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 are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.262 2005/09/07 22:09:48 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.

** in the AggInfo structure.
*/
static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
  Vdbe *v = pParse->pVdbe;
  int i;
  struct AggInfo_func *pF;
  for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
    ExprList *pList = pF->pExpr->pList;
    sqlite3VdbeOp3(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0,
                      (void*)pF->pFunc, P3_FUNCDEF);
  }
}

/*
** Update the accumulator memory cells for an aggregate based on
** the current cursor position.
*/

**
** 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 1.483 2005/09/07 22:09:48 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

  popStack(&pTos, n);
  if( ctx.isError ){
    rc = SQLITE_ERROR;
  }
  break;
}

/* Opcode: AggFinal P1 P2 P3
**
** Execute the finalizer function for an aggregate.  P1 is
** the memory location that is the accumulator for the aggregate.
**
** P2 is the number of arguments that the step function takes and
** P3 is a pointer to the FuncDef for this function.  The P2
** argument is not used by this opcode.  It is only there to disambiguate
** functions that can take varying numbers of arguments.  The
** P3 argument is only needed for the degenerate case where
** the step function was not previously called.
*/
case OP_AggFinal: {        /* no-push */
  Mem *pMem;
  assert( pOp->p1>=0 && pOp->p1<p->nMem );
  pMem = &p->aMem[pOp->p1];
  assert( (pMem->flags & ~(MEM_Null|MEM_Agg))==0 );
  sqlite3VdbeMemFinalize(pMem, (FuncDef*)pOp->p3);
  break;
}


/* Opcode: Vacuum * * *
**
** Vacuum the entire database.  This opcode will cause other virtual

int sqlite3VdbeMemStringify(Mem*, int);
i64 sqlite3VdbeIntValue(Mem*);
int sqlite3VdbeMemIntegerify(Mem*);
double sqlite3VdbeRealValue(Mem*);
int sqlite3VdbeMemRealify(Mem*);
int sqlite3VdbeMemFromBtree(BtCursor*,int,int,int,Mem*);
void sqlite3VdbeMemRelease(Mem *p);
void sqlite3VdbeMemFinalize(Mem*, FuncDef*);
#ifndef NDEBUG
void sqlite3VdbeMemSanity(Mem*, u8);
int sqlite3VdbeOpcodeNoPush(u8);
#endif
int sqlite3VdbeMemTranslate(Mem*, u8);
void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf, int nBuf);
int sqlite3VdbeMemHandleBom(Mem *pMem);

** Allocate or return the aggregate context for a user function.  A new
** context is allocated on the first call.  Subsequent calls return the
** same context that was returned on prior calls.
*/
void *sqlite3_aggregate_context(sqlite3_context *p, int nByte){
  assert( p && p->pFunc && p->pFunc->xStep );
  Mem *pMem = p->pMem;
  if( (pMem->flags & MEM_Agg)==0 ){
    if( nByte==0 ){
      assert( pMem->flags==MEM_Null );
      pMem->z = 0;
    }else{
      pMem->flags = MEM_Agg;
      *(FuncDef**)&pMem->i = p->pFunc;
      if( nByte<=NBFS ){
        pMem->z = pMem->zShort;
        memset(pMem->z, 0, nByte);
      }else{
        pMem->z = sqliteMalloc( nByte );
      }
    }
  }
  return (void*)pMem->z;
}

/*
** Return the auxilary data pointer, if any, for the iArg'th argument to

}

/*
** Memory cell pMem contains the context of an aggregate function.
** This routine calls the finalize method for that function.  The
** result of the aggregate is stored back into pMem.
*/
void sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){


  if( pFunc && pFunc->xFinalize ){
    sqlite3_context ctx;
    assert( (pMem->flags & MEM_Null)!=0 || pFunc==*(FuncDef**)&pMem->i );
    ctx.s.flags = MEM_Null;
    ctx.s.z = pMem->zShort;
    ctx.pMem = pMem;
    ctx.pFunc = pFunc;
    pFunc->xFinalize(&ctx);
    if( pMem->z && pMem->z!=pMem->zShort ){
      sqliteFree( pMem->z );
    }
    *pMem = ctx.s;
    if( pMem->flags & MEM_Short ){
      pMem->z = pMem->zShort;

    }
  }
}

/*
** Release any memory held by the Mem. This may leave the Mem in an
** inconsistent state, for example with (Mem.z==0) and
** (Mem.type==SQLITE_TEXT).
*/
void sqlite3VdbeMemRelease(Mem *p){
  if( p->flags & (MEM_Dyn|MEM_Agg) ){
    if( p->xDel ){
      if( p->flags & MEM_Agg ){
        sqlite3VdbeMemFinalize(p, *(FuncDef**)&p->i);
        assert( (p->flags & MEM_Agg)==0 );
        sqlite3VdbeMemRelease(p);
      }else{
        p->xDel((void *)p->z);
      }
    }else{
      sqliteFree(p->z);