| 1 | /*============================================================================= |
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| 2 | Copyright (c) 2001-2014 Joel de Guzman |
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| 3 | Copyright (c) 2001-2011 Hartmut Kaiser |
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| 4 | |
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| 5 | Distributed under the Boost Software License, Version 1.0. (See accompanying |
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| 6 | file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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| 7 | ==============================================================================*/ |
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| 8 | #if !defined(BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM) |
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| 9 | #define BOOST_SPIRIT_X3_UNUSED_APRIL_16_2006_0616PM |
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| 10 | |
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| 11 | #include <iosfwd> |
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| 12 | |
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| 13 | /////////////////////////////////////////////////////////////////////////////// |
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| 14 | namespace boost { namespace spirit { namespace x3 |
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| 15 | { |
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| 16 | struct unused_type |
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| 17 | { |
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| 18 | unused_type() = default; |
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| 19 | |
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| 20 | template <typename T> |
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| 21 | unused_type(T const&) |
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| 22 | { |
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| 23 | } |
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| 24 | |
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| 25 | template <typename T> |
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| 26 | unused_type const& |
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| 27 | operator=(T const&) const |
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| 28 | { |
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| 29 | return *this; |
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| 30 | } |
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| 31 | |
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| 32 | template <typename T> |
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| 33 | unused_type& |
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| 34 | operator=(T const&) |
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| 35 | { |
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| 36 | return *this; |
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| 37 | } |
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| 38 | |
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| 39 | // unused_type can also masquerade as an empty context (see context.hpp) |
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| 40 | |
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| 41 | template <typename ID> |
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| 42 | unused_type get(ID) const |
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| 43 | { |
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| 44 | return {}; |
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| 45 | } |
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| 46 | |
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| 47 | friend std::ostream& operator<<(std::ostream& out, unused_type const&) |
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| 48 | { |
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| 49 | return out; |
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| 50 | } |
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| 51 | |
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| 52 | friend std::istream& operator>>(std::istream& in, unused_type&) |
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| 53 | { |
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| 54 | return in; |
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| 55 | } |
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| 56 | }; |
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| 57 | |
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| 58 | constexpr auto unused = unused_type{}; |
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| 59 | }}} |
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| 60 | |
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| 61 | #endif |
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| 62 | |
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