boost/boost/iostreams/optimal_buffer_size.hpp

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