SQLite

**    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 used to generate VDBE code
** that implements the ALTER TABLE command.
**
** $Id: alter.c,v 1.36 2008/01/03 00:01:24 drh Exp $
** $Id: alter.c,v 1.37 2008/01/03 18:39:42 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The code in this file only exists if we are not omitting the
** ALTER TABLE logic from the build.

  /* If this is a virtual table, invoke the xRename() function if
  ** one is defined. The xRename() callback will modify the names
  ** of any resources used by the v-table implementation (including other
  ** SQLite tables) that are identified by the name of the virtual table.
  */
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( isVirtualRename ){
    int i;
    sqlite3VdbeAddOp4(v, OP_String8, 0, 0, 0, zName, 0);
    i = sqlite3StackToReg(pParse, 1);
    sqlite3VdbeAddOp4(v, OP_VRename, 0, 0, 0,(const char*)pTab->pVtab, P4_VTAB);
    sqlite3VdbeAddOp4(v, OP_VRename, i, 0, 0,(const char*)pTab->pVtab, P4_VTAB);
  }
#endif

  /* figure out how many UTF-8 characters are in zName */
  zTabName = pTab->zName;
  nTabName = sqlite3Utf8CharLen(zTabName, -1);

**
** 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 1.671 2008/01/03 18:03:09 drh Exp $
** $Id: vdbe.c,v 1.672 2008/01/03 18:39:42 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
** The following global variable is incremented every time a cursor

    }
  }
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VFilter P1 P2 P4
/* Opcode: VFilter P1 P2 P3 P4 *
**
** P1 is a cursor opened using VOpen.  P2 is an address to jump to if
** the filtered result set is empty.
**
** P4 is either NULL or a string that was generated by the xBestIndex
** method of the module.  The interpretation of the P4 string is left
** to the module implementation.
**
** This opcode invokes the xFilter method on the virtual table specified
** by P1.  The integer query plan parameter to xFilter is the top of the
** stack.  Next down on the stack is the argc parameter.  Beneath the
** next of stack are argc additional parameters which are passed to
** by P1.  The integer query plan parameter to xFilter is stored in register
** P3. Register P3+1 stores the argc parameter to be passed to the
** xFilter method. Registers P3+2..P3+1+argc are the argc additional
** parametersneath additional parameters which are passed to
** xFilter as argv. The topmost parameter (i.e. 3rd element popped from
** the stack) becomes argv[argc-1] when passed to xFilter.
** xFilter as argv. Register P3+2 becomes argv[0] when passed to xFilter.
**
** The integer query plan parameter, argc, and all argv stack values 
** are popped from the stack before this instruction completes.
**
** A jump is made to P2 if the result set after filtering would be 
** A jump is made to P2 if the result set after filtering would be empty.
** empty.
*/
case OP_VFilter: {   /* no-push */
  int nArg;

  int iQuery;
  const sqlite3_module *pModule;
  Mem *pQuery = &p->aMem[pOp->p3];
  Mem *pArgc = &pQuery[1];

  Cursor *pCur = p->apCsr[pOp->p1];
  assert( pCur->pVtabCursor );
  pModule = pCur->pVtabCursor->pVtab->pModule;

  /* Grab the index number and argc parameters off the top of the stack. */
  assert( (&pTos[-1])>=p->aStack );
  assert( (pTos[0].flags&MEM_Int)!=0 && pTos[-1].flags==MEM_Int );
  nArg = pTos[-1].u.i;
  assert( (pQuery->flags&MEM_Int)!=0 && pArgc->flags==MEM_Int );
  nArg = pArgc->u.i;
  iQuery = pQuery->u.i;

  /* Invoke the xFilter method */
  {
    int res = 0;
    int i;
    Mem **apArg = p->apArg;
    for(i = 0; i<nArg; i++){
      apArg[i] = &pTos[i+1-2-nArg];
      apArg[i] = &pArgc[i+1];
      storeTypeInfo(apArg[i], 0);
    }

    if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
    p->inVtabMethod = 1;
    rc = pModule->xFilter(pCur->pVtabCursor, pTos->u.i, pOp->p4.z, nArg, apArg);
    rc = pModule->xFilter(pCur->pVtabCursor, iQuery, pOp->p4.z, nArg, apArg);
    p->inVtabMethod = 0;
    if( rc==SQLITE_OK ){
      res = pModule->xEof(pCur->pVtabCursor);
    }
    if( sqlite3SafetyOn(db) ) goto abort_due_to_misuse;

    if( res ){
      pc = pOp->p2 - 1;
    }
  }

  /* Pop the index number, argc value and parameters off the stack */
  popStack(&pTos, 2+nArg);
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VRowid P1 * *
**

