SQLite

**     CREATE INDEX
**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**
** $Id: build.c,v 1.288 2004/11/23 16:31:17 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Check to see if the schema for the database needs

*/ 
static void destroyRootPage(Parse *pParse, int iTable, int iDb){
  Vdbe *v = sqlite3GetVdbe(pParse);
  sqlite3VdbeAddOp(v, OP_Destroy, iTable, iDb);
#ifndef SQLITE_OMIT_AUTOVACUUM
  /* OP_Destroy pushes an integer onto the stack. If this integer
  ** is non-zero, then it is the root page number of a table moved to
  ** location iTable. The following code modifis the sqlite_master table to
  ** reflect this.
  **
  ** The "#0" in the SQL is a special constant that means whatever value
  ** is on the top of the stack.  See sqlite3RegisterExpr().
  */
  sqlite3NestedParse(pParse, 
     "UPDATE %Q.%s SET rootpage=%d WHERE #0 AND rootpage=#0",

**
** 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 1.431 2004/11/23 01:47:30 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

}
#endif


#ifdef VDBE_PROFILE
/*
** The following routine only works on pentium-class processors.
** It uses the RDTSC opcode to read cycle count value out of the
** processor and returns that value.  This can be used for high-res
** profiling.
*/
__inline__ unsigned long long int hwtime(void){
  unsigned long long int x;
  __asm__("rdtsc\n\t"
          "mov %%edx, %%ecx\n\t"

    ctx.pFunc = ctx.pVdbeFunc->pFunc;
  }

  ctx.s.flags = MEM_Null;
  ctx.s.z = 0;
  ctx.s.xDel = 0;
  ctx.isError = 0;
  ctx.isStep = 0;
  if( ctx.pFunc->needCollSeq ){
    assert( pOp>p->aOp );
    assert( pOp[-1].p3type==P3_COLLSEQ );
    assert( pOp[-1].opcode==OP_CollSeq );
    ctx.pColl = (CollSeq *)pOp[-1].p3;
  }
  if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;

**
** If AUTOVACUUM is enabled then it is possible that another root page
** might be moved into the newly deleted root page in order to keep all
** root pages contiguous at the beginning of the database.  The former
** value of the root page that moved - its value before the move occurred -
** is pushed onto the stack.  If no page movement was required (because
** the table being dropped was already the last one in the database) then
** a zero is pushed onto the stack.  If AUTOVACUUM is disabled at 
** then a zero is pushed onto the stack.
**
** See also: Clear
*/
case OP_Destroy: {
  int iMoved;
  if( db->activeVdbeCnt>1 ){

  assert( i>=0 && i<p->agg.nMem );
  ctx.pFunc = (FuncDef*)pOp->p3;
  pMem = &p->agg.pCurrent->aMem[i];
  ctx.s.z = pMem->zShort;  /* Space used for small aggregate contexts */
  ctx.pAgg = pMem->z;
  ctx.cnt = ++pMem->i;
  ctx.isError = 0;
  ctx.isStep = 1;
  ctx.pColl = 0;
  if( ctx.pFunc->needCollSeq ){
    assert( pOp>p->aOp );
    assert( pOp[-1].p3type==P3_COLLSEQ );
    assert( pOp[-1].opcode==OP_CollSeq );
    ctx.pColl = (CollSeq *)pOp[-1].p3;
  }

      FuncDef *pFunc = p->agg.apFunc[i];
      Mem *pMem = &aMem[i];
      if( pFunc==0 || pFunc->xFinalize==0 ) continue;
      ctx.s.flags = MEM_Null;
      ctx.s.z = pMem->zShort;
      ctx.pAgg = (void*)pMem->z;
      ctx.cnt = pMem->i;
      ctx.isStep = 0;
      ctx.pFunc = pFunc;
      pFunc->xFinalize(&ctx);
      pMem->z = ctx.pAgg;
      if( pMem->z && pMem->z!=pMem->zShort ){
        sqliteFree( pMem->z );
      }
      *pMem = ctx.s;

*/
struct sqlite3_context {
  FuncDef *pFunc;   /* Pointer to function information.  MUST BE FIRST */
  VdbeFunc *pVdbeFunc;  /* Auxilary data, if created. */
  Mem s;            /* The return value is stored here */
  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 */
  CollSeq *pColl;
};

/*
** An Agg structure describes an Aggregator.  Each Agg consists of
** zero or more Aggregator elements (AggElem).  Each AggElem contains

    Mem *pMem = &pElem->aMem[i];
    if( pAgg->apFunc && pAgg->apFunc[i] && (pMem->flags & MEM_AggCtx)!=0 ){
      sqlite3_context ctx;
      ctx.pFunc = pAgg->apFunc[i];
      ctx.s.flags = MEM_Null;
      ctx.pAgg = pMem->z;
      ctx.cnt = pMem->i;
      ctx.isStep = 0;
      ctx.isError = 0;
      (*pAgg->apFunc[i]->xFinalize)(&ctx);
      pMem->z = ctx.pAgg;
      if( pMem->z!=0 && pMem->z!=pMem->zShort ){
        sqliteFree(pMem->z);
      }
      sqlite3VdbeMemRelease(&ctx.s);
    }else{
      sqlite3VdbeMemRelease(pMem);