1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
6 
7 /**
8  * A simplere nsIGlobalObject implementation that can be used to set up a new
9  * global without anything interesting in it other than the JS builtins.  This
10  * is safe to use on both mainthread and worker threads.
11  */
12 
13 #ifndef mozilla_dom_SimpleGlobalObject_h__
14 #define mozilla_dom_SimpleGlobalObject_h__
15 
16 #include "nsIGlobalObject.h"
17 #include "nsWrapperCache.h"
18 #include "js/TypeDecls.h"
19 #include "js/Value.h"
20 #include "nsISupportsImpl.h"
21 #include "nsCycleCollectionParticipant.h"
22 
23 namespace mozilla {
24 namespace dom {
25 
26 class SimpleGlobalObject : public nsIGlobalObject, public nsWrapperCache {
27  public:
28   enum class GlobalType {
29     BindingDetail,  // Should only be used by DOM bindings code.
30     WorkerDebuggerSandbox,
31     NotSimpleGlobal  // Sentinel to be used by BasicGlobalType.
32   };
33 
34   // Create a new JS global object that can be used to do some work.  This
35   // global will NOT have any DOM APIs exposed in it, will not be visible to the
36   // debugger, and will not have a useful concept of principals, so don't try to
37   // use it with any DOM objects.  Apart from that, running code with
38   // side-effects is safe in this global.  Importantly, when you are first
39   // handed this global it's guaranteed to have pristine built-ins.  The
40   // corresponding nsIGlobalObject* for this global object will be a
41   // SimpleGlobalObject of the type provided; JS::GetPrivate on the returned
42   // JSObject* will return the SimpleGlobalObject*.
43   //
44   // If the provided prototype value is undefined, it is ignored.  If it's an
45   // object or null, it's set as the prototype of the created global.  If it's
46   // anything else, this function returns null.
47   //
48   // Note that creating new globals is not cheap and should not be done
49   // gratuitously.  Please think carefully before you use this function.
50   static JSObject* Create(GlobalType globalType, JS::Handle<JS::Value> proto =
51                                                      JS::UndefinedHandleValue);
52 
53   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(SimpleGlobalObject,nsIGlobalObject)54   NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(SimpleGlobalObject,
55                                                          nsIGlobalObject)
56 
57   // Gets the GlobalType of this SimpleGlobalObject.
58   GlobalType Type() const { return mType; }
59 
60   // Gets the GlobalType of the SimpleGlobalObject for the given JSObject*, if
61   // the given JSObject* is the global corresponding to a SimpleGlobalObject.
62   // Oherwise, returns GlobalType::NotSimpleGlobal.
63   static GlobalType SimpleGlobalType(JSObject* obj);
64 
GetGlobalJSObject()65   JSObject* GetGlobalJSObject() override { return GetWrapper(); }
GetGlobalJSObjectPreserveColor()66   JSObject* GetGlobalJSObjectPreserveColor() const override {
67     return GetWrapperPreserveColor();
68   }
69 
WrapObject(JSContext * cx,JS::Handle<JSObject * > aGivenProto)70   virtual JSObject* WrapObject(JSContext* cx,
71                                JS::Handle<JSObject*> aGivenProto) override {
72     MOZ_CRASH("SimpleGlobalObject doesn't use DOM bindings!");
73   }
74 
75  private:
SimpleGlobalObject(JSObject * global,GlobalType type)76   SimpleGlobalObject(JSObject* global, GlobalType type) : mType(type) {
77     SetWrapper(global);
78   }
79 
~SimpleGlobalObject()80   virtual ~SimpleGlobalObject() { MOZ_ASSERT(!GetWrapperMaybeDead()); }
81 
82   const GlobalType mType;
83 };
84 
85 }  // namespace dom
86 }  // namespace mozilla
87 
88 #endif /* mozilla_dom_SimpleGlobalObject_h__ */
89