SQLite

  }else{
    sqlite3_result_text(context, x.z, (int)x.nUsed, sqlite3_free);
  }
}
/* End of the eval() implementation
******************************************************************************/

/******************************************************************************
** The generate_series(START,END,STEP) eponymous table-valued function.
**
** This code is copy/pasted from ext/misc/series.c in the SQLite source tree.
*/
/* series_cursor is a subclass of sqlite3_vtab_cursor which will
** serve as the underlying representation of a cursor that scans
** over rows of the result
*/
typedef struct series_cursor series_cursor;
struct series_cursor {
  sqlite3_vtab_cursor base;  /* Base class - must be first */
  int isDesc;                /* True to count down rather than up */
  sqlite3_int64 iRowid;      /* The rowid */
  sqlite3_int64 iValue;      /* Current value ("value") */
  sqlite3_int64 mnValue;     /* Mimimum value ("start") */
  sqlite3_int64 mxValue;     /* Maximum value ("stop") */
  sqlite3_int64 iStep;       /* Increment ("step") */
};

/*
** The seriesConnect() method is invoked to create a new
** series_vtab that describes the generate_series virtual table.
**
** Think of this routine as the constructor for series_vtab objects.
**
** All this routine needs to do is:
**
**    (1) Allocate the series_vtab object and initialize all fields.
**
**    (2) Tell SQLite (via the sqlite3_declare_vtab() interface) what the
**        result set of queries against generate_series will look like.
*/
static int seriesConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  sqlite3_vtab *pNew;
  int rc;

/* Column numbers */
#define SERIES_COLUMN_VALUE 0
#define SERIES_COLUMN_START 1
#define SERIES_COLUMN_STOP  2
#define SERIES_COLUMN_STEP  3

  rc = sqlite3_declare_vtab(db,
     "CREATE TABLE x(value,start hidden,stop hidden,step hidden)");
  if( rc==SQLITE_OK ){
    pNew = *ppVtab = sqlite3_malloc( sizeof(*pNew) );
    if( pNew==0 ) return SQLITE_NOMEM;
    memset(pNew, 0, sizeof(*pNew));
  }
  return rc;
}

/*
** This method is the destructor for series_cursor objects.
*/
static int seriesDisconnect(sqlite3_vtab *pVtab){
  sqlite3_free(pVtab);
  return SQLITE_OK;
}

/*
** Constructor for a new series_cursor object.
*/
static int seriesOpen(sqlite3_vtab *p, sqlite3_vtab_cursor **ppCursor){
  series_cursor *pCur;
  pCur = sqlite3_malloc( sizeof(*pCur) );
  if( pCur==0 ) return SQLITE_NOMEM;
  memset(pCur, 0, sizeof(*pCur));
  *ppCursor = &pCur->base;
  return SQLITE_OK;
}

/*
** Destructor for a series_cursor.
*/
static int seriesClose(sqlite3_vtab_cursor *cur){
  sqlite3_free(cur);
  return SQLITE_OK;
}


/*
** Advance a series_cursor to its next row of output.
*/
static int seriesNext(sqlite3_vtab_cursor *cur){
  series_cursor *pCur = (series_cursor*)cur;
  if( pCur->isDesc ){
    pCur->iValue -= pCur->iStep;
  }else{
    pCur->iValue += pCur->iStep;
  }
  pCur->iRowid++;
  return SQLITE_OK;
}

/*
** Return values of columns for the row at which the series_cursor
** is currently pointing.
*/
static int seriesColumn(
  sqlite3_vtab_cursor *cur,   /* The cursor */
  sqlite3_context *ctx,       /* First argument to sqlite3_result_...() */
  int i                       /* Which column to return */
){
  series_cursor *pCur = (series_cursor*)cur;
  sqlite3_int64 x = 0;
  switch( i ){
    case SERIES_COLUMN_START:  x = pCur->mnValue; break;
    case SERIES_COLUMN_STOP:   x = pCur->mxValue; break;
    case SERIES_COLUMN_STEP:   x = pCur->iStep;   break;
    default:                   x = pCur->iValue;  break;
  }
  sqlite3_result_int64(ctx, x);
  return SQLITE_OK;
}

