boost/iostreams/compose.hpp

0001 // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
0002 // (C) Copyright 2005-2007 Jonathan Turkanis
0003 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0004 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
0005
0006 // See http://www.boost.org/libs/iostreams for documentation.
0007
0008 // Note: bidirectional streams are not supported.
0009
0010 #ifndef BOOST_IOSTREAMS_COMPOSE_HPP_INCLUDED
0011 #define BOOST_IOSTREAMS_COMPOSE_HPP_INCLUDED
0012
0013 #if defined(_MSC_VER)
0014 # pragma once
0015 #endif
0016
0017 #include <algorithm>          // min.
0018 #include <utility>            // pair.
0019 #include <boost/config.hpp>   // DEDUCED_TYPENAME.
0020 #include <boost/iostreams/categories.hpp>
0021 #include <boost/iostreams/detail/adapter/direct_adapter.hpp>
0022 #include <boost/iostreams/detail/call_traits.hpp>
0023 #include <boost/iostreams/detail/enable_if_stream.hpp>
0024 #include <boost/iostreams/detail/execute.hpp>
0025 #include <boost/iostreams/detail/functional.hpp>
0026 #include <boost/iostreams/operations.hpp>
0027 #include <boost/iostreams/traits.hpp>      // mode_of, is_direct.
0028 #include <boost/mpl/if.hpp>
0029 #include <boost/ref.hpp>
0030 #include <boost/static_assert.hpp>
0031 #include <boost/type_traits/is_convertible.hpp>
0032
0033 // Must come last.
0034 #include <boost/iostreams/detail/config/disable_warnings.hpp>  // MSVC.
0035
0036 namespace boost { namespace iostreams {
0037
0038 namespace detail {
0039
0040 template< typename First,
0041           typename Second,
0042           typename FirstMode =
0043               BOOST_DEDUCED_TYPENAME mode_of<First>::type,
0044           typename SecondMode =
0045               BOOST_DEDUCED_TYPENAME mode_of<Second>::type >
0046 struct composite_mode
0047     : select<
0048           is_convertible<SecondMode, FirstMode>, FirstMode,
0049           is_convertible<FirstMode, SecondMode>, SecondMode,
0050           is_convertible<SecondMode, input>,     input,
0051           else_,                                 output
0052       >
0053     { };
0054
0055 //
0056 // Template name: composite_device.
0057 // Description: Provides a Device view of a Filter, Device pair.
0058 // Template parameters:
0059 //      Filter - A model of Filter.
0060 //      Device - An indirect model of Device.
0061 //
0062 template< typename Filter,
0063           typename Device,
0064           typename Mode =
0065               BOOST_DEDUCED_TYPENAME composite_mode<Filter, Device>::type >
0066 class composite_device {
0067 private:
0068     typedef typename detail::param_type<Device>::type       param_type;
0069     typedef typename mode_of<Filter>::type                  filter_mode;
0070     typedef typename mode_of<Device>::type                  device_mode;
0071     typedef typename
0072             iostreams::select<  // Disambiguation for Tru64.
0073                 is_direct<Device>,  direct_adapter<Device>,
0074                 is_std_io<Device>,  Device&,
0075                 else_,              Device
0076             >::type                                         value_type;
0077     BOOST_STATIC_ASSERT(is_filter<Filter>::value);
0078     BOOST_STATIC_ASSERT(is_device<Device>::value);
0079 public:
0080     typedef typename char_type_of<Filter>::type             char_type;
0081     struct category
0082         : Mode,
0083           device_tag,
0084           closable_tag,
0085           flushable_tag,
0086           localizable_tag,
0087           optimally_buffered_tag
0088         { };
0089     composite_device(const Filter& flt, param_type dev);
0090     std::streamsize read(char_type* s, std::streamsize n);
0091     std::streamsize write(const char_type* s, std::streamsize n);
0092     std::streampos seek( stream_offset off, BOOST_IOS::seekdir way,
0093                          BOOST_IOS::openmode which =
0094                              BOOST_IOS::in | BOOST_IOS::out );
0095
0096     void close();
0097     void close(BOOST_IOS::openmode which);
0098     bool flush();
0099     std::streamsize optimal_buffer_size() const;
0100
0101     template<typename Locale> // Avoid dependency on <locale>
0102     void imbue(const Locale& loc)
0103     {
0104         iostreams::imbue(filter_, loc);
0105         iostreams::imbue(device_, loc);
0106     }
0107
0108     Filter& first() { return filter_; }
0109     Device& second() { return device_; }
0110 private:
0111     Filter      filter_;
0112     value_type  device_;
0113 };
0114
0115 //
0116 // Template name: composite_device.
