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 // template<class Y> weak_ptr(const weak_ptr<Y>& r); 15 // template<class Y> weak_ptr(weak_ptr<Y> &&r); 16 17 #include <memory> 18 #include <type_traits> 19 #include <cassert> 20 21 struct B 22 { 23 static int count; 24 BB25 B() {++count;} BB26 B(const B&) {++count;} ~BB27 virtual ~B() {--count;} 28 }; 29 30 int B::count = 0; 31 32 struct A 33 : public B 34 { 35 static int count; 36 AA37 A() {++count;} AA38 A(const A&) {++count;} ~AA39 ~A() {--count;} 40 }; 41 42 int A::count = 0; 43 44 struct C 45 { 46 static int count; 47 CC48 C() {++count;} CC49 C(const C&) {++count;} ~CC50 virtual ~C() {--count;} 51 }; 52 53 int C::count = 0; 54 55 template <class T> source(std::shared_ptr<T> p)56std::weak_ptr<T> source (std::shared_ptr<T> p) { return std::weak_ptr<T>(p); } 57 58 template <class T> sink(std::weak_ptr<T> &&)59void sink (std::weak_ptr<T> &&) {} 60 main()61int main() 62 { 63 static_assert(( std::is_convertible<std::weak_ptr<A>, std::weak_ptr<B> >::value), ""); 64 static_assert((!std::is_convertible<std::weak_ptr<B>, std::weak_ptr<A> >::value), ""); 65 static_assert((!std::is_convertible<std::weak_ptr<A>, std::weak_ptr<C> >::value), ""); 66 { 67 const std::weak_ptr<A> pA(std::shared_ptr<A>(new A)); 68 assert(pA.use_count() == 0); 69 assert(B::count == 0); 70 assert(A::count == 0); 71 { 72 std::weak_ptr<B> pB(pA); 73 assert(B::count == 0); 74 assert(A::count == 0); 75 assert(pB.use_count() == 0); 76 assert(pA.use_count() == 0); 77 } 78 assert(pA.use_count() == 0); 79 assert(B::count == 0); 80 assert(A::count == 0); 81 } 82 assert(B::count == 0); 83 assert(A::count == 0); 84 { 85 std::weak_ptr<A> pA; 86 assert(pA.use_count() == 0); 87 assert(B::count == 0); 88 assert(A::count == 0); 89 { 90 std::weak_ptr<B> pB(pA); 91 assert(B::count == 0); 92 assert(A::count == 0); 93 assert(pB.use_count() == 0); 94 assert(pA.use_count() == 0); 95 } 96 assert(pA.use_count() == 0); 97 assert(B::count == 0); 98 assert(A::count == 0); 99 } 100 assert(B::count == 0); 101 assert(A::count == 0); 102 103 { 104 std::shared_ptr<A> ps(new A); 105 std::weak_ptr<A> pA = source(ps); 106 std::weak_ptr<B> pB(std::move(pA)); 107 assert(pB.use_count() == 1); 108 } 109 assert(B::count == 0); 110 assert(A::count == 0); 111 } 112