From e95946831f8ef53d29590735a2df661385edb008 Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Mon, 6 Aug 2018 10:35:22 +0200
Subject: Replace boost by the standalone asio library

---
 lib/asio/impl/use_future.hpp | 938 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 938 insertions(+)
 create mode 100644 lib/asio/impl/use_future.hpp

(limited to 'lib/asio/impl/use_future.hpp')

diff --git a/lib/asio/impl/use_future.hpp b/lib/asio/impl/use_future.hpp
new file mode 100644
index 0000000..51eb7e2
--- /dev/null
+++ b/lib/asio/impl/use_future.hpp
@@ -0,0 +1,938 @@
+//
+// impl/use_future.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// 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)
+//
+
+#ifndef ASIO_IMPL_USE_FUTURE_HPP
+#define ASIO_IMPL_USE_FUTURE_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <future>
+#include <tuple>
+#include "asio/async_result.hpp"
+#include "asio/detail/memory.hpp"
+#include "asio/error_code.hpp"
+#include "asio/packaged_task.hpp"
+#include "asio/system_error.hpp"
+#include "asio/system_executor.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+namespace detail {
+
+#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename T, typename F, typename... Args>
+inline void promise_invoke_and_set(std::promise<T>& p,
+    F& f, ASIO_MOVE_ARG(Args)... args)
+{
+#if !defined(ASIO_NO_EXCEPTIONS)
+  try
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+  {
+    p.set_value(f(ASIO_MOVE_CAST(Args)(args)...));
+  }
+#if !defined(ASIO_NO_EXCEPTIONS)
+  catch (...)
+  {
+    p.set_exception(std::current_exception());
+  }
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+}
+
+template <typename F, typename... Args>
+inline void promise_invoke_and_set(std::promise<void>& p,
+    F& f, ASIO_MOVE_ARG(Args)... args)
+{
+#if !defined(ASIO_NO_EXCEPTIONS)
+  try
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+  {
+    f(ASIO_MOVE_CAST(Args)(args)...);
+    p.set_value();
+  }
+#if !defined(ASIO_NO_EXCEPTIONS)
+  catch (...)
+  {
+    p.set_exception(std::current_exception());
+  }
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+}
+
+#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename T, typename F>
+inline void promise_invoke_and_set(std::promise<T>& p, F& f)
+{
+#if !defined(ASIO_NO_EXCEPTIONS)
+  try
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+  {
+    p.set_value(f());
+  }
+#if !defined(ASIO_NO_EXCEPTIONS)
+  catch (...)
+  {
+    p.set_exception(std::current_exception());
+  }
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+}
+
+template <typename F, typename Args>
+inline void promise_invoke_and_set(std::promise<void>& p, F& f)
+{
+#if !defined(ASIO_NO_EXCEPTIONS)
+  try
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+  {
+    f();
+    p.set_value();
+#if !defined(ASIO_NO_EXCEPTIONS)
+  }
+  catch (...)
