**    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 1.222 2005/08/30 00:54:02 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**
................................................................................
  pNew->pOrderBy = sqlite3ExprListDup(p->pOrderBy);
  pNew->op = p->op;
  pNew->pPrior = sqlite3SelectDup(p->pPrior);
  pNew->pLimit = sqlite3ExprDup(p->pLimit);
  pNew->pOffset = sqlite3ExprDup(p->pOffset);
  pNew->iLimit = -1;
  pNew->iOffset = -1;
  pNew->ppOpenVirtual = 0;
  pNew->isResolved = p->isResolved;
  pNew->isAgg = p->isAgg;




  return pNew;
}
#else
Select *sqlite3SelectDup(Select *p){
  assert( p==0 );
  return 0;
}

**    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 1.223 2005/09/01 03:07:44 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**
................................................................................
  pNew->pOrderBy = sqlite3ExprListDup(p->pOrderBy);
  pNew->op = p->op;
  pNew->pPrior = sqlite3SelectDup(p->pPrior);
  pNew->pLimit = sqlite3ExprDup(p->pLimit);
  pNew->pOffset = sqlite3ExprDup(p->pOffset);
  pNew->iLimit = -1;
  pNew->iOffset = -1;

  pNew->isResolved = p->isResolved;
  pNew->isAgg = p->isAgg;
  pNew->pRightmost = 0;
  pNew->addrOpenVirt[0] = -1;
  pNew->addrOpenVirt[1] = -1;
  pNew->addrOpenVirt[2] = -1;
  return pNew;
}
#else
Select *sqlite3SelectDup(Select *p){
  assert( p==0 );
  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 1.257 2005/08/31 18:20:00 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.
................................................................................
    pNew->pOrderBy = pOrderBy;
    pNew->isDistinct = isDistinct;
    pNew->op = TK_SELECT;
    pNew->pLimit = pLimit;
    pNew->pOffset = pOffset;
    pNew->iLimit = -1;
    pNew->iOffset = -1;



  }
  return pNew;
}

/*
** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
** type of join.  Return an integer constant that expresses that type
................................................................................

/*
** Insert code into "v" that will push the record on the top of the
** stack into the sorter.
*/
static void pushOntoSorter(Parse *pParse, Vdbe *v, ExprList *pOrderBy){
  sqlite3ExprCodeExprList(pParse, pOrderBy);

  sqlite3VdbeAddOp(v, OP_MakeRecord, pOrderBy->nExpr, 0);
  sqlite3VdbeAddOp(v, OP_SortInsert, 0, 0);
}

/*
** Add code to implement the OFFSET and LIMIT
*/
static void codeLimiter(
  Vdbe *v,          /* Generate code into this VM */
................................................................................
  }
  return 0;
}

/*
** Given an expression list, generate a KeyInfo structure that records
** the collating sequence for each expression in that expression list.






**
** Space to hold the KeyInfo structure is obtain from malloc.  The calling
** function is responsible for seeing that this structure is eventually
** freed.  Add the KeyInfo structure to the P3 field of an opcode using
** P3_KEYINFO_HANDOFF is the usual way of dealing with this.
*/
static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){
................................................................................
  Parse *pParse,   /* The parsing context */
  Select *p,       /* The SELECT statement */
  Vdbe *v,         /* Generate code into this VDBE */
  int nColumn,     /* Number of columns of data */
  int eDest,       /* Write the sorted results here */
  int iParm        /* Optional parameter associated with eDest */
){
  int end1 = sqlite3VdbeMakeLabel(v);
  int end2 = sqlite3VdbeMakeLabel(v);
  int addr;
  KeyInfo *pInfo;


  if( eDest==SRT_Sorter ) return;
  pInfo = keyInfoFromExprList(pParse, p->pOrderBy);
  if( pInfo==0 ) return;
  sqlite3VdbeOp3(v, OP_Sort, 0, 0, (char*)pInfo, P3_KEYINFO_HANDOFF);
  addr = sqlite3VdbeAddOp(v, OP_SortNext, 0, end1);
  codeLimiter(v, p, addr, end2, 1);

  switch( eDest ){
    case SRT_Table:
    case SRT_TempTable: {
      sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
      sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
      sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);
      break;
................................................................................
      sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
      break;
    }
    case SRT_Exists:
    case SRT_Mem: {
      assert( nColumn==1 );
      sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
      sqlite3VdbeAddOp(v, OP_Goto, 0, end1);
      break;
    }
#endif
    case SRT_Callback:
    case SRT_Subroutine: {
      int i;
      sqlite3VdbeAddOp(v, OP_Integer, p->pEList->nExpr, 0);
................................................................................
      break;
    }
    default: {
      /* Do nothing */
      break;
    }
  }
  sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
  sqlite3VdbeResolveLabel(v, end2);
  sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
  sqlite3VdbeResolveLabel(v, end1);
  sqlite3VdbeAddOp(v, OP_SortReset, 0, 0);
}

/*
** Return a pointer to a string containing the 'declaration type' of the
** expression pExpr. The string may be treated as static by the caller.
**
** If the declaration type is the exact datatype definition extracted from
................................................................................
    sqlite3VdbeAddOp(v, OP_MemStore, iMem, 1);
    VdbeComment((v, "# OFFSET counter"));
    p->iOffset = iMem;
  }
}

/*
** Generate VDBE instructions that will open a transient table that
** will be used for an index or to store keyed results for a compound
** select.  In other words, open a transient table that needs a
** KeyInfo structure.  The number of columns in the KeyInfo is determined
** by the result set of the SELECT statement in the second argument.
**
** Specifically, this routine is called to open an index table for
** DISTINCT, UNION, INTERSECT and EXCEPT select statements (but not 
** UNION ALL).
**
** The value returned is the address of the OP_OpenVirtual instruction.
*/
static int openVirtualIndex(Parse *pParse, Select *p, int iTab){
  KeyInfo *pKeyInfo;
  Vdbe *v = pParse->pVdbe;

  int addr;







  if( prepSelectStmt(pParse, p) ){
    return 0;
  }
  pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
  if( pKeyInfo==0 ) return 0;
  addr = sqlite3VdbeOp3(v, OP_OpenVirtual, iTab, 0, 
                        (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
  return addr;
}

#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Add the address "addr" to the set of all OpenVirtual opcode addresses
** that are being accumulated in p->ppOpenVirtual.
*/
static int multiSelectOpenVirtualAddr(Select *p, int addr){
  IdList *pList = *p->ppOpenVirtual = sqlite3IdListAppend(*p->ppOpenVirtual, 0);
  if( pList==0 ){
    return SQLITE_NOMEM;
  }
  pList->a[pList->nId-1].idx = addr;
  return SQLITE_OK;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */

#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Return the appropriate collating sequence for the iCol-th column of
** the result set for the compound-select statement "p".  Return NULL if
** the column has no default collating sequence.
**
** The collating sequence for the compound select is taken from the
................................................................................
  int eDest,            /* \___  Store query results as specified */
  int iParm,            /* /     by these two parameters.         */
  char *aff             /* If eDest is SRT_Union, the affinity string */
){
  int rc = SQLITE_OK;   /* Success code from a subroutine */
  Select *pPrior;       /* Another SELECT immediately to our left */
  Vdbe *v;              /* Generate code to this VDBE */
  IdList *pOpenVirtual = 0;/* OP_OpenVirtual opcodes that need a KeyInfo */
  int aAddr[5];         /* Addresses of SetNumColumns operators */
  int nAddr = 0;        /* Number used */
  int nCol;             /* Number of columns in the result set */




  /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs.  Only
  ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
  */
  if( p==0 || p->pPrior==0 ){
    rc = 1;
    goto multi_select_end;
  }
  pPrior = p->pPrior;


  if( pPrior->pOrderBy ){
    sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before",
      selectOpName(p->op));
    rc = 1;
    goto multi_select_end;
  }
  if( pPrior->pLimit ){
................................................................................
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ){
    rc = 1;
    goto multi_select_end;
  }

