#include <iostream>
#include <functional>

/* Decorator function example,
   returns negative (! operator) of given function
*/
template <typename T>
auto reverse_func(T func)
{
    auto r_func =
    [=](auto ...args)
    { 
        return !func(args...); 
    };

    return r_func; 
}

/* Decorator function example,
   prints result of given function before it's returned
*/
template <typename T>
auto print_result_func(T func)
{
    auto r_func = 
    [=](auto ...args)
    {
        auto result = func(args...);
        std::cout << "Result: " << result << std::endl;
        return result;
    };

    return r_func;
}

/* Function to be decorated example,
   checks whether two given arguments are equal
*/
bool cmp(int x, int y)
{
    return x == y;
}

/* Decorator macro */
#define DECORATE(function, decorator) \
    decorator<decltype(function)>(function)

int main()
{
    auto reversed = DECORATE(cmp, reverse_func);
    auto print_normal = DECORATE(cmp, print_result_func);
    auto print_reversed = DECORATE(reversed, print_result_func);
    auto print_double_normal = DECORATE(print_normal, print_result_func);
    auto print_double_reversed = DECORATE(print_reversed, print_result_func);

    std::cout << cmp(1,2) << reversed(1,2) << std::endl;
    print_double_normal(1,2);
    print_reversed(1,2);
    print_double_reversed(1,2);
}