SQLite

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.48 2002/02/27 19:00:21 drh Exp $
*/
#include "sqliteInt.h"


/*
** Construct a new expression node and return a pointer to it.  Memory
** for this node is obtained from sqliteMalloc().  The calling function

        }
      }
    }
  }
  return 0;
}

#if 0 /* NOT USED */
/*
** Compare a token against a string.  Return TRUE if they match.
*/
static int sqliteTokenCmp(Token *pToken, const char *zStr){
  int n = strlen(zStr);
  if( n!=pToken->n ) return 0;
  return sqliteStrNICmp(pToken->z, zStr, n)==0;
}
#endif

/*
** Convert a function name into its integer identifier.  Return the
** identifier.  Return FN_Unknown if the function name is unknown.
*/
int sqliteFuncId(Token *pToken){
  static const struct {
     char *zName;
     int len;
     int id;
  } aFunc[] = {
     { "count",  5, FN_Count  },
     { "min",    3, FN_Min    },
     { "max",    3, FN_Max    },
     { "sum",    3, FN_Sum    },
     { "avg",    3, FN_Avg    },
     { "length", 6, FN_Length },
     { "substr", 6, FN_Substr },
     { "abs",    3, FN_Abs    },
     { "round",  5, FN_Round  },
  };
  int i;
  for(i=0; i<ArraySize(aFunc); i++){
    if( aFunc[i].len==pToken->n 
     && sqliteStrNICmp(pToken->z, aFunc[i].zName, aFunc[i].len)==0 ){
       return aFunc[i].id;
    }
  }
  return FN_Unknown;
}

/*
** Error check the functions in an expression.  Make sure all
** function names are recognized and all functions have the correct
** number of arguments.  Leave an error message in pParse->zErrMsg
** if anything is amiss.  Return the number of errors.
**
** if pIsAgg is not null and this expression is an aggregate function
** (like count(*) or max(value)) then write a 1 into *pIsAgg.
*/
int sqliteExprCheck(Parse *pParse, Expr *pExpr, int allowAgg, int *pIsAgg){
  int nErr = 0;
  if( pExpr==0 ) return 0;
  switch( pExpr->op ){
    case TK_FUNCTION: {
      int id = sqliteFuncId(&pExpr->token);
      int n = pExpr->pList ? pExpr->pList->nExpr : 0;
      int no_such_func = 0;
      int too_many_args = 0;
      int too_few_args = 0;
      int wrong_num_args = 0;
      int is_agg = 0;
      int i;

      pExpr->iColumn = id;
      switch( id ){
        case FN_Unknown: {
          UserFunc *pUser = sqliteFindUserFunction(pParse->db,
             pExpr->token.z, pExpr->token.n, n, 0);
          if( pUser==0 ){
            pUser = sqliteFindUserFunction(pParse->db,
               pExpr->token.z, pExpr->token.n, -1, 0);
            if( pUser==0 ){
              no_such_func = 1;
            }else{
              wrong_num_args = 1;
            }
          }else{
            is_agg = pUser->xFunc==0;
          }
          break;
        }
        case FN_Count: { 
          too_many_args = n>1;
          is_agg = 1;
          break;
        }
        case FN_Max:
        case FN_Min: {
          too_few_args = n<1;
          is_agg = n==1;
          break;
        }
        case FN_Avg:
        case FN_Sum: {
          too_many_args = n>1;
          too_few_args = n<1;
          is_agg = 1;
          break;
        }
        case FN_Abs:
        case FN_Length: {
          too_few_args = n<1;
          too_many_args = n>1;
          break;
        }
        case FN_Round: {
          too_few_args = n<1;
          too_many_args = n>2;
          break;
        }
        case FN_Substr: {
          too_few_args = n<3;
          too_many_args = n>3;
          break;
        }
        default: break;
      }
      if( is_agg && !allowAgg ){
        sqliteSetNString(&pParse->zErrMsg, "misuse of aggregate function ", -1,
           pExpr->token.z, pExpr->token.n, "()", 2, 0);
        pParse->nErr++;
        nErr++;
        is_agg = 0;
      }else if( no_such_func ){
        sqliteSetNString(&pParse->zErrMsg, "no such function: ", -1,
           pExpr->token.z, pExpr->token.n, 0);
        pParse->nErr++;
        nErr++;
      }else if( too_many_args ){
        sqliteSetNString(&pParse->zErrMsg, "too many arguments to function ",-1,
           pExpr->token.z, pExpr->token.n, "()", 2, 0);
        pParse->nErr++;
        nErr++;
      }else if( too_few_args ){
        sqliteSetNString(&pParse->zErrMsg, "too few arguments to function ",-1,
           pExpr->token.z, pExpr->token.n, "()", 2, 0);
        pParse->nErr++;
        nErr++;
      }else if( wrong_num_args ){
        sqliteSetNString(&pParse->zErrMsg, 
           "wrong number of arguments to function ",-1,
           pExpr->token.z, pExpr->token.n, "()", 2, 0);
        pParse->nErr++;
        nErr++;
      }

