1 files changed, 93 insertions, 0 deletions
diff --git a/xpcom/ds/nsObserverList.h b/xpcom/ds/nsObserverList.h
new file mode 100644
index 0000000000..90a685ea60
--- /dev/null
+++ b/xpcom/ds/nsObserverList.h
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef nsObserverList_h___
+#define nsObserverList_h___
+
+#include "nsISupports.h"
+#include "nsTArray.h"
+#include "nsCOMPtr.h"
+#include "nsCOMArray.h"
+#include "nsIObserver.h"
+#include "nsIWeakReference.h"
+#include "nsHashKeys.h"
+#include "nsISimpleEnumerator.h"
+#include "mozilla/Attributes.h"
+
+struct ObserverRef
+{
+  ObserverRef(const ObserverRef& aO) : isWeakRef(aO.isWeakRef), ref(aO.ref) {}
+  explicit ObserverRef(nsIObserver* aObserver) : isWeakRef(false), ref(aObserver) {}
+  explicit ObserverRef(nsIWeakReference* aWeak) : isWeakRef(true), ref(aWeak) {}
+
+  bool isWeakRef;
+  nsCOMPtr<nsISupports> ref;
+
+  nsIObserver* asObserver()
+  {
+    NS_ASSERTION(!isWeakRef, "Isn't a strong ref.");
+    return static_cast<nsIObserver*>((nsISupports*)ref);
+  }
+
+  nsIWeakReference* asWeak()
+  {
+    NS_ASSERTION(isWeakRef, "Isn't a weak ref.");
+    return static_cast<nsIWeakReference*>((nsISupports*)ref);
+  }
+
+  bool operator==(nsISupports* aRhs) const { return ref == aRhs; }
+};
+
+class nsObserverList : public nsCharPtrHashKey
+{
+  friend class nsObserverService;
+
+public:
+  explicit nsObserverList(const char* aKey) : nsCharPtrHashKey(aKey)
+  {
+    MOZ_COUNT_CTOR(nsObserverList);
+  }
+
+  ~nsObserverList()
+  {
+    MOZ_COUNT_DTOR(nsObserverList);
+  }
+
+  MOZ_MUST_USE nsresult AddObserver(nsIObserver* aObserver, bool aOwnsWeak);
+  MOZ_MUST_USE nsresult RemoveObserver(nsIObserver* aObserver);
+
+  void NotifyObservers(nsISupports* aSubject,
+                       const char* aTopic,
+                       const char16_t* aSomeData);
+  void GetObserverList(nsISimpleEnumerator** aEnumerator);
+
+  // Fill an array with the observers of this category.
+  // The array is filled in last-added-first order.
+  void FillObserverArray(nsCOMArray<nsIObserver>& aArray);
+
+  // Like FillObserverArray(), but only for strongly held observers.
+  void AppendStrongObservers(nsCOMArray<nsIObserver>& aArray);
+
+private:
+  nsTArray<ObserverRef> mObservers;
+};
+
+class nsObserverEnumerator final : public nsISimpleEnumerator
+{
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSISIMPLEENUMERATOR
+
+  explicit nsObserverEnumerator(nsObserverList* aObserverList);
+
+private:
+  ~nsObserverEnumerator() {}
+
+  int32_t mIndex; // Counts up from 0
+  nsCOMArray<nsIObserver> mObservers;
+};
+
+#endif /* nsObserverList_h___ */