0117 // Description: Provides a Device view of a Filter, Device pair.
0118 // Template parameters:
0119 //      Filter - A model of Filter.
0120 //      Device - An indirect model of Device.
0121 //
0122 template< typename Filter1,
0123           typename Filter2,
0124           typename Mode =
0125               BOOST_DEDUCED_TYPENAME composite_mode<Filter1, Filter2>::type >
0126 class composite_filter {
0127 private:
0128     typedef reference_wrapper<Filter2>           filter_ref;
0129     typedef typename mode_of<Filter1>::type      first_mode;
0130     typedef typename mode_of<Filter2>::type      second_mode;
0131
0132     // A dual-use filter cannot be composed with a read-write filter
0133     BOOST_STATIC_ASSERT(
0134         !(is_convertible<first_mode, dual_use>::value) ||
0135         !(is_convertible<second_mode, input>::value) ||
0136         !(is_convertible<second_mode, output>::value) ||
0137          (is_convertible<second_mode, dual_use>::value)
0138     );
0139     BOOST_STATIC_ASSERT(
0140         !(is_convertible<second_mode, dual_use>::value) ||
0141         !(is_convertible<first_mode, input>::value) ||
0142         !(is_convertible<first_mode, output>::value) ||
0143          (is_convertible<first_mode, dual_use>::value)
0144     );
0145     BOOST_STATIC_ASSERT(is_filter<Filter1>::value);
0146     BOOST_STATIC_ASSERT(is_filter<Filter2>::value);
0147 public:
0148     typedef typename char_type_of<Filter1>::type  char_type;
0149     struct category
0150         : Mode,
0151           filter_tag,
0152           multichar_tag,
0153           closable_tag,
0154           flushable_tag,
0155           localizable_tag,
0156           optimally_buffered_tag
0157         { };
0158     composite_filter(const Filter1& filter1, const Filter2& filter2)
0159         : filter1_(filter1), filter2_(filter2)
0160         { }
0161
0162     template<typename Source>
0163     std::streamsize read(Source& src, char_type* s, std::streamsize n)
0164     {
0165         composite_device<filter_ref, Source> cmp(boost::ref(filter2_), src);
0166         return iostreams::read(filter1_, cmp, s, n);
0167     }
0168
0169     template<typename Sink>
0170     std::streamsize write(Sink& snk, const char_type* s, std::streamsize n)
0171     {
0172         composite_device<filter_ref, Sink> cmp(boost::ref(filter2_), snk);
0173         return iostreams::write(filter1_, cmp, s, n);
0174     }
0175
0176     template<typename Device>
0177     std::streampos seek( Device& dev, stream_offset off, BOOST_IOS::seekdir way,
0178                          BOOST_IOS::openmode which =
0179                              BOOST_IOS::in | BOOST_IOS::out )
0180     {
0181         composite_device<filter_ref, Device> cmp(boost::ref(filter2_), dev);
0182         return iostreams::seek(filter1_, cmp, off, way, which);
0183     }
0184
0185     template<typename Device>
0186     void close(Device& dev)
0187     {
0188         BOOST_STATIC_ASSERT((!is_convertible<category, two_sequence>::value));
0189         BOOST_STATIC_ASSERT((!is_convertible<category, dual_use>::value));
0190
0191         // Create a new device by composing the second filter2_ with dev.