      dest = sqliteVdbeCurrentAddr(v) + 2;
      sqliteVdbeAddOp(v, op, 0, dest);
      sqliteVdbeAddOp(v, OP_AddImm, -1, 0);
      break;
    }
    case TK_AGG_FUNCTION: {
      sqliteVdbeAddOp(v, OP_AggGet, 0, pExpr->iAgg);
      if( pExpr->iColumn==FN_Avg ){
        assert( pParse->iAggCount>=0 && pParse->iAggCount<pParse->nAgg );
        sqliteVdbeAddOp(v, OP_AggGet, 0, pParse->iAggCount);
        sqliteVdbeAddOp(v, OP_Divide, 0, 0);
      }
      break;
    }
    case TK_FUNCTION: {
      int id = pExpr->iColumn;
      int op;
      int i;
      ExprList *pList = pExpr->pList;
      switch( id ){
        case FN_Min: 
        case FN_Max: {
          op = id==FN_Min ? OP_Min : OP_Max;
          for(i=0; i<pList->nExpr; i++){
            sqliteExprCode(pParse, pList->a[i].pExpr);
            if( i>0 ){
              sqliteVdbeAddOp(v, op, 0, 0);
            }
          }
          break;
        }
        case FN_Abs: {
          sqliteExprCode(pParse, pList->a[0].pExpr);
          sqliteVdbeAddOp(v, OP_AbsValue, 0, 0);
          break;
        }
        case FN_Round: {
          if( pList->nExpr==2 ){
            sqliteExprCode(pParse, pList->a[1].pExpr);
          }else{
            sqliteVdbeAddOp(v, OP_Integer, 0, 0);
          }
          sqliteExprCode(pParse, pList->a[0].pExpr);
          sqliteVdbeAddOp(v, OP_Precision, 0, 0);
          break;
        }
        case FN_Length: {
          sqliteExprCode(pParse, pList->a[0].pExpr);
          sqliteVdbeAddOp(v, OP_Strlen, 0, 0);
          break;
        }
        case FN_Substr: {
          for(i=0; i<pList->nExpr; i++){
            sqliteExprCode(pParse, pList->a[i].pExpr);
          }
          sqliteVdbeAddOp(v, OP_Substr, 0, 0);
          break;
        }
        case FN_Unknown: {
          UserFunc *pUser;
          pUser = sqliteFindUserFunction(pParse->db,
                      pExpr->token.z, pExpr->token.n, pList->nExpr, 0);
          assert( pUser!=0 );
          for(i=0; i<pList->nExpr; i++){
            sqliteExprCode(pParse, pList->a[i].pExpr);
          }
          sqliteVdbeAddOp(v, OP_UserFunc, pList->nExpr, 0);
          sqliteVdbeChangeP3(v, -1, (char*)pUser, P3_POINTER);
          break;
        }
        default: {
          /* Can't happen! */
          break;
        }
      }
      break;
    }
    case TK_SELECT: {
      sqliteVdbeAddOp(v, OP_MemLoad, pExpr->iColumn, 0);
      break;
    }
    case TK_IN: {

        pParse->aAgg[i].isAgg = 0;
        pParse->aAgg[i].pExpr = pExpr;
      }
      pExpr->iAgg = i;
      break;
    }
    case TK_AGG_FUNCTION: {
      if( pExpr->iColumn==FN_Count || pExpr->iColumn==FN_Avg ){
        if( pParse->iAggCount>=0 ){
          i = pParse->iAggCount;
        }else{
          i = appendAggInfo(pParse);
          if( i<0 ) return 1;
          pParse->aAgg[i].isAgg = 1;
          pParse->aAgg[i].pExpr = 0;
          pParse->iAggCount = i;
        }
        if( pExpr->iColumn==FN_Count ){
          pExpr->iAgg = i;
          break;
        }
      }
      aAgg = pParse->aAgg;
      for(i=0; i<pParse->nAgg; i++){
        if( !aAgg[i].isAgg ) continue;
        if( sqliteExprCompare(aAgg[i].pExpr, pExpr) ){
          break;
        }
      }
      if( i>=pParse->nAgg ){
        i = appendAggInfo(pParse);
        if( i<0 ) return 1;
        pParse->aAgg[i].isAgg = 1;
        pParse->aAgg[i].pExpr = pExpr;
        if( pExpr->iColumn==FN_Unknown ){
          pParse->aAgg[i].pUser = sqliteFindUserFunction(pParse->db,
             pExpr->token.z, pExpr->token.n, pExpr->pList->nExpr, 0);
        }else{
          pParse->aAgg[i].pUser = 0;
        }
      }
      pExpr->iAgg = i;
      break;
    }
    default: {
      if( pExpr->pLeft ){
        nErr = sqliteExprAnalyzeAggregates(pParse, pExpr->pLeft);

