gecko-dev/storage/public/mozIStorageAggregateFunction.idl
2012-05-21 12:12:37 +01:00

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "nsISupports.idl"
interface mozIStorageConnection;
interface mozIStorageValueArray;
interface nsIArray;
interface nsIVariant;
/**
* mozIStorageAggregateFunction represents aggregate SQL function.
* Common examples of aggregate functions are SUM() and COUNT().
*
* An aggregate function calculates one result for a given set of data, where
* a set of data is a group of tuples. There can be one group
* per request or many of them, if GROUP BY clause is used or not.
*/
[scriptable, uuid(763217b7-3123-11da-918d-000347412e16)]
interface mozIStorageAggregateFunction : nsISupports {
/**
* onStep is called when next value should be passed to
* a custom function.
*
* @param aFunctionArguments The arguments passed in to the function
*/
void onStep(in mozIStorageValueArray aFunctionArguments);
/**
* Called when all tuples in a group have been processed and the engine
* needs the aggregate function's value.
*
* @returns aggregate result as Variant.
*/
nsIVariant onFinal();
};