  /* If *p this is the right-most select statement, then initialize
  ** p->ppOpenVirtual to point to pOpenVirtual.  If *p is not the right most
  ** statement then p->ppOpenVirtual will have already been initialized
  ** by a prior call to this same procedure.  Pass along the pOpenVirtual
  ** pointer to pPrior, the next statement to our left.
  */
  if( p->ppOpenVirtual==0 ){
    p->ppOpenVirtual = &pOpenVirtual;
  }
  pPrior->ppOpenVirtual = p->ppOpenVirtual;

  /* Create the destination temporary table if necessary
  */
  if( eDest==SRT_TempTable ){
    assert( p->pEList );
    sqlite3VdbeAddOp(v, OP_OpenVirtual, iParm, 0);
    assert( nAddr==0 );
    aAddr[nAddr++] = sqlite3VdbeAddOp(v, OP_SetNumColumns, iParm, 0);
    eDest = SRT_Table;
  }

  /* Generate code for the left and right SELECT statements.
  */

  switch( p->op ){
    case TK_ALL: {
      if( p->pOrderBy==0 ){
        assert( !pPrior->pLimit );
        pPrior->pLimit = p->pLimit;
        pPrior->pOffset = p->pOffset;
        rc = sqlite3Select(pParse, pPrior, eDest, iParm, 0, 0, 0, aff);
        if( rc ){
          goto multi_select_end;
        }
................................................................................
    }
    case TK_EXCEPT:
    case TK_UNION: {
      int unionTab;    /* Cursor number of the temporary table holding result */
      int op = 0;      /* One of the SRT_ operations to apply to self */
      int priorOp;     /* The SRT_ operation to apply to prior selects */
      Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */
      ExprList *pOrderBy;     /* The ORDER BY clause for the right SELECT */
      int addr;

      priorOp = p->op==TK_ALL ? SRT_Table : SRT_Union;
      if( eDest==priorOp && p->pOrderBy==0 && !p->pLimit && !p->pOffset ){
        /* We can reuse a temporary table generated by a SELECT to our
        ** right.
        */
        unionTab = iParm;
      }else{
        /* We will need to create our own temporary table to hold the
        ** intermediate results.
        */
        unionTab = pParse->nTab++;
        if( p->pOrderBy 
        && matchOrderbyToColumn(pParse, p, p->pOrderBy, unionTab, 1) ){
          rc = 1;
          goto multi_select_end;
        }
        addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, unionTab, 0);
        if( p->op!=TK_ALL ){
          rc = multiSelectOpenVirtualAddr(p, addr);
          if( rc!=SQLITE_OK ){
            goto multi_select_end;
          }
        }
	assert( nAddr<sizeof(aAddr)/sizeof(aAddr[0]) );
        aAddr[nAddr++] = sqlite3VdbeAddOp(v, OP_SetNumColumns, unionTab, 0);

        assert( p->pEList );
      }

      /* Code the SELECT statements to our left
      */
      assert( !pPrior->pOrderBy );
      rc = sqlite3Select(pParse, pPrior, priorOp, unionTab, 0, 0, 0, aff);
................................................................................
      */
      switch( p->op ){
         case TK_EXCEPT:  op = SRT_Except;   break;
         case TK_UNION:   op = SRT_Union;    break;
         case TK_ALL:     op = SRT_Table;    break;
      }
      p->pPrior = 0;
      pOrderBy = p->pOrderBy;
      p->pOrderBy = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      pOffset = p->pOffset;
      p->pOffset = 0;
      rc = sqlite3Select(pParse, p, op, unionTab, 0, 0, 0, aff);
      p->pPrior = pPrior;
................................................................................
        }
        iBreak = sqlite3VdbeMakeLabel(v);
        iCont = sqlite3VdbeMakeLabel(v);
        sqlite3VdbeAddOp(v, OP_Rewind, unionTab, iBreak);
        computeLimitRegisters(pParse, p);
        iStart = sqlite3VdbeCurrentAddr(v);
        rc = selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
                             p->pOrderBy, -1, eDest, iParm, 
                             iCont, iBreak, 0);
        if( rc ){
          rc = 1;
          goto multi_select_end;
        }
        sqlite3VdbeResolveLabel(v, iCont);
        sqlite3VdbeAddOp(v, OP_Next, unionTab, iStart);
................................................................................

      /* INTERSECT is different from the others since it requires
      ** two temporary tables.  Hence it has its own case.  Begin
      ** by allocating the tables we will need.
      */
      tab1 = pParse->nTab++;
      tab2 = pParse->nTab++;
      if( p->pOrderBy && matchOrderbyToColumn(pParse,p,p->pOrderBy,tab1,1) ){
        rc = 1;
        goto multi_select_end;
      }


      addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, tab1, 0);
      rc = multiSelectOpenVirtualAddr(p, addr);
      if( rc!=SQLITE_OK ){
        goto multi_select_end;
      }
      assert( nAddr<sizeof(aAddr)/sizeof(aAddr[0]) );
      aAddr[nAddr++] = sqlite3VdbeAddOp(v, OP_SetNumColumns, tab1, 0);

      assert( p->pEList );

      /* Code the SELECTs to our left into temporary table "tab1".
      */
      rc = sqlite3Select(pParse, pPrior, SRT_Union, tab1, 0, 0, 0, aff);
      if( rc ){
        goto multi_select_end;
      }

      /* Code the current SELECT into temporary table "tab2"
      */
      addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, tab2, 0);
      rc = multiSelectOpenVirtualAddr(p, addr);
      if( rc!=SQLITE_OK ){
        goto multi_select_end;
      }
      assert( nAddr<sizeof(aAddr)/sizeof(aAddr[0]) );
      aAddr[nAddr++] = sqlite3VdbeAddOp(v, OP_SetNumColumns, tab2, 0);
      p->pPrior = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      pOffset = p->pOffset;
      p->pOffset = 0;
      rc = sqlite3Select(pParse, p, SRT_Union, tab2, 0, 0, 0, aff);
      p->pPrior = pPrior;
................................................................................
      iBreak = sqlite3VdbeMakeLabel(v);
      iCont = sqlite3VdbeMakeLabel(v);
      sqlite3VdbeAddOp(v, OP_Rewind, tab1, iBreak);
      computeLimitRegisters(pParse, p);
      iStart = sqlite3VdbeAddOp(v, OP_RowKey, tab1, 0);
      sqlite3VdbeAddOp(v, OP_NotFound, tab2, iCont);
      rc = selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
                             p->pOrderBy, -1, eDest, iParm, 
                             iCont, iBreak, 0);
      if( rc ){
        rc = 1;
        goto multi_select_end;
      }
      sqlite3VdbeResolveLabel(v, iCont);
      sqlite3VdbeAddOp(v, OP_Next, tab1, iStart);
................................................................................
    rc = 1;
    goto multi_select_end;
  }

  /* Set the number of columns in temporary tables
  */
  nCol = p->pEList->nExpr;
  while( nAddr>0 ){
    nAddr--;
    sqlite3VdbeChangeP2(v, aAddr[nAddr], nCol);
  }

