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1 // Copyright (c) 2001-2011 Hartmut Kaiser
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2 //
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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 #if !defined(BOOST_SPIRIT_QI_UNUSED_SKIPPER_JUL_25_2009_0921AM)
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7 #define BOOST_SPIRIT_QI_UNUSED_SKIPPER_JUL_25_2009_0921AM
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8
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9 #if defined(_MSC_VER)
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10 #pragma once
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11 #endif
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12
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13 #include <boost/spirit/home/support/unused.hpp>
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14 #include <boost/mpl/bool.hpp>
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15
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16 namespace boost { namespace spirit { namespace qi { namespace detail
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17 {
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18 template <typename Skipper>
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19 struct unused_skipper : unused_type
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20 {
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21 unused_skipper(Skipper const& skipper_)
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22 : skipper(skipper_) {}
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23 Skipper const& skipper;
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24
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25 private:
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26 // silence MSVC warning C4512: assignment operator could not be generated
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27 unused_skipper& operator= (unused_skipper const&);
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28 };
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29
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30 template <typename Skipper>
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31 struct is_unused_skipper
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32 : mpl::false_ {};
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33
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34 template <typename Skipper>
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35 struct is_unused_skipper<unused_skipper<Skipper> >
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36 : mpl::true_ {};
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37
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38 template <>
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39 struct is_unused_skipper<unused_type>
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40 : mpl::true_ {};
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41
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42 // If a surrounding lexeme[] directive was specified, the current
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43 // skipper is of the type unused_skipper. In this case we
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44 // re-activate the skipper which was active before the skip[]
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45 // directive.
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46 template <typename Skipper>
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47 inline Skipper const&
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48 get_skipper(unused_skipper<Skipper> const& u)
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49 {
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50 return u.skipper;
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51 }
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52
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53 // If no surrounding lexeme[] directive was specified we keep what we got.
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54 template <typename Skipper>
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55 inline Skipper const&
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56 get_skipper(Skipper const& u)
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57 {
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58 return u;
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59 }
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60
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61 }}}}
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62
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63 #endif
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