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| 2 | // Copyright (C) 2009-2012 Lorenzo Caminiti |
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| 3 | // Distributed under the Boost Software License, Version 1.0 |
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| 4 | // (see accompanying file LICENSE_1_0.txt or a copy at |
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| 5 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 6 | // Home at http://www.boost.org/libs/local_function |
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| 7 | |
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| 8 | #ifndef ADDABLE_HPP_ |
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| 9 | #define ADDABLE_HPP_ |
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| 10 | |
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| 11 | #include <boost/concept_check.hpp> |
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| 12 | |
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| 13 | template<typename T> |
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| 14 | struct Addable { // User-defined concept. |
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| 15 | BOOST_CONCEPT_USAGE(Addable) { |
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| 16 | return_type(x + y); // Check addition `T operator+(T x, T y)`. |
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| 17 | } |
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| 18 | |
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| 19 | private: |
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| 20 | void return_type(T) {} // Implementation (required for some linkers). |
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| 21 | static T const& x; |
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| 22 | static T const& y; |
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| 23 | }; |
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| 24 | |
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| 25 | #endif // #include guard |
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| 26 | |
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| 27 | |
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