src/boost/iostreams/compose.hpp
72fef926
 // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
 // (C) Copyright 2005-2007 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.
 
 // Note: bidirectional streams are not supported.
 
 #ifndef BOOST_IOSTREAMS_COMPOSE_HPP_INCLUDED
 #define BOOST_IOSTREAMS_COMPOSE_HPP_INCLUDED
 
 #if defined(_MSC_VER)
 # pragma once
 #endif
 
 #include <algorithm>          // min.
 #include <utility>            // pair.
 #include <boost/config.hpp>   // DEDUCED_TYPENAME.
 #include <boost/iostreams/categories.hpp>
 #include <boost/iostreams/detail/adapter/direct_adapter.hpp>
 #include <boost/iostreams/detail/call_traits.hpp>
 #include <boost/iostreams/detail/enable_if_stream.hpp>
 #include <boost/iostreams/detail/execute.hpp>
 #include <boost/iostreams/detail/functional.hpp>
 #include <boost/iostreams/operations.hpp>
 #include <boost/iostreams/traits.hpp>      // mode_of, is_direct.
 #include <boost/mpl/if.hpp>
 #include <boost/ref.hpp>
 #include <boost/static_assert.hpp>
 #include <boost/type_traits/is_convertible.hpp>
 
 // Must come last.
 #include <boost/iostreams/detail/config/disable_warnings.hpp>  // MSVC.
 
 namespace boost { namespace iostreams {
 
 namespace detail {
 
 template< typename First, 
           typename Second,
           typename FirstMode = 
               BOOST_DEDUCED_TYPENAME mode_of<First>::type,
           typename SecondMode = 
               BOOST_DEDUCED_TYPENAME mode_of<Second>::type >
 struct composite_mode
     : select<
           is_convertible<SecondMode, FirstMode>, FirstMode,
           is_convertible<FirstMode, SecondMode>, SecondMode,
           is_convertible<SecondMode, input>,     input,
           else_,                                 output
       >
     { };
 
 //
 // Template name: composite_device.
 // Description: Provides a Device view of a Filter, Device pair.
 // Template parameters:
 //      Filter - A model of Filter.
 //      Device - An indirect model of Device.
 //
 template< typename Filter,
           typename Device,
           typename Mode =
               BOOST_DEDUCED_TYPENAME composite_mode<Filter, Device>::type >
 class composite_device {
 private:
     typedef typename detail::param_type<Device>::type       param_type;
     typedef typename mode_of<Filter>::type                  filter_mode;
     typedef typename mode_of<Device>::type                  device_mode;
     typedef typename
             iostreams::select<  // Disambiguation for Tru64.
                 is_direct<Device>,  direct_adapter<Device>,
                 is_std_io<Device>,  Device&,
                 else_,              Device
             >::type                                         value_type;
     BOOST_STATIC_ASSERT(is_filter<Filter>::value);
     BOOST_STATIC_ASSERT(is_device<Device>::value);
 public:
     typedef typename char_type_of<Filter>::type             char_type;
     struct category
         : Mode,
           device_tag,
           closable_tag,
           flushable_tag,
           localizable_tag,
           optimally_buffered_tag
         { };
     composite_device(const Filter& flt, param_type dev);
     std::streamsize read(char_type* s, std::streamsize n);
     std::streamsize write(const char_type* s, std::streamsize n);
     std::streampos seek( stream_offset off, BOOST_IOS::seekdir way,
                          BOOST_IOS::openmode which =
                              BOOST_IOS::in | BOOST_IOS::out );
 
     void close();
     void close(BOOST_IOS::openmode which);
     bool flush();
     std::streamsize optimal_buffer_size() const;
 
     template<typename Locale> // Avoid dependency on <locale>
     void imbue(const Locale& loc)
     {
         iostreams::imbue(filter_, loc);
         iostreams::imbue(device_, loc);
     }
 
     Filter& first() { return filter_; }
     Device& second() { return device_; }
 private:
     Filter      filter_;
     value_type  device_;
 };
 
 //
 // Template name: composite_device.
 // Description: Provides a Device view of a Filter, Device pair.
 // Template parameters:
 //      Filter - A model of Filter.
 //      Device - An indirect model of Device.
 //
 template< typename Filter1, 
           typename Filter2,
           typename Mode =
               BOOST_DEDUCED_TYPENAME composite_mode<Filter1, Filter2>::type >
 class composite_filter {
 private:
     typedef reference_wrapper<Filter2>           filter_ref;
     typedef typename mode_of<Filter1>::type      first_mode;
     typedef typename mode_of<Filter2>::type      second_mode;
 
