third_party/boost/thread/example/make_future.cpp

// Copyright (C) 2012 Vicente Botet
//
//  Distributed under the Boost Software License, Version 1.0. (See accompanying
//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <boost/config.hpp>
#if ! defined  BOOST_NO_CXX11_DECLTYPE
#define BOOST_RESULT_OF_USE_DECLTYPE
#endif

#define BOOST_THREAD_VERSION 4

#include <boost/thread/future.hpp>
#include <iostream>

namespace boost
{

  template <typename T>
  exception_ptr make_exception_ptr(T v)
  {
    return copy_exception(v);
  }
}

int p1() { return 5; }
int& p1r() { static int i=0; return i; }

void p() { }

#if defined BOOST_THREAD_USES_MOVE
boost::future<void> void_compute()
{
  return BOOST_THREAD_MAKE_RV_REF(boost::make_ready_future());
}
#endif

boost::future<int> compute(int x)
{
  if (x == 0) return boost::make_ready_future(0);
#ifdef BOOST_NO_CXX11_RVALUE_REFERENCES
  if (x < 0) return boost::make_exceptional_future<int>(std::logic_error("Error"));
#else
  if (x < 0) return boost::make_exceptional(std::logic_error("Error"));
#endif
  //boost::future<int> f1 = boost::async([]() { return x+1; });
  boost::future<int> f1 = boost::async(p1);
  return boost::move(f1);
}

boost::future<int&> compute_ref(int x)
{
  static int i = 0;
  //if (x == 0) return boost::make_ready_future<int&>(i); //This must not compile as the type is deduced as boost::future<int>
  if (x == 0) return boost::make_ready_no_decay_future<int&>(i);
#ifdef BOOST_NO_CXX11_RVALUE_REFERENCES
  if (x < 0) return boost::make_exceptional_future<int&>(std::logic_error("Error"));
#else
  if (x < 0) return boost::make_exceptional(std::logic_error("Error"));
#endif
  boost::future<int&> f1 = boost::async(p1r);
  return boost::move(f1);
}

boost::shared_future<int> shared_compute(int x)
{
  if (x == 0) return boost::make_ready_future(0).share();
#ifdef BOOST_NO_CXX11_RVALUE_REFERENCES
  if (x < 0) return boost::make_exceptional_future<int>(std::logic_error("Error")).share();
#else
  if (x < 0) return boost::make_exceptional(std::logic_error("Error"));
#endif
  //boost::future<int> f1 = boost::async([]() { return x+1; });
  boost::shared_future<int> f1 = boost::async(&p1).share();
  return f1;
}


int main()
{
  const int number_of_tests = 100;
  for (int i=0; i< number_of_tests; i++)
  try
  {
//    {
//    std::cout << __FILE__ << " "<<__LINE__ << std::endl;
//    boost::future<int> f = boost::async(boost::launch::async, p1);
//    std::cout << i << " "<<f.get() << std::endl;
//    }
#if defined BOOST_THREAD_USES_MOVE
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    boost::future<void> f = void_compute();
    f.get();
  }
#endif
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    boost::future<int> f = compute(-1);
    f.wait();
  }
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    boost::future<int> f = compute(0);
    std::cout << f.get() << std::endl;
  }
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    boost::future<int&> f = compute_ref(0);
    std::cout << f.get() << std::endl;
  }
#if __cplusplus > 201103L
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    int i = 0;
    boost::future<int&> f = boost::make_ready_future(std::ref(i));
    std::cout << f.get() << std::endl;
  }
#endif
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    int i = 0;
    boost::future<int&> f = boost::make_ready_future(boost::ref(i));
    std::cout << f.get() << std::endl;
  }
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    const int i = 0;
    boost::future<int const&> f = boost::make_ready_future(boost::cref(i));
    std::cout << f.get() << std::endl;
  }
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    boost::future<int> f = compute(2);
    std::cout << f.get() << std::endl;
  }
  {
    std::cout << __FILE__ << " "<< __LINE__ << std::endl;
    boost::shared_future<int> f = shared_compute(0);
    std::cout << f.get() << std::endl;
  }
  }
  catch (std::exception& ex)
  {
    std::cout << "ERRORRRRR "<<ex.what() << "" << std::endl;
    return 1;
  }
  catch (...)
  {
    std::cout << "ERRORRRRR "<<"ERRORRRRR exception thrown" << std::endl;
    return 2;
  }
  return 0;
}