         /* Integer sum */   
  i64 cnt;          /* Number of elements summed */
  u8 overflow;      /* True if integer overflow seen */
  u8 approx;        /* True if non-integer value was input to the sum */
};

/*
** Routines used to compute the sum, average, and total.
**
** The SUM() function follows the (broken) SQL standard which means
** that it returns NULL if it sums over no inputs.  TOTAL returns
** 0.0 in that case.  In addition, TOTAL always returns a float where
** SUM might return an integer if it never encounters a floating point
** value.  TOTAL never fails, but SUM might through an exception if
** it overflows an integer.
*/
static void sumStep(sqlite3_context *context, int argc, sqlite3_value **argv){
  SumCtx *p;
  int type;
  assert( argc==1 );
  p = sqlite3_aggregate_context(context, sizeof(*p));
  type = sqlite3_value_numeric_type(argv[0]);
  if( p && type!=SQLITE_NULL ){
    p->cnt++;
    if( type==SQLITE_INTEGER ){
      i64 v = sqlite3_value_int64(argv[0]);
      p->rSum += v;
      if( (p->approx|p->overflow)==0 ){
        i64 iNewSum = p->iSum + v;
        int s1 = p->iSum >> (sizeof(i64)*8-1);
        int s2 = v       >> (sizeof(i64)*8-1);
        int s3 = iNewSum >> (sizeof(i64)*8-1);
        p->overflow = (s1&s2&~s3) | (~s1&~s2&s3);
        p->iSum = iNewSum;
      }
    }else{
      p->rSum += sqlite3_value_double(argv[0]);
      p->approx = 1;
    }
  }
}
static void sumFinalize(sqlite3_context *context){
  SumCtx *p;
  p = sqlite3_aggregate_context(context, 0);
  if( p && p->cnt>0 ){
    if( p->overflow ){
      sqlite3_result_error(context,"integer overflow",-1);
    }else if( p->approx ){
      sqlite3_result_double(context, p->rSum);
    }else{
      sqlite3_result_int64(context, p->iSum);
    }
  }
}
static void avgFinalize(sqlite3_context *context){
  SumCtx *p;
  p = sqlite3_aggregate_context(context, 0);
  if( p && p->cnt>0 ){
    sqlite3_result_double(context, p->rSum/(double)p->cnt);
  }
}
static void totalFinalize(sqlite3_context *context){
  SumCtx *p;
  p = sqlite3_aggregate_context(context, 0);
  sqlite3_result_double(context, p ? p->rSum : 0.0);
}

/*
** The following structure keeps track of state information for the
** count() aggregate function.
*/
typedef struct CountCtx CountCtx;
struct CountCtx {
  i64 n;
};

/*
** Routines to implement the count() aggregate function.
*/
static void countStep(sqlite3_context *context, int argc, sqlite3_value **argv){
  CountCtx *p;
  p = sqlite3_aggregate_context(context, sizeof(*p));
  if( (argc==0 || SQLITE_NULL!=sqlite3_value_type(argv[0])) && p ){
    p->n++;
  }
}   
static void countFinalize(sqlite3_context *context){
  CountCtx *p;
  p = sqlite3_aggregate_context(context, 0);
  sqlite3_result_int64(context, p ? p->n : 0);
}

/*
** Routines to implement min() and max() aggregate functions.
*/
static void minmaxStep(sqlite3_context *context, int argc, sqlite3_value **argv){
  Mem *pArg  = (Mem *)argv[0];
  Mem *pBest;

