| 1 | // Copyright Louis Dionne 2013-2022 |
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| 2 | // Distributed under the Boost Software License, Version 1.0. |
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| 3 | // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) |
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| 4 | |
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| 5 | #include <boost/hana/core/tag_of.hpp> |
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| 6 | #include <boost/hana/core/when.hpp> |
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| 7 | |
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| 8 | #include <type_traits> |
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| 9 | namespace hana = boost::hana; |
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| 10 | |
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| 11 | |
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| 12 | template <typename T, typename ExpectedDatatype> |
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| 13 | struct test { |
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| 14 | static_assert(std::is_same<hana::tag_of_t<T>, ExpectedDatatype>::value, "" ); |
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| 15 | static_assert(std::is_same<hana::tag_of_t<T const>, ExpectedDatatype>::value, "" ); |
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| 16 | static_assert(std::is_same<hana::tag_of_t<T volatile>, ExpectedDatatype>::value, "" ); |
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| 17 | static_assert(std::is_same<hana::tag_of_t<T const volatile>, ExpectedDatatype>::value, "" ); |
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| 18 | |
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| 19 | static_assert(std::is_same<hana::tag_of_t<T&>, ExpectedDatatype>::value, "" ); |
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| 20 | static_assert(std::is_same<hana::tag_of_t<T const&>, ExpectedDatatype>::value, "" ); |
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| 21 | static_assert(std::is_same<hana::tag_of_t<T volatile&>, ExpectedDatatype>::value, "" ); |
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| 22 | static_assert(std::is_same<hana::tag_of_t<T const volatile&>, ExpectedDatatype>::value, "" ); |
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| 23 | |
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| 24 | static_assert(std::is_same<hana::tag_of_t<T&&>, ExpectedDatatype>::value, "" ); |
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| 25 | static_assert(std::is_same<hana::tag_of_t<T const&&>, ExpectedDatatype>::value, "" ); |
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| 26 | static_assert(std::is_same<hana::tag_of_t<T volatile&&>, ExpectedDatatype>::value, "" ); |
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| 27 | static_assert(std::is_same<hana::tag_of_t<T const volatile&&>, ExpectedDatatype>::value, "" ); |
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| 28 | }; |
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| 29 | |
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| 30 | struct NestedDatatype; |
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| 31 | struct Nested { struct hana_tag; }; |
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| 32 | template struct test<Nested, Nested::hana_tag>; |
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| 33 | |
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| 34 | struct NoNestedDatatype { }; |
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| 35 | template struct test<NoNestedDatatype, NoNestedDatatype>; |
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| 36 | |
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| 37 | struct NoNestedHana { }; |
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| 38 | template struct test<NoNestedHana, NoNestedHana>; |
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| 39 | |
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| 40 | |
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| 41 | struct FullySpecializedDatatype; |
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| 42 | struct FullySpecialized; |
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| 43 | namespace boost { namespace hana { |
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| 44 | template <> |
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| 45 | struct tag_of<FullySpecialized> { |
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| 46 | using type = FullySpecializedDatatype; |
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| 47 | }; |
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| 48 | }} |
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| 49 | template struct test<FullySpecialized, FullySpecializedDatatype>; |
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| 50 | |
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| 51 | |
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| 52 | struct PartiallySpecializedDatatype; |
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| 53 | template <typename> struct PartiallySpecialized; |
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| 54 | namespace boost { namespace hana { |
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| 55 | template <typename T> |
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| 56 | struct tag_of<PartiallySpecialized<T>> { |
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| 57 | using type = PartiallySpecializedDatatype; |
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| 58 | }; |
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| 59 | }} |
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| 60 | template struct test<PartiallySpecialized<struct anything>, PartiallySpecializedDatatype>; |
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| 61 | |
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| 62 | |
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| 63 | struct PredicatedDatatype; |
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| 64 | struct Predicated { static constexpr bool predicate = true; }; |
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| 65 | namespace boost { namespace hana { |
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| 66 | template <typename T> |
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| 67 | struct tag_of<T, hana::when<T::predicate>> { |
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| 68 | using type = PredicatedDatatype; |
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| 69 | }; |
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| 70 | }} |
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| 71 | template struct test<Predicated, PredicatedDatatype>; |
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| 72 | |
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| 73 | |
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| 74 | int main() { } |
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| 75 | |
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