     // A dual-use filter cannot be composed with a read-write filter
     BOOST_STATIC_ASSERT(
         !(is_convertible<first_mode, dual_use>::value) ||
         !(is_convertible<second_mode, input>::value) ||
         !(is_convertible<second_mode, output>::value) ||
          (is_convertible<second_mode, dual_use>::value)
     );
     BOOST_STATIC_ASSERT(
         !(is_convertible<second_mode, dual_use>::value) ||
         !(is_convertible<first_mode, input>::value) ||
         !(is_convertible<first_mode, output>::value) ||
          (is_convertible<first_mode, dual_use>::value)
     );
     BOOST_STATIC_ASSERT(is_filter<Filter1>::value);
     BOOST_STATIC_ASSERT(is_filter<Filter2>::value);
 public:
     typedef typename char_type_of<Filter1>::type  char_type;
     struct category
         : Mode,
           filter_tag,
           multichar_tag,
           closable_tag,
           flushable_tag,
           localizable_tag,
           optimally_buffered_tag
         { };
     composite_filter(const Filter1& filter1, const Filter2& filter2)
         : filter1_(filter1), filter2_(filter2)
         { }
 
     template<typename Source>
     std::streamsize read(Source& src, char_type* s, std::streamsize n)
     {
         composite_device<filter_ref, Source> cmp(boost::ref(filter2_), src);
         return iostreams::read(filter1_, cmp, s, n);
     }
 
     template<typename Sink>
     std::streamsize write(Sink& snk, const char_type* s, std::streamsize n)
     {
         composite_device<filter_ref, Sink> cmp(boost::ref(filter2_), snk);
         return iostreams::write(filter1_, cmp, s, n);
     }
 
     template<typename Device>
     std::streampos seek( Device& dev, stream_offset off, BOOST_IOS::seekdir way,
                          BOOST_IOS::openmode which =
                              BOOST_IOS::in | BOOST_IOS::out )
     {
         composite_device<filter_ref, Device> cmp(boost::ref(filter2_), dev);
         return iostreams::seek(filter1_, cmp, off, way, which);
     }
 
     template<typename Device>
     void close(Device& dev)
     {
         BOOST_STATIC_ASSERT((!is_convertible<category, two_sequence>::value));
         BOOST_STATIC_ASSERT((!is_convertible<category, dual_use>::value));
 
         // Create a new device by composing the second filter2_ with dev.
         composite_device<filter_ref, Device> cmp(boost::ref(filter2_), dev);
 
         // Close input sequences in reverse order and output sequences in 
         // forward order
         if (!is_convertible<first_mode, dual_use>::value) {
             detail::execute_all(
                 detail::call_close(filter2_, dev, BOOST_IOS::in),
                 detail::call_close(filter1_, cmp, BOOST_IOS::in),
                 detail::call_close(filter1_, cmp, BOOST_IOS::out),
                 detail::call_close(filter2_, dev, BOOST_IOS::out)
             );
         } else if (is_convertible<second_mode, input>::value) {
             detail::execute_all(
                 detail::call_close(filter2_, dev, BOOST_IOS::in),
                 detail::call_close(filter1_, cmp, BOOST_IOS::in)
             );
         } else {
             detail::execute_all(
                 detail::call_close(filter1_, cmp, BOOST_IOS::out),
                 detail::call_close(filter2_, dev, BOOST_IOS::out)
             );
         }
     }
 
     template<typename Device>
     void close(Device& dev, BOOST_IOS::openmode which)
     {
         BOOST_STATIC_ASSERT(
             (is_convertible<category, two_sequence>::value) ||
             (is_convertible<category, dual_use>::value)
         );
 
         // Create a new device by composing the second filter2_ with dev.
         composite_device<filter_ref, Device> cmp(boost::ref(filter2_), dev);
 
         // Close input sequences in reverse order
         if ( which == BOOST_IOS::in &&
              ( !is_convertible<first_mode, dual_use>::value ||
                 is_convertible<second_mode, input>::value ) )
         {
             detail::execute_all(
                 detail::call_close(filter2_, dev, BOOST_IOS::in),
                 detail::call_close(filter1_, cmp, BOOST_IOS::in)
             );
         }
 
         // Close output sequences in forward order
         if ( which == BOOST_IOS::out &&
              ( !is_convertible<first_mode, dual_use>::value ||
                 is_convertible<second_mode, output>::value ) )
         {
             detail::execute_all(
                 detail::call_close(filter1_, cmp, BOOST_IOS::out),
                 detail::call_close(filter2_, dev, BOOST_IOS::out)
             );
         }
     }
 
     template<typename Device>
     bool flush(Device& dev)
     {
         composite_device<Filter2, Device> cmp(filter2_, dev);
         return iostreams::flush(filter1_, cmp);
     }
 
     std::streamsize optimal_buffer_size() const
     {
         std::streamsize first = iostreams::optimal_buffer_size(filter1_);
         std::streamsize second = iostreams::optimal_buffer_size(filter2_);
         return first < second ? second : first;
     }
 
     template<typename Locale> // Avoid dependency on <locale>
     void imbue(const Locale& loc)
     {   // To do: consider using RAII.
         iostreams::imbue(filter1_, loc);
         iostreams::imbue(filter2_, loc);
     }
 
