gecko/js/xpconnect/loader/XPCOMUtils.jsm
Jim Blandy b6b202b6bb Bug 914753: Make Emacs file variable header lines correct, or at least consistent. DONTBUILD r=ehsan
The -*- file variable lines -*- establish per-file settings that Emacs will
pick up. This patch makes the following changes to those lines (and touches
nothing else):

 - Never set the buffer's mode.

   Years ago, Emacs did not have a good JavaScript mode, so it made sense
   to use Java or C++ mode in .js files. However, Emacs has had js-mode for
   years now; it's perfectly serviceable, and is available and enabled by
   default in all major Emacs packagings.

   Selecting a mode in the -*- file variable line -*- is almost always the
   wrong thing to do anyway. It overrides Emacs's default choice, which is
   (now) reasonable; and even worse, it overrides settings the user might
   have made in their '.emacs' file for that file extension. It's only
   useful when there's something specific about that particular file that
   makes a particular mode appropriate.

 - Correctly propagate settings that establish the correct indentation
   level for this file: c-basic-offset and js2-basic-offset should be
   js-indent-level. Whatever value they're given should be preserved;
   different parts of our tree use different indentation styles.

 - We don't use tabs in Mozilla JS code. Always set indent-tabs-mode: nil.
   Remove tab-width: settings, at least in files that don't contain tab
   characters.

 - Remove js2-mode settings that belong in the user's .emacs file, like
   js2-skip-preprocessor-directives.
2014-06-24 22:12:07 -07:00