/*
** Return the rowid for the current row.  In this implementation, the
** rowid is the same as the output value.
*/
static int seriesRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  series_cursor *pCur = (series_cursor*)cur;
  *pRowid = pCur->iRowid;
  return SQLITE_OK;
}

/*
** Return TRUE if the cursor has been moved off of the last
** row of output.
*/
static int seriesEof(sqlite3_vtab_cursor *cur){
  series_cursor *pCur = (series_cursor*)cur;
  if( pCur->isDesc ){
    return pCur->iValue < pCur->mnValue;
  }else{
    return pCur->iValue > pCur->mxValue;
  }
}

/* True to cause run-time checking of the start=, stop=, and/or step= 
** parameters.  The only reason to do this is for testing the
** constraint checking logic for virtual tables in the SQLite core.
*/
#ifndef SQLITE_SERIES_CONSTRAINT_VERIFY
# define SQLITE_SERIES_CONSTRAINT_VERIFY 0
#endif

/*
** This method is called to "rewind" the series_cursor object back
** to the first row of output.  This method is always called at least
** once prior to any call to seriesColumn() or seriesRowid() or 
** seriesEof().
**
** The query plan selected by seriesBestIndex is passed in the idxNum
** parameter.  (idxStr is not used in this implementation.)  idxNum
** is a bitmask showing which constraints are available:
**
**    1:    start=VALUE
**    2:    stop=VALUE
**    4:    step=VALUE
**
** Also, if bit 8 is set, that means that the series should be output
** in descending order rather than in ascending order.
**
** This routine should initialize the cursor and position it so that it
** is pointing at the first row, or pointing off the end of the table
** (so that seriesEof() will return true) if the table is empty.
*/
static int seriesFilter(
  sqlite3_vtab_cursor *pVtabCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  series_cursor *pCur = (series_cursor *)pVtabCursor;
  int i = 0;
  if( idxNum & 1 ){
    pCur->mnValue = sqlite3_value_int64(argv[i++]);
  }else{
    pCur->mnValue = 0;
  }
  if( idxNum & 2 ){
    pCur->mxValue = sqlite3_value_int64(argv[i++]);
  }else{
    pCur->mxValue = 0xffffffff;
  }
  if( idxNum & 4 ){
    pCur->iStep = sqlite3_value_int64(argv[i++]);
    if( pCur->iStep<1 ) pCur->iStep = 1;
  }else{
    pCur->iStep = 1;
  }
  if( idxNum & 8 ){
    pCur->isDesc = 1;
    pCur->iValue = pCur->mxValue;
    if( pCur->iStep>0 ){
      pCur->iValue -= (pCur->mxValue - pCur->mnValue)%pCur->iStep;
    }
  }else{
    pCur->isDesc = 0;
    pCur->iValue = pCur->mnValue;
  }
  pCur->iRowid = 1;
  return SQLITE_OK;
}

/*
** SQLite will invoke this method one or more times while planning a query
** that uses the generate_series virtual table.  This routine needs to create
** a query plan for each invocation and compute an estimated cost for that
** plan.
**
** In this implementation idxNum is used to represent the
** query plan.  idxStr is unused.
**
** The query plan is represented by bits in idxNum:
**
**  (1)  start = $value  -- constraint exists
**  (2)  stop = $value   -- constraint exists
**  (4)  step = $value   -- constraint exists
**  (8)  output in descending order
*/
static int seriesBestIndex(
  sqlite3_vtab *tab,
  sqlite3_index_info *pIdxInfo
){
  int i;                 /* Loop over constraints */
  int idxNum = 0;        /* The query plan bitmask */
  int startIdx = -1;     /* Index of the start= constraint, or -1 if none */
  int stopIdx = -1;      /* Index of the stop= constraint, or -1 if none */
  int stepIdx = -1;      /* Index of the step= constraint, or -1 if none */
  int nArg = 0;          /* Number of arguments that seriesFilter() expects */