+  {
+    p.set_exception(std::current_exception());
+  }
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+}
+
+#if defined(ASIO_NO_EXCEPTIONS)
+
+#define ASIO_PRIVATE_PROMISE_INVOKE_DEF(n) \
+  template <typename T, typename F, ASIO_VARIADIC_TPARAMS(n)> \
+  inline void promise_invoke_and_set(std::promise<T>& p, \
+      F& f, ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    p.set_value(f(ASIO_VARIADIC_MOVE_ARGS(n))); \
+  } \
+  \
+  template <typename F, ASIO_VARIADIC_TPARAMS(n)> \
+  inline void promise_invoke_and_set(std::promise<void>& p, \
+      F& f, ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    f(ASIO_VARIADIC_MOVE_ARGS(n)); \
+    p.set_value(); \
+  } \
+  /**/
+  ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_PROMISE_INVOKE_DEF)
+#undef ASIO_PRIVATE_PROMISE_INVOKE_DEF
+
+#else // defined(ASIO_NO_EXCEPTIONS)
+
+#define ASIO_PRIVATE_PROMISE_INVOKE_DEF(n) \
+  template <typename T, typename F, ASIO_VARIADIC_TPARAMS(n)> \
+  inline void promise_invoke_and_set(std::promise<T>& p, \
+      F& f, ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    try \
+    { \
+      p.set_value(f(ASIO_VARIADIC_MOVE_ARGS(n))); \
+    } \
+    catch (...) \
+    { \
+      p.set_exception(std::current_exception()); \
+    } \
+  } \
+  \
+  template <typename F, ASIO_VARIADIC_TPARAMS(n)> \
+  inline void promise_invoke_and_set(std::promise<void>& p, \
+      F& f, ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  { \
+    try \
+    { \
+      f(ASIO_VARIADIC_MOVE_ARGS(n)); \
+      p.set_value(); \
+    } \
+    catch (...) \
+    { \
+      p.set_exception(std::current_exception()); \
+    } \
+  } \
+  /**/
+  ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_PROMISE_INVOKE_DEF)
+#undef ASIO_PRIVATE_PROMISE_INVOKE_DEF
+
+#endif // defined(ASIO_NO_EXCEPTIONS)
+
+#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+// A function object adapter to invoke a nullary function object and capture
+// any exception thrown into a promise.
+template <typename T, typename F>
+class promise_invoker
+{
+public:
+  promise_invoker(const shared_ptr<std::promise<T> >& p,
+      ASIO_MOVE_ARG(F) f)
+    : p_(p), f_(ASIO_MOVE_CAST(F)(f))
+  {
+  }
+
+  void operator()()
+  {
+#if !defined(ASIO_NO_EXCEPTIONS)
+    try
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+    {
+      f_();
+    }
+#if !defined(ASIO_NO_EXCEPTIONS)
+    catch (...)
+    {
+      p_->set_exception(std::current_exception());
+    }
+#endif // !defined(ASIO_NO_EXCEPTIONS)
+  }
+
+private:
+  shared_ptr<std::promise<T> > p_;
+  typename decay<F>::type f_;
+};
+
+// An executor that adapts the system_executor to capture any exeption thrown
+// by a submitted function object and save it into a promise.
+template <typename T>
+class promise_executor
+{
+public:
+  explicit promise_executor(const shared_ptr<std::promise<T> >& p)
+    : p_(p)
+  {
+  }
+
+  execution_context& context() const ASIO_NOEXCEPT
+  {
+    return system_executor().context();
+  }
+
+  void on_work_started() const ASIO_NOEXCEPT {}
+  void on_work_finished() const ASIO_NOEXCEPT {}
+
+  template <typename F, typename A>
+  void dispatch(ASIO_MOVE_ARG(F) f, const A&) const
+  {
+    promise_invoker<T, F>(p_, ASIO_MOVE_CAST(F)(f))();
+  }
+
+  template <typename F, typename A>
+  void post(ASIO_MOVE_ARG(F) f, const A& a) const
+  {
+    system_executor().post(
+        promise_invoker<T, F>(p_, ASIO_MOVE_CAST(F)(f)), a);
+  }
+
+  template <typename F, typename A>
+  void defer(ASIO_MOVE_ARG(F) f, const A& a) const
+  {
+    system_executor().defer(
+        promise_invoker<T, F>(p_, ASIO_MOVE_CAST(F)(f)), a);
+  }
+
+  friend bool operator==(const promise_executor& a,
+      const promise_executor& b) ASIO_NOEXCEPT
+  {
+    return a.p_ == b.p_;
+  }
+
+  friend bool operator!=(const promise_executor& a,
+      const promise_executor& b) ASIO_NOEXCEPT
+  {
+    return a.p_ != b.p_;
+  }
+
+private:
+  shared_ptr<std::promise<T> > p_;
+};
+
+// The base class for all completion handlers that create promises.