  /* Compute collating sequences used by either the ORDER BY clause or
  ** by any temporary tables needed to implement the compound select.
  ** Attach the KeyInfo structure to all temporary tables.  Invoke the
  ** ORDER BY processing if there is an ORDER BY clause.
  **
  ** This section is run by the right-most SELECT statement only.
  ** SELECT statements to the left always skip this part.  The right-most
  ** SELECT might also skip this part if it has no ORDER BY clause and
  ** no temp tables are required.
  */
  if( p->pOrderBy || (pOpenVirtual && pOpenVirtual->nId>0) ){
    int i;                        /* Loop counter */
    KeyInfo *pKeyInfo;            /* Collating sequence for the result set */




    assert( p->ppOpenVirtual == &pOpenVirtual );

    pKeyInfo = sqliteMalloc(sizeof(*pKeyInfo)+nCol*sizeof(CollSeq*));
    if( !pKeyInfo ){
      rc = SQLITE_NOMEM;
      goto multi_select_end;
    }

    pKeyInfo->enc = pParse->db->enc;
    pKeyInfo->nField = nCol;

    for(i=0; i<nCol; i++){
      pKeyInfo->aColl[i] = multiSelectCollSeq(pParse, p, i);
      if( !pKeyInfo->aColl[i] ){
        pKeyInfo->aColl[i] = pParse->db->pDfltColl;
      }
    }

    for(i=0; pOpenVirtual && i<pOpenVirtual->nId; i++){
      int p3type = (i==0?P3_KEYINFO_HANDOFF:P3_KEYINFO);
      int addr = pOpenVirtual->a[i].idx;







      sqlite3VdbeChangeP3(v, addr, (char *)pKeyInfo, p3type);
    }


    if( p->pOrderBy ){
      struct ExprList_item *pOrderByTerm = p->pOrderBy->a;






      for(i=0; i<p->pOrderBy->nExpr; i++, pOrderByTerm++){
        Expr *pExpr = pOrderByTerm->pExpr;
        char *zName = pOrderByTerm->zName;
        assert( pExpr->op==TK_COLUMN && pExpr->iColumn<nCol );
        /* assert( !pExpr->pColl ); */
        if( zName ){
          pExpr->pColl = sqlite3LocateCollSeq(pParse, zName, -1);
        }else{
          pExpr->pColl = pKeyInfo->aColl[pExpr->iColumn];
        }
      }





      generateSortTail(pParse, p, v, p->pEList->nExpr, eDest, iParm);
    }

    if( !pOpenVirtual ){
      /* This happens for UNION ALL ... ORDER BY */
      sqliteFree(pKeyInfo);
    }
  }

multi_select_end:
  if( pOpenVirtual ){
    sqlite3IdListDelete(pOpenVirtual);
  }
  p->ppOpenVirtual = 0;
  return rc;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */

#ifndef SQLITE_OMIT_VIEW
/*
** Scan through the expression pExpr.  Replace every reference to
................................................................................
  if( sqlite3_malloc_failed || pParse->nErr || p==0 ) return 1;
  if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;

#ifndef SQLITE_OMIT_COMPOUND_SELECT
  /* If there is are a sequence of queries, do the earlier ones first.
  */
  if( p->pPrior ){






    return multiSelect(pParse, p, eDest, iParm, aff);
  }
#endif

  saveAggregateInfo(pParse, &sAggInfo);
  pOrderBy = p->pOrderBy;
  if( eDest==SRT_Union || eDest==SRT_Except || eDest==SRT_Discard ){
................................................................................
#endif

  /* If there is an ORDER BY clause, resolve any collation sequences
  ** names that have been explicitly specified.
  */
  if( pOrderBy ){
    struct ExprList_item *pTerm;


    for(i=0, pTerm=pOrderBy->a; i<pOrderBy->nExpr; i++, pTerm++){
      if( pTerm->zName ){
        pTerm->pExpr->pColl = sqlite3LocateCollSeq(pParse, pTerm->zName, -1);
      }
    }
    if( pParse->nErr ){
      goto select_end;
    }





  }

  /* Set the limiter.
  */
  computeLimitRegisters(pParse, p);

  /* If the output is destined for a temporary table, open that table.
  */
  if( eDest==SRT_TempTable ){
    sqlite3VdbeAddOp(v, OP_OpenVirtual, iParm, 0);
    sqlite3VdbeAddOp(v, OP_SetNumColumns, iParm, pEList->nExpr);
  }

  /* Do an analysis of aggregate expressions.
  */
  if( isAgg || pGroupBy ){
    NameContext sNC;
    memset(&sNC, 0, sizeof(sNC));
................................................................................
    sqlite3VdbeAddOp(v, eDest==SRT_Mem ? OP_Null : OP_Integer, 0, 0);
    sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
  }

  /* Open a virtual index to use for the distinct set.
  */
  if( isDistinct ){

    distinct = pParse->nTab++;
    openVirtualIndex(pParse, p, distinct);



  }else{
    distinct = -1;
  }

  /* Begin the database scan
  */
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,

**    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 1.258 2005/09/01 03:07:44 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.
................................................................................
    pNew->pOrderBy = pOrderBy;
    pNew->isDistinct = isDistinct;
    pNew->op = TK_SELECT;
    pNew->pLimit = pLimit;
    pNew->pOffset = pOffset;
    pNew->iLimit = -1;
    pNew->iOffset = -1;
    pNew->addrOpenVirt[0] = -1;
    pNew->addrOpenVirt[1] = -1;
    pNew->addrOpenVirt[2] = -1;
  }
  return pNew;
}

/*
** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
** type of join.  Return an integer constant that expresses that type
................................................................................

/*
** Insert code into "v" that will push the record on the top of the
** stack into the sorter.
*/
static void pushOntoSorter(Parse *pParse, Vdbe *v, ExprList *pOrderBy){
  sqlite3ExprCodeExprList(pParse, pOrderBy);
  sqlite3VdbeAddOp(v, OP_Pull, pOrderBy->nExpr, 0);
  sqlite3VdbeAddOp(v, OP_MakeRecord, pOrderBy->nExpr + 1, 0);
  sqlite3VdbeAddOp(v, OP_IdxInsert, pOrderBy->iTab, 0);
}

/*
** Add code to implement the OFFSET and LIMIT
*/
static void codeLimiter(
  Vdbe *v,          /* Generate code into this VM */
................................................................................
  }
  return 0;
}

/*
** Given an expression list, generate a KeyInfo structure that records
** the collating sequence for each expression in that expression list.
**
** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
** KeyInfo structure is appropriate for initializing a virtual index to
** implement that clause.  If the ExprList is the result set of a SELECT
** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtain from malloc.  The calling
** function is responsible for seeing that this structure is eventually
** freed.  Add the KeyInfo structure to the P3 field of an opcode using
** P3_KEYINFO_HANDOFF is the usual way of dealing with this.
*/
static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){
................................................................................
  Parse *pParse,   /* The parsing context */
  Select *p,       /* The SELECT statement */
  Vdbe *v,         /* Generate code into this VDBE */
  int nColumn,     /* Number of columns of data */
  int eDest,       /* Write the sorted results here */
  int iParm        /* Optional parameter associated with eDest */
){
  int brk = sqlite3VdbeMakeLabel(v);
  int cont = sqlite3VdbeMakeLabel(v);
  int addr;
  int iTab;
  ExprList *pOrderBy = p->pOrderBy;

  if( eDest==SRT_Sorter ) return;

  iTab = pOrderBy->iTab;

  addr = 1 + sqlite3VdbeAddOp(v, OP_Sort, iTab, brk);
  codeLimiter(v, p, cont, brk, 0);
  sqlite3VdbeAddOp(v, OP_Column, iTab, pOrderBy->nExpr);
  switch( eDest ){
    case SRT_Table:
    case SRT_TempTable: {
      sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
      sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
      sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);
      break;
................................................................................
      sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
      break;
    }
    case SRT_Exists:
    case SRT_Mem: {
      assert( nColumn==1 );
      sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
      sqlite3VdbeAddOp(v, OP_Goto, 0, brk);
      break;
    }
#endif
    case SRT_Callback:
    case SRT_Subroutine: {
      int i;
      sqlite3VdbeAddOp(v, OP_Integer, p->pEList->nExpr, 0);
................................................................................
      break;
    }
    default: {
      /* Do nothing */
      break;
    }
  }

  sqlite3VdbeResolveLabel(v, cont);
  sqlite3VdbeAddOp(v, OP_Next, iTab, addr);
  sqlite3VdbeResolveLabel(v, brk);

}

/*
** Return a pointer to a string containing the 'declaration type' of the
** expression pExpr. The string may be treated as static by the caller.
**
** If the declaration type is the exact datatype definition extracted from
................................................................................
    sqlite3VdbeAddOp(v, OP_MemStore, iMem, 1);
    VdbeComment((v, "# OFFSET counter"));
    p->iOffset = iMem;
  }
}

/*
** Allocate a virtual index to use for sorting.