     Filter1& first() { return filter1_; }
     Filter2& second() { return filter2_; }
 private:
     Filter1  filter1_;
     Filter2  filter2_;
 };
 
 template<typename Filter, typename FilterOrDevice>
 struct composite_traits
     : mpl::if_<
           is_device<FilterOrDevice>,
           composite_device<Filter, FilterOrDevice>,
           composite_filter<Filter, FilterOrDevice>
       >
     { };
 
 } // End namespace detail.
 
 template<typename Filter, typename FilterOrDevice>
 struct composite : detail::composite_traits<Filter, FilterOrDevice>::type {
     typedef typename detail::param_type<FilterOrDevice>::type param_type;
     typedef typename detail::composite_traits<Filter, FilterOrDevice>::type base;
     composite(const Filter& flt, param_type dev)
         : base(flt, dev)
         { }
 };
 
 //--------------Implementation of compose-------------------------------------//
 
 // Note: The following workarounds are patterned after resolve.hpp. It has not
 // yet been confirmed that they are necessary.
 
 #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //-------------------------//
 # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //-------------------------------//
 
 template<typename Filter, typename FilterOrDevice>
 composite<Filter, FilterOrDevice>
 compose( const Filter& filter, const FilterOrDevice& fod
          BOOST_IOSTREAMS_DISABLE_IF_STREAM(FilterOrDevice) )
 { return composite<Filter, FilterOrDevice>(filter, fod); }
 
 template<typename Filter, typename Ch, typename Tr>
 composite< Filter, std::basic_streambuf<Ch, Tr> >
 compose(const Filter& filter, std::basic_streambuf<Ch, Tr>& sb)
 { return composite< Filter, std::basic_streambuf<Ch, Tr> >(filter, sb); }
 
 template<typename Filter, typename Ch, typename Tr>
 composite< Filter, std::basic_istream<Ch, Tr> >
 compose(const Filter& filter, std::basic_istream<Ch, Tr>& is)
 { return composite< Filter, std::basic_istream<Ch, Tr> >(filter, is); }
 
 template<typename Filter, typename Ch, typename Tr>
 composite< Filter, std::basic_ostream<Ch, Tr> >
 compose(const Filter& filter, std::basic_ostream<Ch, Tr>& os)
 { return composite< Filter, std::basic_ostream<Ch, Tr> >(filter, os); }
 
 template<typename Filter, typename Ch, typename Tr>
 composite< Filter, std::basic_iostream<Ch, Tr> >
 compose(const Filter& filter, std::basic_iostream<Ch, Tr>& io)
 { return composite< Filter, std::basic_iostream<Ch, Tr> >(filter, io); }
 
 # else // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //---------------------//
 
 template<typename Filter, typename FilterOrDevice>
 composite<Filter, FilterOrDevice>
 compose( const Filter& filter, const FilterOrDevice& fod
          BOOST_IOSTREAMS_DISABLE_IF_STREAM(FilterOrDevice) )
 { return composite<Filter, FilterOrDevice>(filter, fod); }
 
 template<typename Filter>
 composite<Filter, std::streambuf>
 compose(const Filter& filter, std::streambuf& sb)
 { return composite<Filter, std::streambuf>(filter, sb); }
 
 template<typename Filter>
 composite<Filter, std::istream>
 compose(const Filter& filter, std::istream& is)
 { return composite<Filter, std::istream>(filter, is); }
 
 template<typename Filter>
 composite<Filter, std::ostream>
 compose(const Filter& filter, std::ostream& os)
 { return composite<Filter, std::ostream>(filter, os); }
 
 template<typename Filter>
 composite<Filter, std::iostream>
 compose(const Filter& filter, std::iostream& io)
 { return composite<Filter, std::iostream>(filter, io); }
 
 # endif // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //--------------------//
 #else // #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //----------------//
 
 template<typename Filter, typename Stream>
 composite<Filter, Stream>
 compose(const Filter& flt, const Stream& strm, mpl::true_)
 {   // Bad overload resolution.
     return composite<Filter, Stream>(flt, const_cast<Stream&>(strm));
 }
 
 template<typename Filter, typename FilterOrDevice>
 composite<Filter, FilterOrDevice>
 compose(const Filter& flt, const FilterOrDevice& fod, mpl::false_)
 { return composite<Filter, FilterOrDevice>(flt, fod); }
 
 template<typename Filter, typename FilterOrDevice>
 composite<Filter, FilterOrDevice>
 compose( const Filter& flt, const FilterOrDevice& fod
          BOOST_IOSTREAMS_DISABLE_IF_STREAM(T) )
 { return compose(flt, fod, is_std_io<FilterOrDevice>()); }
 