  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
  pBest = (Mem *)sqlite3_aggregate_context(context, sizeof(*pBest));
  if( !pBest ) return;

  if( pBest->flags ){
    int max;
    int cmp;
    CollSeq *pColl = sqlite3GetFuncCollSeq(context);
    /* This step function is used for both the min() and max() aggregates,
    ** the only difference between the two being that the sense of the
    ** comparison is inverted. For the max() aggregate, the
    ** sqlite3_user_data() function returns (void *)-1. For min() it
    ** returns (void *)db, where db is the sqlite3* database pointer.
    ** Therefore the next statement sets variable 'max' to 1 for the max()
    ** aggregate, or 0 for min().
    */
    max = sqlite3_user_data(context)!=0;
    cmp = sqlite3MemCompare(pBest, pArg, pColl);
    if( (max && cmp<0) || (!max && cmp>0) ){
      sqlite3VdbeMemCopy(pBest, pArg);
    }
  }else{
    sqlite3VdbeMemCopy(pBest, pArg);
  }
}
static void minMaxFinalize(sqlite3_context *context){
  sqlite3_value *pRes;
  pRes = (sqlite3_value *)sqlite3_aggregate_context(context, 0);
  if( pRes ){
    if( pRes->flags ){
      sqlite3_result_value(context, pRes);
    }
    sqlite3VdbeMemRelease(pRes);
  }
}


/*
** This function registered all of the above C functions as SQL
** functions.  This should be the only routine in this file with
** external linkage.
*/
void sqlite3RegisterBuiltinFunctions(sqlite3 *db){
  static const struct {
     char *zName;
     signed char nArg;
     u8 argType;           /* ff: db   1: 0, 2: 1, 3: 2,...  N:  N-1. */
     u8 eTextRep;          /* 1: UTF-16.  0: UTF-8 */
     u8 needCollSeq;
     void (*xFunc)(sqlite3_context*,int,sqlite3_value **);
  } aFuncs[] = {
    { "min",               -1, 0, SQLITE_UTF8,    1, minmaxFunc },
    { "min",                0, 0, SQLITE_UTF8,    1, 0          },
    { "max",               -1, 1, SQLITE_UTF8,    1, minmaxFunc },
    { "max",                0, 1, SQLITE_UTF8,    1, 0          },
    { "typeof",             1, 0, SQLITE_UTF8,    0, typeofFunc },
    { "length",             1, 0, SQLITE_UTF8,    0, lengthFunc },
    { "substr",             3, 0, SQLITE_UTF8,    0, substrFunc },
    { "abs",                1, 0, SQLITE_UTF8,    0, absFunc    },
    { "round",              1, 0, SQLITE_UTF8,    0, roundFunc  },
    { "round",              2, 0, SQLITE_UTF8,    0, roundFunc  },
    { "upper",              1, 0, SQLITE_UTF8,    0, upperFunc  },
    { "lower",              1, 0, SQLITE_UTF8,    0, lowerFunc  },
    { "coalesce",          -1, 0, SQLITE_UTF8,    0, ifnullFunc },
    { "coalesce",           0, 0, SQLITE_UTF8,    0, 0          },
    { "coalesce",           1, 0, SQLITE_UTF8,    0, 0          },
    { "hex",                1, 0, SQLITE_UTF8,    0, hexFunc    },
    { "ifnull",             2, 0, SQLITE_UTF8,    1, ifnullFunc },
    { "random",            -1, 0, SQLITE_UTF8,    0, randomFunc },
    { "randomblob",         1, 0, SQLITE_UTF8,    0, randomBlob },
    { "nullif",             2, 0, SQLITE_UTF8,    1, nullifFunc },
    { "sqlite_version",     0, 0, SQLITE_UTF8,    0, versionFunc},
    { "quote",              1, 0, SQLITE_UTF8,    0, quoteFunc  },
    { "last_insert_rowid",  0, 0xff, SQLITE_UTF8, 0, last_insert_rowid },
    { "changes",            0, 0xff, SQLITE_UTF8, 0, changes           },
    { "total_changes",      0, 0xff, SQLITE_UTF8, 0, total_changes     },
    { "replace",            3, 0, SQLITE_UTF8,    0, replaceFunc       },
    { "ltrim",              1, 1, SQLITE_UTF8,    0, trimFunc          },
    { "ltrim",              2, 1, SQLITE_UTF8,    0, trimFunc          },
    { "rtrim",              1, 2, SQLITE_UTF8,    0, trimFunc          },
    { "rtrim",              2, 2, SQLITE_UTF8,    0, trimFunc          },
    { "trim",               1, 3, SQLITE_UTF8,    0, trimFunc          },
    { "trim",               2, 3, SQLITE_UTF8,    0, trimFunc          },
    { "zeroblob",           1, 0, SQLITE_UTF8,    0, zeroblobFunc      },
#ifdef SQLITE_SOUNDEX
    { "soundex",            1, 0, SQLITE_UTF8,    0, soundexFunc},
#endif
#ifndef SQLITE_OMIT_LOAD_EXTENSION
    { "load_extension",     1, 0xff, SQLITE_UTF8, 0, loadExt },
    { "load_extension",     2, 0xff, SQLITE_UTF8, 0, loadExt },
#endif
#ifdef SQLITE_TEST
    { "randstr",               2, 0,    SQLITE_UTF8, 0, randStr    },
    { "test_destructor",       1, 0xff, SQLITE_UTF8, 0, test_destructor},
    { "test_destructor_count", 0, 0,    SQLITE_UTF8, 0, test_destructor_count},
    { "test_auxdata",         -1, 0,    SQLITE_UTF8, 0, test_auxdata},
    { "test_error",            1, 0,    SQLITE_UTF8, 0, test_error},
#endif
  };
  static const struct {
    char *zName;
    signed char nArg;
    u8 argType;
    u8 needCollSeq;
    void (*xStep)(sqlite3_context*,int,sqlite3_value**);
    void (*xFinalize)(sqlite3_context*);
  } aAggs[] = {
    { "min",    1, 0, 1, minmaxStep,   minMaxFinalize },
    { "max",    1, 1, 1, minmaxStep,   minMaxFinalize },
    { "sum",    1, 0, 0, sumStep,      sumFinalize    },
    { "total",  1, 0, 0, sumStep,      totalFinalize    },
    { "avg",    1, 0, 0, sumStep,      avgFinalize    },
    { "count",  0, 0, 0, countStep,    countFinalize  },
    { "count",  1, 0, 0, countStep,    countFinalize  },
  };
  int i;

