// (C) Copyright Jonathan Turkanis 2005.

 // 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 BOOST_IOSTREAMS_READ_HPP_INCLUDED

 #define BOOST_IOSTREAMS_READ_HPP_INCLUDED

 #if defined(_MSC_VER) && (_MSC_VER >= 1020)

 # pragma once

 #endif

 #include <boost/config.hpp>  // DEDUCED_TYPENAME, MSVC.

 #include <boost/detail/workaround.hpp>

 #include <boost/iostreams/char_traits.hpp>

 #include <boost/iostreams/detail/char_traits.hpp>

 #include <boost/iostreams/detail/dispatch.hpp>

 #include <boost/iostreams/detail/ios.hpp>  // streamsize.

 #include <boost/iostreams/detail/streambuf.hpp>

 #include <boost/iostreams/detail/wrap_unwrap.hpp>

 #include <boost/iostreams/operations_fwd.hpp>

 #include <boost/mpl/if.hpp>

 // Must come last.

 #include <boost/iostreams/detail/config/disable_warnings.hpp>

 #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) //-----------------------------------//

 # include <boost/iostreams/detail/vc6/read.hpp>

 #else // #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) //--------------------------//

 namespace boost { namespace iostreams {

 namespace detail {

 template<typename T>

 struct read_device_impl;

 template<typename T>

 struct read_filter_impl;

 } // End namespace detail.

 template<typename T>

 typename int_type_of<T>::type get(T& t)

 { return detail::read_device_impl<T>::get(detail::unwrap(t)); }

 template<typename T>

 inline std::streamsize

 read(T& t, typename char_type_of<T>::type* s, std::streamsize n)

 { return detail::read_device_impl<T>::read(detail::unwrap(t), s, n); }

 template<typename T, typename Source>

 std::streamsize

 read(T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n)

 { return detail::read_filter_impl<T>::read(detail::unwrap(t), src, s, n); }

 template<typename T>

 bool putback(T& t, typename char_type_of<T>::type c)

 { return detail::read_device_impl<T>::putback(detail::unwrap(t), c); }

 //----------------------------------------------------------------------------//

 namespace detail {

 // Helper function for adding -1 as EOF indicator.

 inline std::streamsize check_eof(std::streamsize n) { return n != 0 ? n : -1; }

 // Helper templates for reading from streambufs.

 template<bool IsLinked>

 struct true_eof_impl;

 template<>

 struct true_eof_impl<true> {

     template<typename T>

     static bool true_eof(T& t) { return t.true_eof(); }

 };

 template<>

 struct true_eof_impl<false> {

     template<typename T>

     static bool true_eof(T& t) { return true; }

 };

 template<typename T>

 inline bool true_eof(T& t)

 {

     const bool linked = is_linked<T>::value;

     return true_eof_impl<linked>::true_eof(t);

 }

 //------------------Definition of read_device_impl----------------------------//

 template<typename T>

 struct read_device_impl

     : mpl::if_<

           detail::is_custom<T>,

           operations<T>,

           read_device_impl<

               BOOST_DEDUCED_TYPENAME

               detail::dispatch<

                   T, istream_tag, streambuf_tag, input

               >::type

           >

       >::type

     { };

 template<>

 struct read_device_impl<istream_tag> {

     template<typename T>

     static typename int_type_of<T>::type get(T& t)

     { return t.get(); }

     template<typename T>

     static std::streamsize

     read(T& t, typename char_type_of<T>::type* s, std::streamsize n)

     { return check_eof(t.rdbuf()->sgetn(s, n)); }

     template<typename T>

     static bool putback(T& t, typename char_type_of<T>::type c)

     {

         typedef typename char_type_of<T>::type          char_type;

         typedef BOOST_IOSTREAMS_CHAR_TRAITS(char_type)  traits_type;

         return !traits_type::eq_int_type( t.rdbuf()->sputbackc(c),

                                           traits_type::eof() );

     }

 };

 template<>

 struct read_device_impl<streambuf_tag> {

     template<typename T>

     static typename int_type_of<T>::type

     get(T& t)

     {   // gcc 2.95 needs namespace qualification for char_traits.

         typedef typename char_type_of<T>::type     char_type;

         typedef iostreams::char_traits<char_type>  traits_type;

         typename int_type_of<T>::type c;

         return !traits_type::is_eof(c = t.sbumpc()) ||

                 detail::true_eof(t)

                     ?

                 c : traits_type::would_block();

     }

     template<typename T>

     static std::streamsize

     read(T& t, typename char_type_of<T>::type* s, std::streamsize n)

     {

         std::streamsize amt;

         return (amt = t.sgetn(s, n)) != 0 ?

             amt :

             detail::true_eof(t) ?

                 -1 :

                 0;

     }

     template<typename T>

     static bool putback(T& t, typename char_type_of<T>::type c)

     {   // gcc 2.95 needs namespace qualification for char_traits.

         typedef typename char_type_of<T>::type     char_type;

         typedef iostreams::char_traits<char_type>  traits_type;

         return !traits_type::is_eof(t.sputbackc(c));

     }

 };

 template<>

 struct read_device_impl<input> {

     template<typename T>

     static typename int_type_of<T>::type

     get(T& t)

     {   // gcc 2.95 needs namespace qualification for char_traits.

         typedef typename char_type_of<T>::type     char_type;

         typedef iostreams::char_traits<char_type>  traits_type;

         char_type c;

         std::streamsize amt;

         return (amt = t.read(&c, 1)) == 1 ?

             traits_type::to_int_type(c) :

             amt == -1 ?

                 traits_type::eof() :

                 traits_type::would_block();

     }

     template<typename T>

     static std::streamsize

     read(T& t, typename char_type_of<T>::type* s, std::streamsize n)

     { return t.read(s, n); }

     template<typename T>

     static bool putback(T& t, typename char_type_of<T>::type c)

     {   // T must be Peekable.

         return t.putback(c);

     }

 };

 //------------------Definition of read_filter_impl----------------------------//

 template<typename T>

 struct read_filter_impl

     : mpl::if_<

           detail::is_custom<T>,

           operations<T>,

           read_filter_impl<

               BOOST_DEDUCED_TYPENAME

               detail::dispatch<

                   T, multichar_tag, any_tag

               >::type

           >

       >::type

     { };

 template<>

 struct read_filter_impl<multichar_tag> {

     template<typename T, typename Source>

     static std::streamsize read

        (T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n)

     { return t.read(src, s, n); }

 };

 template<>

 struct read_filter_impl<any_tag> {

     template<typename T, typename Source>

     static std::streamsize read

        (T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n)

     {   // gcc 2.95 needs namespace qualification for char_traits.

         typedef typename char_type_of<T>::type     char_type;

         typedef iostreams::char_traits<char_type>  traits_type;

         for (std::streamsize off = 0; off < n; ++off) {

             typename traits_type::int_type c = t.get(src);

             if (traits_type::is_eof(c))

                 return check_eof(off);

             if (traits_type::would_block(c))

                 return off;

             s[off] = traits_type::to_char_type(c);

         }

         return n;

     }

 };

 } // End namespace detail.

 } } // End namespaces iostreams, boost.

 #endif // #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) //-------------------------//

 #include <boost/iostreams/detail/config/enable_warnings.hpp>

 #endif // #ifndef BOOST_IOSTREAMS_READ_HPP_INCLUDED