    }
  }
  return nErr;
}

/*
** Locate a user function given a name and a number of arguments.
** Return a pointer to the UserFunc structure that defines that
** function, or return NULL if the function does not exist.
**
** If the createFlag argument is true, then a new (blank) UserFunc
** structure is created and liked into the "db" structure if a
** no matching function previously existed.  When createFlag is true
** and the nArg parameter is -1, then only a function that accepts
** any number of arguments will be returned.
**
** If createFlag is false and nArg is -1, then the first valid
** function found is returned.  A function is valid if either xFunc
** or xStep is non-zero.
*/
UserFunc *sqliteFindUserFunction(
  sqlite *db,        /* An open database */
  const char *zName, /* Name of the function.  Not null-terminated */
  int nName,         /* Number of characters in the name */
  int nArg,          /* Number of arguments.  -1 means any number */
  int createFlag     /* Create new entry if true and does not otherwise exist */
){
  UserFunc *pFirst, *p, *pMaybe;
  pFirst = p = (UserFunc*)sqliteHashFind(&db->userFunc, zName, nName);
  if( p && !createFlag && nArg<0 ){
    while( p && p->xFunc==0 && p->xStep==0 ){ p = p->pNext; }
    return p;
  }
  pMaybe = 0;
  while( p && p->nArg!=nArg ){
    if( p->nArg<0 && !createFlag && (p->xFunc || p->xStep) ) pMaybe = p;
    p = p->pNext;
  }
  if( p && !createFlag && p->xFunc==0 && p->xStep==0 ){
    return 0;
  }
  if( p==0 && pMaybe ){
    assert( createFlag==0 );
    return pMaybe;
  }
  if( p==0 && createFlag ){
    p = sqliteMalloc( sizeof(*p) );
    p->nArg = nArg;
    p->pNext = pFirst;
    sqliteHashInsert(&db->userFunc, zName, nName, (void*)p);
  }
  return p;
}

** This file contains the C functions that implement various SQL
** functions of SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.5 2002/02/27 19:50:59 drh Exp $
*/
#include <ctype.h>
#include <math.h>
#include <stdlib.h>

#include "sqlite.h"






















































































































/*
** Implementation of the upper() and lower() SQL functions.
*/
static void upperFunc(sqlite_func *context, int argc, const char **argv){
  char *z;
  int i;

  StdDevCtx *p = sqlite_aggregate_context(context, sizeof(*p));
  if( p && rN>1.0 ){
    sqlite_set_result_double(context, 
       sqrt((p->sum2 - p->sum*p->sum/rN)/(rN-1.0)));
  }
}
































































































/*
** 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 sqliteRegisterBuildinFunctions(sqlite *db){






























  sqlite_create_function(db, "upper", 1, upperFunc, 0);

  sqlite_create_function(db, "lower", 1, lowerFunc, 0);
  sqlite_create_aggregate(db, "stddev", 1, stdDevStep, stdDevFinalize, 0);



  sqlite_create_aggregate(db, "x_sum", 1, sumStep, sumFinalize, 0);
  sqlite_create_aggregate(db, "x_avg", 1, sumStep, avgFinalize, 0);
}

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.65 2002/02/27 19:00:22 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"

/*
** This is the callback routine for the code that initializes the
** database.  See sqliteInit() below for additional information.

  db = sqliteMalloc( sizeof(sqlite) );
  if( pzErrMsg ) *pzErrMsg = 0;
  if( db==0 ) goto no_mem_on_open;
  sqliteHashInit(&db->tblHash, SQLITE_HASH_STRING, 0);
  sqliteHashInit(&db->idxHash, SQLITE_HASH_STRING, 0);
  sqliteHashInit(&db->tblDrop, SQLITE_HASH_POINTER, 0);
  sqliteHashInit(&db->idxDrop, SQLITE_HASH_POINTER, 0);
  sqliteHashInit(&db->userFunc, SQLITE_HASH_STRING, 1);
  sqliteRegisterBuildinFunctions(db);
  db->onError = OE_Default;
  db->priorNewRowid = 0;
  