0192         composite_device<filter_ref, Device> cmp(boost::ref(filter2_), dev);
0193
0194         // Close input sequences in reverse order and output sequences in
0195         // forward order
0196         if (!is_convertible<first_mode, dual_use>::value) {
0197             detail::execute_all(
0198                 detail::call_close(filter2_, dev, BOOST_IOS::in),
0199                 detail::call_close(filter1_, cmp, BOOST_IOS::in),
0200                 detail::call_close(filter1_, cmp, BOOST_IOS::out),
0201                 detail::call_close(filter2_, dev, BOOST_IOS::out)
0202             );
0203         } else if (is_convertible<second_mode, input>::value) {
0204             detail::execute_all(
0205                 detail::call_close(filter2_, dev, BOOST_IOS::in),
0206                 detail::call_close(filter1_, cmp, BOOST_IOS::in)
0207             );
0208         } else {
0209             detail::execute_all(
0210                 detail::call_close(filter1_, cmp, BOOST_IOS::out),
0211                 detail::call_close(filter2_, dev, BOOST_IOS::out)
0212             );
0213         }
0214     }
0215
0216     template<typename Device>
0217     void close(Device& dev, BOOST_IOS::openmode which)
0218     {
0219         BOOST_STATIC_ASSERT(
0220             (is_convertible<category, two_sequence>::value) ||
0221             (is_convertible<category, dual_use>::value)
0222         );
0223
0224         // Create a new device by composing the second filter2_ with dev.
0225         composite_device<filter_ref, Device> cmp(boost::ref(filter2_), dev);
0226
0227         // Close input sequences in reverse order
0228         if ( which == BOOST_IOS::in &&
0229              ( !is_convertible<first_mode, dual_use>::value ||
0230                 is_convertible<second_mode, input>::value ) )
0231         {
0232             detail::execute_all(
0233                 detail::call_close(filter2_, dev, BOOST_IOS::in),
0234                 detail::call_close(filter1_, cmp, BOOST_IOS::in)
0235             );
0236         }
0237
0238         // Close output sequences in forward order
0239         if ( which == BOOST_IOS::out &&
0240              ( !is_convertible<first_mode, dual_use>::value ||
0241                 is_convertible<second_mode, output>::value ) )
0242         {
0243             detail::execute_all(
0244                 detail::call_close(filter1_, cmp, BOOST_IOS::out),
0245                 detail::call_close(filter2_, dev, BOOST_IOS::out)
0246             );
0247         }
0248     }
0249
0250     template<typename Device>
0251     bool flush(Device& dev)
0252     {
0253         composite_device<Filter2, Device> cmp(filter2_, dev);
0254         return iostreams::flush(filter1_, cmp);
0255     }
0256
0257     std::streamsize optimal_buffer_size() const
0258     {
0259         std::streamsize first = iostreams::optimal_buffer_size(filter1_);
0260         std::streamsize second = iostreams::optimal_buffer_size(filter2_);
0261         return first < second ? second : first;
0262     }
0263
0264     template<typename Locale> // Avoid dependency on <locale>
0265     void imbue(const Locale& loc)
0266     {   // To do: consider using RAII.
0267         iostreams::imbue(filter1_, loc);
0268         iostreams::imbue(filter2_, loc);
0269     }
0270
0271     Filter1& first() { return filter1_; }
0272     Filter2& second() { return filter2_; }
0273 private:
0274     Filter1  filter1_;
0275     Filter2  filter2_;
0276 };
0277
0278 template<typename Filter, typename FilterOrDevice>
0279 struct composite_traits
0280     : mpl::if_<
0281           is_device<FilterOrDevice>,
0282           composite_device<Filter, FilterOrDevice>,
0283           composite_filter<Filter, FilterOrDevice>
0284       >
0285     { };
0286
0287 } // End namespace detail.
0288
0289 template<typename Filter, typename FilterOrDevice>
0290 struct composite : detail::composite_traits<Filter, FilterOrDevice>::type {
0291     typedef typename detail::param_type<FilterOrDevice>::type param_type;
0292     typedef typename detail::composite_traits<Filter, FilterOrDevice>::type base;
0293     composite(const Filter& flt, param_type dev)
0294         : base(flt, dev)
0295         { }
0296 };
0297
0298 //--------------Implementation of compose-------------------------------------//
0299
0300 // Note: The following workarounds are patterned after resolve.hpp. It has not
0301 // yet been confirmed that they are necessary.
