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 shared_ptr<Y>& r); 15 16 #include <memory> 17 #include <type_traits> 18 #include <cassert> 19 20 struct B 21 { 22 static int count; 23 24 B() {++count;} 25 B(const B&) {++count;} 26 virtual ~B() {--count;} 27 }; 28 29 int B::count = 0; 30 31 struct A 32 : public B 33 { 34 static int count; 35 36 A() {++count;} 37 A(const A&) {++count;} 38 ~A() {--count;} 39 }; 40 41 int A::count = 0; 42 43 struct C 44 { 45 static int count; 46 47 C() {++count;} 48 C(const C&) {++count;} 49 virtual ~C() {--count;} 50 }; 51 52 int C::count = 0; 53 54 int main() 55 { 56 static_assert(( std::is_convertible<std::shared_ptr<A>, std::weak_ptr<B> >::value), ""); 57 static_assert((!std::is_convertible<std::weak_ptr<B>, std::shared_ptr<A> >::value), ""); 58 static_assert((!std::is_convertible<std::shared_ptr<A>, std::weak_ptr<C> >::value), ""); 59 { 60 const std::shared_ptr<A> pA(new A); 61 assert(pA.use_count() == 1); 62 assert(B::count == 1); 63 assert(A::count == 1); 64 { 65 std::weak_ptr<B> pB(pA); 66 assert(B::count == 1); 67 assert(A::count == 1); 68 assert(pB.use_count() == 1); 69 assert(pA.use_count() == 1); 70 } 71 assert(pA.use_count() == 1); 72 assert(B::count == 1); 73 assert(A::count == 1); 74 } 75 assert(B::count == 0); 76 assert(A::count == 0); 77 { 78 std::shared_ptr<A> pA; 79 assert(pA.use_count() == 0); 80 assert(B::count == 0); 81 assert(A::count == 0); 82 { 83 std::weak_ptr<B> pB(pA); 84 assert(B::count == 0); 85 assert(A::count == 0); 86 assert(pB.use_count() == 0); 87 assert(pA.use_count() == 0); 88 } 89 assert(pA.use_count() == 0); 90 assert(B::count == 0); 91 assert(A::count == 0); 92 } 93 assert(B::count == 0); 94 assert(A::count == 0); 95 } 96
