72 lines
2.1 KiB
C++
72 lines
2.1 KiB
C++
#pragma once
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#include <algorithm>
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#include <functional>
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#include <limits>
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#include <type_traits>
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#include <utility>
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namespace stdx {
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inline namespace v1 {
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#if __cplusplus >= 202002L
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#define CONSTEXPR_INVOKE constexpr
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#else
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#define CONSTEXPR_INVOKE
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#endif
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template <typename T, typename InputIt, typename ROp, typename TOp,
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typename... InputItN>
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CONSTEXPR_INVOKE auto transform_reduce(InputIt first, InputIt last, T init,
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ROp rop, TOp top,
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InputItN... first_n) -> T {
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while (first != last) {
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init = std::invoke(rop, std::move(init),
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std::invoke(top, *first, *first_n...));
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static_cast<void>(++first), (static_cast<void>(++first_n), ...);
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}
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return init;
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}
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template <typename T, typename InputIt, typename Size, typename ROp,
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typename TOp, typename... InputItN>
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CONSTEXPR_INVOKE auto transform_reduce_n(InputIt first, Size n, T init, ROp rop,
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TOp top, InputItN... first_n) -> T {
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while (n-- != 0) {
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init = std::invoke(rop, std::move(init),
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std::invoke(top, *first, *first_n...));
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static_cast<void>(++first), (static_cast<void>(++first_n), ...);
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}
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return init;
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}
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#undef CONSTEXPR_INVOKE
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template <typename To, typename From>
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constexpr auto saturate_cast(From from) -> To {
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constexpr auto to_min = std::numeric_limits<To>::min();
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constexpr auto to_max = std::numeric_limits<To>::max();
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if constexpr (sizeof(From) > sizeof(To)) {
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auto const clamped = std::clamp<From>(from, to_min, to_max);
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return static_cast<To>(clamped);
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}
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if constexpr (sizeof(From) == sizeof(To)) {
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if constexpr (std::is_unsigned_v<From> and std::is_signed_v<To>) {
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if (from > to_max) {
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return to_max;
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}
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}
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if constexpr (std::is_signed_v<From> and std::is_unsigned_v<To>) {
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if (from < 0) {
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return static_cast<To>(0);
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}
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}
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}
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return static_cast<To>(from);
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}
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} // namespace v1
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} // namespace stdx
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