*/
static createSortingIndex(Parse *pParse, Select *p, ExprList *pOrderBy){


  if( pOrderBy ){
    int addr;
    assert( pOrderBy->iTab==0 );
    pOrderBy->iTab = pParse->nTab++;
    addr = sqlite3VdbeAddOp(pParse->pVdbe, OP_OpenVirtual,
                            pOrderBy->iTab, pOrderBy->nExpr+1);
    assert( p->addrOpenVirt[2] == -1 );
    p->addrOpenVirt[2] = addr;
  }


}






















#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Return the appropriate collating sequence for the iCol-th column of
** the result set for the compound-select statement "p".  Return NULL if
** the column has no default collating sequence.
**
** The collating sequence for the compound select is taken from the
................................................................................
  int eDest,            /* \___  Store query results as specified */
  int iParm,            /* /     by these two parameters.         */
  char *aff             /* If eDest is SRT_Union, the affinity string */
){
  int rc = SQLITE_OK;   /* Success code from a subroutine */
  Select *pPrior;       /* Another SELECT immediately to our left */
  Vdbe *v;              /* Generate code to this VDBE */



  int nCol;             /* Number of columns in the result set */
  ExprList *pOrderBy;   /* The ORDER BY clause on p */
  int aSetP2[2];        /* Set P2 value of these op to number of columns */
  int nSetP2 = 0;       /* Number of slots in aSetP2[] used */

  /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs.  Only
  ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
  */
  if( p==0 || p->pPrior==0 ){
    rc = 1;
    goto multi_select_end;
  }
  pPrior = p->pPrior;
  assert( pPrior->pRightmost!=pPrior );
  assert( pPrior->pRightmost==p->pRightmost );
  if( pPrior->pOrderBy ){
    sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before",
      selectOpName(p->op));
    rc = 1;
    goto multi_select_end;
  }
  if( pPrior->pLimit ){
................................................................................
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ){
    rc = 1;
    goto multi_select_end;
  }












  /* Create the destination temporary table if necessary
  */
  if( eDest==SRT_TempTable ){
    assert( p->pEList );
    assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) );
    aSetP2[nSetP2++] = sqlite3VdbeAddOp(v, OP_OpenVirtual, iParm, 0);

    eDest = SRT_Table;
  }

  /* Generate code for the left and right SELECT statements.
  */
  pOrderBy = p->pOrderBy;
  switch( p->op ){
    case TK_ALL: {
      if( pOrderBy==0 ){
        assert( !pPrior->pLimit );
        pPrior->pLimit = p->pLimit;
        pPrior->pOffset = p->pOffset;
        rc = sqlite3Select(pParse, pPrior, eDest, iParm, 0, 0, 0, aff);
        if( rc ){
          goto multi_select_end;
        }
................................................................................
    }
    case TK_EXCEPT:
    case TK_UNION: {
      int unionTab;    /* Cursor number of the temporary table holding result */
      int op = 0;      /* One of the SRT_ operations to apply to self */
      int priorOp;     /* The SRT_ operation to apply to prior selects */
      Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */

      int addr;

      priorOp = p->op==TK_ALL ? SRT_Table : SRT_Union;
      if( eDest==priorOp && pOrderBy==0 && !p->pLimit && !p->pOffset ){
        /* We can reuse a temporary table generated by a SELECT to our
        ** right.
        */
        unionTab = iParm;
      }else{
        /* We will need to create our own temporary table to hold the
        ** intermediate results.
        */
        unionTab = pParse->nTab++;

        if( pOrderBy && matchOrderbyToColumn(pParse, p, pOrderBy, unionTab,1) ){
          rc = 1;
          goto multi_select_end;
        }
        addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, unionTab, 0);
        if( priorOp==SRT_Table ){
          assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) );
          aSetP2[nSetP2++] = addr;
        }else{
          assert( p->addrOpenVirt[0] == -1 );
          p->addrOpenVirt[0] = addr;
          p->pRightmost->usesVirt = 1;
        }
        createSortingIndex(pParse, p, pOrderBy);
        assert( p->pEList );
      }

      /* Code the SELECT statements to our left
      */
      assert( !pPrior->pOrderBy );
      rc = sqlite3Select(pParse, pPrior, priorOp, unionTab, 0, 0, 0, aff);
................................................................................
      */
      switch( p->op ){
         case TK_EXCEPT:  op = SRT_Except;   break;
         case TK_UNION:   op = SRT_Union;    break;
         case TK_ALL:     op = SRT_Table;    break;
      }
      p->pPrior = 0;

      p->pOrderBy = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      pOffset = p->pOffset;
      p->pOffset = 0;
      rc = sqlite3Select(pParse, p, op, unionTab, 0, 0, 0, aff);
      p->pPrior = pPrior;
................................................................................
        }
        iBreak = sqlite3VdbeMakeLabel(v);
        iCont = sqlite3VdbeMakeLabel(v);
        sqlite3VdbeAddOp(v, OP_Rewind, unionTab, iBreak);
        computeLimitRegisters(pParse, p);
        iStart = sqlite3VdbeCurrentAddr(v);
        rc = selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
                             pOrderBy, -1, eDest, iParm, 
                             iCont, iBreak, 0);
        if( rc ){
          rc = 1;
          goto multi_select_end;
        }
        sqlite3VdbeResolveLabel(v, iCont);
        sqlite3VdbeAddOp(v, OP_Next, unionTab, iStart);
................................................................................

      /* INTERSECT is different from the others since it requires
      ** two temporary tables.  Hence it has its own case.  Begin
      ** by allocating the tables we will need.
      */
      tab1 = pParse->nTab++;
      tab2 = pParse->nTab++;
      if( pOrderBy && matchOrderbyToColumn(pParse,p,pOrderBy,tab1,1) ){
        rc = 1;
        goto multi_select_end;
      }
      createSortingIndex(pParse, p, pOrderBy);

      addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, tab1, 0);

      assert( p->addrOpenVirt[0] == -1 );
      p->addrOpenVirt[0] = addr;



      p->pRightmost->usesVirt = 1;
      assert( p->pEList );

      /* Code the SELECTs to our left into temporary table "tab1".
      */
      rc = sqlite3Select(pParse, pPrior, SRT_Union, tab1, 0, 0, 0, aff);
      if( rc ){
        goto multi_select_end;
      }

      /* Code the current SELECT into temporary table "tab2"
      */
      addr = sqlite3VdbeAddOp(v, OP_OpenVirtual, tab2, 0);
      assert( p->addrOpenVirt[1] == -1 );
      p->addrOpenVirt[1] = addr;




      p->pPrior = 0;
      pLimit = p->pLimit;
      p->pLimit = 0;
      pOffset = p->pOffset;
      p->pOffset = 0;
      rc = sqlite3Select(pParse, p, SRT_Union, tab2, 0, 0, 0, aff);
      p->pPrior = pPrior;
................................................................................
      iBreak = sqlite3VdbeMakeLabel(v);
      iCont = sqlite3VdbeMakeLabel(v);
      sqlite3VdbeAddOp(v, OP_Rewind, tab1, iBreak);
      computeLimitRegisters(pParse, p);
      iStart = sqlite3VdbeAddOp(v, OP_RowKey, tab1, 0);
      sqlite3VdbeAddOp(v, OP_NotFound, tab2, iCont);
      rc = selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
                             pOrderBy, -1, eDest, iParm, 
                             iCont, iBreak, 0);
      if( rc ){
        rc = 1;
        goto multi_select_end;
      }
      sqlite3VdbeResolveLabel(v, iCont);
      sqlite3VdbeAddOp(v, OP_Next, tab1, iStart);
................................................................................
    rc = 1;
    goto multi_select_end;
  }