+template <typename T>
+class promise_creator
+{
+public:
+  typedef promise_executor<T> executor_type;
+
+  executor_type get_executor() const ASIO_NOEXCEPT
+  {
+    return executor_type(p_);
+  }
+
+  typedef std::future<T> future_type;
+
+  future_type get_future()
+  {
+    return p_->get_future();
+  }
+
+protected:
+  template <typename Allocator>
+  void create_promise(const Allocator& a)
+  {
+    ASIO_REBIND_ALLOC(Allocator, char) b(a);
+    p_ = std::allocate_shared<std::promise<T>>(b, std::allocator_arg, b);
+  }
+
+  shared_ptr<std::promise<T> > p_;
+};
+
+// For completion signature void().
+class promise_handler_0
+  : public promise_creator<void>
+{
+public:
+  void operator()()
+  {
+    this->p_->set_value();
+  }
+};
+
+// For completion signature void(error_code).
+class promise_handler_ec_0
+  : public promise_creator<void>
+{
+public:
+  void operator()(const asio::error_code& ec)
+  {
+    if (ec)
+    {
+      this->p_->set_exception(
+          std::make_exception_ptr(
+            asio::system_error(ec)));
+    }
+    else
+    {
+      this->p_->set_value();
+    }
+  }
+};
+
+// For completion signature void(exception_ptr).
+class promise_handler_ex_0
+  : public promise_creator<void>
+{
+public:
+  void operator()(const std::exception_ptr& ex)
+  {
+    if (ex)
+    {
+      this->p_->set_exception(ex);
+    }
+    else
+    {
+      this->p_->set_value();
+    }
+  }
+};
+
+// For completion signature void(T).
+template <typename T>
+class promise_handler_1
+  : public promise_creator<T>
+{
+public:
+  template <typename Arg>
+  void operator()(ASIO_MOVE_ARG(Arg) arg)
+  {
+    this->p_->set_value(ASIO_MOVE_CAST(Arg)(arg));
+  }
+};
+
+// For completion signature void(error_code, T).
+template <typename T>
+class promise_handler_ec_1
+  : public promise_creator<T>
+{
+public:
+  template <typename Arg>
+  void operator()(const asio::error_code& ec,
+      ASIO_MOVE_ARG(Arg) arg)
+  {
+    if (ec)
+    {
+      this->p_->set_exception(
+          std::make_exception_ptr(
+            asio::system_error(ec)));
+    }
+    else
+      this->p_->set_value(ASIO_MOVE_CAST(Arg)(arg));
+  }
+};
+
+// For completion signature void(exception_ptr, T).
+template <typename T>
+class promise_handler_ex_1
+  : public promise_creator<T>
+{
+public:
+  template <typename Arg>
+  void operator()(const std::exception_ptr& ex,
+      ASIO_MOVE_ARG(Arg) arg)
+  {
+    if (ex)
+      this->p_->set_exception(ex);
+    else
+      this->p_->set_value(ASIO_MOVE_CAST(Arg)(arg));
+  }
+};
+
+// For completion signature void(T1, ..., Tn);
+template <typename T>
+class promise_handler_n
+  : public promise_creator<T>
+{
+public:
+#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename... Args>
+  void operator()(ASIO_MOVE_ARG(Args)... args)
+  {
+    this->p_->set_value(
+        std::forward_as_tuple(
+          ASIO_MOVE_CAST(Args)(args)...));
+  }
+
+#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+#define ASIO_PRIVATE_CALL_OP_DEF(n) \
+  template <ASIO_VARIADIC_TPARAMS(n)> \
+  void operator()(ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  {\
+    this->p_->set_value( \
+        std::forward_as_tuple( \
+          ASIO_VARIADIC_MOVE_ARGS(n))); \
+  } \
+  /**/
+  ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_CALL_OP_DEF)
+#undef ASIO_PRIVATE_CALL_OP_DEF
+
+#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+};
+
+// For completion signature void(error_code, T1, ..., Tn);
+template <typename T>
+class promise_handler_ec_n
+  : public promise_creator<T>
+{
+public:
+#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename... Args>
+  void operator()(const asio::error_code& ec,
+      ASIO_MOVE_ARG(Args)... args)
+  {
+    if (ec)
+    {
+      this->p_->set_exception(
+          std::make_exception_ptr(
+            asio::system_error(ec)));
+    }
+    else
+    {
+      this->p_->set_value(
+          std::forward_as_tuple(
+            ASIO_MOVE_CAST(Args)(args)...));
+    }
+  }
+
+#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+#define ASIO_PRIVATE_CALL_OP_DEF(n) \
+  template <ASIO_VARIADIC_TPARAMS(n)> \
+  void operator()(const asio::error_code& ec, \
