gecko-dev/xpcom/ds/nsObserverList.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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/. */

#include "nsObserverList.h"

#include "nsAutoPtr.h"
#include "nsCOMArray.h"
#include "nsISimpleEnumerator.h"
#include "xpcpublic.h"

nsresult
nsObserverList::AddObserver(nsIObserver* anObserver, bool ownsWeak)
{
    NS_ASSERTION(anObserver, "Null input");

    if (!ownsWeak) {
        ObserverRef* o = mObservers.AppendElement(anObserver);
        if (!o)
            return NS_ERROR_OUT_OF_MEMORY;

        return NS_OK;
    }
        
    nsCOMPtr<nsIWeakReference> weak = do_GetWeakReference(anObserver);
    if (!weak)
        return NS_NOINTERFACE;

    ObserverRef *o = mObservers.AppendElement(weak);
    if (!o)
        return NS_ERROR_OUT_OF_MEMORY;

    return NS_OK;
}

nsresult
nsObserverList::RemoveObserver(nsIObserver* anObserver)
{
    NS_ASSERTION(anObserver, "Null input");

    if (mObservers.RemoveElement(static_cast<nsISupports*>(anObserver)))
        return NS_OK;

    nsCOMPtr<nsIWeakReference> observerRef = do_GetWeakReference(anObserver);
    if (!observerRef)
        return NS_ERROR_FAILURE;

    if (!mObservers.RemoveElement(observerRef))
        return NS_ERROR_FAILURE;

    return NS_OK;
}

nsresult
nsObserverList::GetObserverList(nsISimpleEnumerator** anEnumerator)
{
    nsRefPtr<nsObserverEnumerator> e(new nsObserverEnumerator(this));
    if (!e)
        return NS_ERROR_OUT_OF_MEMORY;

    NS_ADDREF(*anEnumerator = e);
    return NS_OK;
}

void
nsObserverList::FillObserverArray(nsCOMArray<nsIObserver> &aArray)
{
    aArray.SetCapacity(mObservers.Length());

    nsTArray<ObserverRef> observers(mObservers);

    for (int32_t i = observers.Length() - 1; i >= 0; --i) {
        if (observers[i].isWeakRef) {
            nsCOMPtr<nsIObserver> o(do_QueryReferent(observers[i].asWeak()));
            if (o) {
                aArray.AppendObject(o);
            }
            else {
                // the object has gone away, remove the weakref
                mObservers.RemoveElement(observers[i].asWeak());
            }
        }
        else {
            aArray.AppendObject(observers[i].asObserver());
        }
    }
}

void
nsObserverList::NotifyObservers(nsISupports *aSubject,
                                const char *aTopic,
                                const PRUnichar *someData)
{
    nsCOMArray<nsIObserver> observers;
    FillObserverArray(observers);

    for (int32_t i = 0; i < observers.Count(); ++i) {
        observers[i]->Observe(aSubject, aTopic, someData);
    }
}

void
nsObserverList::UnmarkGrayStrongObservers()
{
    for (uint32_t i = 0; i < mObservers.Length(); ++i) {
        if (!mObservers[i].isWeakRef) {
            xpc_TryUnmarkWrappedGrayObject(mObservers[i].asObserver());
        }
    }
}

NS_IMPL_ISUPPORTS1(nsObserverEnumerator, nsISimpleEnumerator)

nsObserverEnumerator::nsObserverEnumerator(nsObserverList* aObserverList)
    : mIndex(0)
{
    aObserverList->FillObserverArray(mObservers);
}

NS_IMETHODIMP
nsObserverEnumerator::HasMoreElements(bool *aResult)
{
    *aResult = (mIndex < mObservers.Count());
    return NS_OK;
}

NS_IMETHODIMP
nsObserverEnumerator::GetNext(nsISupports* *aResult)
{
    if (mIndex == mObservers.Count()) {
        NS_ERROR("Enumerating after HasMoreElements returned false.");
        return NS_ERROR_UNEXPECTED;
    }

    NS_ADDREF(*aResult = mObservers[mIndex]);
    ++mIndex;
    return NS_OK;
}