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os/ossrv/ossrv_pub/boost_apis/boost/iostreams/traits.hpp
author sl
Tue, 10 Jun 2014 14:32:02 +0200
changeset 1 260cb5ec6c19
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     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 // 

     8 // Contains metafunctions char_type_of, category_of and mode_of used for

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

    10 //

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

    12 //

    13 

    14 #ifndef BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED

    15 #define BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED

    16 

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

    18 # pragma once

    19 #endif              

    20 

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

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

    23 #include <boost/iostreams/categories.hpp>

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

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

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

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

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

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

    30 #include <boost/iostreams/traits_fwd.hpp> 

    31 #include <boost/mpl/bool.hpp>   

    32 #include <boost/mpl/eval_if.hpp>

    33 #include <boost/mpl/identity.hpp>      

    34 #include <boost/mpl/int.hpp>  

    35 #include <boost/mpl/or.hpp>                         

    36 #include <boost/range/iterator_range.hpp>

    37 #include <boost/range/value_type.hpp>

    38 #include <boost/type_traits/is_convertible.hpp>     

    39 

    40 namespace boost { namespace iostreams {        

    41 

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

    43 

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

    45 

    46 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_istream, std::basic_istream, 2)

    47 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ostream, std::basic_ostream, 2)

    48 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_iostream, std::basic_iostream, 2)

    49 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_streambuf, std::basic_streambuf, 2)

    50 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_stringstream, std::basic_stringstream, 3)

    51 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_stringbuf, std::basic_stringbuf, 3)

    52 

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

    54 

    55 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_istream, std::istream, 0)

    56 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_ostream, std::ostream, 0)

    57 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_iostream, std::iostream, 0)

    58 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_streambuf, std::streambuf, 0)

    59 

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

    61 

    62 template<typename T>

    63 struct is_std_io

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

    65     { };

    66 

    67 namespace detail {

    68 

    69 template<typename T, typename Tr>

    70 class linked_streambuf;

    71 

    72 BOOST_IOSTREAMS_BOOL_TRAIT_DEF(is_linked, linked_streambuf, 2)

    73 

    74 } // End namespace detail.

    75                     

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

    77 

    78 namespace detail {

    79 

    80 template<typename T>

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

    82 

    83 } // End namespace detail.

    84 

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

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

    87 

    88 template<typename T>

    89 struct char_type_of 

    90     : detail::member_char_type<

    91           typename detail::unwrapped_type<T>::type

    92       > 

    93     { };

    94 

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

    96 

    97 template<typename T>

    98 struct char_type_of {

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

   100     typedef typename 

   101             mpl::eval_if<

   102                 is_std_io<U>,

   103                 mpl::identity<char>,

   104                 detail::member_char_type<U>

   105             >::type type;

   106 };

   107 

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

   109 

   110 template<typename Iter>

   111 struct char_type_of< iterator_range<Iter> > {

   112     typedef typename iterator_value<Iter>::type type;

   113 };

   114 

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

   116 

   117 template<typename T>

   118 struct char_type_of {

   119     template<typename U>

   120     struct get_value_type {

   121         typedef typename range_value<U>::type type;

   122     };

   123     typedef typename 

   124             mpl::eval_if<

   125                 is_iterator_range<T>,

   126                 get_value_type<T>,

   127                 detail::member_char_type<

   128                     BOOST_DEDUCED_TYPENAME detail::unwrapped_type<T>::type

   129                 >

   130             >::type type;

   131 };

   132 

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

   134 

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

   136 

   137 namespace detail {

   138 

   139 template<typename T>

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

   141 

   142 } // End namespace detail.

   143 

   144 template<typename T>

   145 struct category_of {

   146     template<typename U>

   147     struct member_category { 

   148         typedef typename U::category type; 

   149     };

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

   151     typedef typename  

   152             mpl::eval_if<

   153                 is_std_io<U>,

   154                 iostreams::select<  // Disambiguation for Tru64

   155                     is_iostream<U>,   iostream_tag, 

   156                     is_istream<U>,    istream_tag, 

   157                     is_ostream<U>,    ostream_tag,

   158                     is_streambuf<U>,  streambuf_tag

   159                 >,

   160                 detail::member_category<U>

   161             >::type type;      

   162 };

   163 

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

   165 

   166 // 

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

   168 // 

   169 template<typename T>

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

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

   172 

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

   174 

   175 template<typename T>

   176 struct int_type_of { 

   177 #ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES

   178     typedef std::char_traits<

   179                 BOOST_DEDUCED_TYPENAME char_type_of<T>::type

   180             > traits_type;      

   181     typedef typename traits_type::int_type type; 

   182 #else  

   183     typedef int                            type; 

   184 #endif

   185 };

   186 

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

   188 

   189 namespace detail {

   190 

   191 template<int N> struct io_mode_impl;

   192 

   193 #define BOOST_IOSTREAMS_MODE_HELPER(tag_, id_) \

   194     case_<id_> io_mode_impl_helper(tag_); \

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

   196     /**/

   197 BOOST_IOSTREAMS_MODE_HELPER(input, 1)

   198 BOOST_IOSTREAMS_MODE_HELPER(output, 2)

   199 BOOST_IOSTREAMS_MODE_HELPER(bidirectional, 3)

   200 BOOST_IOSTREAMS_MODE_HELPER(input_seekable, 4)

   201 BOOST_IOSTREAMS_MODE_HELPER(output_seekable, 5)

   202 BOOST_IOSTREAMS_MODE_HELPER(seekable, 6)

   203 BOOST_IOSTREAMS_MODE_HELPER(dual_seekable, 7)

   204 BOOST_IOSTREAMS_MODE_HELPER(bidirectional_seekable, 8)

   205 BOOST_IOSTREAMS_MODE_HELPER(dual_use, 9)

   206 #undef BOOST_IOSTREAMS_MODE_HELPER

   207 

   208 template<typename T>

   209 struct io_mode_id {

   210     typedef typename category_of<T>::type category;

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

   212 };

   213 

   214 } // End namespace detail.

   215 

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

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

   218                     

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

   220 

   221 namespace detail {

   222 

   223 template<typename T, typename Tag>

   224 struct has_trait_impl {

   225     typedef typename category_of<T>::type category;

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

   227 };

   228 

   229 template<typename T, typename Tag>

   230 struct has_trait 

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

   232     { }; 

   233 

   234 } // End namespace detail.

   235 

   236 template<typename T>

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

   238 

   239 template<typename T>

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

   241 

   242 template<typename T>

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

   244                     

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

   246 

   247 #define BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS(Tr) \

   248     typedef Tr                              traits_type; \

   249     typedef typename traits_type::int_type  int_type; \

   250     typedef typename traits_type::off_type  off_type; \

   251     typedef typename traits_type::pos_type  pos_type; \

   252     /**/

   253 

   254 } } // End namespaces iostreams, boost.

   255 

   256 #endif // #ifndef BOOST_IOSTREAMS_IO_TRAITS_HPP_INCLUDED
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