+      ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  {\
+    if (ec) \
+    { \
+      this->p_->set_exception( \
+          std::make_exception_ptr( \
+            asio::system_error(ec))); \
+    } \
+    else \
+    { \
+      this->p_->set_value( \
+          std::forward_as_tuple( \
+            ASIO_VARIADIC_MOVE_ARGS(n))); \
+    } \
+  } \
+  /**/
+  ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_CALL_OP_DEF)
+#undef ASIO_PRIVATE_CALL_OP_DEF
+
+#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+};
+
+// For completion signature void(exception_ptr, T1, ..., Tn);
+template <typename T>
+class promise_handler_ex_n
+  : public promise_creator<T>
+{
+public:
+#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename... Args>
+  void operator()(const std::exception_ptr& ex,
+      ASIO_MOVE_ARG(Args)... args)
+  {
+    if (ex)
+      this->p_->set_exception(ex);
+    else
+    {
+      this->p_->set_value(
+          std::forward_as_tuple(
+            ASIO_MOVE_CAST(Args)(args)...));
+    }
+  }
+
+#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+#define ASIO_PRIVATE_CALL_OP_DEF(n) \
+  template <ASIO_VARIADIC_TPARAMS(n)> \
+  void operator()(const std::exception_ptr& ex, \
+      ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  {\
+    if (ex) \
+      this->p_->set_exception(ex); \
+    else \
+    { \
+      this->p_->set_value( \
+          std::forward_as_tuple( \
+            ASIO_VARIADIC_MOVE_ARGS(n))); \
+    } \
+  } \
+  /**/
+  ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_CALL_OP_DEF)
+#undef ASIO_PRIVATE_CALL_OP_DEF
+
+#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+};
+
+// Helper template to choose the appropriate concrete promise handler
+// implementation based on the supplied completion signature.
+template <typename> class promise_handler_selector;
+
+template <>
+class promise_handler_selector<void()>
+  : public promise_handler_0 {};
+
+template <>
+class promise_handler_selector<void(asio::error_code)>
+  : public promise_handler_ec_0 {};
+
+template <>
+class promise_handler_selector<void(std::exception_ptr)>
+  : public promise_handler_ex_0 {};
+
+template <typename Arg>
+class promise_handler_selector<void(Arg)>
+  : public promise_handler_1<Arg> {};
+
+template <typename Arg>
+class promise_handler_selector<void(asio::error_code, Arg)>
+  : public promise_handler_ec_1<Arg> {};
+
+template <typename Arg>
+class promise_handler_selector<void(std::exception_ptr, Arg)>
+  : public promise_handler_ex_1<Arg> {};
+
+#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename... Arg>
+class promise_handler_selector<void(Arg...)>
+  : public promise_handler_n<std::tuple<Arg...> > {};
+
+template <typename... Arg>
+class promise_handler_selector<void(asio::error_code, Arg...)>
+  : public promise_handler_ec_n<std::tuple<Arg...> > {};
+
+template <typename... Arg>
+class promise_handler_selector<void(std::exception_ptr, Arg...)>
+  : public promise_handler_ex_n<std::tuple<Arg...> > {};
+
+#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+#define ASIO_PRIVATE_PROMISE_SELECTOR_DEF(n) \
+  template <typename Arg, ASIO_VARIADIC_TPARAMS(n)> \
+  class promise_handler_selector< \
+    void(Arg, ASIO_VARIADIC_TARGS(n))> \
+      : public promise_handler_n< \
+        std::tuple<Arg, ASIO_VARIADIC_TARGS(n)> > {}; \
+  \
+  template <typename Arg, ASIO_VARIADIC_TPARAMS(n)> \
+  class promise_handler_selector< \
+    void(asio::error_code, Arg, ASIO_VARIADIC_TARGS(n))> \
+      : public promise_handler_ec_n< \
+        std::tuple<Arg, ASIO_VARIADIC_TARGS(n)> > {}; \
+  \
+  template <typename Arg, ASIO_VARIADIC_TPARAMS(n)> \
+  class promise_handler_selector< \
+    void(std::exception_ptr, Arg, ASIO_VARIADIC_TARGS(n))> \
+      : public promise_handler_ex_n< \
+        std::tuple<Arg, ASIO_VARIADIC_TARGS(n)> > {}; \
+  /**/
+  ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_PROMISE_SELECTOR_DEF)
+#undef ASIO_PRIVATE_PROMISE_SELECTOR_DEF
+
+#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+// Completion handlers produced from the use_future completion token, when not
+// using use_future::operator().