  /* Open the backend database driver */
  rc = sqliteBtreeOpen(zFilename, mode, MAX_PAGES, &db->pBe);
  if( rc!=SQLITE_OK ){

void sqlite_close(sqlite *db){
  HashElem *i;
  sqliteBtreeClose(db->pBe);
  clearHashTable(db, 0);
  if( db->pBeTemp ){
    sqliteBtreeClose(db->pBeTemp);
  }
  for(i=sqliteHashFirst(&db->userFunc); i; i=sqliteHashNext(i)){
    UserFunc *pFunc, *pNext;
    for(pFunc = (UserFunc*)sqliteHashData(i); pFunc; pFunc=pNext){
      pNext = pFunc->pNext;
      sqliteFree(pFunc);
    }
  }
  sqliteHashClear(&db->userFunc);
  sqliteFree(db);
}

/*
** Return TRUE if the given SQL string ends in a semicolon.
*/
int sqlite_complete(const char *zSql){

int sqlite_create_function(
  sqlite *db,          /* Add the function to this database connection */
  const char *zName,   /* Name of the function to add */
  int nArg,            /* Number of arguments */
  void (*xFunc)(sqlite_func*,int,const char**),  /* The implementation */
  void *pUserData      /* User data */
){
  UserFunc *p;
  if( db==0 || zName==0 ) return 1;
  p = sqliteFindUserFunction(db, zName, strlen(zName), nArg, 1);
  if( p==0 ) return 1;
  p->xFunc = xFunc;
  p->xStep = 0;
  p->xFinalize = 0;
  p->pUserData = pUserData;
  return 0;
}
int sqlite_create_aggregate(
  sqlite *db,          /* Add the function to this database connection */
  const char *zName,   /* Name of the function to add */
  int nArg,            /* Number of arguments */
  void (*xStep)(sqlite_func*,int,const char**), /* The step function */
  void (*xFinalize)(sqlite_func*),              /* The finalizer */
  void *pUserData      /* User data */
){
  UserFunc *p;
  if( db==0 || zName==0 ) return 1;
  p = sqliteFindUserFunction(db, zName, strlen(zName), nArg, 1);
  if( p==0 ) return 1;
  p->xFunc = 0;
  p->xStep = xStep;
  p->xFinalize = xFinalize;
  p->pUserData = pUserData;
  return 0;
}

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.68 2002/02/27 19:00:22 drh Exp $
*/
#include "sqliteInt.h"

/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/

/*
** Delete the aggregate information from the parse structure.
*/
static void sqliteAggregateInfoReset(Parse *pParse){
  sqliteFree(pParse->aAgg);
  pParse->aAgg = 0;
  pParse->nAgg = 0;
  pParse->iAggCount = -1;
  pParse->useAgg = 0;
}

/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**

  */
  if( p->pGroupBy || p->pHaving || p->pWhere ) return 0;
  if( p->pSrc->nId!=1 ) return 0;
  if( p->pEList->nExpr!=1 ) return 0;
  pExpr = p->pEList->a[0].pExpr;
  if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
  if( pExpr->pList==0 || pExpr->pList->nExpr!=1 ) return 0;
  if( pExpr->iColumn!=FN_Min && pExpr->iColumn!=FN_Max ) return 0;



  seekOp = pExpr->iColumn==FN_Min ? OP_Rewind : OP_Last;



  pExpr = pExpr->pList->a[0].pExpr;
  if( pExpr->op!=TK_COLUMN ) return 0;
  iCol = pExpr->iColumn;
  pTab = p->pSrc->a[0].pTab;

  /* If we get to here, it means the query is of the correct form.
  ** Check to make sure we have an index and make pIdx point to the

    pParse->nTab = oldNTab;
  }

  /* Do an analysis of aggregate expressions.
  */
  sqliteAggregateInfoReset(pParse);
  if( isAgg ){
    assert( pParse->nAgg==0 && pParse->iAggCount<0 );
    for(i=0; i<pEList->nExpr; i++){
      if( sqliteExprAnalyzeAggregates(pParse, pEList->a[i].pExpr) ){
        goto select_end;
      }
    }
    if( pGroupBy ){
      for(i=0; i<pGroupBy->nExpr; i++){

