79 lines
2.2 KiB
C++
79 lines
2.2 KiB
C++
#include <vector>
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#include <span>
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#include <thread>
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#include <mutex>
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#include <functional>
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template<typename T>
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class QuickSorterMT {
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public:
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template<typename C>
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QuickSorterMT(C cmp, int max_depth) : cmp(cmp), max_depth(max_depth) {
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static_assert(std::is_same<std::invoke_result_t<C, T, T>, bool>(), "C must be a function that returns a bool");
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}
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auto sort(std::vector<T> &data) -> void {
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std::span<T> sortable(data);
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qsort(sortable, 0, max_depth);
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}
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private:
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auto parition(std::span<T> &data) -> std::pair<std::span<T>, std::span<T>> {
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std::vector<T> buf(data);
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auto pivot = buf.begin();
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std::advance(pivot, std::distance(buf.begin(), buf.end()) / 2);
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auto lefti = buf.begin();
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auto righti = buf.end();
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while (1) {
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for (; cmp(*lefti, *pivot); lefti++);
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for (; !cmp(*righti, *pivot); righti--);
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if (lefti >= righti) {
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break;
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}
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std::swap(lefti, righti);
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}
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std::move(buf.begin(), buf.end(), data.begin());
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return {std::span<T>(data.begin(), lefti), std::span<T>(lefti, data.end())};
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}
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auto qsort(std::span<T> &data, int depth, const int &mdepth) -> void {
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if (std::distance(data.begin(), data.end()) <= 1) {
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return;
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} else if (std::distance(data.begin(), data.end()) == 2) {
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if (cmp(data[1], data[0])) {
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std::swap(data[0], data[1]);
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return;
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}
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}
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// Determine mid of data
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auto mid = data.begin();
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std::advance(mid, std::distance(data.begin(), data.end()) / 2);
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// Generate left and right view on data (no copies are made here)
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std::span<T> left(data.begin(), mid);
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std::span<T> right(mid, data.end());
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if (depth < mdepth) {
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std::thread left_thread([&]() { qsort(left, depth + 1, mdepth); });
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std::thread right_thread([&]() { qsort(right, depth + 1, mdepth); });
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left_thread.join();
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right_thread.join();
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} else {
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qsort(left, depth + 1, mdepth);
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qsort(right, depth + 1, mdepth);
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}
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}
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std::function<bool(T, T)> cmp;
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const int max_depth;
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}; |