added coroutine

include/boost/process/detail/async_handler.hpp

@@ -76,6 +76,41 @@ struct has_async_handler<T>
     typedef typename is_async_handler<T>::type type;
 };
 
+
+template<typename T>
+struct is_yield_context
+{
+	typedef std::false_type type;
+};
+
+template<typename T>
+struct is_yield_context<::boost::asio::basic_yield_context<T>>
+{
+	typedef std::true_type type;
+};
+
+template<typename ...Args>
+struct has_yield_context;
+
+template<typename T, typename ...Args>
+struct has_yield_context<T, Args...>
+{
+    typedef typename has_yield_context<Args...>::type next;
+    typedef typename is_yield_context<
+    		typename std::remove_reference<T>::type>::type is_ios;
+    typedef typename std::conditional<is_ios::value,
+            std::true_type,
+            next>::type type;
+};
+
+template<typename T>
+struct has_yield_context<T>
+{
+    typedef typename is_yield_context<
+    		typename std::remove_reference<T>::type>::type type;
+};
+
+
 template<typename ...Args>
 boost::asio::io_service &get_io_service_var(boost::asio::io_service & f, Args&...args)
 {

include/boost/process/detail/posix/asio_fwd.hpp

@@ -29,7 +29,8 @@ template <typename SignalSetService>
 class basic_signal_set;
 typedef basic_signal_set<signal_set_service> signal_set;
 
-
+template <typename Handler>
+class basic_yield_context;
 
 namespace posix {
 

include/boost/process/detail/windows/asio_fwd.hpp

@@ -21,6 +21,9 @@ class basic_streambuf;
 typedef basic_streambuf<std::allocator<char>> streambuf;
 class io_service;
 
+template <typename Handler>
+class basic_yield_context;
+
 namespace windows {
 
 class stream_handle_service;

include/boost/process/system.hpp

@@ -41,6 +41,7 @@ template<typename IoService, typename ...Args>
 inline int system_impl(
         std::true_type, /*has async */
         std::true_type, /*has io_service*/
+        std::false_type, /* has_yield */
         Args && ...args)
 {
     IoService & ios = ::boost::process::detail::get_io_service_var(args...);
@@ -84,6 +85,7 @@ template<typename IoService, typename ...Args>
 inline int system_impl(
         std::true_type, /*has async */
         std::false_type, /*has io_service*/
+        std::false_type, /* has_yield */
         Args && ...args)
 {
     IoService ios;
@@ -100,6 +102,7 @@ template<typename IoService, typename ...Args>
 inline int system_impl(
         std::false_type, /*has async */
         std::true_type, /*has io_service*/
+        std::false_type, /* has_yield */
         Args && ...args)
 {
     child c(std::forward<Args>(args)...);
@@ -113,6 +116,7 @@ template<typename IoService, typename ...Args>
 inline int system_impl(
         std::false_type, /*has async */
         std::false_type, /*has io_service*/
+        std::false_type, /* has_yield */
         Args && ...args)
 {
     child c(std::forward<Args>(args)...);
@@ -122,6 +126,127 @@ inline int system_impl(
     return c.exit_code();
 }
 
+template<typename T>
+constexpr T& remove_yield(T& t) noexcept
+{
+    return t;
+}
+
+template<typename T>
+constexpr T&& remove_yield(T&& t) noexcept
+{
+    return static_cast<T&&>(t);
+}
+
+template<typename Handler>
+constexpr ::boost::process::detail::handler
+    remove_yield(::boost::asio::basic_yield_context<Handler> & yield_) noexcept
+{
+    return {}; //essentially nop.
+}
+
+template<typename Handler>
+constexpr ::boost::process::detail::handler
+    remove_yield(::boost::asio::basic_yield_context<Handler> && yield_) noexcept
+{
+    return {}; //essentially nop.
+}
+
+template<typename ...Args>
+struct get_yield_t;
+
+template<typename First, typename ... Args>
+struct get_yield_t<First, Args...>
+{
+    typedef typename get_yield_t<Args...>::type type;
+};
+
+template<typename First, typename ... Args>
+struct get_yield_t<boost::asio::basic_yield_context<First>, Args...>
+{
+    typedef boost::asio::basic_yield_context<First> type;
+};
+
+template<typename First>
+struct get_yield_t<boost::asio::basic_yield_context<First>>
+{
+    typedef boost::asio::basic_yield_context<First> type;
+};
+
+template<typename Handler, typename ...Args>
+auto get_yield(boost::asio::basic_yield_context<Handler> &&yield_) ->
+        boost::asio::basic_yield_context<Handler> &
+{
+    return yield_;
+}
+
+template<typename Handler, typename ...Args>
+auto get_yield(boost::asio::basic_yield_context<Handler> &yield_) ->
+        boost::asio::basic_yield_context<Handler> &
+{
+    return yield_;
+}
+
+
+template<typename First, typename ...Args>
+auto get_yield(First &&f, Args&&...args) ->
+    typename get_yield_t<typename std::remove_reference<Args>::type...>::type &
+{
+    return get_yield(args...);
+}
+
+template<typename Handler, typename ...Args>
+auto get_yield(boost::asio::basic_yield_context<Handler> &&yield_, Args&&...args) ->
+    typename get_yield_t<typename std::remove_reference<Args>::type...>::type &
+{
+    return yield_;
+}
+
+template<typename Handler, typename ...Args>
+auto get_yield(boost::asio::basic_yield_context<Handler> &yield_, Args&&...args) ->
+    typename get_yield_t<typename std::remove_reference<Args>::type...>::type &
+{
+    return yield_;
+}
+
+
+template<typename IoService, typename T1, typename T2, typename ...Args>
+inline int system_impl(
+        T1, /*has async */
+        T2, /*has io_service*/
+        std::true_type, /* has_yield */
+        Args && ...args)
+{
+
+    auto &yield_ = get_yield(args...);
+    auto coro = yield_.coro_.lock();
+    auto & ios = yield_.handler_.dispatcher_.get_io_service();
+    BOOST_ASSERT(coro);
+
+    int ret = -1;
+    auto l = [coro, &ret, &ios](int ret_, const std::error_code& ec_)
+    {
+        ret = ret_;
+        ios.post(
+        		[coro]
+			    {
+                    auto & c = *coro;
+        			if (c)
+        				c();
+				 });
+    };
+
+    child c(remove_yield(std::forward<Args>(args))...,
+            ios,
+            boost::process::on_exit=l);
+    if (!c.valid())
+        return -1;
+
+    yield_.ca_();
+
+    return ret;
+}
+
 }
 
 /** Launches a process and waits for its exit. Similar to std::system. */
@@ -132,9 +257,11 @@ inline int system(Args && ...args)
             has_async;
     typedef typename ::boost::process::detail::has_io_service<Args...>::type
             has_ios;
+    typedef typename ::boost::process::detail::has_yield_context<Args...>::type
+            has_yield;
 
     return ::boost::process::detail::system_impl<boost::asio::io_service>(
-            has_async(), has_ios(),
+            has_async(), has_ios(), has_yield(),
 #if defined(BOOST_POSIX_API)
             ::boost::process::posix::sig.dfl(),
 #endif