ranges::any_view bench

bench_any_view.cpp

#include <iostream>
#include <chrono>

#include "range-v3/include/range/v3/all.hpp"

using namespace std::chrono;

template<typename T, CONCEPT_REQUIRES_(ranges::Integral<T>())>
class odd : public ranges::view_facade<odd<T>> {
    friend ranges::range_access;
    T max_, curr_;

    const T& get() const { return curr_; }
    bool done() const { return curr_ >= max_; }
    void next() { curr_ += 2; }

public:
    odd() = default;
    odd(T min, T max) : max_(max), curr_(min % 2 ? min : min + 1) { }
};


#define BENCH(what) { \
    auto t0 = high_resolution_clock::now(); \
    what \
    auto t1 = high_resolution_clock::now(); \
    std::cout << duration_cast<milliseconds>(t1 - t0).count() << "ms" << std::endl; \
}

int main() {
    using T = unsigned int;
    T N = 100000000;

    BENCH(
        ranges::any_view<const T&> r = odd<T>(0, N);
        volatile T s = 0;
        RANGES_FOR(auto x, r)
        s += x;
    )
    BENCH(
        auto r = odd<T>(0, N);
        volatile T s = 0;
        RANGES_FOR(auto x, r)
            s += x;
    )
    BENCH(
        volatile T s = 0;
        for (T x = 1; x < N; x += 2)
            s += x;
    )
}

Output:

856ms
115ms
113ms