SQLite

** This file contains the C functions that implement various SQL
** functions of SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.106 2005/08/28 17:00:23 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <assert.h>
#include "vdbeInt.h"

  if( p && SQLITE_NULL!=sqlite3_value_type(argv[0]) ){
    p->sum += sqlite3_value_double(argv[0]);
    p->cnt++;
  }
}
static void sumFinalize(sqlite3_context *context){
  SumCtx *p;
  p = sqlite3_aggregate_context(context, sizeof(*p));
  sqlite3_result_double(context, p ? p->sum : 0.0);
}
static void avgFinalize(sqlite3_context *context){
  SumCtx *p;
  p = sqlite3_aggregate_context(context, sizeof(*p));
  if( p && p->cnt>0 ){
    sqlite3_result_double(context, p->sum/(double)p->cnt);
  }
}

/*
** An instance of the following structure holds the context of a

  p = sqlite3_aggregate_context(context, sizeof(*p));
  if( (argc==0 || SQLITE_NULL!=sqlite3_value_type(argv[0])) && p ){
    p->n++;
  }
}   
static void countFinalize(sqlite3_context *context){
  CountCtx *p;
  p = sqlite3_aggregate_context(context, sizeof(*p));
  sqlite3_result_int(context, p ? p->n : 0);
}

/*
** Routines to implement min() and max() aggregate functions.
*/
static void minmaxStep(sqlite3_context *context, int argc, sqlite3_value **argv){

    }
  }else{
    sqlite3VdbeMemCopy(pBest, pArg);
  }
}
static void minMaxFinalize(sqlite3_context *context){
  sqlite3_value *pRes;
  pRes = (sqlite3_value *)sqlite3_aggregate_context(context, sizeof(Mem));

  if( pRes->flags ){
    sqlite3_result_value(context, pRes);
  }
  sqlite3VdbeMemRelease(pRes);

}


/*
** This function registered all of the above C functions as SQL
** functions.  This should be the only routine in this file with
** external linkage.

**
** 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 1.480 2005/09/01 12:16:29 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

  for(i=0; i<n; i++, pRec++){
    apVal[i] = pRec;
    storeTypeInfo(pRec, db->enc);
  }
  i = pTos->i;
  assert( i>=0 && i<p->pAgg->nMem );
  ctx.pFunc = (FuncDef*)pOp->p3;
  pMem = &p->pAgg->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.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;
  }
  (ctx.pFunc->xStep)(&ctx, n, apVal);
  pMem->z = ctx.pAgg;
  pMem->flags = MEM_AggCtx;
  popStack(&pTos, n+1);
  if( ctx.isError ){
    rc = SQLITE_ERROR;
  }
  break;
}

    }
  }
  if( rc!=SQLITE_OK ) goto abort_due_to_error;
  if( res!=0 ){
    pc = pOp->p2 - 1;
  }else{
    int i;
    sqlite3_context ctx;
    Mem *aMem;

    if( p->pAgg->pCsr ){
      rc = sqlite3BtreeData(p->pAgg->pCsr, 0, sizeof(AggElem*),
          (char *)&p->pAgg->pCurrent);
      if( rc!=SQLITE_OK ) goto abort_due_to_error;
    }
    aMem = p->pAgg->pCurrent->aMem;
    for(i=0; i<p->pAgg->nMem; i++){
      FuncDef *pFunc = p->pAgg->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.pFunc = pFunc;
      pFunc->xFinalize(&ctx);
      pMem->z = ctx.pAgg;
      if( pMem->z && pMem->z!=pMem->zShort ){
        sqliteFree( pMem->z );
      }
      *pMem = ctx.s;
      if( pMem->flags & MEM_Short ){
        pMem->z = pMem->zShort;
      }
    }
  }
  break;
}

/* Opcode: Vacuum * * *
**

**
** Each value has a manifest type. The manifest type of the value stored
** in a Mem struct is returned by the MemType(Mem*) macro. The type is
** one of SQLITE_NULL, SQLITE_INTEGER, SQLITE_REAL, SQLITE_TEXT or
** SQLITE_BLOB.
*/
struct Mem {
  i64 i;              /* Integer value */


  int n;              /* Number of characters in string value, including '\0' */
  u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
  u8  type;           /* One of MEM_Null, MEM_Str, etc. */
  u8  enc;            /* TEXT_Utf8, TEXT_Utf16le, or TEXT_Utf16be */
  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.

