The Tor Browser: mfbt/tests/TestWeakPtr.cpp@925c144e1f1f

     1 /* This Source Code Form is subject to the terms of the Mozilla Public

     2  * License, v. 2.0. If a copy of the MPL was not distributed with this

     3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

     5 #include "mozilla/WeakPtr.h"

     7 using mozilla::SupportsWeakPtr;

     8 using mozilla::WeakPtr;

    10 // To have a class C support weak pointers, inherit from SupportsWeakPtr<C>.

    11 class C : public SupportsWeakPtr<C>

    12 {

    13   public:

    14     MOZ_DECLARE_REFCOUNTED_TYPENAME(C)

    15     int num;

    16     void act() {}

    17 };

    19 static void

    20 Example()

    21 {

    23   C* ptr =  new C();

    25   // Get weak pointers to ptr. The first time asWeakPtr is called

    26   // a reference counted WeakReference object is created that

    27   // can live beyond the lifetime of 'ptr'. The WeakReference

    28   // object will be notified of 'ptr's destruction.

    29   WeakPtr<C> weak = ptr->asWeakPtr();

    30   WeakPtr<C> other = ptr->asWeakPtr();

    32   // Test a weak pointer for validity before using it.

    33   if (weak) {

    34     weak->num = 17;

    35     weak->act();

    36   }

    38   // Destroying the underlying object clears weak pointers to it.

    39   delete ptr;

    41   MOZ_RELEASE_ASSERT(!weak, "Deleting |ptr| clears weak pointers to it.");

    42   MOZ_RELEASE_ASSERT(!other, "Deleting |ptr| clears all weak pointers to it.");

    43 }

    45 struct A : public SupportsWeakPtr<A>

    46 {

    47     MOZ_DECLARE_REFCOUNTED_TYPENAME(A)

    48     int data;

    49 };

    52 int

    53 main()

    54 {

    56   A* a = new A;

    58   // a2 is unused to test the case when we haven't initialized

    59   // the internal WeakReference pointer.

    60   A* a2 = new A;

    62   a->data = 5;

    63   WeakPtr<A> ptr = a->asWeakPtr();

    64   {

    65       WeakPtr<A> ptr2 = a->asWeakPtr();

    66       MOZ_RELEASE_ASSERT(ptr->data == 5);

    67       WeakPtr<A> ptr3 = a->asWeakPtr();

    68       MOZ_RELEASE_ASSERT(ptr->data == 5);

    69   }

    71   delete a;

    72   MOZ_RELEASE_ASSERT(!ptr);

    74   delete a2;

    76   Example();

    78   return 0;

    79 }

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