  for(i=0; i<sizeof(aFuncs)/sizeof(aFuncs[0]); i++){
    void *pArg;
    u8 argType = aFuncs[i].argType;
    if( argType==0xff ){
      pArg = db;
    }else{
      pArg = (void*)(int)argType;
    }
    sqlite3CreateFunc(db, aFuncs[i].zName, aFuncs[i].nArg,
        aFuncs[i].eTextRep, pArg, aFuncs[i].xFunc, 0, 0);
    if( aFuncs[i].needCollSeq ){
      FuncDef *pFunc = sqlite3FindFunction(db, aFuncs[i].zName, 
          strlen(aFuncs[i].zName), aFuncs[i].nArg, aFuncs[i].eTextRep, 0);
      if( pFunc && aFuncs[i].needCollSeq ){
        pFunc->needCollSeq = 1;
      }
    }
  }
#ifndef SQLITE_OMIT_ALTERTABLE
  sqlite3AlterFunctions(db);
#endif
#ifndef SQLITE_OMIT_PARSER
  sqlite3AttachFunctions(db);
#endif
  for(i=0; i<sizeof(aAggs)/sizeof(aAggs[0]); i++){
    void *pArg = (void*)(int)aAggs[i].argType;
    sqlite3CreateFunc(db, aAggs[i].zName, aAggs[i].nArg, SQLITE_UTF8, 
        pArg, 0, aAggs[i].xStep, aAggs[i].xFinalize);
    if( aAggs[i].needCollSeq ){
      FuncDef *pFunc = sqlite3FindFunction( db, aAggs[i].zName,
          strlen(aAggs[i].zName), aAggs[i].nArg, SQLITE_UTF8, 0);
      if( pFunc && aAggs[i].needCollSeq ){
        pFunc->needCollSeq = 1;
      }
    }
  }
  sqlite3RegisterDateTimeFunctions(db);
  if( !sqlite3MallocFailed() ){
    int rc = sqlite3_overload_function(db, "MATCH", 2);
    assert( rc==SQLITE_NOMEM || rc==SQLITE_OK );
    if( rc==SQLITE_NOMEM ){
      sqlite3FailedMalloc();
    }
  }
#ifdef SQLITE_SSE
  (void)sqlite3SseFunctions(db);
#endif
#ifdef SQLITE_CASE_SENSITIVE_LIKE
  sqlite3RegisterLikeFunctions(db, 1);
#else
  sqlite3RegisterLikeFunctions(db, 0);
#endif
}

