libcxx/test/std/thread/futures/futures.promise/swap.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 // UNSUPPORTED: no-threads
  10 // UNSUPPORTED: c++03
  11
  12 // <future>
  13
  14 // class promise<R>
  15
  16 // void swap(promise& other);
  17
  18 // template <class R> void swap(promise<R>& x, promise<R>& y);
  19
  20 #include <future>
  21 #include <cassert>
  22
  23 #include "test_macros.h"
  24 #include "test_allocator.h"
  25
  26 int main(int, char**)
  27 {
  28     test_allocator_statistics alloc_stats;
  29     assert(alloc_stats.alloc_count == 0);
  30     {
  31         std::promise<int> p0(std::allocator_arg, test_allocator<int>(&alloc_stats));
  32         std::promise<int> p(std::allocator_arg, test_allocator<int>(&alloc_stats));
  33         assert(alloc_stats.alloc_count == 2);
  34         p.swap(p0);
  35         assert(alloc_stats.alloc_count == 2);
  36         std::future<int> f = p.get_future();
  37         assert(alloc_stats.alloc_count == 2);
  38         assert(f.valid());
  39         f = p0.get_future();
  40         assert(f.valid());
  41         assert(alloc_stats.alloc_count == 2);
  42     }
  43     assert(alloc_stats.alloc_count == 0);
  44     {
  45         std::promise<int> p0(std::allocator_arg, test_allocator<int>(&alloc_stats));
  46         std::promise<int> p(std::allocator_arg, test_allocator<int>(&alloc_stats));
  47         assert(alloc_stats.alloc_count == 2);
  48         swap(p, p0);
  49         assert(alloc_stats.alloc_count == 2);
  50         std::future<int> f = p.get_future();
  51         assert(alloc_stats.alloc_count == 2);
  52         assert(f.valid());
  53         f = p0.get_future();
  54         assert(f.valid());
  55         assert(alloc_stats.alloc_count == 2);
  56     }
  57     assert(alloc_stats.alloc_count == 0);
  58     {
  59         std::promise<int> p0(std::allocator_arg, test_allocator<int>(&alloc_stats));
  60         std::promise<int> p;
  61         assert(alloc_stats.alloc_count == 1);
  62         p.swap(p0);
  63         assert(alloc_stats.alloc_count == 1);
  64         std::future<int> f = p.get_future();
  65         assert(alloc_stats.alloc_count == 1);
  66         assert(f.valid());
  67         f = p0.get_future();
  68         assert(f.valid());
  69         assert(alloc_stats.alloc_count == 1);
  70     }
  71     assert(alloc_stats.alloc_count == 0);
  72     {
  73         std::promise<int> p0(std::allocator_arg, test_allocator<int>(&alloc_stats));
  74         std::promise<int> p;
  75         assert(alloc_stats.alloc_count == 1);
  76         swap(p, p0);
  77         assert(alloc_stats.alloc_count == 1);
  78         std::future<int> f = p.get_future();
  79         assert(alloc_stats.alloc_count == 1);
  80         assert(f.valid());
  81         f = p0.get_future();
  82         assert(f.valid());
  83         assert(alloc_stats.alloc_count == 1);
  84     }
  85     assert(alloc_stats.alloc_count == 0);
  86
  87   return 0;
  88 }