boost/iostreams/traits.hpp
// (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. // // 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> #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300) # include <boost/range/iterator_range.hpp> # include <boost/range/value_type.hpp> #endif // #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) #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_ifstream, std::basic_ifstream, 2) BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ofstream, std::basic_ofstream, 2) BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_fstream, std::basic_fstream, 2) BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_filebuf, std::basic_filebuf, 2) BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_istringstream, std::basic_istringstream, 3) BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ostringstream, std::basic_ostringstream, 3) 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> > { }; template<typename T> struct is_std_file_device : mpl::or_< is_ifstream<T>, is_ofstream<T>, is_fstream<T>, is_filebuf<T> > { }; template<typename T> struct is_std_string_device : mpl::or_< is_istringstream<T>, is_ostringstream<T>, is_stringstream<T>, is_stringbuf<T> > { }; template<typename Device, typename Tr, typename Alloc> struct stream; template<typename T, typename Tr, typename Alloc, typename Mode> class stream_buffer; template< typename Mode, typename Ch, typename Tr, typename Alloc, typename Access > class filtering_stream; template< typename Mode, typename Ch, typename Tr, typename Alloc, typename Access > class wfiltering_stream; template< typename Mode, typename Ch, typename Tr, typename Alloc, typename Access > class filtering_streambuf; template< typename Mode, typename Ch, typename Tr, typename Alloc, typename Access > class filtering_wstreambuf; namespace detail { template<typename T, typename Tr> class linked_streambuf; BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_boost_stream, boost::iostreams::stream, 3 ) BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_boost_stream_buffer, boost::iostreams::stream_buffer, 4 ) BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_filtering_stream_impl, boost::iostreams::filtering_stream, 5 ) BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_filtering_wstream_impl, boost::iostreams::wfiltering_stream, 5 ) BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_filtering_streambuf_impl, boost::iostreams::filtering_streambuf, 5 ) BOOST_IOSTREAMS_BOOL_TRAIT_DEF( is_filtering_wstreambuf_impl, boost::iostreams::filtering_wstreambuf, 5 ) BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_linked, linked_streambuf, 2) template<typename T> struct is_filtering_stream : mpl::or_< is_filtering_stream_impl<T>, is_filtering_wstream_impl<T> > { }; template<typename T> struct is_filtering_streambuf : mpl::or_< is_filtering_streambuf_impl<T>, is_filtering_wstreambuf_impl<T> > { }; template<typename T> struct is_boost : mpl::or_< is_boost_stream<T>, is_boost_stream_buffer<T>, is_filtering_stream<T>, is_filtering_streambuf<T> > { }; } // 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 { #if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300) typedef typename range_value<U>::type type; #endif // #if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) }; 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< mpl::and_< is_std_io<U>, mpl::not_< detail::is_boost<U> > >, iostreams::select< // Disambiguation for Tru64 is_filebuf<U>, filebuf_tag, is_ifstream<U>, ifstream_tag, is_ofstream<U>, ofstream_tag, is_fstream<U>, fstream_tag, is_stringbuf<U>, stringbuf_tag, is_istringstream<U>, istringstream_tag, is_ostringstream<U>, ostringstream_tag, is_stringstream<U>, stringstream_tag, is_streambuf<U>, generic_streambuf_tag, is_iostream<U>, generic_iostream_tag, is_istream<U>, generic_istream_tag, is_ostream<U>, generic_ostream_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