From cc309eef8d2ae2f107ee0331f3587ea8f79a4d35 Mon Sep 17 00:00:00 2001
From: "Vicente J. Botet Escriba" <vicente.botet@wanadoo.fr>
Date: Thu, 15 Oct 2015 23:31:38 +0200
Subject: [PATCH] refactor ::then(f) in function of ::then(launch_policy, f).

---
 include/boost/thread/future.hpp | 99 ++++-----------------------------
 1 file changed, 12 insertions(+), 87 deletions(-)

diff --git a/include/boost/thread/future.hpp b/include/boost/thread/future.hpp
index 159099b3..23b08651 100644
--- a/include/boost/thread/future.hpp
+++ b/include/boost/thread/future.hpp
@@ -1309,6 +1309,15 @@ namespace boost
             else return launch(launch::none);
         }
 
+        launch launch_policy() const
+        {
+          if ( future_ ) {
+            boost::unique_lock<boost::mutex> lk(this->future_->mutex);
+            return future_->launch_policy(lk);
+          }
+          else return launch(launch::none);
+        }
+
         exception_ptr get_exception_ptr()
         {
             return future_
@@ -4896,36 +4905,7 @@ namespace detail {
   template <typename F>
   inline BOOST_THREAD_FUTURE<typename boost::result_of<F(BOOST_THREAD_FUTURE<R>)>::type>
   BOOST_THREAD_FUTURE<R>::then(BOOST_THREAD_FWD_REF(F) func)  {
-    typedef typename boost::result_of<F(BOOST_THREAD_FUTURE<R>)>::type future_type;
-    BOOST_THREAD_ASSERT_PRECONDITION(this->future_!=0, future_uninitialized());
-
-    boost::unique_lock<boost::mutex> lock(this->future_->mutex);
-    if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::async)) {
-      lock.unlock();
-      return boost::detail::make_future_async_continuation_shared_state<BOOST_THREAD_FUTURE<R>, future_type>(
-          lock, boost::move(*this), boost::forward<F>(func)
-      );
-    } else if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::deferred)) {
-      this->future_->wait_internal(lock);
-      lock.unlock();
-      return boost::detail::make_future_deferred_continuation_shared_state<BOOST_THREAD_FUTURE<R>, future_type>(
-          lock, boost::move(*this), boost::forward<F>(func)
-      );
-#ifdef BOOST_THREAD_PROVIDES_EXECUTORS
-    } else if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::executor)) {
-      typedef executor Ex;
-      Ex& ex = *(this->future_->get_executor());
-      lock.unlock();
-      return BOOST_THREAD_MAKE_RV_REF((boost::detail::make_future_executor_continuation_shared_state<Ex, BOOST_THREAD_FUTURE<R>, future_type>(ex,
-                    lock, boost::move(*this), boost::forward<F>(func)
-                )));
-#endif
-    } else {
-      lock.unlock();
-      return boost::detail::make_future_async_continuation_shared_state<BOOST_THREAD_FUTURE<R>, future_type>(
-          lock, boost::move(*this), boost::forward<F>(func)
-      );
-    }
+    return this->then(this->launch_policy(), boost::forward<F>(func));
   }
 
   ////////////////////////////////
@@ -4996,37 +4976,7 @@ namespace detail {
   template <typename F>
   inline BOOST_THREAD_FUTURE<typename boost::result_of<F(BOOST_THREAD_FUTURE<BOOST_THREAD_FUTURE<R2> >)>::type>
   BOOST_THREAD_FUTURE<BOOST_THREAD_FUTURE<R2> >::then(BOOST_THREAD_FWD_REF(F) func)  {
-    typedef BOOST_THREAD_FUTURE<R2> R;
-    typedef typename boost::result_of<F(BOOST_THREAD_FUTURE<R>)>::type future_type;
-    BOOST_THREAD_ASSERT_PRECONDITION(this->future_!=0, future_uninitialized());
-
-    boost::unique_lock<boost::mutex> lock(this->future_->mutex);
-    if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::async)) {
-      lock.unlock();
-      return boost::detail::make_future_async_continuation_shared_state<BOOST_THREAD_FUTURE<R>, future_type>(
-          lock, boost::move(*this), boost::forward<F>(func)
-      );
-    } else if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::deferred)) {
-      this->future_->wait_internal(lock);
-      lock.unlock();
-      return boost::detail::make_future_deferred_continuation_shared_state<BOOST_THREAD_FUTURE<R>, future_type>(
-          lock, boost::move(*this), boost::forward<F>(func)
-      );
-#ifdef BOOST_THREAD_PROVIDES_EXECUTORS
-    } else if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::executor)) {
-      typedef executor Ex;
-      Ex& ex = *(this->future_->get_executor());
-      lock.unlock();
-      return BOOST_THREAD_MAKE_RV_REF((boost::detail::make_future_executor_continuation_shared_state<Ex, BOOST_THREAD_FUTURE<R>, future_type>(ex,
-                    lock, boost::move(*this), boost::forward<F>(func)
-                )));
-#endif
-      } else {
-      lock.unlock();
-      return boost::detail::make_future_async_continuation_shared_state<BOOST_THREAD_FUTURE<R>, future_type>(
-          lock, boost::move(*this), boost::forward<F>(func)
-      );
-    }
+    return this->then(this->launch_policy(), boost::forward<F>(func));
   }
 
   ////////////////////////////////
@@ -5098,34 +5048,9 @@ namespace detail {
   template <typename F>
   inline BOOST_THREAD_FUTURE<typename boost::result_of<F(shared_future<R>)>::type>
   shared_future<R>::then(BOOST_THREAD_FWD_REF(F) func)  const {
-    typedef typename boost::result_of<F(shared_future<R>)>::type future_type;
 
-    BOOST_THREAD_ASSERT_PRECONDITION(this->future_!=0, future_uninitialized());
+    return this->then(this->launch_policy(), boost::forward<F>(func));
 
-    boost::unique_lock<boost::mutex> lock(this->future_->mutex);
-    if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::async)) {
-      lock.unlock();
-      return boost::detail::make_shared_future_async_continuation_shared_state<shared_future<R>, future_type>(
-          lock, *this, boost::forward<F>(func));
-    } else if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::deferred)) {
-      this->future_->wait_internal(lock);
-      lock.unlock();
-      return boost::detail::make_shared_future_deferred_continuation_shared_state<shared_future<R>, future_type>(
-          lock, *this, boost::forward<F>(func));
-#ifdef BOOST_THREAD_PROVIDES_EXECUTORS
-    } else if (underlying_cast<int>(this->launch_policy(lock)) & int(launch::executor)) {
-      typedef executor Ex;
-      Ex& ex = *(this->future_->get_executor());
-      lock.unlock();
-      return BOOST_THREAD_MAKE_RV_REF((boost::detail::make_shared_future_executor_continuation_shared_state<Ex, shared_future<R>, future_type>(ex,
-                    lock, *this, boost::forward<F>(func)
-                )));
-#endif
-      } else {
-      lock.unlock();
-      return boost::detail::make_shared_future_async_continuation_shared_state<shared_future<R>, future_type>(
-          lock, *this, boost::forward<F>(func));
-    }
   }
 
 namespace detail