340 lines
12 KiB
JavaScript

/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
* vim: sw=2 ts=2 sts=2 et filetype=javascript
* 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/. */
/**
* Utilities for JavaScript components loaded by the JS component
* loader.
*
* Import into a JS component using
* 'Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");'
*
* Exposing a JS 'class' as a component using these utility methods consists
* of several steps:
* 0. Import XPCOMUtils, as described above.
* 1. Declare the 'class' (or multiple classes) implementing the component(s):
* function MyComponent() {
* // constructor
* }
* MyComponent.prototype = {
* // properties required for XPCOM registration:
* classID: Components.ID("{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}"),
*
* // [optional] custom factory (an object implementing nsIFactory). If not
* // provided, the default factory is used, which returns
* // |(new MyComponent()).QueryInterface(iid)| in its createInstance().
* _xpcom_factory: { ... },
*
* // QueryInterface implementation, e.g. using the generateQI helper
* QueryInterface: XPCOMUtils.generateQI(
* [Components.interfaces.nsIObserver,
* Components.interfaces.nsIMyInterface,
* "nsIFoo",
* "nsIBar" ]),
*
* // [optional] classInfo implementation, e.g. using the generateCI helper.
* // Will be automatically returned from QueryInterface if that was
* // generated with the generateQI helper.
* classInfo: XPCOMUtils.generateCI(
* {classID: Components.ID("{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}"),
* contractID: "@example.com/xxx;1",
* classDescription: "unique text description",
* interfaces: [Components.interfaces.nsIObserver,
* Components.interfaces.nsIMyInterface,
* "nsIFoo",
* "nsIBar"],
* flags: Ci.nsIClassInfo.SINGLETON}),
*
* // The following properties were used prior to Mozilla 2, but are no
* // longer supported. They may still be included for compatibility with
* // prior versions of XPCOMUtils. In Mozilla 2, this information is
* // included in the .manifest file which registers this JS component.
* classDescription: "unique text description",
* contractID: "@example.com/xxx;1",
*
* // [optional] an array of categories to register this component in.
* _xpcom_categories: [{
* // Each object in the array specifies the parameters to pass to
* // nsICategoryManager.addCategoryEntry(). 'true' is passed for
* // both aPersist and aReplace params.
* category: "some-category",
* // optional, defaults to the object's classDescription
* entry: "entry name",
* // optional, defaults to the object's contractID (unless
* // 'service' is specified)
* value: "...",
* // optional, defaults to false. When set to true, and only if 'value'
* // is not specified, the concatenation of the string "service," and the
* // object's contractID is passed as aValue parameter of addCategoryEntry.
* service: true,
* // optional, it can be an array of applications' IDs in the form:
* // [ "{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}", ... ]
* // If defined the component will be registered in this category only for
* // the provided applications.
* apps: [...]
* }],
*
* // ...component implementation...
* };
*
* 2. Create an array of component constructors (like the one
* created in step 1):
* var components = [MyComponent];
*
* 3. Define the NSGetFactory entry point:
* this.NSGetFactory = XPCOMUtils.generateNSGetFactory(components);
*/
this.EXPORTED_SYMBOLS = [ "XPCOMUtils" ];
const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;
const Cu = Components.utils;
this.XPCOMUtils = {
/**
* Generate a QueryInterface implementation. The returned function must be
* assigned to the 'QueryInterface' property of a JS object. When invoked on
* that object, it checks if the given iid is listed in the |interfaces|
* param, and if it is, returns |this| (the object it was called on).
* If the JS object has a classInfo property it'll be returned for the
* nsIClassInfo IID, generateCI can be used to generate the classInfo
* property.
*/
generateQI: function XPCU_generateQI(interfaces) {
/* Note that Ci[Ci.x] == Ci.x for all x */
return makeQI([Ci[i].name for each (i in interfaces) if (Ci[i])]);
},
/**
* Generate a ClassInfo implementation for a component. The returned object
* must be assigned to the 'classInfo' property of a JS object. The first and
* only argument should be an object that contains a number of optional
* properties: "interfaces", "contractID", "classDescription", "classID" and
* "flags". The values of the properties will be returned as the values of the
* various properties of the nsIClassInfo implementation.
*/
generateCI: function XPCU_generateCI(classInfo)
{
if (QueryInterface in classInfo)
throw Error("In generateCI, don't use a component for generating classInfo");
/* Note that Ci[Ci.x] == Ci.x for all x */
var _interfaces = [Ci[i] for each (i in classInfo.interfaces) if (Ci[i])];
return {
getInterfaces: function XPCU_getInterfaces(countRef) {
countRef.value = _interfaces.length;
return _interfaces;
},
getHelperForLanguage: function XPCU_getHelperForLanguage(language) null,
contractID: classInfo.contractID,
classDescription: classInfo.classDescription,
classID: classInfo.classID,
implementationLanguage: Ci.nsIProgrammingLanguage.JAVASCRIPT,
flags: classInfo.flags,
QueryInterface: this.generateQI([Ci.nsIClassInfo])
