| 1 | // Boost.Units - A C++ library for zero-overhead dimensional analysis and |
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| 2 | // unit/quantity manipulation and conversion |
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| 3 | // |
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| 4 | // Copyright (C) 2003-2008 Matthias Christian Schabel |
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| 5 | // Copyright (C) 2008 Steven Watanabe |
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| 6 | // |
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| 7 | // Distributed under the Boost Software License, Version 1.0. (See |
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| 8 | // accompanying file LICENSE_1_0.txt or copy at |
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| 9 | // http://www.boost.org/LICENSE_1_0.txt) |
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| 10 | |
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| 11 | #ifndef BOOST_UNITS_STATIC_CONSTANT_HPP |
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| 12 | #define BOOST_UNITS_STATIC_CONSTANT_HPP |
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| 13 | |
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| 14 | #include <boost/units/config.hpp> |
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| 15 | |
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| 16 | /// A convenience macro that allows definition of static |
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| 17 | /// constants in headers in an ODR-safe way. |
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| 18 | #define BOOST_UNITS_STATIC_CONSTANT(name, type) \ |
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| 19 | template<bool b> \ |
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| 20 | struct name##_instance_t \ |
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| 21 | { \ |
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| 22 | static const type instance; \ |
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| 23 | }; \ |
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| 24 | \ |
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| 25 | namespace \ |
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| 26 | { \ |
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| 27 | static const type& name = name##_instance_t<true>::instance; \ |
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| 28 | } \ |
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| 29 | \ |
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| 30 | template<bool b> \ |
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| 31 | const type name##_instance_t<b>::instance |
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| 32 | |
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| 33 | /// A convenience macro for static constants with auto |
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| 34 | /// type deduction. |
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| 35 | #if BOOST_UNITS_HAS_TYPEOF |
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| 36 | |
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| 37 | #if BOOST_UNITS_HAS_BOOST_TYPEOF |
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| 38 | |
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| 39 | #define BOOST_UNITS_AUTO_STATIC_CONSTANT(name, value) \ |
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| 40 | BOOST_TYPEOF_NESTED_TYPEDEF(name##_nested_t, value) \ |
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| 41 | BOOST_UNITS_STATIC_CONSTANT(name, name##_nested_t::type) = (value) |
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| 42 | |
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| 43 | #elif BOOST_UNITS_HAS_MWERKS_TYPEOF |
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| 44 | |
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| 45 | #define BOOST_UNITS_AUTO_STATIC_CONSTANT(name, value) \ |
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| 46 | BOOST_UNITS_STATIC_CONSTANT(name, __typeof__(value)) = (value) |
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| 47 | |
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| 48 | #elif BOOST_UNITS_HAS_GNU_TYPEOF |
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| 49 | |
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| 50 | #define BOOST_UNITS_AUTO_STATIC_CONSTANT(name, value) \ |
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| 51 | BOOST_UNITS_STATIC_CONSTANT(name, typeof(value)) = (value) |
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| 52 | |
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| 53 | #endif // BOOST_UNITS_HAS_BOOST_TYPEOF |
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| 54 | |
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| 55 | #endif // BOOST_UNITS_HAS_TYPEOF |
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| 56 | |
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| 57 | #endif // BOOST_UNITS_STATIC_CONSTANT_HPP |
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| 58 | |
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