0302
0303 #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //-------------------------//
0304 # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //-------------------------------//
0305
0306 template<typename Filter, typename FilterOrDevice>
0307 composite<Filter, FilterOrDevice>
0308 compose( const Filter& filter, const FilterOrDevice& fod
0309          BOOST_IOSTREAMS_DISABLE_IF_STREAM(FilterOrDevice) )
0310 { return composite<Filter, FilterOrDevice>(filter, fod); }
0311
0312 template<typename Filter, typename Ch, typename Tr>
0313 composite< Filter, std::basic_streambuf<Ch, Tr> >
0314 compose(const Filter& filter, std::basic_streambuf<Ch, Tr>& sb)
0315 { return composite< Filter, std::basic_streambuf<Ch, Tr> >(filter, sb); }
0316
0317 template<typename Filter, typename Ch, typename Tr>
0318 composite< Filter, std::basic_istream<Ch, Tr> >
0319 compose(const Filter& filter, std::basic_istream<Ch, Tr>& is)
0320 { return composite< Filter, std::basic_istream<Ch, Tr> >(filter, is); }
0321
0322 template<typename Filter, typename Ch, typename Tr>
0323 composite< Filter, std::basic_ostream<Ch, Tr> >
0324 compose(const Filter& filter, std::basic_ostream<Ch, Tr>& os)
0325 { return composite< Filter, std::basic_ostream<Ch, Tr> >(filter, os); }
0326
0327 template<typename Filter, typename Ch, typename Tr>
0328 composite< Filter, std::basic_iostream<Ch, Tr> >
0329 compose(const Filter& filter, std::basic_iostream<Ch, Tr>& io)
0330 { return composite< Filter, std::basic_iostream<Ch, Tr> >(filter, io); }
0331
0332 # else // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //---------------------//
0333
0334 template<typename Filter, typename FilterOrDevice>
0335 composite<Filter, FilterOrDevice>
0336 compose( const Filter& filter, const FilterOrDevice& fod
0337          BOOST_IOSTREAMS_DISABLE_IF_STREAM(FilterOrDevice) )
0338 { return composite<Filter, FilterOrDevice>(filter, fod); }
0339
0340 template<typename Filter>
0341 composite<Filter, std::streambuf>
0342 compose(const Filter& filter, std::streambuf& sb)
0343 { return composite<Filter, std::streambuf>(filter, sb); }
0344
0345 template<typename Filter>
0346 composite<Filter, std::istream>
0347 compose(const Filter& filter, std::istream& is)
0348 { return composite<Filter, std::istream>(filter, is); }
0349
0350 template<typename Filter>
0351 composite<Filter, std::ostream>
0352 compose(const Filter& filter, std::ostream& os)
0353 { return composite<Filter, std::ostream>(filter, os); }
0354
0355 template<typename Filter>
0356 composite<Filter, std::iostream>
0357 compose(const Filter& filter, std::iostream& io)
0358 { return composite<Filter, std::iostream>(filter, io); }
0359
0360 # endif // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //--------------------//
0361 #else // #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //----------------//
0362
0363 template<typename Filter, typename Stream>
0364 composite<Filter, Stream>
0365 compose(const Filter& flt, const Stream& strm, mpl::true_)
0366 {   // Bad overload resolution.
0367     return composite<Filter, Stream>(flt, const_cast<Stream&>(strm));
0368 }
0369
0370 template<typename Filter, typename FilterOrDevice>
0371 composite<Filter, FilterOrDevice>
0372 compose(const Filter& flt, const FilterOrDevice& fod, mpl::false_)
0373 { return composite<Filter, FilterOrDevice>(flt, fod); }
0374
0375 template<typename Filter, typename FilterOrDevice>
0376 composite<Filter, FilterOrDevice>
0377 compose( const Filter& flt, const FilterOrDevice& fod
0378          BOOST_IOSTREAMS_DISABLE_IF_STREAM(T) )
0379 { return compose(flt, fod, is_std_io<FilterOrDevice>()); }
0380
0381 # if !BOOST_WORKAROUND(BOOST_BORLANDC, < 0x600) && \
0382      !defined(__GNUC__) // ---------------------------------------------------//
0383
0384 template<typename Filter, typename FilterOrDevice>
0385 composite<Filter, FilterOrDevice>
0386 compose (const Filter& filter, FilterOrDevice& fod)
0387 { return composite<Filter, FilterOrDevice>(filter, fod); }
0388
0389 # endif // Borland 5.x or GCC //--------------------------------//
0390 #endif // #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //---------------//
0391