};
},
/**
* Generate a NSGetFactory function given an array of components.
*/
generateNSGetFactory: function XPCU_generateNSGetFactory(componentsArray) {
let classes = {};
for each (let component in componentsArray) {
if (!(component.prototype.classID instanceof Components.ID))
throw Error("In generateNSGetFactory, classID missing or incorrect for component " + component);
classes[component.prototype.classID] = this._getFactory(component);
}
return function NSGetFactory(cid) {
let cidstring = cid.toString();
if (cidstring in classes)
return classes[cidstring];
throw Cr.NS_ERROR_FACTORY_NOT_REGISTERED;
}
},
/**
* Defines a getter on a specified object that will be created upon first use.
*
* @param aObject
* The object to define the lazy getter on.
* @param aName
* The name of the getter to define on aObject.
* @param aLambda
* A function that returns what the getter should return. This will
* only ever be called once.
*/
defineLazyGetter: function XPCU_defineLazyGetter(aObject, aName, aLambda)
{
Object.defineProperty(aObject, aName, {
get: function () {
delete aObject[aName];
return aObject[aName] = aLambda.apply(aObject);
},
configurable: true,
enumerable: true
});
},
/**
* Defines a getter on a specified object for a service. The service will not
* be obtained until first use.
*
* @param aObject
* The object to define the lazy getter on.
* @param aName
* The name of the getter to define on aObject for the service.
* @param aContract
* The contract used to obtain the service.
* @param aInterfaceName
* The name of the interface to query the service to.
*/
defineLazyServiceGetter: function XPCU_defineLazyServiceGetter(aObject, aName,
aContract,
aInterfaceName)
{
this.defineLazyGetter(aObject, aName, function XPCU_serviceLambda() {
return Cc[aContract].getService(Ci[aInterfaceName]);
});
},
/**
* Defines a getter on a specified object for a module. The module will not
* be imported until first use.
*
* @param aObject
* The object to define the lazy getter on.
* @param aName
* The name of the getter to define on aObject for the module.
* @param aResource
* The URL used to obtain the module.
* @param aSymbol
* The name of the symbol exported by the module.
* This parameter is optional and defaults to aName.
*/
defineLazyModuleGetter: function XPCU_defineLazyModuleGetter(aObject, aName,
aResource,
aSymbol)
{
this.defineLazyGetter(aObject, aName, function XPCU_moduleLambda() {
var temp = {};
try {
Cu.import(aResource, temp);
} catch (ex) {
Cu.reportError("Failed to load module " + aResource + ".");
throw ex;
}
return temp[aSymbol || aName];
});
},
/**
* Convenience access to category manager
*/
get categoryManager() {
return Components.classes["@mozilla.org/categorymanager;1"]
.getService(Ci.nsICategoryManager);
},
/**
* Helper which iterates over a nsISimpleEnumerator.
* @param e The nsISimpleEnumerator to iterate over.
* @param i The expected interface for each element.
*/
IterSimpleEnumerator: function XPCU_IterSimpleEnumerator(e, i)
{
while (e.hasMoreElements())
yield e.getNext().QueryInterface(i);
},
/**
* Helper which iterates over a string enumerator.
* @param e The string enumerator (nsIUTF8StringEnumerator or
* nsIStringEnumerator) over which to iterate.
*/
IterStringEnumerator: function XPCU_IterStringEnumerator(e)
{
while (e.hasMore())
yield e.getNext();
},
/**
* Returns an nsIFactory for |component|.
*/
_getFactory: function XPCOMUtils__getFactory(component) {
var factory = component.prototype._xpcom_factory;
if (!factory) {
factory = {
createInstance: function(outer, iid) {
if (outer)
throw Cr.NS_ERROR_NO_AGGREGATION;
return (new component()).QueryInterface(iid);
}
}
}
return factory;
},
/**
* Allows you to fake a relative import. Expects the global object from the
* module that's calling us, and the relative filename that we wish to import.
*/
importRelative: function XPCOMUtils__importRelative(that, path, scope) {
if (!("__URI__" in that))
throw Error("importRelative may only be used from a JSM, and its first argument "+
"must be that JSM's global object (hint: use this)");
let uri = that.__URI__;
let i = uri.lastIndexOf("/");
Components.utils.import(uri.substring(0, i+1) + path, scope || that);
},
/**
* generates a singleton nsIFactory implementation that can be used as
* the _xpcom_factory of the component.
* @param aServiceConstructor
* Constructor function of the component.
*/
generateSingletonFactory:
function XPCOMUtils_generateSingletonFactory(aServiceConstructor) {
return {
_instance: null,
createInstance: function XPCU_SF_createInstance(aOuter, aIID) {
if (aOuter !== null) {
throw Cr.NS_ERROR_NO_AGGREGATION;
}
if (this._instance === null) {
this._instance = new aServiceConstructor();
}
return this._instance.QueryInterface(aIID);
},
lockFactory: function XPCU_SF_lockFactory(aDoLock) {
throw Cr.NS_ERROR_NOT_IMPLEMENTED;
},
QueryInterface: XPCOMUtils.generateQI([Ci.nsIFactory])
};
},
};
/**
* Helper for XPCOMUtils.generateQI to avoid leaks - see bug 381651#c1
*/
function makeQI(interfaceNames) {
return function XPCOMUtils_QueryInterface(iid) {
if (iid.equals(Ci.nsISupports))
return this;
if (iid.equals(Ci.nsIClassInfo) && "classInfo" in this)
return this.classInfo;
for each(let interfaceName in interfaceNames) {
if (Ci[interfaceName].equals(iid))
return this;
}
throw Cr.NS_ERROR_NO_INTERFACE;
};
}