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 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 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