  }

  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VRename * * P4
/* Opcode: VRename P1 * P4
**
** P4 is a pointer to a virtual table object, an sqlite3_vtab structure.
** This opcode invokes the corresponding xRename method. The value
** on the top of the stack is popped and passed as the zName argument
** to the xRename method.
** in register P1 is passed as the zName argument to the xRename method.
*/
case OP_VRename: {   /* no-push */
  sqlite3_vtab *pVtab = pOp->p4.pVtab;
  Mem *pName = &p->aMem[pOp->p1];
  assert( pVtab->pModule->xRename );

  Stringify(pTos, encoding);
  Stringify(pName, encoding);

  if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
  sqlite3VtabLock(pVtab);
  rc = pVtab->pModule->xRename(pVtab, pTos->z);
  rc = pVtab->pModule->xRename(pVtab, pName->z);
  sqlite3VtabUnlock(db, pVtab);
  if( sqlite3SafetyOn(db) ) goto abort_due_to_misuse;

  popStack(&pTos, 1);
  break;
}
#endif

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VUpdate P1 P2 P3 P4
**

      doesStatementRollback = 1;
#ifndef SQLITE_OMIT_VIRTUALTABLE
    }else if( opcode==OP_VUpdate || opcode==OP_VRename ){
      doesStatementRollback = 1;
    }else if( opcode==OP_VFilter ){
      int n;
      assert( p->nOp - i >= 3 );
      assert( pOp[-2].opcode==OP_Integer );
      n = pOp[-2].p1;
      assert( pOp[-1].opcode==OP_MemInt );
      n = pOp[-1].p1;
      if( n>nMaxArgs ) nMaxArgs = n;
#endif
    }
    if( opcodeNoPush(opcode) ){
      nMaxStack--;
    }

** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  This module is reponsible for
** generating the code that loops through a table looking for applicable
** rows.  Indices are selected and used to speed the search when doing
** so is applicable.  Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
** $Id: where.c,v 1.270 2008/01/03 18:03:09 drh Exp $
** $Id: where.c,v 1.271 2008/01/03 18:39:42 danielk1977 Exp $
*/
#include "sqliteInt.h"

/*
** The number of bits in a Bitmask.  "BMS" means "BitMask Size".
*/
#define BMS  (sizeof(Bitmask)*8)

#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( pLevel->pBestIdx ){
      /* Case 0:  The table is a virtual-table.  Use the VFilter and VNext
      **          to access the data.
      */
      int j;
      int iReg;   /* P3 Value for OP_VFilter */
      sqlite3_index_info *pBestIdx = pLevel->pBestIdx;
      int nConstraint = pBestIdx->nConstraint;
      struct sqlite3_index_constraint_usage *aUsage =
                                                  pBestIdx->aConstraintUsage;
      const struct sqlite3_index_constraint *aConstraint =
                                                  pBestIdx->aConstraint;

      for(j=1; j<=nConstraint; j++){
        int k;
        for(k=0; k<nConstraint; k++){
          if( aUsage[k].argvIndex==j ){
            int iTerm = aConstraint[k].iTermOffset;
            sqlite3ExprCode(pParse, wc.a[iTerm].pExpr->pRight);
            break;
          }
        }
        if( k==nConstraint ) break;
      }
      iReg = ++pParse->nMem;
      pParse->nMem++;
      sqlite3StackToReg(pParse, j-1);
      sqlite3VdbeAddOp2(v, OP_Integer, j-1, 0);
      sqlite3VdbeAddOp2(v, OP_Integer, pBestIdx->idxNum, 0);
      sqlite3VdbeAddOp4(v, OP_VFilter, iCur, brk, 0, pBestIdx->idxStr,
      sqlite3VdbeAddOp2(v, OP_MemInt, pBestIdx->idxNum, iReg);
      sqlite3VdbeAddOp2(v, OP_MemInt, j-1, iReg+1);
      sqlite3VdbeAddOp4(v, OP_VFilter, iCur, brk, iReg, pBestIdx->idxStr,
                        pBestIdx->needToFreeIdxStr ? P4_MPRINTF : P4_STATIC);
      pBestIdx->needToFreeIdxStr = 0;
      for(j=0; j<pBestIdx->nConstraint; j++){
        if( aUsage[j].omit ){
          int iTerm = aConstraint[j].iTermOffset;
          disableTerm(pLevel, &wc.a[iTerm]);
        }