boost/iostreams/detail/streambuf/indirect_streambuf.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. // This material is heavily indebted to the discussion and code samples in // A. Langer and K. Kreft, "Standard C++ IOStreams and Locales", // Addison-Wesley, 2000, pp. 228-43. // User "GMSB" provided an optimization for small seeks. #ifndef BOOST_IOSTREAMS_DETAIL_INDIRECT_STREAMBUF_HPP_INCLUDED #define BOOST_IOSTREAMS_DETAIL_INDIRECT_STREAMBUF_HPP_INCLUDED #include <algorithm> // min, max. #include <cassert> #include <exception> #include <boost/config.hpp> // Member template friends. #include <boost/detail/workaround.hpp> #include <boost/core/typeinfo.hpp> #include <boost/iostreams/constants.hpp> #include <boost/iostreams/detail/adapter/concept_adapter.hpp> #include <boost/iostreams/detail/buffer.hpp> #include <boost/iostreams/detail/config/wide_streams.hpp> #include <boost/iostreams/detail/double_object.hpp> #include <boost/iostreams/detail/execute.hpp> #include <boost/iostreams/detail/functional.hpp> #include <boost/iostreams/detail/ios.hpp> #include <boost/iostreams/detail/optional.hpp> #include <boost/iostreams/detail/push.hpp> #include <boost/iostreams/detail/streambuf/linked_streambuf.hpp> #include <boost/iostreams/operations.hpp> #include <boost/iostreams/positioning.hpp> #include <boost/iostreams/traits.hpp> #include <boost/iostreams/operations.hpp> #include <boost/mpl/if.hpp> #include <boost/throw_exception.hpp> #include <boost/type_traits/is_convertible.hpp> // Must come last. #include <boost/iostreams/detail/config/disable_warnings.hpp> // MSVC, BCC 5.x namespace boost { namespace iostreams { namespace detail { // // Description: The implementation of basic_streambuf used by chains. // template<typename T, typename Tr, typename Alloc, typename Mode> class indirect_streambuf : public linked_streambuf<BOOST_DEDUCED_TYPENAME char_type_of<T>::type, Tr> { public: typedef typename char_type_of<T>::type char_type; BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS(Tr) private: typedef typename category_of<T>::type category; typedef concept_adapter<T> wrapper; typedef detail::basic_buffer<char_type, Alloc> buffer_type; typedef indirect_streambuf<T, Tr, Alloc, Mode> my_type; typedef detail::linked_streambuf<char_type, traits_type> base_type; typedef linked_streambuf<char_type, Tr> streambuf_type; public: indirect_streambuf(); void open(const T& t BOOST_IOSTREAMS_PUSH_PARAMS()); bool is_open() const; void close(); bool auto_close() const; void set_auto_close(bool close); bool strict_sync(); // Declared in linked_streambuf. T* component() { return &*obj(); } protected: BOOST_IOSTREAMS_USING_PROTECTED_STREAMBUF_MEMBERS(base_type) //----------virtual functions---------------------------------------------// #ifndef BOOST_IOSTREAMS_NO_LOCALE void imbue(const std::locale& loc); #endif #ifdef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES public: #endif int_type underflow(); int_type pbackfail(int_type c); int_type overflow(int_type c); int sync(); pos_type seekoff( off_type off, BOOST_IOS::seekdir way, BOOST_IOS::openmode which ); pos_type seekpos(pos_type sp, BOOST_IOS::openmode which); // Declared in linked_streambuf. void set_next(streambuf_type* next); void close_impl(BOOST_IOS::openmode m); const boost::core::typeinfo& component_type() const { return BOOST_CORE_TYPEID(T); } void* component_impl() { return component(); } private: //----------Accessor functions--------------------------------------------// wrapper& obj() { return *storage_; } streambuf_type* next() const { return next_; } buffer_type& in() { return buffer_.first(); } buffer_type& out() { return buffer_.second(); } bool can_read() const { return is_convertible<Mode, input>::value; } bool can_write() const { return is_convertible<Mode, output>::value; } bool output_buffered() const { return (flags_ & f_output_buffered) != 0; } bool shared_buffer() const { return is_convertible<Mode, seekable>::value || is_convertible<Mode, dual_seekable>::value; } void set_flags(int f) { flags_ = f; } //----------State changing functions--------------------------------------// virtual void init_get_area(); virtual void init_put_area(); //----------Utility function----------------------------------------------// pos_type seek_impl( stream_offset off, BOOST_IOS::seekdir way, BOOST_IOS::openmode which ); void sync_impl(); enum flag_type { f_open = 1, f_output_buffered = f_open << 1, f_auto_close = f_output_buffered << 1 }; optional<wrapper> storage_; streambuf_type* next_; double_object< buffer_type, is_convertible< Mode, two_sequence > > buffer_; std::streamsize pback_size_; int flags_; }; //--------------Implementation of indirect_streambuf--------------------------// template<typename T, typename Tr, typename Alloc, typename Mode> indirect_streambuf<T, Tr, Alloc, Mode>::indirect_streambuf() : next_(0), pback_size_(0), flags_(f_auto_close) { } //--------------Implementation of open, is_open and close---------------------// template<typename T, typename Tr, typename Alloc, typename Mode> void indirect_streambuf<T, Tr, Alloc, Mode>::open (const T& t, std::streamsize buffer_size, std::streamsize pback_size) { using namespace std; // Normalize buffer sizes. buffer_size = (buffer_size != -1) ? buffer_size : iostreams::optimal_buffer_size(t); pback_size = (pback_size != -1) ? pback_size : default_pback_buffer_size; // Construct input buffer. if (can_read()) { pback_size_ = (std::max)(std::streamsize(2), pback_size); // STLPort needs 2. std::streamsize size = pback_size_ + ( buffer_size ? buffer_size: std::streamsize(1) ); in().resize(static_cast<int>(size)); if (!shared_buffer()) init_get_area(); } // Construct output buffer. if (can_write() && !shared_buffer()) { if (buffer_size != std::streamsize(0)) out().resize(static_cast<int>(buffer_size)); init_put_area(); } storage_.reset(wrapper(t)); flags_ |= f_open; if (can_write() && buffer_size > 1) flags_ |= f_output_buffered; this->set_true_eof(false); this->set_needs_close(); } template<typename T, typename Tr, typename Alloc, typename Mode> inline bool indirect_streambuf<T, Tr, Alloc, Mode>::is_open() const { return (flags_ & f_open) != 0; } template<typename T, typename Tr, typename Alloc, typename Mode> void indirect_streambuf<T, Tr, Alloc, Mode>::close() { using namespace std; base_type* self = this; detail::execute_all( detail::call_member_close(*self, BOOST_IOS::in), detail::call_member_close(*self, BOOST_IOS::out), detail::call_reset(storage_), detail::clear_flags(flags_) ); } template<typename T, typename Tr, typename Alloc, typename Mode> bool indirect_streambuf<T, Tr, Alloc, Mode>::auto_close() const { return (flags_ & f_auto_close) != 0; } template<typename T, typename Tr, typename Alloc, typename Mode> void indirect_streambuf<T, Tr, Alloc, Mode>::set_auto_close(bool close) { flags_ = (flags_ & ~f_auto_close) | (close ? f_auto_close : 0); } //--------------Implementation virtual functions------------------------------// #ifndef BOOST_IOSTREAMS_NO_LOCALE template<typename T, typename Tr, typename Alloc, typename Mode> void indirect_streambuf<T, Tr, Alloc, Mode>::imbue(const std::locale& loc) { if (is_open()) { obj().imbue(loc); if (next_) next_->pubimbue(loc); } } #endif template<typename T, typename Tr, typename Alloc, typename Mode> typename indirect_streambuf<T, Tr, Alloc, Mode>::int_type indirect_streambuf<T, Tr, Alloc, Mode>::underflow() { using namespace std; if (!gptr()) init_get_area(); buffer_type& buf = in(); if (gptr() < egptr()) return traits_type::to_int_type(*gptr()); // Fill putback buffer. std::streamsize keep = (std::min)( static_cast<std::streamsize>(gptr() - eback()), pback_size_ ); if (keep) traits_type::move( buf.data() + (pback_size_ - keep), gptr() - keep, keep ); // Set pointers to reasonable values in case read throws. setg( buf.data() + pback_size_ - keep, buf.data() + pback_size_, buf.data() + pback_size_ ); // Read from source. std::streamsize chars = obj().read(buf.data() + pback_size_, buf.size() - pback_size_, next_); if (chars == -1) { this->set_true_eof(true); chars = 0; } setg(eback(), gptr(), buf.data() + pback_size_ + chars); return chars != 0 ? traits_type::to_int_type(*gptr()) : traits_type::eof(); } template<typename T, typename Tr, typename Alloc, typename Mode> typename indirect_streambuf<T, Tr, Alloc, Mode>::int_type indirect_streambuf<T, Tr, Alloc, Mode>::pbackfail(int_type c) { if (gptr() != eback()) { gbump(-1); if (!traits_type::eq_int_type(c, traits_type::eof())) *gptr() = traits_type::to_char_type(c); return traits_type::not_eof(c); } else { boost::throw_exception(bad_putback()); } } template<typename T, typename Tr, typename Alloc, typename Mode> typename indirect_streambuf<T, Tr, Alloc, Mode>::int_type indirect_streambuf<T, Tr, Alloc, Mode>::overflow(int_type c) { if ( (output_buffered() && pptr() == 0) || (shared_buffer() && gptr() != 0) ) { init_put_area(); } if (!traits_type::eq_int_type(c, traits_type::eof())) { if (output_buffered()) { if (pptr() == epptr()) { sync_impl(); if (pptr() == epptr()) return traits_type::eof(); } *pptr() = traits_type::to_char_type(c); pbump(1); } else { char_type d = traits_type::to_char_type(c); if (obj().write(&d, 1, next_) != 1) return traits_type::eof(); } } return traits_type::not_eof(c); } template<typename T, typename Tr, typename Alloc, typename Mode> int indirect_streambuf<T, Tr, Alloc, Mode>::sync() { try { // sync() is no-throw. sync_impl(); obj().flush(next_); return 0; } catch (...) { return -1; } } template<typename T, typename Tr, typename Alloc, typename Mode> bool indirect_streambuf<T, Tr, Alloc, Mode>::strict_sync() { try { // sync() is no-throw. sync_impl(); return obj().flush(next_); } catch (...) { return false; } } template<typename T, typename Tr, typename Alloc, typename Mode> inline typename indirect_streambuf<T, Tr, Alloc, Mode>::pos_type indirect_streambuf<T, Tr, Alloc, Mode>::seekoff (off_type off, BOOST_IOS::seekdir way, BOOST_IOS::openmode which) { return seek_impl(off, way, which); } template<typename T, typename Tr, typename Alloc, typename Mode> inline typename indirect_streambuf<T, Tr, Alloc, Mode>::pos_type indirect_streambuf<T, Tr, Alloc, Mode>::seekpos (pos_type sp, BOOST_IOS::openmode which) { return seek_impl(position_to_offset(sp), BOOST_IOS::beg, which); } template<typename T, typename Tr, typename Alloc, typename Mode> typename indirect_streambuf<T, Tr, Alloc, Mode>::pos_type indirect_streambuf<T, Tr, Alloc, Mode>::seek_impl (stream_offset off, BOOST_IOS::seekdir way, BOOST_IOS::openmode which) { if ( gptr() != 0 && way == BOOST_IOS::cur && which == BOOST_IOS::in && eback() - gptr() <= off && off <= egptr() - gptr() ) { // Small seek optimization gbump(static_cast<int>(off)); return obj().seek(stream_offset(0), BOOST_IOS::cur, BOOST_IOS::in, next_) - static_cast<off_type>(egptr() - gptr()); } if (pptr() != 0) this->BOOST_IOSTREAMS_PUBSYNC(); // sync() confuses VisualAge 6. if (way == BOOST_IOS::cur && gptr()) off -= static_cast<off_type>(egptr() - gptr()); bool two_head = is_convertible<category, dual_seekable>::value || is_convertible<category, bidirectional_seekable>::value; if (two_head) { BOOST_IOS::openmode both = BOOST_IOS::in | BOOST_IOS::out; if ((which & both) == both) boost::throw_exception(bad_seek()); if (which & BOOST_IOS::in) { setg(0, 0, 0); } if (which & BOOST_IOS::out) { setp(0, 0); } } else { setg(0, 0, 0); setp(0, 0); } return obj().seek(off, way, which, next_); } template<typename T, typename Tr, typename Alloc, typename Mode> inline void indirect_streambuf<T, Tr, Alloc, Mode>::set_next (streambuf_type* next) { next_ = next; } template<typename T, typename Tr, typename Alloc, typename Mode> inline void indirect_streambuf<T, Tr, Alloc, Mode>::close_impl (BOOST_IOS::openmode which) { if (which == BOOST_IOS::in && is_convertible<Mode, input>::value) { setg(0, 0, 0); } if (which == BOOST_IOS::out && is_convertible<Mode, output>::value) { sync(); setp(0, 0); } #if defined(BOOST_MSVC) #pragma warning(push) #pragma warning(disable: 4127) // conditional expression is constant #endif if ( !is_convertible<category, dual_use>::value || is_convertible<Mode, input>::value == (which == BOOST_IOS::in) ) { obj().close(which, next_); } #if defined(BOOST_MSVC) #pragma warning(pop) #endif } //----------State changing functions------------------------------------------// template<typename T, typename Tr, typename Alloc, typename Mode> void indirect_streambuf<T, Tr, Alloc, Mode>::sync_impl() { std::streamsize avail, amt; if ((avail = static_cast<std::streamsize>(pptr() - pbase())) > 0) { if ((amt = obj().write(pbase(), avail, next())) == avail) setp(out().begin(), out().end()); else { const char_type* ptr = pptr(); setp(out().begin() + amt, out().end()); pbump(static_cast<int>(ptr - pptr())); } } } template<typename T, typename Tr, typename Alloc, typename Mode> void indirect_streambuf<T, Tr, Alloc, Mode>::init_get_area() { if (shared_buffer() && pptr() != 0) { sync_impl(); setp(0, 0); } setg(in().begin(), in().begin(), in().begin()); } template<typename T, typename Tr, typename Alloc, typename Mode> void indirect_streambuf<T, Tr, Alloc, Mode>::init_put_area() { using namespace std; if (shared_buffer() && gptr() != 0) { obj().seek(static_cast<off_type>(gptr() - egptr()), BOOST_IOS::cur, BOOST_IOS::in, next_); setg(0, 0, 0); } if (output_buffered()) setp(out().begin(), out().end()); else setp(0, 0); } //----------------------------------------------------------------------------// } } } // End namespaces detail, iostreams, boost. #include <boost/iostreams/detail/config/enable_warnings.hpp> // MSVC, BCC 5.x #endif // #ifndef BOOST_IOSTREAMS_DETAIL_INDIRECT_STREAMBUF_HPP_INCLUDED