  }

  /* Reset the aggregator
  */
  if( isAgg ){
    sqliteVdbeAddOp(v, OP_AggReset, 0, pParse->nAgg);
    for(i=0; i<pParse->nAgg; i++){
      UserFunc *pUser;
      if( (pUser = pParse->aAgg[i].pUser)!=0 && pUser->xFinalize!=0 ){
        sqliteVdbeAddOp(v, OP_AggInit, 0, i);
        sqliteVdbeChangeP3(v, -1, (char*)pUser, P3_POINTER);
      }
    }
    if( pGroupBy==0 ){
      sqliteVdbeAddOp(v, OP_String, 0, 0);
      sqliteVdbeAddOp(v, OP_AggFocus, 0, 0);
      for(i=0; i<pParse->nAgg; i++){
        Expr *pE;
        if( !pParse->aAgg[i].isAgg ) continue;
        pE = pParse->aAgg[i].pExpr;
        assert( pE==0 || pE->op==TK_AGG_FUNCTION );
        assert( pE==0 || (pE->pList!=0 && pE->pList->nExpr==1) );
        if( pE==0 || pE->iColumn==FN_Sum ){
          sqliteVdbeAddOp(v, OP_Integer, 0, 0);
          sqliteVdbeAddOp(v, OP_AggSet, 0, i);
          continue;
        }
      }
    }
  }

  /* Initialize the memory cell to NULL
  */
  if( eDest==SRT_Mem ){
    sqliteVdbeAddOp(v, OP_String, 0, 0);

        sqliteExprCode(pParse, pParse->aAgg[i].pExpr);
        sqliteVdbeAddOp(v, OP_AggSet, 0, i);
      }
      sqliteVdbeResolveLabel(v, lbl1);
    }
    for(i=0; i<pParse->nAgg; i++){
      Expr *pE;
      int op, j;
      if( !pParse->aAgg[i].isAgg ) continue;
      pE = pParse->aAgg[i].pExpr;
      if( pE==0 ){
        sqliteVdbeAddOp(v, OP_AggIncr, 1, i);
        continue;
      }
      assert( pE->op==TK_AGG_FUNCTION );
      assert( pE->pList!=0 );
      for(j=0; j<pE->pList->nExpr; j++){
        sqliteExprCode(pParse, pE->pList->a[j].pExpr);
      }
      switch( pE->iColumn ){
        case FN_Min:      op = OP_Min;     break;
        case FN_Max:      op = OP_Max;     break;
        case FN_Avg:      op = OP_Add;     break;
        case FN_Sum:      op = OP_Add;     break;
        case FN_Unknown:  op = OP_AggFunc; break;
      }
      if( op!=OP_AggFunc ){
        sqliteVdbeAddOp(v, OP_AggGet, 0, i);
        sqliteVdbeAddOp(v, op, 0, 0);
        sqliteVdbeAddOp(v, OP_AggSet, 0, i);
      }else{
        sqliteVdbeAddOp(v, OP_Integer, i, 0);
        sqliteVdbeAddOp(v, OP_AggFunc, 0, pE->pList->nExpr);
        assert( pParse->aAgg[i].pUser!=0 );
        assert( pParse->aAgg[i].pUser->xStep!=0 );
        sqliteVdbeChangeP3(v, -1, (char*)pParse->aAgg[i].pUser, P3_POINTER);
      }
    }
  }

  /* End the database scan loop.
  */
  sqliteWhereEnd(pWInfo);

/*
** 2001 September 15
**
** 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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.95 2002/02/27 19:00:22 drh Exp $
*/
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
#include <stdio.h>

/*
** A convenience macro that returns the number of elements in
** an array.
*/
#define ArraySize(X)    (sizeof(X)/sizeof(X[0]))

/*
** Integer identifiers for built-in SQL functions.
*/
#define FN_Unknown    0      /* Not a built-in.  Might be user defined */
#define FN_Count      1
#define FN_Min        2
#define FN_Max        3
#define FN_Sum        4
#define FN_Avg        5
#define FN_Fcnt       6
#define FN_Length     7
#define FN_Substr     8
#define FN_Abs        9
#define FN_Round      10

/*
** Forward references to structures
*/
typedef struct Column Column;
typedef struct Table Table;
typedef struct Index Index;
typedef struct Instruction Instruction;
typedef struct Expr Expr;
typedef struct ExprList ExprList;
typedef struct Parse Parse;
typedef struct Token Token;
typedef struct IdList IdList;
typedef struct WhereInfo WhereInfo;
typedef struct WhereLevel WhereLevel;
typedef struct Select Select;
typedef struct AggExpr AggExpr;
typedef struct UserFunc UserFunc;

