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