C++11 function memoizator [http://barmaley-exe.koding.com/en/memoization-using-cpp11]

main.cpp

#include <iostream>

#include "Memoizator.hpp"

int f(int a) {
    std::cout << __func__ << "(" << a << ")\n";
    return a*a;
}

int g(int a, int b) {
    std::cout << __func__ << "(" << a << ", " << b << ")\n";
    return a*b;
}


int main() {
    auto memo_f = memoize(f);
    auto memo_g = memoize(g);

    int v;
    for (int i = 0; i < 100; ++i) {
        v += memo_f(i % 17) * memo_g(i % 91, i % 37);
    }

    std::cout << v << std::endl;

    return 0;
}

Memoizator.hpp

#ifndef MEMOIZATOR
#define MEMOIZATOR

#include <tuple>
#include <map>

template<class R, class... Args>
class Memoizator {
    typedef std::tuple<Args...> tuple;
public:
    typedef R (*function)(Args...);

    Memoizator(function f) : f(f) {}

    R operator()(Args... args) {
        tuple argset(args...);

        auto it = map.find(argset);
        if (it != map.end()) {
            return it->second;
        }

        return map[argset] = f(args...);
    }

private:
    
    function f;
    std::map<tuple, R> map;
};

template<class R, class... Args>
Memoizator<R, Args...> memoize(R (*f)(Args...)) {
    return Memoizator<R, Args...>(f);
}

#endif // MEMOIZATOR