/*
** Each database is an instance of the following structure
*/
struct sqlite {
  Btree *pBe;                   /* The B*Tree backend */
  Btree *pBeTemp;               /* Backend for session temporary tables */
  int flags;                    /* Miscellanous flags. See below */
  int file_format;              /* What file format version is this database? */
  int schema_cookie;            /* Magic number that changes with the schema */
  int next_cookie;              /* Value of schema_cookie after commit */
  int nTable;                   /* Number of tables in the database */
  void *pBusyArg;               /* 1st Argument to the busy callback */
  int (*xBusyCallback)(void *,const char*,int);  /* The busy callback */
  Hash tblHash;                 /* All tables indexed by name */
  Hash idxHash;                 /* All (named) indices indexed by name */
  Hash tblDrop;                 /* Uncommitted DROP TABLEs */
  Hash idxDrop;                 /* Uncommitted DROP INDEXs */
  Hash userFunc;                /* User defined functions */
  int lastRowid;                /* ROWID of most recent insert */
  int priorNewRowid;            /* Last randomly generated ROWID */
  int onError;                  /* Default conflict algorithm */
};

/*
** Possible values for the sqlite.flags.

                                          /*   DELETE, or UPDATE and return */
                                          /*   the count using a callback. */
#define SQLITE_NullCallback   0x00000080  /* Invoke the callback once if the */
                                          /*   result set is empty */
#define SQLITE_ResultDetails  0x00000100  /* Details added to result set */

/*
** Each user-defined function is defined by an instance of the following
** structure.  A pointer to this structure is stored in the sqlite.userFunc
** hash table.  When multiple functions have the same name, the hash table
** points to a linked list of these structures.
*/
struct UserFunc {
  void (*xFunc)(sqlite_func*,int,const char**);   /* Regular function */
  void *(*xStep)(sqlite_func*,int,const char**);  /* Aggregate function step */
  void (*xFinalize)(sqlite_func*);           /* Aggregate function finializer */
  int nArg;                                  /* Number of arguments */
  void *pUserData;                           /* User data parameter */
  UserFunc *pNext;                           /* Next function with same name */
};

/*
** information about each column of an SQL table is held in an instance
** of this structure.
*/
struct Column {

** up.  Do not try to delete the expression attached to AggExpr.pExpr.
**
** If AggExpr.pExpr==0, that means the expression is "count(*)".
*/
struct AggExpr {
  int isAgg;        /* if TRUE contains an aggregate function */
  Expr *pExpr;      /* The expression */
  UserFunc *pUser;  /* User-defined aggregate function */
};

/*
** An SQL parser context.  A copy of this structure is passed through
** the parser and down into all the parser action routine in order to
** carry around information that is global to the entire parse.
*/

  int newTnum;         /* Table number to use when reparsing CREATE TABLEs */
  int nErr;            /* Number of errors seen */
  int nTab;            /* Number of previously allocated cursors */
  int nMem;            /* Number of memory cells used so far */
  int nSet;            /* Number of sets used so far */
  int nAgg;            /* Number of aggregate expressions */
  AggExpr *aAgg;       /* An array of aggregate expressions */
  int iAggCount;       /* Index of the count(*) aggregate in aAgg[] */
  int useAgg;          /* If true, extract field values from the aggregator
                       ** while generating expressions.  Normally false */
  int schemaVerified;  /* True if an OP_VerifySchema has been coded someplace
                       ** other than after an OP_Transaction */
};

/*

void sqliteExprMoveStrings(Expr*, int);
void sqliteExprListMoveStrings(ExprList*, int);
void sqliteSelectMoveStrings(Select*, int);
Expr *sqliteExprDup(Expr*);
ExprList *sqliteExprListDup(ExprList*);
IdList *sqliteIdListDup(IdList*);
Select *sqliteSelectDup(Select*);
UserFunc *sqliteFindUserFunction(sqlite*,const char*,int,int,int);
void sqliteRegisterBuildinFunctions(sqlite*);

**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.38 2002/02/27 01:47:12 drh Exp $
*/
#include "sqliteInt.h"
#include <stdarg.h>
#include <ctype.h>

/*
** If malloc() ever fails, this global variable gets set to 1.

