fizzbuzz_with_ranges.cpp

#include <initializer_list>
#include <range/v3/view/cycle.hpp>
#include <optional>
#include <range/v3/view/zip_with.hpp>
#include <string>
#include <iostream>
#include <range/v3/algorithm/for_each.hpp>
#include <range/v3/view/iota.hpp>
#include <range/v3/view/transform.hpp>

using std::vector;
using std::nullopt;
using std::optional;
using std::make_optional;
using std::string;

template<class A>
optional<A> operator+(optional<A> a, optional<A> b)
{
    if(a)
    {
        if(b)
            return a.value() + b.value();
        else
            return a;
    }
    else
        return b;
        
}

int main()
{
    namespace rv = ranges::views;
    vector<optional<string>> fizz = {nullopt, nullopt, make_optional("fizz")};
    auto fizz_cycle = fizz | rv::cycle;
    vector<optional<string>> buzz = {nullopt, nullopt, nullopt, nullopt, make_optional("buzz")};
    auto buzz_cycle = buzz | rv::cycle;

    auto fizzbuzz = rv::zip_with([] (auto a, auto b) { return a+b; }, 
                                            fizz_cycle, buzz_cycle);

    auto numbers = rv::iota(1,101) | rv::transform([](auto i) { return std::to_string(i); });
    auto elements = rv::zip_with([] (auto n, auto fb) { return fb.value_or(n); },
                                            numbers, fizzbuzz);

    ranges::for_each(elements, [](auto elem){ std::cout << elem  << '\n'; });

    return 0;
}