libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.weak/util.smartptr.weak.obs/expired.pass.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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // <memory>
  10
  11 // weak_ptr
  12
  13 // bool expired() const;
  14
  15 #include <memory>
  16 #include <cassert>
  17
  18 #include "test_macros.h"
  19
  20 struct A
  21 {
  22     static int count;
  23
  24     A() {++count;}
  25     A(const A&) {++count;}
  26     ~A() {--count;}
  27 };
  28
  29 int A::count = 0;
  30
  31 int main(int, char**)
  32 {
  33     {
  34         std::weak_ptr<A> wp;
  35         assert(wp.use_count() == 0);
  36         assert(wp.expired() == (wp.use_count() == 0));
  37     }
  38     {
  39         std::shared_ptr<A> sp0(new A);
  40         std::weak_ptr<A> wp(sp0);
  41         assert(wp.use_count() == 1);
  42         assert(wp.expired() == (wp.use_count() == 0));
  43         sp0.reset();
  44         assert(wp.use_count() == 0);
  45         assert(wp.expired() == (wp.use_count() == 0));
  46     }
  47
  48   return 0;
  49 }