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: #include "mozilla/WeakPtr.h"
michael@0: 
michael@0: using mozilla::SupportsWeakPtr;
michael@0: using mozilla::WeakPtr;
michael@0: 
michael@0: // To have a class C support weak pointers, inherit from SupportsWeakPtr<C>.
michael@0: class C : public SupportsWeakPtr<C>
michael@0: {
michael@0:   public:
michael@0:     MOZ_DECLARE_REFCOUNTED_TYPENAME(C)
michael@0:     int num;
michael@0:     void act() {}
michael@0: };
michael@0: 
michael@0: static void
michael@0: Example()
michael@0: {
michael@0: 
michael@0:   C* ptr =  new C();
michael@0: 
michael@0:   // Get weak pointers to ptr. The first time asWeakPtr is called
michael@0:   // a reference counted WeakReference object is created that
michael@0:   // can live beyond the lifetime of 'ptr'. The WeakReference
michael@0:   // object will be notified of 'ptr's destruction.
michael@0:   WeakPtr<C> weak = ptr->asWeakPtr();
michael@0:   WeakPtr<C> other = ptr->asWeakPtr();
michael@0: 
michael@0:   // Test a weak pointer for validity before using it.
michael@0:   if (weak) {
michael@0:     weak->num = 17;
michael@0:     weak->act();
michael@0:   }
michael@0: 
michael@0:   // Destroying the underlying object clears weak pointers to it.
michael@0:   delete ptr;
michael@0: 
michael@0:   MOZ_RELEASE_ASSERT(!weak, "Deleting |ptr| clears weak pointers to it.");
michael@0:   MOZ_RELEASE_ASSERT(!other, "Deleting |ptr| clears all weak pointers to it.");
michael@0: }
michael@0: 
michael@0: struct A : public SupportsWeakPtr<A>
michael@0: {
michael@0:     MOZ_DECLARE_REFCOUNTED_TYPENAME(A)
michael@0:     int data;
michael@0: };
michael@0: 
michael@0: 
michael@0: int
michael@0: main()
michael@0: {
michael@0: 
michael@0:   A* a = new A;
michael@0: 
michael@0:   // a2 is unused to test the case when we haven't initialized
michael@0:   // the internal WeakReference pointer.
michael@0:   A* a2 = new A;
michael@0: 
michael@0:   a->data = 5;
michael@0:   WeakPtr<A> ptr = a->asWeakPtr();
michael@0:   {
michael@0:       WeakPtr<A> ptr2 = a->asWeakPtr();
michael@0:       MOZ_RELEASE_ASSERT(ptr->data == 5);
michael@0:       WeakPtr<A> ptr3 = a->asWeakPtr();
michael@0:       MOZ_RELEASE_ASSERT(ptr->data == 5);
michael@0:   }
michael@0: 
michael@0:   delete a;
michael@0:   MOZ_RELEASE_ASSERT(!ptr);
michael@0: 
michael@0:   delete a2;
michael@0: 
michael@0:   Example();
michael@0: 
michael@0:   return 0;
michael@0: }