  /* Set the number of columns in temporary tables
  */
  nCol = p->pEList->nExpr;
  while( nSetP2 ){

    sqlite3VdbeChangeP2(v, aSetP2[--nSetP2], nCol);
  }

  /* Compute collating sequences used by either the ORDER BY clause or
  ** by any temporary tables needed to implement the compound select.
  ** Attach the KeyInfo structure to all temporary tables.  Invoke the
  ** ORDER BY processing if there is an ORDER BY clause.
  **
  ** This section is run by the right-most SELECT statement only.
  ** SELECT statements to the left always skip this part.  The right-most
  ** SELECT might also skip this part if it has no ORDER BY clause and
  ** no temp tables are required.
  */
  if( pOrderBy || p->usesVirt ){
    int i;                        /* Loop counter */
    KeyInfo *pKeyInfo;            /* Collating sequence for the result set */
    Select *pLoop;                /* For looping through SELECT statements */
    CollSeq **apColl;
    CollSeq **aCopy;


    assert( p->pRightmost==p );
    pKeyInfo = sqliteMalloc(sizeof(*pKeyInfo)+nCol*2*sizeof(CollSeq*));
    if( !pKeyInfo ){
      rc = SQLITE_NOMEM;
      goto multi_select_end;
    }

    pKeyInfo->enc = pParse->db->enc;
    pKeyInfo->nField = nCol;

    for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
      *apColl = multiSelectCollSeq(pParse, p, i);
      if( 0==*apColl ){
        *apColl = pParse->db->pDfltColl;
      }
    }

    for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
      for(i=0; i<2; i++){
        int addr = pLoop->addrOpenVirt[i];
        if( addr<0 ){
          /* If [0] is unused then [1] is also unused.  So we can
          ** always safely abort as soon as the first unused slot is found */
          assert( pLoop->addrOpenVirt[1]<0 );
          break;
        }
        sqlite3VdbeChangeP2(v, addr, nCol);
        sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO);
      }
    }

    if( pOrderBy ){
      struct ExprList_item *pOTerm = pOrderBy->a;
      int nExpr = pOrderBy->nExpr;
      int addr;

      aCopy = (CollSeq**)&pKeyInfo[1];
      memcpy(aCopy, pKeyInfo->aColl, nCol*sizeof(CollSeq*));
      apColl = pKeyInfo->aColl;
      for(i=0; i<pOrderBy->nExpr; i++, pOTerm++, apColl++){
        Expr *pExpr = pOTerm->pExpr;
        char *zName = pOTerm->zName;
        assert( pExpr->op==TK_COLUMN && pExpr->iColumn<nCol );

        if( zName ){
          *apColl = sqlite3LocateCollSeq(pParse, zName, -1);
        }else{
          *apColl = aCopy[pExpr->iColumn];
        }
      }
      assert( p->pRightmost==p );
      assert( p->addrOpenVirt[2]>=0 );
      addr = p->addrOpenVirt[2];
      sqlite3VdbeChangeP2(v, addr, p->pEList->nExpr+1);
      sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO);
      generateSortTail(pParse, p, v, p->pEList->nExpr, eDest, iParm);
    }



    sqliteFree(pKeyInfo);

  }

multi_select_end:




  return rc;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */

#ifndef SQLITE_OMIT_VIEW
/*
** Scan through the expression pExpr.  Replace every reference to
................................................................................
  if( sqlite3_malloc_failed || pParse->nErr || p==0 ) return 1;
  if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;

#ifndef SQLITE_OMIT_COMPOUND_SELECT
  /* If there is are a sequence of queries, do the earlier ones first.
  */
  if( p->pPrior ){
    if( p->pRightmost==0 ){
      Select *pLoop;
      for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
        pLoop->pRightmost = p;
      }
    }
    return multiSelect(pParse, p, eDest, iParm, aff);
  }
#endif

  saveAggregateInfo(pParse, &sAggInfo);
  pOrderBy = p->pOrderBy;
  if( eDest==SRT_Union || eDest==SRT_Except || eDest==SRT_Discard ){
................................................................................
#endif

  /* If there is an ORDER BY clause, resolve any collation sequences
  ** names that have been explicitly specified.
  */
  if( pOrderBy ){
    struct ExprList_item *pTerm;
    KeyInfo *pKeyInfo;
    int addr;
    for(i=0, pTerm=pOrderBy->a; i<pOrderBy->nExpr; i++, pTerm++){
      if( pTerm->zName ){
        pTerm->pExpr->pColl = sqlite3LocateCollSeq(pParse, pTerm->zName, -1);
      }
    }
    if( pParse->nErr ){
      goto select_end;
    }
    pKeyInfo = keyInfoFromExprList(pParse, pOrderBy);
    pOrderBy->iTab = pParse->nTab++;
    addr = sqlite3VdbeOp3(v, OP_OpenVirtual, pOrderBy->iTab, pOrderBy->nExpr+1, 
                        (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
    p->addrOpenVirt[2] = addr;
  }

  /* Set the limiter.
  */
  computeLimitRegisters(pParse, p);

  /* If the output is destined for a temporary table, open that table.
  */
  if( eDest==SRT_TempTable ){
    sqlite3VdbeAddOp(v, OP_OpenVirtual, iParm, pEList->nExpr);

  }

  /* Do an analysis of aggregate expressions.
  */
  if( isAgg || pGroupBy ){
    NameContext sNC;
    memset(&sNC, 0, sizeof(sNC));
................................................................................
    sqlite3VdbeAddOp(v, eDest==SRT_Mem ? OP_Null : OP_Integer, 0, 0);
    sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
  }

  /* Open a virtual index to use for the distinct set.
  */
  if( isDistinct ){
    KeyInfo *pKeyInfo;
    distinct = pParse->nTab++;

    pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
    sqlite3VdbeOp3(v, OP_OpenVirtual, distinct, 0, 
                        (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
  }else{
    distinct = -1;
  }

  /* Begin the database scan
  */
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,

**    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 1.406 2005/08/30 00:54:03 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
................................................................................
** list of "ID = expr" items in an UPDATE.  A list of expressions can
** also be used as the argument to a function, in which case the a.zName
** field is not used.
*/
struct ExprList {
  int nExpr;             /* Number of expressions on the list */
  int nAlloc;            /* Number of entries allocated below */

  struct ExprList_item {
    Expr *pExpr;           /* The list of expressions */
    char *zName;           /* Token associated with this expression */
    u8 sortOrder;          /* 1 for DESC or 0 for ASC */
    u8 isAgg;              /* True if this is an aggregate like count(*) */
    u8 done;               /* A flag to indicate when processing is finished */
    u8 orderByDup[2];      /* Corresponding term in OrderBy/GroupBy clause */
  } *a;                  /* One entry for each expression */
};

/*
** An instance of this structure can hold a simple list of identifiers,
** such as the list "a,b,c" in the following statements:
**
................................................................................
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the
** limit and nOffset to the value of the offset (or 0 if there is not
** offset).  But later on, nLimit and nOffset become the memory locations
** in the VDBE that record the limit and offset counters.










