Additional constructors for consuming_buffers

include/beast/core/impl/consuming_buffers.ipp

@@ -109,6 +109,14 @@ private:
     }
 };
 
+template<class BufferSequence>
+consuming_buffers<BufferSequence>::
+consuming_buffers()
+    : begin_(bs_.begin())
+    , end_(bs_.end())
+{
+}
+
 template<class BufferSequence>
 consuming_buffers<BufferSequence>::
 consuming_buffers(consuming_buffers&& other)
@@ -167,6 +175,21 @@ consuming_buffers(BufferSequence const& bs)
             "BufferSequence requirements not met");
 }
 
+template<class BufferSequence>
+template<class... Args>
+consuming_buffers<BufferSequence>::
+consuming_buffers(boost::in_place_init_t, Args&&... args)
+    : bs_(std::forward<Args>(args)...)
+    , begin_(bs_.begin())
+    , end_(bs_.end())
+{
+    static_assert(sizeof...(Args) > 0,
+        "Missing constructor arguments");
+    static_assert(
+        std::is_constructible<BufferSequence, Args...>::value,
+            "BufferSequence is not constructible from arguments");
+}
+
 template<class BufferSequence>
 inline
 auto