+template <typename Signature, typename Allocator>
+class promise_handler
+  : public promise_handler_selector<Signature>
+{
+public:
+  typedef Allocator allocator_type;
+  typedef void result_type;
+
+  promise_handler(use_future_t<Allocator> u)
+    : allocator_(u.get_allocator())
+  {
+    this->create_promise(allocator_);
+  }
+
+  allocator_type get_allocator() const ASIO_NOEXCEPT
+  {
+    return allocator_;
+  }
+
+private:
+  Allocator allocator_;
+};
+
+template <typename Function, typename Signature, typename Allocator>
+inline void asio_handler_invoke(Function& f,
+    promise_handler<Signature, Allocator>* h)
+{
+  typename promise_handler<Signature, Allocator>::executor_type
+    ex(h->get_executor());
+  ex.dispatch(ASIO_MOVE_CAST(Function)(f), std::allocator<void>());
+}
+
+template <typename Function, typename Signature, typename Allocator>
+inline void asio_handler_invoke(const Function& f,
+    promise_handler<Signature, Allocator>* h)
+{
+  typename promise_handler<Signature, Allocator>::executor_type
+    ex(h->get_executor());
+  ex.dispatch(f, std::allocator<void>());
+}
+
+// Helper base class for async_result specialisation.
+template <typename Signature, typename Allocator>
+class promise_async_result
+{
+public:
+  typedef promise_handler<Signature, Allocator> completion_handler_type;
+  typedef typename completion_handler_type::future_type return_type;
+
+  explicit promise_async_result(completion_handler_type& h)
+    : future_(h.get_future())
+  {
+  }
+
+  return_type get()
+  {
+    return ASIO_MOVE_CAST(return_type)(future_);
+  }
+
+private:
+  return_type future_;
+};
+
+// Return value from use_future::operator().
+template <typename Function, typename Allocator>
+class packaged_token
+{
+public:
+  packaged_token(Function f, const Allocator& a)
+    : function_(ASIO_MOVE_CAST(Function)(f)),
+      allocator_(a)
+  {
+  }
+
+//private:
+  Function function_;
+  Allocator allocator_;
+};
+
+// Completion handlers produced from the use_future completion token, when
+// using use_future::operator().
