boost/iostreams/read.hpp
// (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. #ifndef BOOST_IOSTREAMS_READ_HPP_INCLUDED #define BOOST_IOSTREAMS_READ_HPP_INCLUDED #if defined(_MSC_VER) # pragma once #endif #include <boost/config.hpp> // DEDUCED_TYPENAME, MSVC. #include <boost/detail/workaround.hpp> #include <boost/iostreams/char_traits.hpp> #include <boost/iostreams/detail/char_traits.hpp> #include <boost/iostreams/detail/dispatch.hpp> #include <boost/iostreams/detail/ios.hpp> // streamsize. #include <boost/iostreams/detail/streambuf.hpp> #include <boost/iostreams/detail/wrap_unwrap.hpp> #include <boost/iostreams/operations_fwd.hpp> #include <boost/mpl/if.hpp> // Must come last. #include <boost/iostreams/detail/config/disable_warnings.hpp> namespace boost { namespace iostreams { namespace detail { template<typename T> struct read_device_impl; template<typename T> struct read_filter_impl; } // End namespace detail. template<typename T> typename int_type_of<T>::type get(T& t) { return detail::read_device_impl<T>::get(detail::unwrap(t)); } template<typename T> inline std::streamsize read(T& t, typename char_type_of<T>::type* s, std::streamsize n) { return detail::read_device_impl<T>::read(detail::unwrap(t), s, n); } template<typename T, typename Source> std::streamsize read(T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n) { return detail::read_filter_impl<T>::read(detail::unwrap(t), src, s, n); } template<typename T> bool putback(T& t, typename char_type_of<T>::type c) { return detail::read_device_impl<T>::putback(detail::unwrap(t), c); } //----------------------------------------------------------------------------// namespace detail { // Helper function for adding -1 as EOF indicator. inline std::streamsize check_eof(std::streamsize n) { return n != 0 ? n : -1; } // Helper templates for reading from streambufs. template<bool IsLinked> struct true_eof_impl; template<> struct true_eof_impl<true> { template<typename T> static bool true_eof(T& t) { return t.true_eof(); } }; template<> struct true_eof_impl<false> { template<typename T> static bool true_eof(T&) { return true; } }; template<typename T> inline bool true_eof(T& t) { const bool linked = is_linked<T>::value; return true_eof_impl<linked>::true_eof(t); } //------------------Definition of read_device_impl----------------------------// template<typename T> struct read_device_impl : mpl::if_< detail::is_custom<T>, operations<T>, read_device_impl< BOOST_DEDUCED_TYPENAME detail::dispatch< T, istream_tag, streambuf_tag, input >::type > >::type { }; template<> struct read_device_impl<istream_tag> { template<typename T> static typename int_type_of<T>::type get(T& t) { return t.get(); } template<typename T> static std::streamsize read(T& t, typename char_type_of<T>::type* s, std::streamsize n) { return check_eof(t.rdbuf()->sgetn(s, n)); } template<typename T> static bool putback(T& t, typename char_type_of<T>::type c) { typedef typename char_type_of<T>::type char_type; typedef BOOST_IOSTREAMS_CHAR_TRAITS(char_type) traits_type; return !traits_type::eq_int_type( t.rdbuf()->sputbackc(c), traits_type::eof() ); } }; template<> struct read_device_impl<streambuf_tag> { template<typename T> static typename int_type_of<T>::type get(T& t) { // gcc 2.95 needs namespace qualification for char_traits. typedef typename char_type_of<T>::type char_type; typedef iostreams::char_traits<char_type> traits_type; typename int_type_of<T>::type c; return !traits_type::is_eof(c = t.sbumpc()) || detail::true_eof(t) ? c : traits_type::would_block(); } template<typename T> static std::streamsize read(T& t, typename char_type_of<T>::type* s, std::streamsize n) { std::streamsize amt; return (amt = t.sgetn(s, n)) != 0 ? amt : detail::true_eof(t) ? -1 : 0; } template<typename T> static bool putback(T& t, typename char_type_of<T>::type c) { // gcc 2.95 needs namespace qualification for char_traits. typedef typename char_type_of<T>::type char_type; typedef iostreams::char_traits<char_type> traits_type; return !traits_type::is_eof(t.sputbackc(c)); } }; template<> struct read_device_impl<input> { template<typename T> static typename int_type_of<T>::type get(T& t) { // gcc 2.95 needs namespace qualification for char_traits. typedef typename char_type_of<T>::type char_type; typedef iostreams::char_traits<char_type> traits_type; char_type c; std::streamsize amt; return (amt = t.read(&c, 1)) == 1 ? traits_type::to_int_type(c) : amt == -1 ? traits_type::eof() : traits_type::would_block(); } template<typename T> static std::streamsize read(T& t, typename char_type_of<T>::type* s, std::streamsize n) { return t.read(s, n); } template<typename T> static bool putback(T& t, typename char_type_of<T>::type c) { // T must be Peekable. return t.putback(c); } }; //------------------Definition of read_filter_impl----------------------------// template<typename T> struct read_filter_impl : mpl::if_< detail::is_custom<T>, operations<T>, read_filter_impl< BOOST_DEDUCED_TYPENAME detail::dispatch< T, multichar_tag, any_tag >::type > >::type { }; template<> struct read_filter_impl<multichar_tag> { template<typename T, typename Source> static std::streamsize read (T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n) { return t.read(src, s, n); } }; template<> struct read_filter_impl<any_tag> { template<typename T, typename Source> static std::streamsize read (T& t, Source& src, typename char_type_of<T>::type* s, std::streamsize n) { // gcc 2.95 needs namespace qualification for char_traits. typedef typename char_type_of<T>::type char_type; typedef iostreams::char_traits<char_type> traits_type; for (std::streamsize off = 0; off < n; ++off) { typename traits_type::int_type c = t.get(src); if (traits_type::is_eof(c)) return check_eof(off); if (traits_type::would_block(c)) return off; s[off] = traits_type::to_char_type(c); } return n; } }; } // End namespace detail. } } // End namespaces iostreams, boost. #include <boost/iostreams/detail/config/enable_warnings.hpp> #endif // #ifndef BOOST_IOSTREAMS_READ_HPP_INCLUDED