** string is \000 or \u0000 terminated
*/
#define MEM_Term      0x0020   /* String rep is nul terminated */
#define MEM_Dyn       0x0040   /* Need to call sqliteFree() on Mem.z */
#define MEM_Static    0x0080   /* Mem.z points to a static string */
#define MEM_Ephem     0x0100   /* Mem.z points to an ephemeral string */
#define MEM_Short     0x0200   /* Mem.z points to Mem.zShort */

/* The following MEM_ value appears only in AggElem.aMem.s.flag fields.
** It indicates that the corresponding AggElem.aMem.z points to a
** aggregate function context that needs to be finalized.
*/
#define MEM_AggCtx    0x0400  /* Mem.z points to an agg function context */


/* A VdbeFunc is just a FuncDef (defined in sqliteInt.h) that contains
** additional information about auxiliary information bound to arguments
** of the function.  This is used to implement the sqlite3_get_auxdata()
** and sqlite3_set_auxdata() APIs.  The "auxdata" is some auxiliary data
** that can be associated with a constant argument to a function.  This

** implement the SQL functions.
**
** There is a typedef for this structure in sqlite.h.  So all routines,
** even the public interface to SQLite, can use a pointer to this structure.
** But this file is the only place where the internal details of this
** structure are known.
**
** This structure is defined inside of vdbe.c because it uses substructures
** (Mem) which are only defined there.
*/
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 */
  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
** a key and one or more values.  The values are used in processing
** aggregate functions in a SELECT.  The key is used to implement

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);

#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);
void sqlite3VdbeFifoInit(Fifo*);
int sqlite3VdbeFifoPush(Fifo*, i64);
int sqlite3VdbeFifoPop(Fifo*, i64*);
void sqlite3VdbeFifoClear(Fifo*);

/*
** 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 );
  if( p->pAgg==0 ){



    if( nByte<=NBFS ){
      p->pAgg = (void*)p->s.z;
      memset(p->pAgg, 0, nByte);
    }else{
      p->pAgg = sqliteMalloc( nByte );
    }
  }
  return p->pAgg;
}

/*
** Return the auxilary data pointer, if any, for the iArg'th argument to
** the user-function defined by pCtx.
*/
void *sqlite3_get_auxdata(sqlite3_context *pCtx, int iArg){

**
** This routine is defined here in vdbe.c because it depends on knowing
** the internals of the sqlite3_context structure which is only defined in
** this source file.
*/
int sqlite3_aggregate_count(sqlite3_context *p){
  assert( p && p->pFunc && p->pFunc->xStep );
  return p->cnt;
}

/*
** Return the number of columns in the result set for the statement pStmt.
*/
int sqlite3_column_count(sqlite3_stmt *pStmt){
  Vdbe *pVm = (Vdbe *)pStmt;

** 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++){
    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.isError = 0;
      (*ctx.pFunc->xFinalize)(&ctx);
      pMem->z = ctx.pAgg;
      if( pMem->z!=0 && pMem->z!=pMem->zShort ){
        sqliteFree(pMem->z);
      }
      sqlite3VdbeMemRelease(&ctx.s);
    }else{
      sqlite3VdbeMemRelease(pMem);
    }
  }
  sqliteFree(pElem);
}

/*
** Reset an Agg structure.  Delete all its contents.
**

  pMem->n = strlen(z);
  pMem->z = z;
  pMem->enc = SQLITE_UTF8;
  pMem->flags |= MEM_Str | MEM_Short | MEM_Term;
  sqlite3VdbeChangeEncoding(pMem, enc);
  return rc;
}
























/*
** 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 ){
    if( p->xDel ){





      p->xDel((void *)p->z);

    }else{
      sqliteFree(p->z);
    }
    p->z = 0;
    p->xDel = 0;
  }
}