/* ***** 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 Pseudo Weak References for Web Content.
 *
 * The Initial Developer of the Original Code is Mozilla.
 * Portions created by the Initial Developer are Copyright (C) 2007
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Atul Varma <atul@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

// This Ubiquity page-load function injects the following functions for memory
// debugging into webpages:
//
// * window.PseudoWeakRef(object) makes a pseudo-weak reference for the
//   object.  It has one method, exists(), which returns whether or not
//   the referent still exists (i.e., has not been garbage collected).
//
// * window.forceGC() forces garbage collection.

function pageLoad_injectPseudoWeakRefs(document) {
  var sandbox = Components.utils.Sandbox(document.defaultView);
  var weakrefs = [];

  function makePseudoWeakRef(object) {
    var weakref = new Components.utils.getWeakReference(object);
    object = null;
    weakrefs.push(weakref);
    return weakrefs.length - 1;
  }

  function isReferentAlive(id) {
    if (typeof(id) == "number" && weakrefs[id]) {
      if (weakrefs[id].get() != null)
        return true;
      else
        delete weakrefs[id];
    }
    return false;
  }

  function forceGC() {
    Components.utils.forceGC();
  }

  sandbox.importFunction(makePseudoWeakRef);
  sandbox.importFunction(isReferentAlive);
  sandbox.importFunction(forceGC);

  function PseudoWeakRef(object) {
    var id = makePseudoWeakRef(object);
    object = null;
    this.exists = function() {
      return isReferentAlive(id);
    };
  }

  Components.utils.evalInSandbox(PseudoWeakRef.toString(), sandbox);

  sandbox.window = document.defaultView.wrappedJSObject;
  Components.utils.evalInSandbox(
    ("window.PseudoWeakRef = PseudoWeakRef;" +
     "window.forceGC = forceGC;"),
    sandbox
  );
}