+template <typename Function, typename Allocator, typename Result>
+class packaged_handler
+  : public promise_creator<Result>
+{
+public:
+  typedef Allocator allocator_type;
+  typedef void result_type;
+
+  packaged_handler(packaged_token<Function, Allocator> t)
+    : function_(ASIO_MOVE_CAST(Function)(t.function_)),
+      allocator_(t.allocator_)
+  {
+    this->create_promise(allocator_);
+  }
+
+  allocator_type get_allocator() const ASIO_NOEXCEPT
+  {
+    return allocator_;
+  }
+
+#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+  template <typename... Args>
+  void operator()(ASIO_MOVE_ARG(Args)... args)
+  {
+    (promise_invoke_and_set)(*this->p_,
+        function_, ASIO_MOVE_CAST(Args)(args)...);
+  }
+
+#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+  void operator()()
+  {
+    (promise_invoke_and_set)(*this->p_, function_);
+  }
+
+#define ASIO_PRIVATE_CALL_OP_DEF(n) \
+  template <ASIO_VARIADIC_TPARAMS(n)> \
+  void operator()(ASIO_VARIADIC_MOVE_PARAMS(n)) \
+  {\
+    (promise_invoke_and_set)(*this->p_, \
+        function_, ASIO_VARIADIC_MOVE_ARGS(n)); \
+  } \
+  /**/
+  ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_CALL_OP_DEF)
+#undef ASIO_PRIVATE_CALL_OP_DEF
+
+#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+private:
+  Function function_;
+  Allocator allocator_;
+};
+
+template <typename Function,
+    typename Function1, typename Allocator, typename Result>
+inline void asio_handler_invoke(Function& f,
+    packaged_handler<Function1, Allocator, Result>* h)
+{
+  typename packaged_handler<Function1, Allocator, Result>::executor_type
+    ex(h->get_executor());
+  ex.dispatch(ASIO_MOVE_CAST(Function)(f), std::allocator<void>());
+}
+
+template <typename Function,
+    typename Function1, typename Allocator, typename Result>
+inline void asio_handler_invoke(const Function& f,
+    packaged_handler<Function1, Allocator, Result>* h)
+{
+  typename packaged_handler<Function1, Allocator, Result>::executor_type
+    ex(h->get_executor());
+  ex.dispatch(f, std::allocator<void>());
+}
+
+// Helper base class for async_result specialisation.
+template <typename Function, typename Allocator, typename Result>
+class packaged_async_result
+{
+public:
+  typedef packaged_handler<Function, Allocator, Result> completion_handler_type;
+  typedef typename completion_handler_type::future_type return_type;
+
+  explicit packaged_async_result(completion_handler_type& h)
+    : future_(h.get_future())
+  {
+  }
+
+  return_type get()
+  {
+    return ASIO_MOVE_CAST(return_type)(future_);
+  }
+
+private:
+  return_type future_;
+};
+
+} // namespace detail
+
+template <typename Allocator> template <typename Function>
+inline detail::packaged_token<typename decay<Function>::type, Allocator>
+use_future_t<Allocator>::operator()(ASIO_MOVE_ARG(Function) f) const
+{
+  return detail::packaged_token<typename decay<Function>::type, Allocator>(
+      ASIO_MOVE_CAST(Function)(f), allocator_);
+}
+
+#if !defined(GENERATING_DOCUMENTATION)
+
+#if defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename Allocator, typename Result, typename... Args>
+class async_result<use_future_t<Allocator>, Result(Args...)>
+  : public detail::promise_async_result<
+      void(typename decay<Args>::type...), Allocator>
+{
+public:
+  explicit async_result(
+    typename detail::promise_async_result<void(typename decay<Args>::type...),
+      Allocator>::completion_handler_type& h)
+    : detail::promise_async_result<
+        void(typename decay<Args>::type...), Allocator>(h)
+  {
+  }
+};
+
+template <typename Function, typename Allocator,
+    typename Result, typename... Args>
+class async_result<detail::packaged_token<Function, Allocator>, Result(Args...)>
+  : public detail::packaged_async_result<Function, Allocator,
+      typename result_of<Function(Args...)>::type>
+{
+public:
+  explicit async_result(
+    typename detail::packaged_async_result<Function, Allocator,
+      typename result_of<Function(Args...)>::type>::completion_handler_type& h)
+    : detail::packaged_async_result<Function, Allocator,
+        typename result_of<Function(Args...)>::type>(h)
+  {
+  }
+};
+
+#else // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+template <typename Allocator, typename Result>