/*
** Set the LIKEOPT flag on the 2-argument function with the given name.
*/
static void setLikeOptFlag(sqlite3 *db, const char *zName, int flagVal){
  FuncDef *pDef;
  pDef = sqlite3FindFunction(db, zName, strlen(zName), 2, SQLITE_UTF8, 0);
  if( pDef ){
    pDef->flags = flagVal;
  }
}

/*
** Register the built-in LIKE and GLOB functions.  The caseSensitive
** parameter determines whether or not the LIKE operator is case
** sensitive.  GLOB is always case sensitive.
*/
void sqlite3RegisterLikeFunctions(sqlite3 *db, int caseSensitive){
  struct compareInfo *pInfo;
  if( caseSensitive ){
    pInfo = (struct compareInfo*)&likeInfoAlt;
  }else{
    pInfo = (struct compareInfo*)&likeInfoNorm;
  }
  sqlite3CreateFunc(db, "like", 2, SQLITE_UTF8, pInfo, likeFunc, 0, 0);
  sqlite3CreateFunc(db, "like", 3, SQLITE_UTF8, pInfo, likeFunc, 0, 0);
  sqlite3CreateFunc(db, "glob", 2, SQLITE_UTF8, 
      (struct compareInfo*)&globInfo, likeFunc, 0,0);
  setLikeOptFlag(db, "glob", SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE);
  setLikeOptFlag(db, "like", 
      caseSensitive ? (SQLITE_FUNC_LIKE | SQLITE_FUNC_CASE) : SQLITE_FUNC_LIKE);
}

/*
** pExpr points to an expression which implements a function.  If
** it is appropriate to apply the LIKE optimization to that function
** then set aWc[0] through aWc[2] to the wildcard characters and
** return TRUE.  If the function is not a LIKE-style function then
** return FALSE.
*/
int sqlite3IsLikeFunction(sqlite3 *db, Expr *pExpr, int *pIsNocase, char *aWc){
  FuncDef *pDef;
  if( pExpr->op!=TK_FUNCTION || !pExpr->pList ){
    return 0;
  }
  if( pExpr->pList->nExpr!=2 ){
    return 0;
  }
  pDef = sqlite3FindFunction(db, (char*)pExpr->token.z, pExpr->token.n, 2,
                             SQLITE_UTF8, 0);
  if( pDef==0 || (pDef->flags & SQLITE_FUNC_LIKE)==0 ){
    return 0;
  }

  /* The memcpy() statement assumes that the wildcard characters are
  ** the first three statements in the compareInfo structure.  The
  ** asserts() that follow verify that assumption
  */
  memcpy(aWc, pDef->pUserData, 3);
  assert( (char*)&likeInfoAlt == (char*)&likeInfoAlt.matchAll );
  assert( &((char*)&likeInfoAlt)[1] == (char*)&likeInfoAlt.matchOne );
  assert( &((char*)&likeInfoAlt)[2] == (char*)&likeInfoAlt.matchSet );
  *pIsNocase = (pDef->flags & SQLITE_FUNC_CASE)==0;
  return 1;
}