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96 lines
2.3 KiB
96 lines
2.3 KiB
#ifndef _LEVEN_H
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#define _LEVEN_H
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#include "exopt.h"
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#ifdef __cplusplus
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//#include "util.hh"
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#include <string_view>
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#include <concepts>
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#include <vector>
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#include <array>
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#include <span>
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#include <tuple>
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extern "C" {
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#endif
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size_t _EO(leven_diff)(const char* _EO(restrict), const char* _EO(restrict), size_t)
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_EO(internal)
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_EO(readonly)
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__attribute__((nonnull(1, 2)))
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;
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#ifdef __cplusplus
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}
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namespace exopt { namespace util [[gnu::visibility("internal")]] {
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template<size_t N =0> // NOTE: Do not change this manually //
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constexpr auto leven_diff(std::string_view s1, std::string_view s2) noexcept {
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const size_t
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m(s1.size()),
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n(s2.size());
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if(__builtin_expect(!m, false)) return n;
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if(__builtin_expect(!n, false)) return m;
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auto&& work_on_d = [&](auto&& costs) {
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for(size_t i=0;i <= n; i++) costs[i] = i;
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size_t i{0};
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for(auto const& c1: s1) {
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costs[0] = i + 1;
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size_t corner { i },
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j { 0 };
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for(auto const& c2: s2) {
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size_t upper { costs[j+1] };
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if( c1 == c2 ) costs[j+1] = corner;
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else {
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using std::min;
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size_t t{min(upper, corner)};//upper<corner ? upper : corner
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costs[j+1] = min(costs[j], t) + 1;
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}
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corner = upper;
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j += 1;
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}
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i += 1;
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}
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return costs[n];
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};
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if constexpr(N > 0) {
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return work_on_d(std::array<size_t, N+1>{});
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} else if consteval {
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return work_on_d(std::vector<size_t>(n + 1));
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} else {
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thread_local static std::vector<size_t> d;
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const size_t n1 = n + 1;
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if(__builtin_expect(d.size() < n1, false)) d.resize(n1);
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// We don't need to clear the buffer, it will be reinitialised by `work_on_d()`.
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return work_on_d(std::span<size_t>{d.begin(), n1});
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}
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}
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template<std::convertible_to<std::string_view> S1, std::convertible_to<std::string_view> S2>
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constexpr decltype(auto) leven_diff(const S1& sa, const S2& sb) noexcept {
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using str = std::string_view;
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return leven_diff(str{sa}, str{sb});
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}
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template<size_t M, size_t N>
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constexpr decltype(auto) leven_diff(const char (&sa)[M], const char (&sb)[N]) noexcept {
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if constexpr(!N) return M;
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else if constexpr(!M) return N;
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else if constexpr(M < N) return N - M; //XXX: Are these lines correct?
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else if constexpr(N < M) return M - N; // ^
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else return leven_diff<N>(std::string_view{sa}, std::string_view{sb});
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}
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} }
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#endif
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#endif /* _LEVEN_H */
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