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1 // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
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2 // (C) Copyright 2004-2007 Jonathan Turkanis
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3 // Distributed under the Boost Software License, Version 1.0. (See accompanying
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4 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
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5
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6 // See http://www.boost.org/libs/iostreams for documentation.
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7
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8 // Inspired by Daryle Walker's nullbuf from his More I/O submission.
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9
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10 #ifndef BOOST_IOSTREAMS_NULL_HPP_INCLUDED
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11 #define BOOST_IOSTREAMS_NULL_HPP_INCLUDED
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12
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13 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
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14 # pragma once
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15 #endif
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16
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17 #include <boost/iostreams/categories.hpp>
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18 #include <boost/iostreams/detail/ios.hpp> // openmode, streamsize.
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19 #include <boost/iostreams/positioning.hpp>
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20
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21 namespace boost { namespace iostreams {
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22
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23 template<typename Ch, typename Mode>
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24 class basic_null_device {
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25 public:
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26 typedef Ch char_type;
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27 struct category
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28 : public Mode,
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29 public device_tag,
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30 public closable_tag
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31 { };
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32 std::streamsize read(Ch*, std::streamsize) { return 0; }
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33 std::streamsize write(const Ch*, std::streamsize n) { return n; }
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34 std::streampos seek( stream_offset, BOOST_IOS::seekdir,
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35 BOOST_IOS::openmode =
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36 BOOST_IOS::in | BOOST_IOS::out )
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37 { return -1; }
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38 void close() { }
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39 void close(BOOST_IOS::openmode) { }
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40 };
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41
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42 template<typename Ch>
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43 struct basic_null_source : private basic_null_device<Ch, input> {
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44 typedef Ch char_type;
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45 typedef source_tag category;
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46 using basic_null_device<Ch, input>::read;
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47 using basic_null_device<Ch, input>::close;
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48 };
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49
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50 typedef basic_null_source<char> null_source;
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51 typedef basic_null_source<wchar_t> wnull_source;
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52
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53 template<typename Ch>
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54 struct basic_null_sink : private basic_null_device<Ch, output> {
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55 typedef Ch char_type;
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56 typedef sink_tag category;
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57 using basic_null_device<Ch, output>::write;
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58 using basic_null_device<Ch, output>::close;
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59 };
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60
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61 typedef basic_null_sink<char> null_sink;
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62 typedef basic_null_sink<wchar_t> wnull_sink;
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63
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64 } } // End namespaces iostreams, boost.
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65
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66 #endif // #ifndef BOOST_IOSTREAMS_NULL_HPP_INCLUDED
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