*/
struct Select {
  ExprList *pEList;      /* The fields of the result */
  u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
  u8 isDistinct;         /* True if the DISTINCT keyword is present */



  SrcList *pSrc;         /* The FROM clause */
  Expr *pWhere;          /* The WHERE clause */
  ExprList *pGroupBy;    /* The GROUP BY clause */
  Expr *pHaving;         /* The HAVING clause */
  ExprList *pOrderBy;    /* The ORDER BY clause */
  Select *pPrior;        /* Prior select in a compound select statement */

  Expr *pLimit;          /* LIMIT expression. NULL means not used. */
  Expr *pOffset;         /* OFFSET expression. NULL means not used. */
  int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
  IdList **ppOpenVirtual;/* OP_OpenVirtual addresses used by multi-selects */
  u8 isResolved;         /* True once sqlite3SelectResolve() has run. */
  u8 isAgg;              /* True if this is an aggregate query */
};

/*
** The results of a select can be distributed in several ways.
*/
#define SRT_Callback     1  /* Invoke a callback with each row of result */
#define SRT_Mem          2  /* Store result in a memory cell */

**    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 1.407 2005/09/01 03:07:44 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
................................................................................
** list of "ID = expr" items in an UPDATE.  A list of expressions can
** also be used as the argument to a function, in which case the a.zName
** field is not used.
*/
struct ExprList {
  int nExpr;             /* Number of expressions on the list */
  int nAlloc;            /* Number of entries allocated below */
  int iTab;              /* VDBE Cursor associated with this ExprList */
  struct ExprList_item {
    Expr *pExpr;           /* The list of expressions */
    char *zName;           /* Token associated with this expression */
    u8 sortOrder;          /* 1 for DESC or 0 for ASC */
    u8 isAgg;              /* True if this is an aggregate like count(*) */
    u8 done;               /* A flag to indicate when processing is finished */

  } *a;                  /* One entry for each expression */
};

/*
** An instance of this structure can hold a simple list of identifiers,
** such as the list "a,b,c" in the following statements:
**
................................................................................
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the
** limit and nOffset to the value of the offset (or 0 if there is not
** offset).  But later on, nLimit and nOffset become the memory locations
** in the VDBE that record the limit and offset counters.
**
** addrOpenVirt[] entries contain the address of OP_OpenVirtual opcodes.
** These addresses must be stored so that we can go back and fill in
** the P3_KEYINFO and P2 parameters later.  Neither the KeyInfo nor
** the number of columns in P2 can be computed at the same time
** as the OP_OpenVirtual instruction is coded because not
** enough information about the compound query is known at that point.
** The KeyInfo for addrOpenVirt[0] and [1] contains collating sequences
** for the result set.  The KeyInfo for addrOpenVirt[2] contains collating
** sequences for the ORDER BY clause.
*/
struct Select {
  ExprList *pEList;      /* The fields of the result */
  u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
  u8 isDistinct;         /* True if the DISTINCT keyword is present */
  u8 isResolved;         /* True once sqlite3SelectResolve() has run. */
  u8 isAgg;              /* True if this is an aggregate query */
  u8 usesVirt;           /* True if uses an OpenVirtual opcode */
  SrcList *pSrc;         /* The FROM clause */
  Expr *pWhere;          /* The WHERE clause */
  ExprList *pGroupBy;    /* The GROUP BY clause */
  Expr *pHaving;         /* The HAVING clause */
  ExprList *pOrderBy;    /* The ORDER BY clause */
  Select *pPrior;        /* Prior select in a compound select statement */
  Select *pRightmost;    /* Right-most select in a compound select statement */
  Expr *pLimit;          /* LIMIT expression. NULL means not used. */
  Expr *pOffset;         /* OFFSET expression. NULL means not used. */
  int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
  int addrOpenVirt[3];   /* OP_OpenVirtual opcodes related to this select */


};

/*
** The results of a select can be distributed in several ways.
*/
#define SRT_Callback     1  /* Invoke a callback with each row of result */
#define SRT_Mem          2  /* Store result in a memory cell */

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.478 2005/07/28 20:51:19 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
    N--;
    Release(pTos);
    pTos--;
  }
  *ppTos = pTos;
}

/*
** The parameters are pointers to the head of two sorted lists
** of Sorter structures.  Merge these two lists together and return
** a single sorted list.  This routine forms the core of the merge-sort
** algorithm.
**
** In the case of a tie, left sorts in front of right.
*/
static Sorter *Merge(Sorter *pLeft, Sorter *pRight, KeyInfo *pKeyInfo){
  Sorter sHead;
  Sorter *pTail;
  pTail = &sHead;
  pTail->pNext = 0;
  while( pLeft && pRight ){
    int c = sqlite3VdbeRecordCompare(pKeyInfo, pLeft->nKey, pLeft->zKey,
                                     pRight->nKey, pRight->zKey);
    if( c<=0 ){
      pTail->pNext = pLeft;
      pLeft = pLeft->pNext;
    }else{
      pTail->pNext = pRight;
      pRight = pRight->pNext;
    }
    pTail = pTail->pNext;
  }
  if( pLeft ){
    pTail->pNext = pLeft;
  }else if( pRight ){
    pTail->pNext = pRight;
  }
  return sHead.pNext;
}

/*
** Allocate cursor number iCur.  Return a pointer to it.  Return NULL
** if we run out of memory.
*/
static Cursor *allocateCursor(Vdbe *p, int iCur){
  Cursor *pCx;
  assert( iCur<p->nCursor );
................................................................................
  p->returnDepth--;
  pc = p->returnStack[p->returnDepth] - 1;
  break;
}

/* Opcode:  Halt P1 P2 P3
**
** Exit immediately.  All open cursors, Lists, Sorts, etc are closed
** automatically.
**
** P1 is the result code returned by sqlite3_exec(), sqlite3_reset(),
** or sqlite3_finalize().  For a normal halt, this should be SQLITE_OK (0).
** For errors, it can be some other value.  If P1!=0 then P2 will determine
** whether or not to rollback the current transaction.  Do not rollback
** if P2==OE_Fail. Do the rollback if P2==OE_Rollback.  If P2==OE_Abort,
................................................................................
    default: {
      goto abort_due_to_error;
    }
  }
  break;
}

/* Opcode: OpenVirtual P1 * P3
**
** Open a new cursor to a transient or virtual table.
** The cursor is always opened read/write even if 
** the main database is read-only.  The transient or virtual
** table is deleted automatically when the cursor is closed.
**

** The cursor points to a BTree table if P3==0 and to a BTree index
** if P3 is not 0.  If P3 is not NULL, it points to a KeyInfo structure
** that defines the format of keys in the index.
*/
case OP_OpenVirtual: {       /* no-push */
  int i = pOp->p1;
  Cursor *pCx;
................................................................................
      pCx->isTable = 0;
    }else{
      rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, 1, 0, 0, &pCx->pCursor);
      pCx->isTable = 1;
      pCx->pIncrKey = &pCx->bogusIncrKey;
    }
  }

  pCx->isIndex = !pCx->isTable;
  break;
}

#ifndef SQLITE_OMIT_TRIGGER
/* Opcode: OpenPseudo P1 * *
**
................................................................................
    }
  }else{
    pC->nullRow = 0;
  }
  break;
}


















/* Opcode: Rewind P1 P2 *
**
** The next use of the Rowid or Column or Next instruction for P1 
** will refer to the first entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.
................................................................................
  p->nChange = pContext->nChange;
  sqlite3VdbeFifoClear(&p->sFifo);
  p->sFifo = pContext->sFifo;
  break;
}
#endif /* #ifndef SQLITE_OMIT_TRIGGER */

/* Opcode: SortInsert * * *
**
** The TOS is the key and the NOS is the data.  Pop both from the stack
** and put them on the sorter.  The key and data should have been
** made using the MakeRecord opcode.
*/
case OP_SortInsert: {        /* no-push */
  Mem *pNos = &pTos[-1];
  Sorter *pSorter;
  assert( pNos>=p->aStack );
  if( Dynamicify(pTos, db->enc) ) goto no_mem;
  pSorter = sqliteMallocRaw( sizeof(Sorter) );
  if( pSorter==0 ) goto no_mem;
  pSorter->pNext = 0;
  if( p->pSortTail ){
    p->pSortTail->pNext = pSorter;
  }else{
    p->pSort = pSorter;
  }
  p->pSortTail = pSorter;
  assert( pTos->flags & MEM_Dyn );
  pSorter->nKey = pTos->n;
  pSorter->zKey = pTos->z;
  pSorter->data.flags = MEM_Null;
  rc = sqlite3VdbeMemMove(&pSorter->data, pNos);
  pTos -= 2;
  break;
}

