| Jeff Thompson | 86b6d64 | 2013-10-17 15:01:56 -0700 | [diff] [blame] | 1 | // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com) |
| 2 | // (C) Copyright 2003-2007 Jonathan Turkanis |
| 3 | // Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 4 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.) |
| 5 | |
| 6 | // See http://www.boost.org/libs/iostreams for documentation. |
| 7 | |
| 8 | // To do: handle bidirection streams and output-seekable components. |
| 9 | |
| 10 | #ifndef NDNBOOST_IOSTREAMS_SKIP_HPP_INCLUDED |
| 11 | #define NDNBOOST_IOSTREAMS_SKIP_HPP_INCLUDED |
| 12 | |
| 13 | #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
| 14 | # pragma once |
| 15 | #endif |
| 16 | |
| 17 | #include <ndnboost/iostreams/char_traits.hpp> |
| 18 | #include <ndnboost/iostreams/detail/ios.hpp> // failure. |
| 19 | #include <ndnboost/iostreams/operations.hpp> |
| 20 | #include <ndnboost/iostreams/seek.hpp> |
| 21 | #include <ndnboost/iostreams/traits.hpp> |
| 22 | #include <ndnboost/mpl/and.hpp> |
| 23 | #include <ndnboost/mpl/bool.hpp> |
| 24 | #include <ndnboost/mpl/or.hpp> |
| 25 | #include <ndnboost/throw_exception.hpp> |
| 26 | #include <ndnboost/type_traits/is_convertible.hpp> |
| 27 | |
| 28 | namespace ndnboost { namespace iostreams { |
| 29 | |
| 30 | namespace detail { |
| 31 | |
| 32 | template<typename Device> |
| 33 | void skip(Device& dev, stream_offset off, mpl::true_) |
| 34 | { iostreams::seek(dev, off, NDNBOOST_IOS::cur); } |
| 35 | |
| 36 | template<typename Device> |
| 37 | void skip(Device& dev, stream_offset off, mpl::false_) |
| 38 | { // gcc 2.95 needs namespace qualification for char_traits. |
| 39 | typedef typename char_type_of<Device>::type char_type; |
| 40 | typedef iostreams::char_traits<char_type> traits_type; |
| 41 | for (stream_offset z = 0; z < off; ) { |
| 42 | typename traits_type::int_type c; |
| 43 | if (traits_type::is_eof(c = iostreams::get(dev))) |
| 44 | ndnboost::throw_exception(NDNBOOST_IOSTREAMS_FAILURE("bad skip offset")); |
| 45 | if (!traits_type::would_block(c)) |
| 46 | ++z; |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | template<typename Filter, typename Device> |
| 51 | void skip( Filter& flt, Device& dev, stream_offset off, |
| 52 | NDNBOOST_IOS::openmode which, mpl::true_ ) |
| 53 | { ndnboost::iostreams::seek(flt, dev, off, NDNBOOST_IOS::cur, which); } |
| 54 | |
| 55 | template<typename Filter, typename Device> |
| 56 | void skip( Filter& flt, Device& dev, stream_offset off, |
| 57 | NDNBOOST_IOS::openmode, mpl::false_ ) |
| 58 | { |
| 59 | typedef typename char_type_of<Device>::type char_type; |
| 60 | char_type c; |
| 61 | for (stream_offset z = 0; z < off; ) { |
| 62 | std::streamsize amt; |
| 63 | if ((amt = iostreams::read(flt, dev, &c, 1)) == -1) |
| 64 | ndnboost::throw_exception(NDNBOOST_IOSTREAMS_FAILURE("bad skip offset")); |
| 65 | if (amt == 1) |
| 66 | ++z; |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | } // End namespace detail. |
| 71 | |
| 72 | template<typename Device> |
| 73 | void skip(Device& dev, stream_offset off) |
| 74 | { |
| 75 | typedef typename mode_of<Device>::type mode; |
| 76 | typedef mpl::or_< |
| 77 | is_convertible<mode, input_seekable>, |
| 78 | is_convertible<mode, output_seekable> |
| 79 | > can_seek; |
| 80 | NDNBOOST_STATIC_ASSERT( |
| 81 | (can_seek::value || is_convertible<mode, input>::value) |
| 82 | ); |
| 83 | detail::skip(dev, off, can_seek()); |
| 84 | } |
| 85 | |
| 86 | template<typename Filter, typename Device> |
| 87 | void skip( Filter& flt, Device& dev, stream_offset off, |
| 88 | NDNBOOST_IOS::openmode which = NDNBOOST_IOS::in | NDNBOOST_IOS::out ) |
| 89 | { |
| 90 | typedef typename mode_of<Filter>::type filter_mode; |
| 91 | typedef typename mode_of<Device>::type device_mode; |
| 92 | typedef mpl::or_< |
| 93 | mpl::and_< |
| 94 | is_convertible<filter_mode, input_seekable>, |
| 95 | is_convertible<device_mode, input_seekable> |
| 96 | >, |
| 97 | mpl::and_< |
| 98 | is_convertible<filter_mode, output_seekable>, |
| 99 | is_convertible<device_mode, output_seekable> |
| 100 | > |
| 101 | > can_seek; |
| 102 | NDNBOOST_STATIC_ASSERT( |
| 103 | ( can_seek::value || |
| 104 | (is_convertible<filter_mode, input>::value && |
| 105 | is_convertible<device_mode, input>::value) ) |
| 106 | ); |
| 107 | detail::skip(flt, dev, off, which, can_seek()); |
| 108 | } |
| 109 | |
| 110 | } } // End namespaces iostreams, boost. |
| 111 | |
| 112 | #endif // #ifndef NDNBOOST_IOSTREAMS_SKIP_HPP_INCLUDED //------------------------// |