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 // bool expired() const; 15 16 #include <memory> 17 #include <cassert> 18 19 struct A 20 { 21 static int count; 22 23 A() {++count;} 24 A(const A&) {++count;} 25 ~A() {--count;} 26 }; 27 28 int A::count = 0; 29 30 int main() 31 { 32 { 33 std::weak_ptr<A> wp; 34 assert(wp.use_count() == 0); 35 assert(wp.expired() == (wp.use_count() == 0)); 36 } 37 { 38 std::shared_ptr<A> sp0(new A); 39 std::weak_ptr<A> wp(sp0); 40 assert(wp.use_count() == 1); 41 assert(wp.expired() == (wp.use_count() == 0)); 42 sp0.reset(); 43 assert(wp.use_count() == 0); 44 assert(wp.expired() == (wp.use_count() == 0)); 45 } 46 } 47