**
** This is NOT the comparison function used for sorting.  The sort
** order is a little bit different.  See sqliteSortCompare below
** for additional information.
*/
int sqliteCompare(const char *atext, const char *btext){
  int result;






  int isNumA = isNum(atext);
  int isNumB = isNum(btext);
  if( isNumA ){
    if( !isNumB ){
      result = -1;
    }else{
      double rA, rB;
      rA = atof(atext);
      rB = atof(btext);

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.125 2002/02/27 19:50:59 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_MoveTo or the OP_Next opcode.  The test

#define STK_Int       0x0004   /* Value is an integer */
#define STK_Real      0x0008   /* Value is a real number */
#define STK_Dyn       0x0010   /* Need to call sqliteFree() on zStack[*] */
#define STK_Static    0x0020   /* zStack[] points to a static string */

/* The following STK_ value appears only in AggElem.aMem.s.flag fields.
** It indicates that the corresponding AggElem.aMem.z points to a
** user-defined aggregate context that needs to be finalized.
*/
#define STK_AggCtx    0x0040   /* zStack[] points to an agg function context */

/*
** The "context" argument for a user-defined function.  A pointer to an
** instance of this structure is the first argument to the routines used
** implement user-defined SQL functions.
**
** There is a typedef for this structure in sqlite.h.  So all routines,
** even the public interface to SQLite, can use a pointer to this structure.
** But this file is the only place where the internal details of this
** structure are known.
**
** This structure is defined inside of vdbe.c because it uses substructures
** (Stack) which are only defined there.
*/
struct sqlite_func {
  UserFunc *pFunc;  /* Pointer to function information.  MUST BE FIRST */
  Stack s;          /* Small strings, ints, and double values go here */
  char *z;          /* Space for holding dynamic string results */
  void *pAgg;       /* Aggregate context */
  u8 isError;       /* Set to true for an error */
  u8 isStep;        /* Current in the step function */
  int cnt;          /* Number of times that the step function has been called */
};

typedef struct Agg Agg;
typedef struct AggElem AggElem;
struct Agg {
  int nMem;            /* Number of values stored in each AggElem */
  AggElem *pCurrent;   /* The AggElem currently in focus */
  HashElem *pSearch;   /* The hash element for pCurrent */
  Hash hash;           /* Hash table of all aggregate elements */
  UserFunc **apFunc;   /* Information about user-defined aggregate functions */
};
struct AggElem {
  char *zKey;          /* The key to this AggElem */
  int nKey;            /* Number of bytes in the key, including '\0' at end */
  Mem aMem[1];         /* The values for this AggElem */
};

    }
  }
  while( j>0 && isspace(z[j-1]) ){ j--; }
  z[j] = 0;
}

/*
** The following group or routines are employed by user-defined functions
** to return their results.
**
** The sqlite_set_result_string() routine can be used to return a string
** value or to return a NULL.  To return a NULL, pass in NULL for zResult.
** A copy is made of the string before this routine returns so it is safe
** to pass in a ephemeral string.
**

      p->pAgg = sqliteMalloc( nByte );
    }
  }
  return p->pAgg;
}

/*
** Return the number of times the Step function of a user-defined 
** aggregate has been called.
**
** This routine is defined here in vdbe.c because it depends on knowing
** the internals of the sqlite_func structure which is only defined in that
** one source file.
*/
int sqlite_aggregate_count(sqlite_func *p){
  assert( p && p->pFunc && p->pFunc->xStep );
  return p->cnt;
}

/*
** Reset an Agg structure.  Delete all its contents. 
**
** For user-defined aggregate functions, if the step function has been
** called, make sure the finalizer function has also been called.  The
** finalizer might need to free memory that was allocated as part of its
** private context.  If the finalizer has not been called yet, call it
** now.
*/
static void AggReset(Agg *pAgg){
  int i;

  "Subtract",          "Multiply",          "Divide",            "Remainder",
  "BitAnd",            "BitOr",             "BitNot",            "ShiftLeft",
  "ShiftRight",        "AbsValue",          "Precision",         "Min",
  "Max",               "Like",              "Glob",              "Eq",
  "Ne",                "Lt",                "Le",                "Gt",
  "Ge",                "IsNull",            "NotNull",           "Negative",
  "And",               "Or",                "Not",               "Concat",
  "Noop",              "Strlen",            "Substr",            "UserFunc",
  "Limit",           
};

/*
** Given the name of an opcode, return its number.  Return 0 if
** there is no match.
**