  const struct sqlite3_index_constraint *pConstraint;
  pConstraint = pIdxInfo->aConstraint;
  for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
    if( pConstraint->usable==0 ) continue;
    if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
    switch( pConstraint->iColumn ){
      case SERIES_COLUMN_START:
        startIdx = i;
        idxNum |= 1;
        break;
      case SERIES_COLUMN_STOP:
        stopIdx = i;
        idxNum |= 2;
        break;
      case SERIES_COLUMN_STEP:
        stepIdx = i;
        idxNum |= 4;
        break;
    }
  }
  if( startIdx>=0 ){
    pIdxInfo->aConstraintUsage[startIdx].argvIndex = ++nArg;
    pIdxInfo->aConstraintUsage[startIdx].omit= !SQLITE_SERIES_CONSTRAINT_VERIFY;
  }
  if( stopIdx>=0 ){
    pIdxInfo->aConstraintUsage[stopIdx].argvIndex = ++nArg;
    pIdxInfo->aConstraintUsage[stopIdx].omit = !SQLITE_SERIES_CONSTRAINT_VERIFY;
  }
  if( stepIdx>=0 ){
    pIdxInfo->aConstraintUsage[stepIdx].argvIndex = ++nArg;
    pIdxInfo->aConstraintUsage[stepIdx].omit = !SQLITE_SERIES_CONSTRAINT_VERIFY;
  }
  if( (idxNum & 3)==3 ){
    /* Both start= and stop= boundaries are available.  This is the 
    ** the preferred case */
    pIdxInfo->estimatedCost = (double)(2 - ((idxNum&4)!=0));
    pIdxInfo->estimatedRows = 1000;
    if( pIdxInfo->nOrderBy==1 ){
      if( pIdxInfo->aOrderBy[0].desc ) idxNum |= 8;
      pIdxInfo->orderByConsumed = 1;
    }
  }else{
    /* If either boundary is missing, we have to generate a huge span
    ** of numbers.  Make this case very expensive so that the query
    ** planner will work hard to avoid it. */
    pIdxInfo->estimatedCost = (double)2147483647;
    pIdxInfo->estimatedRows = 2147483647;
  }
  pIdxInfo->idxNum = idxNum;
  return SQLITE_OK;
}

/*
** This following structure defines all the methods for the 
** generate_series virtual table.
*/
static sqlite3_module seriesModule = {
  0,                         /* iVersion */
  0,                         /* xCreate */
  seriesConnect,             /* xConnect */
  seriesBestIndex,           /* xBestIndex */
  seriesDisconnect,          /* xDisconnect */
  0,                         /* xDestroy */
  seriesOpen,                /* xOpen - open a cursor */
  seriesClose,               /* xClose - close a cursor */
  seriesFilter,              /* xFilter - configure scan constraints */
  seriesNext,                /* xNext - advance a cursor */
  seriesEof,                 /* xEof - check for end of scan */
  seriesColumn,              /* xColumn - read data */
  seriesRowid,               /* xRowid - read data */
  0,                         /* xUpdate */
  0,                         /* xBegin */
  0,                         /* xSync */
  0,                         /* xCommit */
  0,                         /* xRollback */
  0,                         /* xFindMethod */
  0,                         /* xRename */
};
/* END the generate_series(START,END,STEP) implementation
*********************************************************************************/

/*
** Print sketchy documentation for this utility program
*/
static void showHelp(void){
  printf("Usage: %s [options] ?FILE...?\n", g.zArgv0);
  printf(
"Read SQL text from FILE... (or from standard input if FILE... is omitted)\n"

          if( rc!=SQLITE_OK ) abendError("lookaside configuration filed: %d", rc);
        }
    #ifndef SQLITE_OMIT_TRACE
        sqlite3_trace(db, verboseFlag ? traceCallback : traceNoop, 0);
    #endif
        sqlite3_create_function(db, "eval", 1, SQLITE_UTF8, 0, sqlEvalFunc, 0, 0);
        sqlite3_create_function(db, "eval", 2, SQLITE_UTF8, 0, sqlEvalFunc, 0, 0);
        sqlite3_create_module(db, "generate_series", &seriesModule, 0);
        sqlite3_limit(db, SQLITE_LIMIT_LENGTH, 1000000);
        if( zEncoding ) sqlexec(db, "PRAGMA encoding=%s", zEncoding);
        if( pageSize ) sqlexec(db, "PRAGMA pagesize=%d", pageSize);
        if( doAutovac ) sqlexec(db, "PRAGMA auto_vacuum=FULL");
        iStart = timeOfDay();
        g.bOomEnable = 1;
        if( verboseFlag ){