boost/iostreams/optimal_buffer_size.hpp

   1 // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
   2 // (C) Copyright 2003-2007 Jonathan Turkanis
   3 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   4 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
   5
   6 // See http://www.boost.org/libs/iostreams for documentation.
   7
   8 #ifndef BOOST_IOSTREAMS_OPTIMAL_BUFFER_SIZE_HPP_INCLUDED
   9 #define BOOST_IOSTREAMS_OPTIMAL_BUFFER_SIZE_HPP_INCLUDED
  10
  11 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
  12 # pragma once
  13 #endif
  14
  15 #include <boost/config.hpp>  // DEDUCED_TYPENAME, MSVC.
  16 #include <boost/detail/workaround.hpp>
  17 #include <boost/iostreams/constants.hpp>  // constants.
  18 #include <boost/iostreams/detail/dispatch.hpp>
  19 #include <boost/iostreams/detail/wrap_unwrap.hpp>
  20 #include <boost/iostreams/operations_fwd.hpp>
  21 #include <boost/mpl/if.hpp>
  22
  23 // Must come last.
  24 #include <boost/iostreams/detail/config/disable_warnings.hpp>
  25
  26 namespace boost { namespace iostreams {
  27
  28 namespace detail {
  29
  30 template<typename T>
  31 struct optimal_buffer_size_impl;
  32
  33 } // End namespace detail.
  34
  35 template<typename T>
  36 std::streamsize optimal_buffer_size(const T& t)
  37 {
  38     typedef detail::optimal_buffer_size_impl<T> impl;
  39     return impl::optimal_buffer_size(detail::unwrap(t));
  40 }
  41
  42 namespace detail {
  43
  44 //------------------Definition of optimal_buffer_size_impl--------------------//
  45
  46 template<typename T>
  47 struct optimal_buffer_size_impl
  48     : mpl::if_<
  49           is_custom<T>,
  50           operations<T>,
  51           optimal_buffer_size_impl<
  52               BOOST_DEDUCED_TYPENAME
  53               dispatch<
  54                   T, optimally_buffered_tag, device_tag, filter_tag
  55               >::type
  56           >
  57       >::type
  58     { };
  59
  60 template<>
  61 struct optimal_buffer_size_impl<optimally_buffered_tag> {
  62     template<typename T>
  63     static std::streamsize optimal_buffer_size(const T& t)
  64     { return t.optimal_buffer_size(); }
  65 };
  66
  67 template<>
  68 struct optimal_buffer_size_impl<device_tag> {
  69     template<typename T>
  70     static std::streamsize optimal_buffer_size(const T&)
  71     { return default_device_buffer_size; }
  72 };
  73
  74 template<>
  75 struct optimal_buffer_size_impl<filter_tag> {
  76     template<typename T>
  77     static std::streamsize optimal_buffer_size(const T&)
  78     { return default_filter_buffer_size; }
  79 };
  80
  81 } // End namespace detail.
  82
  83 } } // End namespaces iostreams, boost.
  84
  85 #include <boost/iostreams/detail/config/enable_warnings.hpp>
  86
  87 #endif // #ifndef BOOST_IOSTREAMS_OPTIMAL_BUFFER_SIZE_HPP_INCLUDED