/* Opcode: Sort * * P3
**
** Sort all elements on the sorter.  The algorithm is a
** mergesort.  The P3 argument is a pointer to a KeyInfo structure
** that describes the keys to be sorted.
*/
case OP_Sort: {        /* no-push */
  int i;
  KeyInfo *pKeyInfo = (KeyInfo*)pOp->p3;
  Sorter *pElem;
  Sorter *apSorter[NSORT];
  sqlite3_sort_count++;
  pKeyInfo->enc = p->db->enc;
  for(i=0; i<NSORT; i++){
    apSorter[i] = 0;
  }
  while( p->pSort ){
    pElem = p->pSort;
    p->pSort = pElem->pNext;
    pElem->pNext = 0;
    for(i=0; i<NSORT-1; i++){
      if( apSorter[i]==0 ){
        apSorter[i] = pElem;
        break;
      }else{
        pElem = Merge(apSorter[i], pElem, pKeyInfo);
        apSorter[i] = 0;
      }
    }
    if( i>=NSORT-1 ){
      apSorter[NSORT-1] = Merge(apSorter[NSORT-1],pElem, pKeyInfo);
    }
  }
  pElem = 0;
  for(i=0; i<NSORT; i++){
    pElem = Merge(apSorter[i], pElem, pKeyInfo);
  }
  p->pSort = pElem;
  break;
}

/* Opcode: SortNext * P2 *
**
** Push the data for the topmost element in the sorter onto the
** stack, then remove the element from the sorter.  If the sorter
** is empty, push nothing on the stack and instead jump immediately 
** to instruction P2.
*/
case OP_SortNext: {
  Sorter *pSorter = p->pSort;
  CHECK_FOR_INTERRUPT;
  if( pSorter!=0 ){
    p->pSort = pSorter->pNext;
    pTos++;
    pTos->flags = MEM_Null;
    rc = sqlite3VdbeMemMove(pTos, &pSorter->data);
    sqliteFree(pSorter->zKey);
    sqliteFree(pSorter);
  }else{
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: SortReset * * *
**
** Remove any elements that remain on the sorter.
*/
case OP_SortReset: {        /* no-push */
  sqlite3VdbeSorterReset(p);
  break;
}

/* Opcode: MemStore P1 P2 *
**
** Write the top of the stack into memory location P1.
** P1 should be a small integer since space is allocated
** for all memory locations between 0 and P1 inclusive.
**
** After the data is stored in the memory location, the

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.479 2005/09/01 03:07:44 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
    N--;
    Release(pTos);
    pTos--;
  }
  *ppTos = pTos;
}


































/*
** Allocate cursor number iCur.  Return a pointer to it.  Return NULL
** if we run out of memory.
*/
static Cursor *allocateCursor(Vdbe *p, int iCur){
  Cursor *pCx;
  assert( iCur<p->nCursor );
................................................................................
  p->returnDepth--;
  pc = p->returnStack[p->returnDepth] - 1;
  break;
}

/* Opcode:  Halt P1 P2 P3
**
** Exit immediately.  All open cursors, Fifos, etc are closed
** automatically.
**
** P1 is the result code returned by sqlite3_exec(), sqlite3_reset(),
** or sqlite3_finalize().  For a normal halt, this should be SQLITE_OK (0).
** For errors, it can be some other value.  If P1!=0 then P2 will determine
** whether or not to rollback the current transaction.  Do not rollback
** if P2==OE_Fail. Do the rollback if P2==OE_Rollback.  If P2==OE_Abort,
................................................................................
    default: {
      goto abort_due_to_error;
    }
  }
  break;
}

/* Opcode: OpenVirtual P1 P2 P3
**
** Open a new cursor P1 to a transient or virtual table.
** The cursor is always opened read/write even if 
** the main database is read-only.  The transient or virtual
** table is deleted automatically when the cursor is closed.
**
** P2 is the number of columns in the virtual table.
** The cursor points to a BTree table if P3==0 and to a BTree index
** if P3 is not 0.  If P3 is not NULL, it points to a KeyInfo structure
** that defines the format of keys in the index.
*/
case OP_OpenVirtual: {       /* no-push */
  int i = pOp->p1;
  Cursor *pCx;
................................................................................
      pCx->isTable = 0;
    }else{
      rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, 1, 0, 0, &pCx->pCursor);
      pCx->isTable = 1;
      pCx->pIncrKey = &pCx->bogusIncrKey;
    }
  }
  pCx->nField = pOp->p2;
  pCx->isIndex = !pCx->isTable;
  break;
}

#ifndef SQLITE_OMIT_TRIGGER
/* Opcode: OpenPseudo P1 * *
**
................................................................................
    }
  }else{
    pC->nullRow = 0;
  }
  break;
}


/* Opcode: Sort P1 P2 *
**
** This opcode does exactly the same thing as OP_Rewind except that
** it increments an undocumented global variable used for testing.
**
** Sorting is accomplished by writing records into a sorting index,
** then rewinding that index and playing it back from beginning to
** end.  We use the OP_Sort opcode instead of OP_Rewind to do the
** rewinding so that the global variable will be incremented and
** regression tests can determine whether or not the optimizer is
** correctly optimizing out sorts.
*/
case OP_Sort: {        /* no-push */
  sqlite3_sort_count++;
  /* Fall through into OP_Rewind */
}
/* Opcode: Rewind P1 P2 *
**
** The next use of the Rowid or Column or Next instruction for P1 
** will refer to the first entry in the database table or index.
** If the table or index is empty and P2>0, then jump immediately to P2.
** If P2 is 0 or if the table or index is not empty, fall through
** to the following instruction.
................................................................................
  p->nChange = pContext->nChange;
  sqlite3VdbeFifoClear(&p->sFifo);
  p->sFifo = pContext->sFifo;
  break;
}
#endif /* #ifndef SQLITE_OMIT_TRIGGER */







































































































/* Opcode: MemStore P1 P2 *
**
** Write the top of the stack into memory location P1.
** P1 should be a small integer since space is allocated
** for all memory locations between 0 and P1 inclusive.
**
** After the data is stored in the memory location, the

  double r;           /* Real value */
  char *z;            /* String or BLOB value */
  void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
  char zShort[NBFS];  /* Space for short strings */
};
typedef struct Mem Mem;

/*
** A sorter builds a list of elements to be sorted.  Each element of
** the list is an instance of the following structure.
*/
typedef struct Sorter Sorter;
struct Sorter {
  int nKey;           /* Number of bytes in the key */
  char *zKey;         /* The key by which we will sort */
  Mem data;
  Sorter *pNext;      /* Next in the list */
};

/* 
** Number of buckets used for merge-sort.  
*/
#define NSORT 30

/* One or more of the following flags are set to indicate the validOK
** representations of the value stored in the Mem struct.
**
** If the MEM_Null flag is set, then the value is an SQL NULL value.
** No other flags may be set in this case.
**
** If the MEM_Str flag is set then Mem.z points at a string representation.
................................................................................
  int *aLabel;        /* Space to hold the labels */
  Mem *aStack;        /* The operand stack, except string values */
  Mem *pTos;          /* Top entry in the operand stack */
  Mem **apArg;        /* Arguments to currently executing user function */
  Mem *aColName;      /* Column names to return */
  int nCursor;        /* Number of slots in apCsr[] */
  Cursor **apCsr;     /* One element of this array for each open cursor */
  Sorter *pSort;      /* A linked list of objects to be sorted */
  Sorter *pSortTail;  /* Last element on the pSort list */
  int nVar;           /* Number of entries in aVar[] */
  Mem *aVar;          /* Values for the OP_Variable opcode. */
  char **azVar;       /* Name of variables */
  int okVar;          /* True if azVar[] has been initialized */
  int magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  Mem *aMem;              /* The memory locations */
................................................................................
#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */

/*
** Function prototypes
*/
void sqlite3VdbeFreeCursor(Cursor*);
void sqlite3VdbeSorterReset(Vdbe*);
int sqlite3VdbeAggReset(sqlite3*, Agg *, KeyInfo *);
void sqliteVdbePopStack(Vdbe*,int);
int sqlite3VdbeCursorMoveto(Cursor*);
#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
void sqlite3VdbePrintOp(FILE*, int, Op*);
#endif
#ifdef SQLITE_DEBUG

  double r;           /* Real value */
  char *z;            /* String or BLOB value */
  void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
  char zShort[NBFS];  /* Space for short strings */
};
typedef struct Mem Mem;


















