ndnboost: Include boost::iostreams for internal use.
diff --git a/include/ndnboost/iostreams/optimal_buffer_size.hpp b/include/ndnboost/iostreams/optimal_buffer_size.hpp
new file mode 100644
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+++ b/include/ndnboost/iostreams/optimal_buffer_size.hpp
@@ -0,0 +1,87 @@
+// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
+// (C) Copyright 2003-2007 Jonathan Turkanis
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
+
+// See http://www.boost.org/libs/iostreams for documentation.
+
+#ifndef NDNBOOST_IOSTREAMS_OPTIMAL_BUFFER_SIZE_HPP_INCLUDED
+#define NDNBOOST_IOSTREAMS_OPTIMAL_BUFFER_SIZE_HPP_INCLUDED
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+#include <ndnboost/config.hpp>  // DEDUCED_TYPENAME, MSVC.
+#include <ndnboost/detail/workaround.hpp>
+#include <ndnboost/iostreams/constants.hpp>  // constants.
+#include <ndnboost/iostreams/detail/dispatch.hpp>
+#include <ndnboost/iostreams/detail/wrap_unwrap.hpp>
+#include <ndnboost/iostreams/operations_fwd.hpp>
+#include <ndnboost/mpl/if.hpp>
+
+// Must come last.
+#include <ndnboost/iostreams/detail/config/disable_warnings.hpp>
+
+namespace ndnboost { namespace iostreams {
+
+namespace detail {
+
+template<typename T>
+struct optimal_buffer_size_impl;
+
+} // End namespace detail.
+
+template<typename T>
+std::streamsize optimal_buffer_size(const T& t)
+{
+    typedef detail::optimal_buffer_size_impl<T> impl;
+    return impl::optimal_buffer_size(detail::unwrap(t));
+}
+
+namespace detail {
+
+//------------------Definition of optimal_buffer_size_impl--------------------//
+
+template<typename T>
+struct optimal_buffer_size_impl
+    : mpl::if_<
+          is_custom<T>,
+          operations<T>,
+          optimal_buffer_size_impl<
+              NDNBOOST_DEDUCED_TYPENAME
+              dispatch<
+                  T, optimally_buffered_tag, device_tag, filter_tag
+              >::type
+          >
+      >::type
+    { };
+
+template<>
+struct optimal_buffer_size_impl<optimally_buffered_tag> {
+    template<typename T>
+    static std::streamsize optimal_buffer_size(const T& t)
+    { return t.optimal_buffer_size(); }
+};
+
+template<>
+struct optimal_buffer_size_impl<device_tag> {
+    template<typename T>
+    static std::streamsize optimal_buffer_size(const T&)
+    { return default_device_buffer_size; }
+};
+
+template<>
+struct optimal_buffer_size_impl<filter_tag> {
+    template<typename T>
+    static std::streamsize optimal_buffer_size(const T&)
+    { return default_filter_buffer_size; }
+};
+
+} // End namespace detail.
+
+} } // End namespaces iostreams, boost.
+
+#include <ndnboost/iostreams/detail/config/enable_warnings.hpp>
+
+#endif // #ifndef NDNBOOST_IOSTREAMS_OPTIMAL_BUFFER_SIZE_HPP_INCLUDED