// (C) Copyright Jonathan Turkanis 2003.

// 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.

// 

// Contains metafunctions char_type_of, category_of and mode_of used for

// deducing the i/o category and i/o mode of a model of Filter or Device.

//

// Also contains several utility metafunctions, functions and macros.

//

#ifndef BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED

#define BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED

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

# pragma once

#endif              

#include <iosfwd>            // stream types, char_traits.

#include <boost/config.hpp>  // partial spec, deduced typename.

#include <boost/iostreams/categories.hpp>

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

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

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

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

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

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

#include <boost/iostreams/traits_fwd.hpp> 

#include <boost/mpl/bool.hpp>   

#include <boost/mpl/eval_if.hpp>

#include <boost/mpl/identity.hpp>      

#include <boost/mpl/int.hpp>  

#include <boost/mpl/or.hpp>                         

#include <boost/range/iterator_range.hpp>

#include <boost/range/value_type.hpp>

#include <boost/type_traits/is_convertible.hpp>     

namespace boost { namespace iostreams {        

//------------------Definitions of predicates for streams and stream buffers--//

#ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //--------------------------------//

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_istream, std::basic_istream, 2)

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ostream, std::basic_ostream, 2)

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_iostream, std::basic_iostream, 2)

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_streambuf, std::basic_streambuf, 2)

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_stringstream, std::basic_stringstream, 3)

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_stringbuf, std::basic_stringbuf, 3)

#else // #ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //-----------------------//

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_istream, std::istream, 0)

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ostream, std::ostream, 0)

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_iostream, std::iostream, 0)

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_streambuf, std::streambuf, 0)

#endif // #ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //----------------------//

template<typename T>

struct is_std_io

    : mpl::or_< is_istream<T>, is_ostream<T>, is_streambuf<T> >

    { };

namespace detail {

template<typename T, typename Tr>

class linked_streambuf;

BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_linked, linked_streambuf, 2)

} // End namespace detail.

//------------------Definitions of char_type_of-------------------------------//

namespace detail {

template<typename T>

struct member_char_type { typedef typename T::char_type type; };

} // End namespace detail.

#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //---------------------------//

# ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //-------------------------------//

template<typename T>

struct char_type_of 

    : detail::member_char_type<

          typename detail::unwrapped_type<T>::type

      > 

    { };

# else // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //---------------------//

template<typename T>

struct char_type_of {

    typedef typename detail::unwrapped_type<T>::type U;

    typedef typename 

            mpl::eval_if<

                is_std_io<U>,

                mpl::identity<char>,

                detail::member_char_type<U>

            >::type type;

};

# endif // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //--------------------//

template<typename Iter>

struct char_type_of< iterator_range<Iter> > {

    typedef typename iterator_value<Iter>::type type;

};

#else // #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //------------------//

template<typename T>

struct char_type_of {

    template<typename U>

    struct get_value_type {

        typedef typename range_value<U>::type type;

    };

    typedef typename 

            mpl::eval_if<

                is_iterator_range<T>,

                get_value_type<T>,

                detail::member_char_type<

                    BOOST_DEDUCED_TYPENAME detail::unwrapped_type<T>::type

                >

            >::type type;

};

#endif // #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION //-----------------//

//------------------Definitions of category_of--------------------------------//

namespace detail {

template<typename T>

struct member_category { typedef typename T::category type; };

} // End namespace detail.

template<typename T>

struct category_of {

    template<typename U>

    struct member_category { 

        typedef typename U::category type; 

    };

    typedef typename detail::unwrapped_type<T>::type U;

    typedef typename  

            mpl::eval_if<

                is_std_io<U>,

                iostreams::select<  // Disambiguation for Tru64

                    is_iostream<U>,   iostream_tag, 

                    is_istream<U>,    istream_tag, 

                    is_ostream<U>,    ostream_tag,

                    is_streambuf<U>,  streambuf_tag

                >,

                detail::member_category<U>

            >::type type;      

};

//------------------Definition of get_category--------------------------------//

// 

// Returns an object of type category_of<T>::type.

// 

template<typename T>

inline typename category_of<T>::type get_category(const T&) 

{ typedef typename category_of<T>::type category; return category(); }

//------------------Definition of int_type_of---------------------------------//

template<typename T>

struct int_type_of { 

#ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES

    typedef std::char_traits<

                BOOST_DEDUCED_TYPENAME char_type_of<T>::type

            > traits_type;      

    typedef typename traits_type::int_type type; 

#else  

    typedef int                            type; 

#endif

};

//------------------Definition of mode----------------------------------------//

namespace detail {

template<int N> struct io_mode_impl;

#define BOOST_IOSTREAMS_MODE_HELPER(tag_, id_) \

    case_<id_> io_mode_impl_helper(tag_); \

    template<> struct io_mode_impl<id_> { typedef tag_ type; }; \

    /**/

BOOST_IOSTREAMS_MODE_HELPER(input, 1)

BOOST_IOSTREAMS_MODE_HELPER(output, 2)

BOOST_IOSTREAMS_MODE_HELPER(bidirectional, 3)

BOOST_IOSTREAMS_MODE_HELPER(input_seekable, 4)

BOOST_IOSTREAMS_MODE_HELPER(output_seekable, 5)

BOOST_IOSTREAMS_MODE_HELPER(seekable, 6)

BOOST_IOSTREAMS_MODE_HELPER(dual_seekable, 7)

BOOST_IOSTREAMS_MODE_HELPER(bidirectional_seekable, 8)

BOOST_IOSTREAMS_MODE_HELPER(dual_use, 9)

#undef BOOST_IOSTREAMS_MODE_HELPER

template<typename T>

struct io_mode_id {

    typedef typename category_of<T>::type category;

    BOOST_SELECT_BY_SIZE(int, value, detail::io_mode_impl_helper(category()));

};

} // End namespace detail.

template<typename T> // Borland 5.6.4 requires this circumlocution.

struct mode_of : detail::io_mode_impl< detail::io_mode_id<T>::value > { };

//------------------Definition of is_device, is_filter and is_direct----------//

namespace detail {

template<typename T, typename Tag>

struct has_trait_impl {

    typedef typename category_of<T>::type category;

    BOOST_STATIC_CONSTANT(bool, value = (is_convertible<category, Tag>::value));

};

template<typename T, typename Tag>

struct has_trait 

    : mpl::bool_<has_trait_impl<T, Tag>::value>

    { }; 

} // End namespace detail.

template<typename T>

struct is_device : detail::has_trait<T, device_tag> { };

template<typename T>

struct is_filter : detail::has_trait<T, filter_tag> { };

template<typename T>

struct is_direct : detail::has_trait<T, direct_tag> { };

//------------------Definition of BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS----------//

#define BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS(Tr) \

    typedef Tr                              traits_type; \

    typedef typename traits_type::int_type  int_type; \

    typedef typename traits_type::off_type  off_type; \

    typedef typename traits_type::pos_type  pos_type; \

    /**/

} } // End namespaces iostreams, boost.

#endif // #ifndef BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED