xpcom/ds/nsObserverList.cpp

   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 #include "nsObserverList.h"
   8
   9 #include "mozilla/ResultExtensions.h"
  10 #include "mozilla/Try.h"
  11 #include "nsCOMArray.h"
  12 #include "xpcpublic.h"
  13
  14 nsresult nsObserverList::AddObserver(nsIObserver* anObserver, bool ownsWeak) {
  15   NS_ASSERTION(anObserver, "Null input");
  16
  17   MOZ_TRY(mObservers.AppendWeakElement(anObserver, ownsWeak));
  18   return NS_OK;
  19 }
  20
  21 nsresult nsObserverList::RemoveObserver(nsIObserver* anObserver) {
  22   NS_ASSERTION(anObserver, "Null input");
  23
  24   MOZ_TRY(mObservers.RemoveWeakElement(anObserver));
  25   return NS_OK;
  26 }
  27
  28 void nsObserverList::GetObserverList(nsISimpleEnumerator** anEnumerator) {
  29   RefPtr<nsObserverEnumerator> e(new nsObserverEnumerator(this));
  30   e.forget(anEnumerator);
  31 }
  32
  33 nsCOMArray<nsIObserver> nsObserverList::ReverseCloneObserverArray() {
  34   nsCOMArray<nsIObserver> array;
  35   array.SetCapacity(mObservers.Length());
  36
  37   // XXX This could also use RemoveElementsBy if we lifted the promise to fill
  38   // aArray in reverse order. Although there shouldn't be anyone explicitly
  39   // relying on the order, changing this might cause subtle problems, so we
  40   // better leave it as it is.
  41
  42   for (int32_t i = mObservers.Length() - 1; i >= 0; --i) {
  43     nsCOMPtr<nsIObserver> observer = mObservers[i].GetValue();
  44     if (observer) {
  45       array.AppendElement(observer.forget());
  46     } else {
  47       // the object has gone away, remove the weakref
  48       mObservers.RemoveElementAt(i);
  49     }
  50   }
  51
  52   return array;
  53 }
  54
  55 void nsObserverList::AppendStrongObservers(nsCOMArray<nsIObserver>& aArray) {
  56   aArray.SetCapacity(aArray.Length() + mObservers.Length());
  57
  58   for (int32_t i = mObservers.Length() - 1; i >= 0; --i) {
  59     if (!mObservers[i].IsWeak()) {
  60       nsCOMPtr<nsIObserver> observer = mObservers[i].GetValue();
  61       aArray.AppendObject(observer);
  62     }
  63   }
  64 }
  65
  66 void nsObserverList::NotifyObservers(nsISupports* aSubject, const char* aTopic,
  67                                      const char16_t* someData) {
  68   const nsCOMArray<nsIObserver> observers = ReverseCloneObserverArray();
  69
  70   for (int32_t i = 0; i < observers.Count(); ++i) {
  71     observers[i]->Observe(aSubject, aTopic, someData);
  72   }
  73 }
  74
  75 nsObserverEnumerator::nsObserverEnumerator(nsObserverList* aObserverList)
  76     : mIndex(0), mObservers(aObserverList->ReverseCloneObserverArray()) {}
  77
  78 NS_IMETHODIMP
  79 nsObserverEnumerator::HasMoreElements(bool* aResult) {
  80   *aResult = (mIndex < mObservers.Count());
  81   return NS_OK;
  82 }
  83
  84 NS_IMETHODIMP
  85 nsObserverEnumerator::GetNext(nsISupports** aResult) {
  86   if (mIndex == mObservers.Count()) {
  87     return NS_ERROR_FAILURE;
  88   }
  89
  90   NS_ADDREF(*aResult = mObservers[mIndex]);
  91   ++mIndex;
  92   return NS_OK;
  93 }