blob: 4b811a44ceea934cdf52b3497317a8b19bac813d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
|
/* 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 "mozilla/WeakPtr.h"
using mozilla::SupportsWeakPtr;
using mozilla::WeakPtr;
// To have a class C support weak pointers, inherit from SupportsWeakPtr<C>.
class C : public SupportsWeakPtr<C>
{
public:
int num;
void act() {}
};
static void
example()
{
C* ptr = new C();
// Get weak pointers to ptr. The first time asWeakPtr is called
// a reference counted WeakReference object is created that
// can live beyond the lifetime of 'ptr'. The WeakReference
// object will be notified of 'ptr's destruction.
WeakPtr<C> weak = ptr->asWeakPtr();
WeakPtr<C> other = ptr->asWeakPtr();
// Test a weak pointer for validity before using it.
if (weak) {
weak->num = 17;
weak->act();
}
// Destroying the underlying object clears weak pointers to it.
delete ptr;
MOZ_ASSERT(!weak, "Deleting |ptr| clears weak pointers to it.");
MOZ_ASSERT(!other, "Deleting |ptr| clears all weak pointers to it.");
}
struct A : public SupportsWeakPtr<A>
{
int data;
};
int main()
{
A* a = new A;
// a2 is unused to test the case when we haven't initialized
// the internal WeakReference pointer.
A* a2 = new A;
a->data = 5;
WeakPtr<A> ptr = a->asWeakPtr();
{
WeakPtr<A> ptr2 = a->asWeakPtr();
MOZ_ASSERT(ptr->data == 5);
WeakPtr<A> ptr3 = a->asWeakPtr();
MOZ_ASSERT(ptr->data == 5);
}
delete a;
MOZ_ASSERT(!ptr);
delete a2;
example();
return 0;
}
|