  }else{
    Release(p, tos);
  }
  p->tos = nos;
  break;
}

/* Opcode: UserFunc P1 * P3
**
** Invoke a user function (P3 is a pointer to a UserFunc structure that
** defines the function) with P1 string arguments taken from the stack.
** Pop all arguments from the stack and push back the result.
**
** See also: AggFunc
*/
case OP_UserFunc: {
  int n, i;
  sqlite_func ctx;

  n = pOp->p1;
  VERIFY( if( n<=0 ) goto bad_instruction; )
  VERIFY( if( p->tos+1<n ) goto not_enough_stack; )
  for(i=p->tos-n+1; i<=p->tos; i++){
    if( (aStack[i].flags & STK_Null)==0 ){
      if( Stringify(p, i) ) goto no_mem;
    }
  }
  ctx.pFunc = (UserFunc*)pOp->p3;
  ctx.s.flags = STK_Null;
  ctx.z = 0;
  ctx.isError = 0;
  ctx.isStep = 0;
  (*ctx.pFunc->xFunc)(&ctx, n, (const char**)&zStack[p->tos-n+1]);
  PopStack(p, n);
  VERIFY( NeedStack(p, p->tos+1); )

  p->agg.nMem = pOp->p2;
  p->agg.apFunc = sqliteMalloc( p->agg.nMem*sizeof(p->agg.apFunc[0]) );
  break;
}

/* Opcode: AggInit * P2 P3
**
** Initialize the function parameters for a user-defined aggregate function.
** The user-defined aggregate will operate out of aggregate column P2.
** P3 is a pointer to the UserFunc structure for the function.
*/
case OP_AggInit: {
  int i = pOp->p2;
  VERIFY( if( i<0 || i>=p->agg.nMem ) goto bad_instruction; )
  p->agg.apFunc[i] = (UserFunc*)pOp->p3;
  break;
}

/* Opcode: AggFunc * P2 P3
**
** Execute the step function for a user-defined aggregate.  The
** function has P2 arguments.  P3 is a pointer to the UserFunc
** structure that specifies the user-defined function.
**
** The top of the stack must be an integer which is the index of
** the aggregate column that corresponds to this aggregate function.
** Ideally, this index would be another parameter, but there are
** no free parameters left.  The integer is popped from the stack.
*/
case OP_AggFunc: {

  for(i=p->tos-n; i<p->tos; i++){
    if( (aStack[i].flags & STK_Null)==0 ){
      if( Stringify(p, i) ) goto no_mem;
    }
  }
  i = aStack[p->tos].i;
  VERIFY( if( i<0 || i>=p->agg.nMem ) goto bad_instruction; )
  ctx.pFunc = (UserFunc*)pOp->p3;
  pMem = &p->agg.pCurrent->aMem[i];
  ctx.z = pMem->s.z;
  ctx.pAgg = pMem->z;
  ctx.cnt = ++pMem->s.i;
  ctx.isError = 0;
  ctx.isStep = 1;
  (ctx.pFunc->xStep)(&ctx, n, (const char**)&zStack[p->tos-n]);

    int i;
    sqlite_func ctx;
    Mem *aMem;
    int nErr = 0;
    p->agg.pCurrent = sqliteHashData(p->agg.pSearch);
    aMem = p->agg.pCurrent->aMem;
    for(i=0; i<p->agg.nMem; i++){

      if( p->agg.apFunc[i]==0 ) continue;
      if( p->agg.apFunc[i]->xFinalize==0 ) continue;
      if( (aMem[i].s.flags & STK_AggCtx)==0 ) continue;
      ctx.s.flags = STK_Null;
      ctx.z = 0;
      ctx.pAgg = (void*)aMem[i].z;

      ctx.cnt = aMem[i].s.i;
      ctx.isStep = 0;
      ctx.pFunc = p->agg.apFunc[i];
      (*p->agg.apFunc[i]->xFinalize)(&ctx);

      sqliteFree( aMem[i].z );

      aMem[i].s = ctx.s;
      aMem[i].z = ctx.z;
      if( (aMem[i].s.flags & STK_Str) &&
              (aMem[i].s.flags & (STK_Dyn|STK_Static))==0 ){
        aMem[i].z = aMem[i].s.z;
      }
      nErr += ctx.isError;

*************************************************************************
** Header file for the Virtual DataBase Engine (VDBE)
**
** This header defines the interface to the virtual database engine
** or VDBE.  The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
**
** $Id: vdbe.h,v 1.47 2002/02/27 19:00:22 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
#include <stdio.h>

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines

#define OP_And               113
#define OP_Or                114
#define OP_Not               115
#define OP_Concat            116
#define OP_Noop              117
#define OP_Strlen            118
#define OP_Substr            119
#define OP_UserFunc          120

#define OP_Limit             121

#define OP_MAX               121

/*
** Prototypes for the VDBE interface.  See comments on the implementation