/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla.
 *
 * The Initial Developer of the Original Code is
 * Darin Fisher <darin@meer.net>.
 * Portions created by the Initial Developer are Copyright (C) 2004
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
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 * ***** END LICENSE BLOCK ***** */

#include "nsISupports.idl"

/**
 * This interface exposes the general notion of a scheduled object with a
 * integral priority value.  Following UNIX conventions, smaller (and possibly
 * negative) values have higher priority.
 *
 * This interface does not strictly define what happens when the priority of an
 * object is changed.  An implementation of this interface is free to define
 * the side-effects of changing the priority of an object.  In some cases,
 * changing the priority of an object may be disallowed (resulting in an
 * exception being thrown) or may simply be ignored.
 */
[scriptable, uuid(aa578b44-abd5-4c19-8b14-36d4de6fdc36)]
interface nsISupportsPriority : nsISupports
{
  /**
   * Typical priority values.
   */
  const long PRIORITY_HIGHEST = -20;
  const long PRIORITY_HIGH    = -10;
  const long PRIORITY_NORMAL  =   0;
  const long PRIORITY_LOW     =  10;
  const long PRIORITY_LOWEST  =  20;
  
  /**
   * This attribute may be modified to change the priority of this object.  The
   * implementation of this interface is free to truncate a given priority
   * value to whatever limits are appropriate.  Typically, this attribute is
   * initialized to PRIORITY_NORMAL, but implementations may choose to assign a
   * different initial value.
   */
  attribute long priority;

  /**
   * This method adjusts the priority attribute by a given delta.  It helps
   * reduce the amount of coding required to increment or decrement the value
   * of the priority attribute.
   */
  void adjustPriority(in long delta);
};