storage/mozIStorageAggregateFunction.idl

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsISupports.idl"
   7
   8 interface mozIStorageConnection;
   9 interface mozIStorageValueArray;
  10 interface nsIArray;
  11 interface nsIVariant;
  12
  13 /**
  14  * mozIStorageAggregateFunction represents aggregate SQL function.
  15  * Common examples of aggregate functions are SUM() and COUNT().
  16  *
  17  * An aggregate function calculates one result for a given set of data, where
  18  * a set of data is a group of tuples. There can be one group
  19  * per request or many of them, if GROUP BY clause is used or not.
  20  */
  21 [scriptable, uuid(763217b7-3123-11da-918d-000347412e16)]
  22 interface mozIStorageAggregateFunction : nsISupports {
  23   /**
  24    * onStep is called when next value should be passed to
  25    * a custom function.
  26    *
  27    * @param aFunctionArguments    The arguments passed in to the function
  28    */
  29   void onStep(in mozIStorageValueArray aFunctionArguments);
  30
  31   /**
  32    * Called when all tuples in a group have been processed and the engine
  33    * needs the aggregate function's value.
  34    *
  35    * @returns aggregate result as Variant.
  36    */
  37   nsIVariant onFinal();
  38 };