Imported Upstream version 1.49.0upstream/1.49.0

1 files changed, 112 insertions, 0 deletions

diff --git a/boost/iostreams/skip.hpp b/boost/iostreams/skip.hpp
new file mode 100644
index 0000000000..4c62d4528b
--- /dev/null
+++ b/boost/iostreams/skip.hpp
@@ -0,0 +1,112 @@
+// (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.
+
+// To do: handle bidirection streams and output-seekable components.
+
+#ifndef BOOST_IOSTREAMS_SKIP_HPP_INCLUDED
+#define BOOST_IOSTREAMS_SKIP_HPP_INCLUDED
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+#include <boost/iostreams/char_traits.hpp>
+#include <boost/iostreams/detail/ios.hpp>  // failure.
+#include <boost/iostreams/operations.hpp>
+#include <boost/iostreams/seek.hpp>
+#include <boost/iostreams/traits.hpp>
+#include <boost/mpl/and.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/or.hpp>
+#include <boost/throw_exception.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+
+namespace boost { namespace iostreams {
+
+namespace detail {
+
+template<typename Device>
+void skip(Device& dev, stream_offset off, mpl::true_)
+{ iostreams::seek(dev, off, BOOST_IOS::cur); }
+
+template<typename Device>
+void skip(Device& dev, stream_offset off, mpl::false_)
+{   // gcc 2.95 needs namespace qualification for char_traits.
+    typedef typename char_type_of<Device>::type  char_type;
+    typedef iostreams::char_traits<char_type>    traits_type;
+    for (stream_offset z = 0; z < off; ) {
+        typename traits_type::int_type c;
+        if (traits_type::is_eof(c = iostreams::get(dev)))
+            boost::throw_exception(BOOST_IOSTREAMS_FAILURE("bad skip offset"));
+        if (!traits_type::would_block(c))
+            ++z;
+    }
+}
+
+template<typename Filter, typename Device>
+void skip( Filter& flt, Device& dev, stream_offset off,
+           BOOST_IOS::openmode which, mpl::true_ )
+{ boost::iostreams::seek(flt, dev, off, BOOST_IOS::cur, which); }
+
+template<typename Filter, typename Device>
+void skip( Filter& flt, Device& dev, stream_offset off,
+           BOOST_IOS::openmode, mpl::false_ )
+{ 
+    typedef typename char_type_of<Device>::type char_type;
+    char_type c;
+    for (stream_offset z = 0; z < off; ) {
+        std::streamsize amt;
+        if ((amt = iostreams::read(flt, dev, &c, 1)) == -1)
+            boost::throw_exception(BOOST_IOSTREAMS_FAILURE("bad skip offset"));
+        if (amt == 1)
+            ++z;
+    }
+}
+
+} // End namespace detail.
+
+template<typename Device>
+void skip(Device& dev, stream_offset off)
+{ 
+    typedef typename mode_of<Device>::type     mode;
+    typedef mpl::or_<
+        is_convertible<mode, input_seekable>,
+        is_convertible<mode, output_seekable>
+    >                                          can_seek;
+    BOOST_STATIC_ASSERT(
+        (can_seek::value || is_convertible<mode, input>::value)
+    );
+    detail::skip(dev, off, can_seek());
+}
+
+template<typename Filter, typename Device>
+void skip( Filter& flt, Device& dev, stream_offset off, 
+           BOOST_IOS::openmode which = BOOST_IOS::in | BOOST_IOS::out )
+{ 
+    typedef typename mode_of<Filter>::type                 filter_mode;
+    typedef typename mode_of<Device>::type                 device_mode;
+    typedef mpl::or_<
+        mpl::and_<
+            is_convertible<filter_mode, input_seekable>,
+            is_convertible<device_mode, input_seekable>
+        >,
+        mpl::and_<
+            is_convertible<filter_mode, output_seekable>,
+            is_convertible<device_mode, output_seekable>
+        >
+    >                                                      can_seek;
+    BOOST_STATIC_ASSERT(
+        ( can_seek::value || 
+          (is_convertible<filter_mode, input>::value &&
+          is_convertible<device_mode, input>::value) )
+    );
+    detail::skip(flt, dev, off, which, can_seek());
+}
+
+} } // End namespaces iostreams, boost.
+
+#endif // #ifndef BOOST_IOSTREAMS_SKIP_HPP_INCLUDED //------------------------//