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
5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 
7 #ifndef nsObserverList_h___
8 #define nsObserverList_h___
9 
10 #include "nsISupports.h"
11 #include "nsTArray.h"
12 #include "nsCOMPtr.h"
13 #include "nsCOMArray.h"
14 #include "nsIObserver.h"
15 #include "nsIWeakReference.h"
16 #include "nsHashKeys.h"
17 #include "nsISimpleEnumerator.h"
18 #include "mozilla/Attributes.h"
19 
20 struct ObserverRef {
ObserverRefObserverRef21   ObserverRef(const ObserverRef& aO) : isWeakRef(aO.isWeakRef), ref(aO.ref) {}
ObserverRefObserverRef22   explicit ObserverRef(nsIObserver* aObserver)
23       : isWeakRef(false), ref(aObserver) {}
ObserverRefObserverRef24   explicit ObserverRef(nsIWeakReference* aWeak) : isWeakRef(true), ref(aWeak) {}
25 
26   bool isWeakRef;
27   nsCOMPtr<nsISupports> ref;
28 
asObserverObserverRef29   nsIObserver* asObserver() {
30     NS_ASSERTION(!isWeakRef, "Isn't a strong ref.");
31     return static_cast<nsIObserver*>((nsISupports*)ref);
32   }
33 
asWeakObserverRef34   nsIWeakReference* asWeak() {
35     NS_ASSERTION(isWeakRef, "Isn't a weak ref.");
36     return static_cast<nsIWeakReference*>((nsISupports*)ref);
37   }
38 
39   bool operator==(nsISupports* aRhs) const { return ref == aRhs; }
40 };
41 
42 class nsObserverList : public nsCharPtrHashKey {
43   friend class nsObserverService;
44 
45  public:
nsObserverList(const char * aKey)46   explicit nsObserverList(const char* aKey) : nsCharPtrHashKey(aKey) {
47     MOZ_COUNT_CTOR(nsObserverList);
48   }
49 
~nsObserverList()50   ~nsObserverList() { MOZ_COUNT_DTOR(nsObserverList); }
51 
52   MOZ_MUST_USE nsresult AddObserver(nsIObserver* aObserver, bool aOwnsWeak);
53   MOZ_MUST_USE nsresult RemoveObserver(nsIObserver* aObserver);
54 
55   void NotifyObservers(nsISupports* aSubject, const char* aTopic,
56                        const char16_t* aSomeData);
57   void GetObserverList(nsISimpleEnumerator** aEnumerator);
58 
59   // Fill an array with the observers of this category.
60   // The array is filled in last-added-first order.
61   void FillObserverArray(nsCOMArray<nsIObserver>& aArray);
62 
63   // Like FillObserverArray(), but only for strongly held observers.
64   void AppendStrongObservers(nsCOMArray<nsIObserver>& aArray);
65 
66  private:
67   nsTArray<ObserverRef> mObservers;
68 };
69 
70 class nsObserverEnumerator final : public nsISimpleEnumerator {
71  public:
72   NS_DECL_ISUPPORTS
73   NS_DECL_NSISIMPLEENUMERATOR
74 
75   explicit nsObserverEnumerator(nsObserverList* aObserverList);
76 
77  private:
~nsObserverEnumerator()78   ~nsObserverEnumerator() {}
79 
80   int32_t mIndex;  // Counts up from 0
81   nsCOMArray<nsIObserver> mObservers;
82 };
83 
84 #endif /* nsObserverList_h___ */
85