+class async_result<use_future_t<Allocator>, Result()>
+  : public detail::promise_async_result<void(), Allocator>
+{
+public:
+  explicit async_result(
+    typename detail::promise_async_result<
+      void(), Allocator>::completion_handler_type& h)
+    : detail::promise_async_result<void(), Allocator>(h)
+  {
+  }
+};
+
+template <typename Function, typename Allocator, typename Result>
+class async_result<detail::packaged_token<Function, Allocator>, Result()>
+  : public detail::packaged_async_result<Function, Allocator,
+      typename result_of<Function()>::type>
+{
+public:
+  explicit async_result(
+    typename detail::packaged_async_result<Function, Allocator,
+      typename result_of<Function()>::type>::completion_handler_type& h)
+    : detail::packaged_async_result<Function, Allocator,
+        typename result_of<Function()>::type>(h)
+  {
+  }
+};
+
+#define ASIO_PRIVATE_ASYNC_RESULT_DEF(n) \
+  template <typename Allocator, \
+      typename Result, ASIO_VARIADIC_TPARAMS(n)> \
+  class async_result<use_future_t<Allocator>, \
+      Result(ASIO_VARIADIC_TARGS(n))> \
+    : public detail::promise_async_result< \
+        void(ASIO_VARIADIC_DECAY(n)), Allocator> \
+  { \
+  public: \
+    explicit async_result( \
+      typename detail::promise_async_result< \
+        void(ASIO_VARIADIC_DECAY(n)), \
+        Allocator>::completion_handler_type& h) \
+      : detail::promise_async_result< \
+          void(ASIO_VARIADIC_DECAY(n)), Allocator>(h) \
+    { \
+    } \
+  }; \
+  \
+  template <typename Function, typename Allocator, \
+      typename Result, ASIO_VARIADIC_TPARAMS(n)> \
+  class async_result<detail::packaged_token<Function, Allocator>, \
+      Result(ASIO_VARIADIC_TARGS(n))> \
+    : public detail::packaged_async_result<Function, Allocator, \
+        typename result_of<Function(ASIO_VARIADIC_TARGS(n))>::type> \
+  { \
+  public: \
+    explicit async_result( \
+      typename detail::packaged_async_result<Function, Allocator, \
+        typename result_of<Function(ASIO_VARIADIC_TARGS(n))>::type \
+        >::completion_handler_type& h) \
+      : detail::packaged_async_result<Function, Allocator, \
+          typename result_of<Function(ASIO_VARIADIC_TARGS(n))>::type>(h) \
+    { \
+    } \
+  }; \
+  /**/
+  ASIO_VARIADIC_GENERATE(ASIO_PRIVATE_ASYNC_RESULT_DEF)
+#undef ASIO_PRIVATE_ASYNC_RESULT_DEF
+
+#endif // defined(ASIO_HAS_VARIADIC_TEMPLATES)
+
+#if !defined(ASIO_NO_DEPRECATED)
+
+template <typename Allocator, typename Signature>
+struct handler_type<use_future_t<Allocator>, Signature>
+{
+  typedef typename async_result<use_future_t<Allocator>,
+    Signature>::completion_handler_type type;
+};
+
+template <typename Signature, typename Allocator>
+class async_result<detail::promise_handler<Signature, Allocator> >
+  : public detail::promise_async_result<Signature, Allocator>
+{
+public:
+  typedef typename detail::promise_async_result<
+    Signature, Allocator>::return_type type;
+
+  explicit async_result(
+    typename detail::promise_async_result<
+      Signature, Allocator>::completion_handler_type& h)
+    : detail::promise_async_result<Signature, Allocator>(h)
+  {
+  }
+};
+
+template <typename Function, typename Allocator, typename Signature>
+struct handler_type<detail::packaged_token<Function, Allocator>, Signature>
+{
+  typedef typename async_result<detail::packaged_token<Function, Allocator>,
+    Signature>::completion_handler_type type;
+};
+
+template <typename Function, typename Allocator, typename Result>
+class async_result<detail::packaged_handler<Function, Allocator, Result> >
+  : public detail::packaged_async_result<Function, Allocator, Result>
+{
+public:
+  typedef typename detail::packaged_async_result<
+    Function, Allocator, Result>::return_type type;
+
+  explicit async_result(
+    typename detail::packaged_async_result<
+      Function, Allocator, Result>::completion_handler_type& h)
+    : detail::packaged_async_result<Function, Allocator, Result>(h)
+  {
+  }
+};
+
+#endif // !defined(ASIO_NO_DEPRECATED)
+
+#endif // !defined(GENERATING_DOCUMENTATION)
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_IMPL_USE_FUTURE_HPP
-- 
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