0392 //----------------------------------------------------------------------------//
0393
0394 namespace detail {
0395
0396 //--------------Implementation of composite_device---------------------------//
0397
0398 template<typename Filter, typename Device, typename Mode>
0399 composite_device<Filter, Device, Mode>::composite_device
0400     (const Filter& flt, param_type dev)
0401     : filter_(flt), device_(dev)
0402     { }
0403
0404 template<typename Filter, typename Device, typename Mode>
0405 inline std::streamsize composite_device<Filter, Device, Mode>::read
0406     (char_type* s, std::streamsize n)
0407 { return iostreams::read(filter_, device_, s, n); }
0408
0409 template<typename Filter, typename Device, typename Mode>
0410 inline std::streamsize composite_device<Filter, Device, Mode>::write
0411     (const char_type* s, std::streamsize n)
0412 { return iostreams::write(filter_, device_, s, n); }
0413
0414 template<typename Filter, typename Device, typename Mode>
0415 std::streampos composite_device<Filter, Device, Mode>::seek
0416     (stream_offset off, BOOST_IOS::seekdir way, BOOST_IOS::openmode which)
0417 { return iostreams::seek(filter_, device_, off, way, which); }
0418
0419 template<typename Filter, typename Device, typename Mode>
0420 void composite_device<Filter, Device, Mode>::close()
0421 {
0422     BOOST_STATIC_ASSERT((!is_convertible<Mode, two_sequence>::value));
0423     BOOST_STATIC_ASSERT(
0424         !(is_convertible<filter_mode, dual_use>::value) ||
0425         !(is_convertible<device_mode, input>::value) ||
0426         !(is_convertible<device_mode, output>::value)
0427     );
0428
0429     // Close input sequences in reverse order and output sequences
0430     // in forward order
0431     if (!is_convertible<filter_mode, dual_use>::value) {
0432         detail::execute_all(
0433             detail::call_close(device_, BOOST_IOS::in),
0434             detail::call_close(filter_, device_, BOOST_IOS::in),
0435             detail::call_close(filter_, device_, BOOST_IOS::out),
0436             detail::call_close(device_, BOOST_IOS::out)
0437         );
0438     } else if (is_convertible<device_mode, input>::value) {
0439         detail::execute_all(
0440             detail::call_close(device_, BOOST_IOS::in),
0441             detail::call_close(filter_, device_, BOOST_IOS::in)
0442         );
0443     } else {
0444         detail::execute_all(
0445             detail::call_close(filter_, device_, BOOST_IOS::out),
0446             detail::call_close(device_, BOOST_IOS::out)
0447         );
0448     }
0449 }
0450
0451 template<typename Filter, typename Device, typename Mode>
0452 void composite_device<Filter, Device, Mode>::close(BOOST_IOS::openmode which)
0453 {
0454     BOOST_STATIC_ASSERT((is_convertible<Mode, two_sequence>::value));
0455     BOOST_STATIC_ASSERT(!(is_convertible<filter_mode, dual_use>::value));
0456
0457     // Close input sequences in reverse order
0458     if (which == BOOST_IOS::in) {
0459         detail::execute_all(
0460             detail::call_close(device_, BOOST_IOS::in),
0461             detail::call_close(filter_, device_, BOOST_IOS::in)
0462         );
0463     }
0464
0465     // Close output sequences in forward order
0466     if (which == BOOST_IOS::out) {
0467         detail::execute_all(
0468             detail::call_close(filter_, device_, BOOST_IOS::out),
0469             detail::call_close(device_, BOOST_IOS::out)
0470         );
0471     }
0472 }
0473
0474 template<typename Filter, typename Device, typename Mode>
0475 bool composite_device<Filter, Device, Mode>::flush()
0476 {
0477     bool r1 = iostreams::flush(filter_, device_);
0478     bool r2 = iostreams::flush(device_);
0479     return r1 && r2;
0480 }
0481
0482 template<typename Filter, typename Device, typename Mode>
0483 std::streamsize
0484 composite_device<Filter, Device, Mode>::optimal_buffer_size() const
0485 { return iostreams::optimal_buffer_size(device_); }
0486
0487 } // End namespace detail.
0488
0489 } } // End namespaces iostreams, boost.
0490
0491 #include <boost/iostreams/detail/config/enable_warnings.hpp>
0492
0493 #endif // #ifndef BOOST_IOSTREAMS_COMPOSE_HPP_INCLUDED