SQLite

** KEYWORDS: {function creation routines}
** KEYWORDS: {application-defined SQL function}
** KEYWORDS: {application-defined SQL functions}
** METHOD: sqlite3
**
** ^These functions (collectively known as "function creation routines")
** are used to add SQL functions or aggregates or to redefine the behavior
** of existing SQL functions or aggregates. The only differences between
** the three "sqlite3_create_function*" routines are the text encoding 
** expected for the second parameter (the name of the function being 
** created) and the presence or absence of a destructor callback for
** the application data pointer. Function sqlite3_create_window_function()
** is similar, but allows the user to supply the extra callback functions
** needed by [aggregate window functions].
**
** ^The first parameter is the [database connection] to which the SQL
** function is to be added.  ^If an application uses more than one database
** connection then application-defined SQL functions must be added
** to each database connection separately.
**
** ^The second parameter is the name of the SQL function to be created or

** function that is not deterministic.  The SQLite query planner is able to
** perform additional optimizations on deterministic functions, so use
** of the [SQLITE_DETERMINISTIC] flag is recommended where possible.
**
** ^(The fifth parameter is an arbitrary pointer.  The implementation of the
** function can gain access to this pointer using [sqlite3_user_data()].)^
**
** ^The sixth, seventh and eighth parameters passed to the three
** "sqlite3_create_function*" functions, xFunc, xStep and xFinal, are
** pointers to C-language functions that implement the SQL function or
** aggregate. ^A scalar SQL function requires an implementation of the xFunc
** callback only; NULL pointers must be passed as the xStep and xFinal
** parameters. ^An aggregate SQL function requires an implementation of xStep
** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
** SQL function or aggregate, pass NULL pointers for all three function
** callbacks.
**
** ^The sixth, seventh, eighth and ninth parameters (xStep, xFinal, xValue 
** and xInverse) passed to sqlite3_create_window_function are pointers to
** C-lanugage callbacks that implement the new function. xStep and xFinal
** must both be non-NULL. xValue and xInverse may either both be NULL, in
** which case a regular aggregate function is created, or must both be 
** non-NULL, in which case the new function may be used as either an aggregate
** or aggregate window function. More details regarding the implementation
** of aggregate window functions are 
** [user-defined window functions|available here].
**
** ^(If the final parameter to sqlite3_create_function_v2() or
** sqlite3_create_window_function() is not NULL, then it is destructor for
** the application data pointer. The destructor is invoked when the function 
** is deleted, either by being overloaded or when the database connection 
** closes.)^ ^The destructor is also invoked if the call to 
** sqlite3_create_function_v2() fails.  ^When the destructor callback is

** invoked, it is passed a single argument which is a copy of the application
** data pointer which was the fifth parameter to sqlite3_create_function_v2().
**
** ^It is permitted to register multiple implementations of the same
** functions with the same name but with either differing numbers of
** arguments or differing preferred text encodings.  ^SQLite will use
** the implementation that most closely matches the way in which the
** SQL function is used.  ^A function implementation with a non-negative
** nArg parameter is a better match than a function implementation with

  return TCL_OK;

 error:
  Tcl_SetObjResult(interp, Tcl_NewStringObj("misuse test error", -1));
  return TCL_ERROR;
}

/*
** xStep for sumint().
*/
static void sumintStep(
  sqlite3_context *ctx, 
  int nArg, 
  sqlite3_value *apArg[]
){
  sqlite3_int64 *pInt;

  assert( nArg==1 );
  if( sqlite3_value_type(apArg[0])!=SQLITE_INTEGER ){
    sqlite3_result_error(ctx, "invalid argument", -1);
    return;
  }
  pInt = (sqlite3_int64*)sqlite3_aggregate_context(ctx, sizeof(sqlite3_int64));
  if( pInt ){
    *pInt += sqlite3_value_int64(apArg[0]);
  }
}

/*
** xInverse for sumint().
*/
static void sumintInverse(
  sqlite3_context *ctx, 
  int nArg, 
  sqlite3_value *apArg[]
){
  sqlite3_int64 *pInt;
  pInt = (sqlite3_int64*)sqlite3_aggregate_context(ctx, sizeof(sqlite3_int64));
  *pInt -= sqlite3_value_int64(apArg[0]);
}

/*
** xFinal for sumint().
*/
static void sumintFinal(sqlite3_context *ctx){
  sqlite3_int64 res = 0;
  sqlite3_int64 *pInt;
  pInt = (sqlite3_int64*)sqlite3_aggregate_context(ctx, 0);
  if( pInt ) res = *pInt;
  sqlite3_result_int64(ctx, res);
}

/*
** xValue for sumint().
*/
static void sumintValue(sqlite3_context *ctx){
  sqlite3_int64 res = 0;
  sqlite3_int64 *pInt;
  pInt = (sqlite3_int64*)sqlite3_aggregate_context(ctx, 0);
  if( pInt ) res = *pInt;
  sqlite3_result_int64(ctx, res);
}

static int SQLITE_TCLAPI test_create_sumint(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3 *db;
  int rc;

  if( objc!=2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;

  rc = sqlite3_create_window_function(db, "sumint", 1, SQLITE_UTF8, 0,
      sumintStep, sumintFinal, sumintValue, sumintInverse,
      0
  );

  if( rc!=SQLITE_OK ){
    Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
    return TCL_ERROR;
  }
  return TCL_OK;
}

int Sqlitetest_window_Init(Tcl_Interp *interp){
  static struct {
     char *zName;
     Tcl_ObjCmdProc *xProc;
     int clientData;
  } aObjCmd[] = {
     { "sqlite3_create_window_function", test_create_window, 0 },
     { "test_create_window_function_misuse", test_create_window_misuse, 0 },
     { "test_create_sumint", test_create_sumint, 0 },
  };
  int i;
  for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
    ClientData c = (ClientData)SQLITE_INT_TO_PTR(aObjCmd[i].clientData);
    Tcl_CreateObjCommand(interp, aObjCmd[i].zName, aObjCmd[i].xProc, c, 0);
  }
  return TCL_OK;

  INSERT INTO t1 VALUES(2, 'e');
  INSERT INTO t1 VALUES(3, 'f');
}

do_execsql_test 1.1 {
  SELECT win(a) OVER (ORDER BY b), median(a) OVER (ORDER BY b) FROM t1;
} {4 4  {4 6} 5  {1 4 6} 4  {1 4 5 6} 4.5  {1 2 4 5 6} 4 {1 2 3 4 5 6} 3.5}

test_create_sumint db
do_execsql_test 2.0 {
  SELECT sumint(a) OVER (ORDER BY rowid) FROM t1 ORDER BY rowid;
} {4 10 11 16 18 21}

do_execsql_test 2.1 {
  SELECT sumint(a) OVER (ORDER BY rowid ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING) FROM t1 ORDER BY rowid;
} {10 11 12 8 10 5}


finish_test