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2492322 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 | // Copyright (c) 2023, QuantStack and Mamba Contributors
//
// Distributed under the terms of the BSD 3-Clause License.
//
// The full license is in the file LICENSE, distributed with this software.
#ifndef MAMBA_UTIL_VARIANT_CMP_HPP
#define MAMBA_UTIL_VARIANT_CMP_HPP
#include <type_traits>
#include <utility>
#include <variant>
namespace mamba::util
{
template <typename IndexCmp, typename AlternativeCmp>
[[nodiscard]] auto make_variant_cmp(IndexCmp&& index_cmp, AlternativeCmp&& alternative_cmp);
/********************
* Implementation *
********************/
template <typename IndexCmp, typename AlternativeCmp>
auto make_variant_cmp(IndexCmp&& index_cmp, AlternativeCmp&& alternative_cmp)
{
return [int_cmp = std::forward<IndexCmp>(index_cmp),
alt_cmp = std::forward<AlternativeCmp>(alternative_cmp) //
](const auto& lhs, const auto& rhs) -> bool
{
// When alternatives are different, compare the index.
if (lhs.index() != rhs.index())
{
return int_cmp(lhs.index(), rhs.index());
}
// When alternatives are the same, compare the underlying type.
return std::visit(
[&](const auto& l) -> bool
{
using Alt = std::decay_t<decltype(l)>;
const auto& r = std::get<Alt>(rhs);
return alt_cmp(l, r);
},
lhs
);
};
}
}
#endif
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