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https://github.com/boostorg/hana.git
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0660af6a8f
- Fix ambiguous specialization in core/datatype - [Config] Turn #errors into #warnings - Qualify recursive calls to `apply` to make sure the right function is selected - Remove usages of when_valid to workaround ambiguous specializations - Use multiline comments to remove some GCC warnings with LaTeX's double backslash - Specialize operators::of in the boost::hana::operators namespace - Manually perform more conversions in constexpr-context - Workaround the lack of support for constexpr-but-non-const member functions - Disambiguate unqualified uses of size_t with hana::size_t and ::size_t
49 lines
1.6 KiB
C++
49 lines
1.6 KiB
C++
/*
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@copyright Louis Dionne 2015
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#include <boost/hana/integral_constant.hpp>
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#include <boost/hana/pair.hpp>
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#include <boost/hana/range.hpp>
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#include <boost/hana/tuple.hpp>
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#include <boost/hana/type.hpp>
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#include <type_traits>
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using namespace boost::hana;
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using namespace boost::hana::literals;
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auto indexed_sort = [](auto list, auto predicate) {
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auto indexed_list = zip(list, to<Tuple>(range(0_c, size(list))));
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auto sorted = sort.by(predicate ^on^ head, indexed_list);
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return make_pair(transform(sorted, head), transform(sorted, last));
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};
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int main() {
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auto types = tuple_t<char[4], char[2], char[1], char[5], char[3]>;
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auto sorted = indexed_sort(types, [](auto t, auto u) {
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return sizeof_(t) < sizeof_(u);
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});
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using Tup = decltype(unpack(first(sorted), template_<_tuple>))::type;
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auto indices = second(indexed_sort(second(sorted), less));
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// When accessed through the indices sequence, the tuple appears to be
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// ordered as the `types` above. However, as can be seen in the
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// static_assert below, the tuple is actually ordered differently.
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Tup tup;
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char const(&a)[4] = tup[indices[0_c]];
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char const(&b)[2] = tup[indices[1_c]];
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char const(&c)[1] = tup[indices[2_c]];
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char const(&d)[5] = tup[indices[3_c]];
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char const(&e)[3] = tup[indices[4_c]];
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static_assert(std::is_same<
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Tup,
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_tuple<char[1], char[2], char[3], char[4], char[5]>
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>{}, "");
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(void)a; (void)b; (void)c; (void)d; (void)e;
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}
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