From 8c6e7d8bf78b4950d5d7d38e48dc0ec8ceae0d22 Mon Sep 17 00:00:00 2001
From: q66 <daniel@octaforge.org>
Date: Sat, 11 Mar 2017 14:51:34 +0100
Subject: [PATCH] add a generic way to get an yielder for a coroutine/generator

---
 ostd/coroutine.hh | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/ostd/coroutine.hh b/ostd/coroutine.hh
index e775732..0b48215 100644
--- a/ostd/coroutine.hh
+++ b/ostd/coroutine.hh
@@ -567,6 +567,20 @@ inline void swap(generator<T> &a, generator<T> &b) {
     a.swap(b);
 }
 
+namespace detail {
+    template<typename T>
+    struct yield_type_base {
+        using type = typename generator<T>::yield_type;
+    };
+    template<typename R, typename ...A>
+    struct yield_type_base<R(A...)> {
+        using type = typename coroutine<R(A...)>::yield_type;
+    };
+}
+
+template<typename T>
+using yield_type = typename detail::yield_type_base<T>::type;
+
 template<typename T>
 struct generator_range: input_range<generator_range<T>> {
     using range_category  = input_range_tag;