boost/boost/iostreams/filtering_stream.hpp

   1 // (C) Copyright Jonathan Turkanis 2004
   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_FILTER_STREAM_HPP_INCLUDED
   8 #define BOOST_IOSTREAMS_FILTER_STREAM_HPP_INCLUDED
   9
  10 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
  11 # pragma once
  12 #endif
  13
  14 #include <memory>                                     // allocator.
  15 #include <boost/iostreams/detail/access_control.hpp>
  16 #include <boost/iostreams/detail/char_traits.hpp>
  17 #include <boost/iostreams/detail/iostream.hpp>        // standard streams.
  18 #include <boost/iostreams/detail/push.hpp>
  19 #include <boost/iostreams/detail/select.hpp>
  20 #include <boost/iostreams/detail/streambuf.hpp>       // pubsync.
  21 #include <boost/iostreams/filtering_streambuf.hpp>
  22 #include <boost/mpl/and.hpp>
  23 #include <boost/mpl/bool.hpp>
  24 #include <boost/static_assert.hpp>
  25 #include <boost/type_traits/is_convertible.hpp>
  26
  27 // Must come last.
  28 #include <boost/iostreams/detail/config/disable_warnings.hpp>  // MSVC.
  29
  30 namespace boost { namespace iostreams {
  31
  32 //--------------Definition of filtered_istream--------------------------------//
  33
  34 namespace detail {
  35
  36 template<typename Mode, typename Ch, typename Tr>
  37 struct filtering_stream_traits {
  38     typedef typename
  39             iostreams::select<  // Disambiguation for Tru64
  40                 mpl::and_<
  41                     is_convertible<Mode, input>,
  42                     is_convertible<Mode, output>
  43                 >,
  44                 BOOST_IOSTREAMS_BASIC_IOSTREAM(Ch, Tr),
  45                 is_convertible<Mode, input>,
  46                 BOOST_IOSTREAMS_BASIC_ISTREAM(Ch, Tr),
  47                 else_,
  48                 BOOST_IOSTREAMS_BASIC_OSTREAM(Ch, Tr)
  49             >::type type;
  50 };
  51
  52 template<typename Chain, typename Access>
  53 class filtering_stream_base
  54     : public access_control<
  55                  boost::iostreams::detail::chain_client<Chain>,
  56                  Access
  57              >,
  58       public filtering_stream_traits<
  59                  typename Chain::mode,
  60                  typename Chain::char_type,
  61                  typename Chain::traits_type
  62              >::type
  63 {
  64 public:
  65     typedef Chain                                         chain_type;
  66     typedef access_control<
  67                  boost::iostreams::detail::chain_client<Chain>,
  68                  Access
  69              >                                            client_type;
  70 protected:
  71     typedef typename
  72             filtering_stream_traits<
  73                  typename Chain::mode,
  74                  typename Chain::char_type,
  75                  typename Chain::traits_type
  76             >::type                                       stream_type;
  77     filtering_stream_base() : stream_type(0) { this->set_chain(&chain_); }
  78 private:
  79     void notify() { this->rdbuf(chain_.empty() ? 0 : &chain_.front()); }
  80     Chain chain_;
  81 };
  82
  83 } // End namespace detail.
  84
  85 //
  86 // Macro: BOOST_IOSTREAMS_DEFINE_FILTER_STREAM(name_, chain_type_, default_char_)
  87 // Description: Defines a template derived from std::basic_streambuf which uses
  88 //      a chain to perform i/o. The template has the following parameters:
  89 //      Mode - the i/o mode.
  90 //      Ch - The character type.
  91 //      Tr - The character traits type.
  92 //      Alloc - The allocator type.
  93 //      Access - Indicates accessibility of the chain interface; must be either
  94 //          public_ or protected_; defaults to public_.
  95 // Macro parameters:
  96 //      name_ - The name of the template to be defined.
  97 //      chain_type_ - The name of the chain template.
  98 //      default_char_ - The default value for the char template parameter.
  99 //
 100 #define BOOST_IOSTREAMS_DEFINE_FILTER_STREAM(name_, chain_type_, default_char_) \
 101     template< typename Mode, \
 102               typename Ch = default_char_, \
 103               typename Tr = BOOST_IOSTREAMS_CHAR_TRAITS(Ch), \
 104               typename Alloc = std::allocator<Ch>, \
 105               typename Access = public_ > \
 106     class name_ \
 107         : public boost::iostreams::detail::filtering_stream_base< \
 108                      chain_type_<Mode, Ch, Tr, Alloc>, Access \
 109                  > \
 110     { \
 111     public: \
 112         typedef Ch                                char_type; \
 113         BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS(Tr) \
 114         typedef Mode                              mode; \
 115         typedef chain_type_<Mode, Ch, Tr, Alloc>  chain_type; \
 116         name_() { } \
 117         BOOST_IOSTREAMS_DEFINE_PUSH_CONSTRUCTOR(name_, mode, Ch, push_impl) \
 118         ~name_() { \
 119             if (this->is_complete()) \
 120                  this->rdbuf()->BOOST_IOSTREAMS_PUBSYNC(); \
 121         } \
 122     private: \
 123         typedef access_control< \
 124                     boost::iostreams::detail::chain_client< \
 125                         chain_type_<Mode, Ch, Tr, Alloc> \
 126                     >, \
 127                     Access \
 128                 > client_type; \
 129         template<typename T> \
 130         void push_impl(const T& t BOOST_IOSTREAMS_PUSH_PARAMS()) \
 131         { client_type::push(t BOOST_IOSTREAMS_PUSH_ARGS()); } \
 132     }; \
 133     /**/
 134 BOOST_IOSTREAMS_DEFINE_FILTER_STREAM(filtering_stream, boost::iostreams::chain, char)
 135 BOOST_IOSTREAMS_DEFINE_FILTER_STREAM(wfiltering_stream, boost::iostreams::chain, wchar_t)
 136
 137 typedef filtering_stream<input>    filtering_istream;
 138 typedef filtering_stream<output>   filtering_ostream;
 139 typedef wfiltering_stream<input>   filtering_wistream;
 140 typedef wfiltering_stream<output>  filtering_wostream;
 141
 142 //----------------------------------------------------------------------------//
 143
 144 } } // End namespace iostreams, boost
 145
 146 #include <boost/iostreams/detail/config/enable_warnings.hpp> // MSVC
 147
 148 #endif // #ifndef BOOST_IOSTREAMS_FILTER_STREAM_HPP_INCLUDED