 # if !BOOST_WORKAROUND(BOOST_BORLANDC, < 0x600) && \
      !defined(__GNUC__) // ---------------------------------------------------//
 
 template<typename Filter, typename FilterOrDevice>
 composite<Filter, FilterOrDevice>
 compose (const Filter& filter, FilterOrDevice& fod)
 { return composite<Filter, FilterOrDevice>(filter, fod); }
 
 # endif // Borland 5.x or GCC //--------------------------------//
 #endif // #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //---------------//
 
 //----------------------------------------------------------------------------//
 
 namespace detail {
 
 //--------------Implementation of composite_device---------------------------//
 
 template<typename Filter, typename Device, typename Mode>
 composite_device<Filter, Device, Mode>::composite_device
     (const Filter& flt, param_type dev)
     : filter_(flt), device_(dev)
     { }
 
 template<typename Filter, typename Device, typename Mode>
 inline std::streamsize composite_device<Filter, Device, Mode>::read
     (char_type* s, std::streamsize n)
 { return iostreams::read(filter_, device_, s, n); }
 
 template<typename Filter, typename Device, typename Mode>
 inline std::streamsize composite_device<Filter, Device, Mode>::write
     (const char_type* s, std::streamsize n)
 { return iostreams::write(filter_, device_, s, n); }
 
 template<typename Filter, typename Device, typename Mode>
 std::streampos composite_device<Filter, Device, Mode>::seek
     (stream_offset off, BOOST_IOS::seekdir way, BOOST_IOS::openmode which)
 { return iostreams::seek(filter_, device_, off, way, which); }
 
 template<typename Filter, typename Device, typename Mode>
 void composite_device<Filter, Device, Mode>::close()
 {
     BOOST_STATIC_ASSERT((!is_convertible<Mode, two_sequence>::value));
     BOOST_STATIC_ASSERT(
         !(is_convertible<filter_mode, dual_use>::value) ||
         !(is_convertible<device_mode, input>::value) ||
         !(is_convertible<device_mode, output>::value)
     );
 
     // Close input sequences in reverse order and output sequences 
     // in forward order
     if (!is_convertible<filter_mode, dual_use>::value) {
         detail::execute_all(
             detail::call_close(device_, BOOST_IOS::in),
             detail::call_close(filter_, device_, BOOST_IOS::in),
             detail::call_close(filter_, device_, BOOST_IOS::out),
             detail::call_close(device_, BOOST_IOS::out)
         );
     } else if (is_convertible<device_mode, input>::value) {
         detail::execute_all(
             detail::call_close(device_, BOOST_IOS::in),
             detail::call_close(filter_, device_, BOOST_IOS::in)
         );
     } else {
         detail::execute_all(
             detail::call_close(filter_, device_, BOOST_IOS::out),
             detail::call_close(device_, BOOST_IOS::out)
         );
     }
 }
 
 template<typename Filter, typename Device, typename Mode>
 void composite_device<Filter, Device, Mode>::close(BOOST_IOS::openmode which)
 {
     BOOST_STATIC_ASSERT((is_convertible<Mode, two_sequence>::value));
     BOOST_STATIC_ASSERT(!(is_convertible<filter_mode, dual_use>::value));
 
     // Close input sequences in reverse order
     if (which == BOOST_IOS::in) {
         detail::execute_all(
             detail::call_close(device_, BOOST_IOS::in),
             detail::call_close(filter_, device_, BOOST_IOS::in) 
         );
     }
 
     // Close output sequences in forward order
     if (which == BOOST_IOS::out) {
         detail::execute_all(
             detail::call_close(filter_, device_, BOOST_IOS::out),
             detail::call_close(device_, BOOST_IOS::out)
         );
     }
 }
 
 template<typename Filter, typename Device, typename Mode>
 bool composite_device<Filter, Device, Mode>::flush()
 {
     bool r1 = iostreams::flush(filter_, device_);
     bool r2 = iostreams::flush(device_);
     return r1 && r2;
 }
 
 template<typename Filter, typename Device, typename Mode>
 std::streamsize
 composite_device<Filter, Device, Mode>::optimal_buffer_size() const
 { return iostreams::optimal_buffer_size(device_); }
 
 } // End namespace detail.
 
 } } // End namespaces iostreams, boost.
 
 #include <boost/iostreams/detail/config/enable_warnings.hpp>
 
 #endif // #ifndef BOOST_IOSTREAMS_COMPOSE_HPP_INCLUDED