1//===----------------------------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10// <memory>
11
12// weak_ptr
13
14// weak_ptr(const weak_ptr& r);
15// weak_ptr(weak_ptr &&r)
16
17#include <memory>
18#include <type_traits>
19#include <cassert>
20
21struct B
22{
23    static int count;
24
25    B() {++count;}
26    B(const B&) {++count;}
27    virtual ~B() {--count;}
28};
29
30int B::count = 0;
31
32struct A
33    : public B
34{
35    static int count;
36
37    A() {++count;}
38    A(const A&) {++count;}
39    ~A() {--count;}
40};
41
42int A::count = 0;
43
44struct C
45{
46    static int count;
47
48    C() {++count;}
49    C(const C&) {++count;}
50    virtual ~C() {--count;}
51};
52
53int C::count = 0;
54
55template <class T>
56std::weak_ptr<T> source (std::shared_ptr<T> p) { return std::weak_ptr<T>(p); }
57
58template <class T>
59void sink (std::weak_ptr<T> &&) {}
60
61int main()
62{
63    {
64        const std::shared_ptr<A> ps(new A);
65        const std::weak_ptr<A> pA(ps);
66        assert(pA.use_count() == 1);
67        assert(B::count == 1);
68        assert(A::count == 1);
69        {
70            std::weak_ptr<A> pB(pA);
71            assert(B::count == 1);
72            assert(A::count == 1);
73            assert(pB.use_count() == 1);
74            assert(pA.use_count() == 1);
75        }
76        assert(pA.use_count() == 1);
77        assert(B::count == 1);
78        assert(A::count == 1);
79    }
80    assert(B::count == 0);
81    assert(A::count == 0);
82    {
83        std::weak_ptr<A> pA;
84        assert(pA.use_count() == 0);
85        assert(B::count == 0);
86        assert(A::count == 0);
87        {
88            std::weak_ptr<A> pB(pA);
89            assert(B::count == 0);
90            assert(A::count == 0);
91            assert(pB.use_count() == 0);
92            assert(pA.use_count() == 0);
93        }
94        assert(pA.use_count() == 0);
95        assert(B::count == 0);
96        assert(A::count == 0);
97    }
98    assert(B::count == 0);
99    assert(A::count == 0);
100
101    {
102        std::shared_ptr<A> ps(new A);
103        std::weak_ptr<A> pA = source(ps);
104        assert(pA.use_count() == 1);
105        assert(A::count == 1);
106        sink(std::move(pA)); // kill off the weak pointer
107    }
108    assert(B::count == 0);
109    assert(A::count == 0);
110}
111