michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* vim: set ts=8 sts=2 et sw=2 tw=80: */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /* A class for non-null strong pointers to reference-counted objects. */
michael@0: 
michael@0: #ifndef mozilla_dom_OwningNonNull_h
michael@0: #define mozilla_dom_OwningNonNull_h
michael@0: 
michael@0: #include "nsAutoPtr.h"
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace dom {
michael@0: 
michael@0: template<class T>
michael@0: class OwningNonNull
michael@0: {
michael@0: public:
michael@0:   OwningNonNull()
michael@0: #ifdef DEBUG
michael@0:     : mInited(false)
michael@0: #endif
michael@0:   {}
michael@0: 
michael@0:   operator T&()
michael@0:   {
michael@0:     MOZ_ASSERT(mInited);
michael@0:     MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
michael@0:     return *mPtr;
michael@0:   }
michael@0: 
michael@0:   operator T*()
michael@0:   {
michael@0:     MOZ_ASSERT(mInited);
michael@0:     MOZ_ASSERT(mPtr, "OwningNonNull<T> was set to null");
michael@0:     return mPtr;
michael@0:   }
michael@0: 
michael@0:   void operator=(T* aValue)
michael@0:   {
michael@0:     init(aValue);
michael@0:   }
michael@0: 
michael@0:   void operator=(const already_AddRefed<T>& aValue)
michael@0:   {
michael@0:     init(aValue);
michael@0:   }
michael@0: 
michael@0:   already_AddRefed<T> forget()
michael@0:   {
michael@0: #ifdef DEBUG
michael@0:     mInited = false;
michael@0: #endif
michael@0:     return mPtr.forget();
michael@0:   }
michael@0: 
michael@0:   // Make us work with smart pointer helpers that expect a get().
michael@0:   T* get() const
michael@0:   {
michael@0:     MOZ_ASSERT(mInited);
michael@0:     MOZ_ASSERT(mPtr);
michael@0:     return mPtr;
michael@0:   }
michael@0: 
michael@0: protected:
michael@0:   template<typename U>
michael@0:   void init(U aValue)
michael@0:   {
michael@0:     mPtr = aValue;
michael@0:     MOZ_ASSERT(mPtr);
michael@0: #ifdef DEBUG
michael@0:     mInited = true;
michael@0: #endif
michael@0:   }
michael@0: 
michael@0:   nsRefPtr<T> mPtr;
michael@0: #ifdef DEBUG
michael@0:   bool mInited;
michael@0: #endif
michael@0: };
michael@0: 
michael@0: } // namespace dom
michael@0: } // namespace mozilla
michael@0: 
michael@0: #endif // mozilla_dom_OwningNonNull_h