Additional constructors for consuming_buffers

include/beast/core/consuming_buffers.hpp

@@ -10,6 +10,7 @@
 
 #include <beast/config.hpp>
 #include <boost/asio/buffer.hpp>
+#include <boost/optional.hpp>
 #include <cstdint>
 #include <iterator>
 #include <type_traits>
@@ -78,6 +79,9 @@ public:
 
 #endif
 
+    /// Default constructor.
+    consuming_buffers();
+
     /// Move constructor.
     consuming_buffers(consuming_buffers&&);
 
@@ -98,6 +102,13 @@ public:
     explicit
     consuming_buffers(BufferSequence const& buffers);
 
+    /** Construct a buffer sequence in-place.
+
+        @param args Arguments forwarded to the contained buffers constructor.
+    */
+    template<class... Args>
+    consuming_buffers(boost::in_place_init_t, Args&&... args);
+
     /// Get a bidirectional iterator to the first element.
     const_iterator
     begin() const;

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