| 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.hpp> |
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| 6 | |
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| 7 | #include <functional> |
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| 8 | #include <string> |
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| 9 | #include <type_traits> |
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| 10 | #include <utility> |
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| 11 | #include <vector> |
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| 12 | namespace hana = boost::hana; |
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| 13 | using namespace hana::literals; |
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| 14 | using namespace std::literals; |
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| 15 | |
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| 16 | |
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| 17 | int main() { |
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| 18 | |
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| 19 | { |
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| 20 | |
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| 21 | //! [make<tuple_tag>] |
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| 22 | auto xs = hana::make<hana::tuple_tag>(1, 2.2, 'a', "bcde"s ); |
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| 23 | //! [make<tuple_tag>] |
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| 24 | |
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| 25 | }{ |
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| 26 | |
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| 27 | //! [make<range_tag>] |
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| 28 | constexpr auto r = hana::make<hana::range_tag>(hana::int_c<3>, hana::int_c<10>); |
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| 29 | static_assert(r == hana::make_range(hana::int_c<3>, hana::int_c<10>), "" ); |
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| 30 | //! [make<range_tag>] |
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| 31 | |
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| 32 | }{ |
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| 33 | |
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| 34 | //! [tuple_constructor] |
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| 35 | hana::tuple<int, double, char, std::string> xs{1, 2.2, 'a', "bcde"s }; |
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| 36 | //! [tuple_constructor] |
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| 37 | (void)xs; |
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| 38 | |
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| 39 | }{ |
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| 40 | |
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| 41 | //! [types] |
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| 42 | auto xs = hana::make_tuple(1, '2', "345" ); |
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| 43 | auto ints = hana::make_range(hana::int_c<0>, hana::int_c<100>); |
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| 44 | // what can we say about the types of `xs` and `ints`? |
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| 45 | //! [types] |
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| 46 | (void)xs; |
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| 47 | (void)ints; |
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| 48 | |
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| 49 | }{ |
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| 50 | |
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| 51 | //! [types_maximally_specified] |
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| 52 | hana::tuple<int, char, char const*> xs = hana::make_tuple(1, '2', "345" ); |
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| 53 | auto ints = hana::make_range(hana::int_c<0>, hana::int_c<100>); |
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| 54 | // can't specify the type of ints, however |
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| 55 | //! [types_maximally_specified] |
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| 56 | (void)xs; |
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| 57 | (void)ints; |
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| 58 | |
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| 59 | }{ |
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| 60 | |
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| 61 | //! [lifetime] |
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| 62 | std::string hello = "Hello" ; |
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| 63 | std::vector<char> world = {'W', 'o', 'r', 'l', 'd'}; |
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| 64 | |
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| 65 | // hello is copied, world is moved-in |
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| 66 | auto xs = hana::make_tuple(hello, std::move(world)); |
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| 67 | |
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| 68 | // s is a reference to the copy of hello inside xs. |
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| 69 | // It becomes a dangling reference as soon as xs is destroyed. |
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| 70 | std::string& s = xs[0_c]; |
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| 71 | //! [lifetime] |
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| 72 | (void)s; |
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| 73 | |
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| 74 | }{ |
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| 75 | |
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| 76 | //! [reference_wrapper] |
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| 77 | std::vector<int> ints = { /* huge vector of ints */ }; |
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| 78 | std::vector<std::string> strings = { /* huge vector of strings */ }; |
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| 79 | |
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| 80 | auto map = hana::make_map( |
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| 81 | hana::make_pair(hana::type_c<int>, std::ref(t&: ints)), |
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| 82 | hana::make_pair(hana::type_c<std::string>, std::ref(t&: strings)) |
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| 83 | ); |
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| 84 | |
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| 85 | auto& v = map[hana::type_c<int>].get(); |
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| 86 | BOOST_HANA_RUNTIME_CHECK(&v == &ints); |
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| 87 | //! [reference_wrapper] |
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| 88 | |
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| 89 | } |
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| 90 | |
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| 91 | } |
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| 92 | |
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| 93 | |
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| 94 | namespace overloading { |
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| 95 | //! [overloading] |
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| 96 | template <typename T> |
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| 97 | void f(std::vector<T> xs) { |
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| 98 | // ... |
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| 99 | } |
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| 100 | |
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| 101 | template <typename R, typename = std::enable_if_t<hana::is_a<hana::range_tag, R>()>> |
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| 102 | void f(R r) { |
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| 103 | // ... |
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| 104 | } |
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| 105 | //! [overloading] |
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| 106 | } |
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| 107 | |
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