/* -*- 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/. */

// nsWeakReference.cpp

#include "mozilla/Attributes.h"

#include "nsWeakReference.h"

#include "nsCOMPtr.h"

#include "nsDebug.h"

class nsWeakReference final : public nsIWeakReference

{

public:

  // nsISupports...

  NS_DECL_ISUPPORTS

  // nsIWeakReference...

  NS_DECL_NSIWEAKREFERENCE

  size_t SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const override;

private:

  friend class nsSupportsWeakReference;

  explicit nsWeakReference(nsSupportsWeakReference* aReferent)

    : nsIWeakReference(aReferent)

    // ...I can only be constructed by an |nsSupportsWeakReference|

  {

  }

  ~nsWeakReference()

  // ...I will only be destroyed by calling |delete| myself.

  {

    MOZ_WEAKREF_ASSERT_OWNINGTHREAD;

    if (mObject) {

      static_cast<nsSupportsWeakReference*>(mObject)->NoticeProxyDestruction();

    }

  }

  void

  NoticeReferentDestruction()

  // ...called (only) by an |nsSupportsWeakReference| from _its_ dtor.

  {

    MOZ_WEAKREF_ASSERT_OWNINGTHREAD;

    mObject = nullptr;

  }

};

nsresult

nsQueryReferent::operator()(const nsIID& aIID, void** aAnswer) const

{

  nsresult status;

  if (mWeakPtr) {

    if (NS_FAILED(status = mWeakPtr->QueryReferent(aIID, aAnswer))) {

      *aAnswer = 0;

    }

  } else {

    status = NS_ERROR_NULL_POINTER;

  }

  if (mErrorPtr) {

    *mErrorPtr = status;

  }

  return status;

}

nsIWeakReference*

NS_GetWeakReference(nsISupportsWeakReference* aInstancePtr, nsresult* aErrorPtr)

{

  nsresult status;

  nsIWeakReference* result = nullptr;

  if (aInstancePtr) {

    status = aInstancePtr->GetWeakReference(&result);

  } else {

    status = NS_ERROR_NULL_POINTER;

  }

  if (aErrorPtr) {

    *aErrorPtr = status;

  }

  return result;

}

nsIWeakReference*  // or else |already_AddRefed<nsIWeakReference>|

NS_GetWeakReference(nsISupports* aInstancePtr, nsresult* aErrorPtr)

{

  nsresult status;

  nsIWeakReference* result = nullptr;

  if (aInstancePtr) {

    nsCOMPtr<nsISupportsWeakReference> factoryPtr =

      do_QueryInterface(aInstancePtr, &status);

    if (factoryPtr) {

      status = factoryPtr->GetWeakReference(&result);

    }

    // else, |status| has already been set by |do_QueryInterface|

  } else {

    status = NS_ERROR_NULL_POINTER;

  }

  if (aErrorPtr) {

    *aErrorPtr = status;

  }

  return result;

}

nsresult

nsSupportsWeakReference::GetWeakReference(nsIWeakReference** aInstancePtr)

{

  if (!aInstancePtr) {

    return NS_ERROR_NULL_POINTER;

  }

  if (!mProxy) {

    mProxy = new nsWeakReference(this);

  } else {

    MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(mProxy);

  }

  *aInstancePtr = mProxy;

  nsresult status;

  if (!*aInstancePtr) {

    status = NS_ERROR_OUT_OF_MEMORY;

  } else {

    NS_ADDREF(*aInstancePtr);

    status = NS_OK;

  }

  return status;

}

NS_IMPL_ISUPPORTS(nsWeakReference, nsIWeakReference)

NS_IMETHODIMP

nsWeakReference::QueryReferentFromScript(const nsIID& aIID, void** aInstancePtr)

{

  return QueryReferent(aIID, aInstancePtr);

}

nsresult

nsIWeakReference::QueryReferent(const nsIID& aIID, void** aInstancePtr)

{

  MOZ_WEAKREF_ASSERT_OWNINGTHREAD;

  if (!mObject) {

    return NS_ERROR_NULL_POINTER;

  }

  return mObject->QueryInterface(aIID, aInstancePtr);

}

size_t

nsWeakReference::SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const

{

  return aMallocSizeOf(this);

}

void

nsSupportsWeakReference::ClearWeakReferences()

{

  if (mProxy) {

    mProxy->NoticeReferentDestruction();

    mProxy = nullptr;

  }

}