/* One or more of the following flags are set to indicate the validOK
** representations of the value stored in the Mem struct.
**
** If the MEM_Null flag is set, then the value is an SQL NULL value.
** No other flags may be set in this case.
**
** If the MEM_Str flag is set then Mem.z points at a string representation.
................................................................................
  int *aLabel;        /* Space to hold the labels */
  Mem *aStack;        /* The operand stack, except string values */
  Mem *pTos;          /* Top entry in the operand stack */
  Mem **apArg;        /* Arguments to currently executing user function */
  Mem *aColName;      /* Column names to return */
  int nCursor;        /* Number of slots in apCsr[] */
  Cursor **apCsr;     /* One element of this array for each open cursor */


  int nVar;           /* Number of entries in aVar[] */
  Mem *aVar;          /* Values for the OP_Variable opcode. */
  char **azVar;       /* Name of variables */
  int okVar;          /* True if azVar[] has been initialized */
  int magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  Mem *aMem;              /* The memory locations */
................................................................................
#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */

/*
** Function prototypes
*/
void sqlite3VdbeFreeCursor(Cursor*);

int sqlite3VdbeAggReset(sqlite3*, Agg *, KeyInfo *);
void sqliteVdbePopStack(Vdbe*,int);
int sqlite3VdbeCursorMoveto(Cursor*);
#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
void sqlite3VdbePrintOp(FILE*, int, Op*);
#endif
#ifdef SQLITE_DEBUG

      p->aOp[i].cnt = 0;
      p->aOp[i].cycles = 0;
    }
  }
#endif
}


/*
** Remove any elements that remain on the sorter for the VDBE given.
*/
void sqlite3VdbeSorterReset(Vdbe *p){
  while( p->pSort ){
    Sorter *pSorter = p->pSort;
    p->pSort = pSorter->pNext;
    sqliteFree(pSorter->zKey);
    sqlite3VdbeMemRelease(&pSorter->data);
    sqliteFree(pSorter);
  }
  p->pSortTail = 0;
}

/*
** Free all resources allociated with AggElem pElem, an element of
** aggregate pAgg.
*/
static void freeAggElem(AggElem *pElem, Agg *pAgg){
  int i;
  for(i=0; i<pAgg->nMem; i++){
................................................................................
  sqlite3VdbeFifoClear(&p->sFifo);
  if( p->contextStack ){
    for(i=0; i<p->contextStackTop; i++){
      sqlite3VdbeFifoClear(&p->contextStack[i].sFifo);
    }
    sqliteFree(p->contextStack);
  }
  sqlite3VdbeSorterReset(p);
  for(i=0; i<p->nAgg; i++){
    sqlite3VdbeAggReset(0, &p->apAgg[i], 0);
  }
  p->contextStack = 0;
  p->contextStackDepth = 0;
  p->contextStackTop = 0;
  sqliteFree(p->zErrMsg);

      p->aOp[i].cnt = 0;
      p->aOp[i].cycles = 0;
    }
  }
#endif
}
















/*
** Free all resources allociated with AggElem pElem, an element of
** aggregate pAgg.
*/
static void freeAggElem(AggElem *pElem, Agg *pAgg){
  int i;
  for(i=0; i<pAgg->nMem; i++){
................................................................................
  sqlite3VdbeFifoClear(&p->sFifo);
  if( p->contextStack ){
    for(i=0; i<p->contextStackTop; i++){
      sqlite3VdbeFifoClear(&p->contextStack[i].sFifo);
    }
    sqliteFree(p->contextStack);
  }

  for(i=0; i<p->nAgg; i++){
    sqlite3VdbeAggReset(0, &p->apAgg[i], 0);
  }
  p->contextStack = 0;
  p->contextStackDepth = 0;
  p->contextStackTop = 0;
  sqliteFree(p->zErrMsg);

#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests for the conflict resolution extension
# to SQLite.
#
# $Id: conflict.test,v 1.24 2005/06/07 02:12:30 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Create tables for the first group of tests.
#
do_test conflict-1.0 {
................................................................................
#   t0     True if there is an error from $cmd
#   t1     Content of "b" column of t1 assuming no error in $cmd
#   t2     Content of "x" column of t3
#   t3     Number of temporary files created
#
foreach {i conf1 cmd t0 t1 t2 t3} {
  1 {}       UPDATE                  1 {6 7 8 9}  1 1
  2 REPLACE  UPDATE                  0 {7 6 9}    1 0
  3 IGNORE   UPDATE                  0 {6 7 3 9}  1 0
  4 FAIL     UPDATE                  1 {6 7 3 4}  1 0
  5 ABORT    UPDATE                  1 {1 2 3 4}  1 1
  6 ROLLBACK UPDATE                  1 {1 2 3 4}  0 0
  7 REPLACE  {UPDATE OR IGNORE}      0 {6 7 3 9}  1 0
  8 IGNORE   {UPDATE OR REPLACE}     0 {7 6 9}    1 0
  9 FAIL     {UPDATE OR IGNORE}      0 {6 7 3 9}  1 0
 10 ABORT    {UPDATE OR REPLACE}     0 {7 6 9}    1 0
 11 ROLLBACK {UPDATE OR IGNORE}      0 {6 7 3 9}  1 0
 12 {}       {UPDATE OR IGNORE}      0 {6 7 3 9}  1 0
 13 {}       {UPDATE OR REPLACE}     0 {7 6 9}    1 0
 14 {}       {UPDATE OR FAIL}        1 {6 7 3 4}  1 0
 15 {}       {UPDATE OR ABORT}       1 {1 2 3 4}  1 1
 16 {}       {UPDATE OR ROLLBACK}    1 {1 2 3 4}  0 0
} {
  if {$t0} {set t1 {column a is not unique}}
  do_test conflict-6.$i {
    db close

#
#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests for the conflict resolution extension
# to SQLite.
#
# $Id: conflict.test,v 1.25 2005/09/01 03:07:45 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Create tables for the first group of tests.
#
do_test conflict-1.0 {
................................................................................
#   t0     True if there is an error from $cmd
#   t1     Content of "b" column of t1 assuming no error in $cmd
#   t2     Content of "x" column of t3
#   t3     Number of temporary files created
#
foreach {i conf1 cmd t0 t1 t2 t3} {
  1 {}       UPDATE                  1 {6 7 8 9}  1 1
  2 REPLACE  UPDATE                  0 {7 6 9}    1 1
  3 IGNORE   UPDATE                  0 {6 7 3 9}  1 1
  4 FAIL     UPDATE                  1 {6 7 3 4}  1 0
  5 ABORT    UPDATE                  1 {1 2 3 4}  1 1
  6 ROLLBACK UPDATE                  1 {1 2 3 4}  0 0
  7 REPLACE  {UPDATE OR IGNORE}      0 {6 7 3 9}  1 1
  8 IGNORE   {UPDATE OR REPLACE}     0 {7 6 9}    1 1
  9 FAIL     {UPDATE OR IGNORE}      0 {6 7 3 9}  1 1
 10 ABORT    {UPDATE OR REPLACE}     0 {7 6 9}    1 1
 11 ROLLBACK {UPDATE OR IGNORE}      0 {6 7 3 9}  1 1
 12 {}       {UPDATE OR IGNORE}      0 {6 7 3 9}  1 1
 13 {}       {UPDATE OR REPLACE}     0 {7 6 9}    1 1
 14 {}       {UPDATE OR FAIL}        1 {6 7 3 4}  1 0
 15 {}       {UPDATE OR ABORT}       1 {1 2 3 4}  1 1
 16 {}       {UPDATE OR ROLLBACK}    1 {1 2 3 4}  0 0
} {
  if {$t0} {set t1 {column a is not unique}}
  do_test conflict-6.$i {
    db close