GenerationStampSet.hpp

#pragma once
 
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <memory>
 
namespace mmcfilters {
 
struct GenerationStampSet {
    using gen_t = uint32_t;
 
    std::unique_ptr<gen_t[]> stamp;
 
    size_t n{0};
 
    gen_t cur{1};
 
    GenerationStampSet() = default;
 
    explicit GenerationStampSet(size_t n) { resize(n); }
 
    void resize(size_t newN) {
        n = newN;
        stamp = std::make_unique<gen_t[]>(n);
        std::fill_n(stamp.get(), n, 0);
        cur = 1;
    }
 
    inline void mark(size_t idx) noexcept {
        stamp[idx] = cur;
    }
 
    inline bool isMarked(size_t idx) const noexcept {
        return stamp[idx] == cur;
    }
 
    inline void unmark(size_t idx) noexcept {
        if (stamp[idx] == cur) {
            stamp[idx] = 0;
        }
    }
 
    void resetAll() {
        if (++cur == 0) {
            std::fill_n(stamp.get(), n, 0);
            cur = 1;
        }
    }
 
    void clearAll() {
        std::fill_n(stamp.get(), n, 0);
        cur = 1;
    }
 
    gen_t generation() const noexcept { return cur; }
};
 
} // namespace mmcfilters