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/* 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/. */
/**
* This module implements the folder lookup service. Presently, this uses RDF as
* the backing store, but the intent is that this will eventually become the
* authoritative map.
*/
"use strict";
var Cc = Components.classes;
var Ci = Components.interfaces;
var Cr = Components.results;
Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
function isValidFolder(folder) {
// RDF is liable to return folders that don't exist, and we may be working
// with a deleted folder but we're still holding on to the reference. For
// valid folders, one of two scenarios is true: either the folder has a parent
// (the deletion code clears the parent to indicate its nonvalidity), or the
// folder is a root folder of some server. Getting the root folder may throw
// an exception if we attempted to create a server that doesn't exist, so we
// need to guard for that error.
try {
return folder.parent != null || folder.rootFolder == folder;
} catch (e) {
return false;
}
}
// This insures that the service is only created once
var gCreated = false;
function folderLookupService() {
if (gCreated)
throw Cr.NS_ERROR_ALREADY_INITIALIZED;
this._map = new Map();
gCreated = true;
}
folderLookupService.prototype = {
// XPCOM registration stuff
QueryInterface: XPCOMUtils.generateQI([Ci.nsIFolderLookupService]),
classID: Components.ID("{a30be08c-afc8-4fed-9af7-79778a23db23}"),
// nsIFolderLookupService impl
getFolderForURL: function (aUrl) {
let folder = null;
// First, see if the folder is in our cache.
if (this._map.has(aUrl)) {
let valid = false;
try {
folder = this._map.get(aUrl).QueryReferent(Ci.nsIMsgFolder);
valid = isValidFolder(folder);
} catch (e) {
// The object was deleted, so it's not valid
}
if (valid)
return folder;
// Don't keep around invalid folders.
this._map.delete(aUrl);
folder = null;
}
// If we get here, then the folder was not in our map. It could be that the
// folder was created by somebody else, so try to find that folder.
// For now, we use the RDF service, since it results in minimal changes. But
// RDF has a tendency to create objects without checking to see if they
// really exist---use the parent property to see if the folder is a real
// folder.
if (folder == null) {
let rdf = Cc["@mozilla.org/rdf/rdf-service;1"]
.getService(Ci.nsIRDFService);
try {
folder = rdf.GetResource(aUrl)
.QueryInterface(Ci.nsIMsgFolder);
} catch (e) {
// If the QI fails, then we somehow picked up an RDF resource that isn't
// a folder. Return null in this case.
return null;
}
}
if (!isValidFolder(folder))
return null;
// Add the new folder to our map. Store a weak reference instead, so that
// the folder can be closed when necessary.
let weakRef = folder.QueryInterface(Ci.nsISupportsWeakReference)
.GetWeakReference();
this._map.set(aUrl, weakRef);
return folder;
},
};
var NSGetFactory = XPCOMUtils.generateNSGetFactory([folderLookupService]);
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