SQLite

**
** 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 1.180 2002/10/19 20:16:38 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The makefile scans this source file and creates the following
** array of string constants which are the names of all VDBE opcodes.

** 
** Every cursor that the virtual machine has open is represented by an
** instance of the following structure.
*/
struct Cursor {
  BtCursor *pCursor;    /* The cursor structure of the backend */
  int lastRecno;        /* Last recno from a Next or NextIdx operation */
  int nextRowid;        /* Next rowid returned by OP_NewRowid */
  Bool recnoIsValid;    /* True if lastRecno is valid */
  Bool keyAsData;       /* The OP_Column command works on key instead of data */
  Bool atFirst;         /* True if pointing to first entry */
  Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
  Bool nullRow;         /* True if pointing to a row with no data */
  Bool nextRowidValid;  /* True if the nextRowid field is valid */
  Btree *pBt;           /* Separate file holding temporary table */
};
typedef struct Cursor Cursor;

/*
** A sorter builds a list of elements to be sorted.  Each element of
** the list is an instance of the following structure.

    ** first few attempts at chosing a random rowid pick values just a little
    ** larger than the previous rowid.  This has been shown experimentally
    ** to double the speed of the COPY operation.
    */
    int res, rx, cnt, x;
    cnt = 0;
    if( !pC->useRandomRowid ){
      if( pC->nextRowidValid ){
        v = pC->nextRowid;
      }else{
        rx = sqliteBtreeLast(pC->pCursor, &res);
        if( res ){
          v = 1;
        }else{
          sqliteBtreeKey(pC->pCursor, 0, sizeof(v), (void*)&v);
          v = keyToInt(v);
          if( v==0x7fffffff ){
            pC->useRandomRowid = 1;
          }else{
            v++;
          }
        }
      }
      if( v<0x7fffffff ){
        pC->nextRowidValid = 1;
        pC->nextRowid = v+1;
      }else{
        pC->nextRowidValid = 0;
      }
    }
    if( pC->useRandomRowid ){
      v = db->priorNewRowid;
      cnt = 0;
      do{
        if( v==0 || cnt>2 ){

** be a string.  The stack is popped twice by this instruction.
*/
case OP_PutIntKey:
case OP_PutStrKey: {
  int tos = p->tos;
  int nos = p->tos-1;
  int i = pOp->p1;
  Cursor *pC;
  VERIFY( if( nos<0 ) goto not_enough_stack; )
  if( VERIFY( i>=0 && i<p->nCursor && ) (pC = &p->aCsr[i])->pCursor!=0 ){
    char *zKey;
    int nKey, iKey;
    if( pOp->opcode==OP_PutStrKey ){
      if( Stringify(p, nos) ) goto no_mem;
      nKey = aStack[nos].n;
      zKey = zStack[nos];
    }else{
      assert( aStack[nos].flags & STK_Int );
      nKey = sizeof(int);
      iKey = intToKey(aStack[nos].i);
      zKey = (char*)&iKey;
      db->lastRowid = aStack[nos].i;
      if( pOp->p2 ) db->nChange++;
      if( pC->nextRowidValid && aStack[nos].i>=pC->nextRowid ){
        pC->nextRowidValid = 0;
      }
    }
    rc = sqliteBtreeInsert(pC->pCursor, zKey, nKey,
                        zStack[tos], aStack[tos].n);
    pC->recnoIsValid = 0;
  }
  POPSTACK;
  POPSTACK;
  break;
}

/* Opcode: Delete P1 P2 *
**
** Delete the record at which the P1 cursor is currently pointing.
**
** The cursor will be left pointing at either the next or the previous
** record in the table. If it is left pointing at the next record, then
** the next Next instruction will be a no-op.  Hence it is OK to delete
** a record from within an Next loop.
**
** The row change counter is incremented if P2==1 and is unmodified
** if P2==0.
*/
case OP_Delete: {
  int i = pOp->p1;
  Cursor *pC;
  if( VERIFY( i>=0 && i<p->nCursor && ) (pC = &p->aCsr[i])->pCursor!=0 ){
    rc = sqliteBtreeDelete(pC->pCursor);
    pC->nextRowidValid = 0;
  }
  if( pOp->p2 ) db->nChange++;
  break;
}

/* Opcode: KeyAsData P1 P2 *
**