53 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// <memory>10 11// weak_ptr12 13// template<class T> void swap(weak_ptr<T>& a, weak_ptr<T>& b)14 15#include <memory>16#include <cassert>17 18#include "test_macros.h"19 20struct A21{22 static int count;23 24 A() {++count;}25 A(const A&) {++count;}26 ~A() {--count;}27};28 29int A::count = 0;30 31int main(int, char**)32{33 {34 A* ptr1 = new A;35 A* ptr2 = new A;36 std::shared_ptr<A> p1(ptr1);37 std::weak_ptr<A> w1(p1);38 {39 std::shared_ptr<A> p2(ptr2);40 std::weak_ptr<A> w2(p2);41 swap(w1, w2);42 assert(w1.use_count() == 1);43 assert(w1.lock().get() == ptr2);44 assert(w2.use_count() == 1);45 assert(w2.lock().get() == ptr1);46 assert(A::count == 2);47 }48 }49 assert(A::count == 0);50 51 return 0;52}53