boost/iostreams/restrict.hpp
// (C) Copyright Jonathan Turkanis 2005. // 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. #ifndef BOOST_IOSTREAMS_RESTRICT_HPP_INCLUDED #define BOOST_IOSTREAMS_RESTRICT_HPP_INCLUDED #if defined(_MSC_VER) && (_MSC_VER >= 1020) # pragma once #endif #include <algorithm> // min. #include <utility> // pair. #include <boost/cstdint.hpp> // intmax_t. #include <boost/config.hpp> // DEDUCED_TYPENAME. #include <boost/iostreams/categories.hpp> #include <boost/iostreams/char_traits.hpp> #include <boost/iostreams/detail/adapter/basic_adapter.hpp> #include <boost/iostreams/detail/call_traits.hpp> #include <boost/iostreams/detail/enable_if_stream.hpp> #include <boost/iostreams/detail/error.hpp> #include <boost/iostreams/detail/ios.hpp> // failure. #include <boost/iostreams/detail/select.hpp> #include <boost/iostreams/operations.hpp> #include <boost/iostreams/skip.hpp> #include <boost/iostreams/traits.hpp> // mode_of, is_direct. #include <boost/mpl/bool.hpp> #include <boost/static_assert.hpp> #include <boost/type_traits/is_convertible.hpp> #include <boost/iostreams/detail/config/disable_warnings.hpp> // VC7.1 C4244. namespace boost { namespace iostreams { namespace detail { // // Template name: restricted_indirect_device. // Description: Provides an restricted view of an indirect Device. // Template paramters: // Device - An indirect model of Device that models either Source or // SeekableDevice. // template<typename Device> class restricted_indirect_device : public basic_adapter<Device> { private: typedef typename detail::param_type<Device>::type param_type; public: typedef typename char_type_of<Device>::type char_type; struct category : mode_of<Device>::type, device_tag, closable_tag, flushable_tag, localizable_tag, optimally_buffered_tag { }; restricted_indirect_device( param_type dev, stream_offset off, stream_offset len = -1 ); 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); private: stream_offset beg_, pos_, end_; }; // // Template name: restricted_direct_device. // Description: Provides an restricted view of a Direct Device. // Template paramters: // Device - A model of Direct and Device. // template<typename Device> class restricted_direct_device : public basic_adapter<Device> { public: typedef typename char_type_of<Device>::type char_type; typedef std::pair<char_type*, char_type*> pair_type; struct category : mode_of<Device>::type, device_tag, direct_tag, closable_tag, localizable_tag { }; restricted_direct_device( const Device& dev, stream_offset off, stream_offset len = -1 ); pair_type input_sequence(); pair_type output_sequence(); private: pair_type sequence(mpl::true_); pair_type sequence(mpl::false_); char_type *beg_, *end_; }; // // Template name: restricted_filter. // Description: Provides an restricted view of a Filter. // Template paramters: // Filter - An indirect model of Filter. // template<typename Filter> class restricted_filter : public basic_adapter<Filter> { public: typedef typename char_type_of<Filter>::type char_type; struct category : mode_of<Filter>::type, filter_tag, multichar_tag, closable_tag, localizable_tag, optimally_buffered_tag { }; restricted_filter( const Filter& flt, stream_offset off, stream_offset len = -1 ); template<typename Source> std::streamsize read(Source& src, char_type* s, std::streamsize n) { using namespace std; if (!open_) open(src); streamsize amt = end_ != -1 ? (std::min) (n, static_cast<streamsize>(end_ - pos_)) : n; streamsize result = iostreams::read(this->component(), src, s, amt); if (result != -1) pos_ += result; return result; } template<typename Sink> std::streamsize write(Sink& snk, const char_type* s, std::streamsize n) { if (!open_) open(snk); if (end_ != -1 && pos_ + n >= end_) bad_write(); std::streamsize result = iostreams::write(this->component(), snk, s, n); pos_ += result; return result; } template<typename Device> std::streampos seek(Device& dev, stream_offset off, BOOST_IOS::seekdir way) { stream_offset next; if (way == BOOST_IOS::beg) { next = beg_ + off; } else if (way == BOOST_IOS::cur) { next = pos_ + off; } else if (end_ != -1) { next = end_ + off; } else { // Restriction is half-open; seek relative to the actual end. pos_ = this->component().seek(dev, off, BOOST_IOS::end); if (pos_ < beg_) bad_seek(); return offset_to_position(pos_ - beg_); } if (next < beg_ || end_ != -1 && next >= end_) bad_seek(); pos_ = this->component().seek(dev, next, BOOST_IOS::cur); return offset_to_position(pos_ - beg_); } private: template<typename Device> void open(Device& dev) { open_ = true; iostreams::skip(this->component(), dev, beg_); } stream_offset beg_, pos_, end_; bool open_; }; template<typename T> struct restriction_traits : iostreams::select< // Disambiguation for Tru64. is_filter<T>, restricted_filter<T>, is_direct<T>, restricted_direct_device<T>, else_, restricted_indirect_device<T> > { }; } // End namespace detail. template<typename T> struct restriction : public detail::restriction_traits<T>::type { typedef typename detail::param_type<T>::type param_type; typedef typename detail::restriction_traits<T>::type base_type; restriction(param_type t, stream_offset off, stream_offset len = -1) : base_type(t, off, len) { } }; //--------------Implementation of restrict------------------------------------// // 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 T> restriction<T> restrict( const T& t, stream_offset off, stream_offset len = -1 BOOST_IOSTREAMS_DISABLE_IF_STREAM(T) ) { return restriction<T>(t, off, len); } template<typename Ch, typename Tr> restriction< std::basic_streambuf<Ch, Tr> > restrict(std::basic_streambuf<Ch, Tr>& sb, stream_offset off, stream_offset len = -1) { return restriction< std::basic_streambuf<Ch, Tr> >(sb, off, len); } template<typename Ch, typename Tr> restriction< std::basic_istream<Ch, Tr> > restrict(std::basic_istream<Ch, Tr>& is, stream_offset off, stream_offset len = -1) { return restriction< std::basic_istream<Ch, Tr> >(is, off, len); } template<typename Ch, typename Tr> restriction< std::basic_ostream<Ch, Tr> > restrict(std::basic_ostream<Ch, Tr>& os, stream_offset off, stream_offset len = -1) { return restriction< std::basic_ostream<Ch, Tr> >(os, off, len); } template<typename Ch, typename Tr> restriction< std::basic_iostream<Ch, Tr> > restrict(std::basic_iostream<Ch, Tr>& io, stream_offset off, stream_offset len = -1) { return restriction< std::basic_iostream<Ch, Tr> >(io, off, len); } # else // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //---------------------// template<typename T> restriction<T> restrict( const T& t, stream_offset off, stream_offset len = -1 BOOST_IOSTREAMS_DISABLE_IF_STREAM(T) ) { return restriction<T>(t, off, len); } restriction<std::streambuf> restrict(std::streambuf& sb, stream_offset off, stream_offset len = -1) { return restriction<std::streambuf>(sb, off, len); } restriction<std::istream> restrict(std::istream<Ch, Tr>& is, stream_offset off, stream_offset len = -1) { return restriction<std::istream>(is, off, len); } restriction<std::ostream> restrict(std::ostream<Ch, Tr>& os, stream_offset off, stream_offset len = -1) { return restriction<std::ostream>(os, off, len); } restriction<std::iostream> restrict(std::iostream<Ch, Tr>& io, stream_offset off, stream_offset len = -1) { return restriction<std::iostream>(io, off, len); } # endif // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //--------------------// #else // #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //----------------// template<typename T> restriction<T> restrict(const T& t, stream_offset off, stream_offset len, mpl::true_) { // Bad overload resolution. return restriction<T>(const_cast<T&>(t, off, len)); } template<typename T> restriction<T> restrict(const T& t, stream_offset off, stream_offset len, mpl::false_) { return restriction<T>(t, off, len); } template<typename T> restriction<T> restrict( const T& t, stream_offset off, stream_offset len = -1 BOOST_IOSTREAMS_DISABLE_IF_STREAM(T) ) { return restrict(t, off, len, is_std_io<T>()); } # if !BOOST_WORKAROUND(__BORLANDC__, < 0x600) && \ !BOOST_WORKAROUND(BOOST_MSVC, <= 1300) && \ !defined(__GNUC__) // ---------------------------------------------------// template<typename T> restriction<T> restrict(T& t, stream_offset off, stream_offset len = -1) { return restriction<T>(t, off, len); } # endif // Borland 5.x, VC6-7.0 or GCC 2.9x //--------------------------------// #endif // #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //---------------// //----------------------------------------------------------------------------// namespace detail { //--------------Implementation of restricted_indirect_device------------------// template<typename Device> restricted_indirect_device<Device>::restricted_indirect_device (param_type dev, stream_offset off, stream_offset len) : basic_adapter<Device>(dev), beg_(off), pos_(off), end_(len != -1 ? off + len : -1) { if (len < -1 || off < 0) throw BOOST_IOSTREAMS_FAILURE("bad offset"); iostreams::skip(this->component(), off); } template<typename Device> inline std::streamsize restricted_indirect_device<Device>::read (char_type* s, std::streamsize n) { using namespace std; streamsize amt = end_ != -1 ? (std::min) (n, static_cast<streamsize>(end_ - pos_)) : n; streamsize result = iostreams::read(this->component(), s, amt); if (result != -1) pos_ += result; return result; } template<typename Device> inline std::streamsize restricted_indirect_device<Device>::write (const char_type* s, std::streamsize n) { if (end_ != -1 && pos_ + n >= end_) bad_write(); std::streamsize result = iostreams::write(this->component(), s, n); pos_ += result; return result; } template<typename Device> std::streampos restricted_indirect_device<Device>::seek (stream_offset off, BOOST_IOS::seekdir way) { stream_offset next; if (way == BOOST_IOS::beg) { next = beg_ + off; } else if (way == BOOST_IOS::cur) { next = pos_ + off; } else if (end_ != -1) { next = end_ + off; } else { // Restriction is half-open; seek relative to the actual end. pos_ = iostreams::seek(this->component(), off, BOOST_IOS::end); if (pos_ < beg_) bad_seek(); return offset_to_position(pos_ - beg_); } if (next < beg_ || end_ != -1 && next >= end_) bad_seek(); pos_ = iostreams::seek(this->component(), next - pos_, BOOST_IOS::cur); return offset_to_position(pos_ - beg_); } //--------------Implementation of restricted_direct_device--------------------// template<typename Device> restricted_direct_device<Device>::restricted_direct_device (const Device& dev, stream_offset off, stream_offset len) : basic_adapter<Device>(dev), beg_(0), end_(0) { std::pair<char_type*, char_type*> seq = sequence(is_convertible<category, input>()); if ( off < 0 || len < -1 || len != -1 && off + len > seq.second - seq.first ) { throw BOOST_IOSTREAMS_FAILURE("bad offset"); } beg_ = seq.first + off; end_ = len != -1 ? seq.first + off + len : seq.second; } template<typename Device> typename restricted_direct_device<Device>::pair_type restricted_direct_device<Device>::input_sequence() { BOOST_STATIC_ASSERT((is_convertible<category, input>::value)); return std::make_pair(beg_, end_); } template<typename Device> typename restricted_direct_device<Device>::pair_type restricted_direct_device<Device>::output_sequence() { BOOST_STATIC_ASSERT((is_convertible<category, output>::value)); return std::make_pair(beg_, end_); } template<typename Device> typename restricted_direct_device<Device>::pair_type restricted_direct_device<Device>::sequence(mpl::true_) { return iostreams::input_sequence(this->component()); } template<typename Device> typename restricted_direct_device<Device>::pair_type restricted_direct_device<Device>::sequence(mpl::false_) { return iostreams::output_sequence(this->component()); } //--------------Implementation of restricted_filter---------------------------// template<typename Filter> restricted_filter<Filter>::restricted_filter (const Filter& flt, stream_offset off, stream_offset len) : basic_adapter<Filter>(flt), beg_(off), pos_(off), end_(len != -1 ? off + len : -1), open_(false) { if (len < -1 || off < 0) throw BOOST_IOSTREAMS_FAILURE("bad offset"); } } // End namespace detail. } } // End namespaces iostreams, boost. #endif // #ifndef BOOST_IOSTREAMS_RESTRICT_HPP_INCLUDED