gistfile1.cpp

#include <type_traits>

template<unsigned Depth, typename Container, typename Function>
struct deep_for_each_helper {
	static void deep_for_each(Container& cont, const Function& fun) {
		for(auto& elem: cont) {
			deep_for_each_helper<Depth-1, typename std::decay<decltype(elem)>::type, Function>::deep_for_each(elem, fun);
		}
	}
};

template<typename Container, typename Function>
struct deep_for_each_helper<0, Container, Function> {
	static void deep_for_each(Container& cont, const Function& fun) {
		for(auto& elem: cont) {
			fun(elem);
		}
	}
};


template<unsigned Depth, typename Container, typename Function>
void deep_for_each(Container& cont, const Function& fun) {
	deep_for_each_helper<Depth, Container, Function>::deep_for_each(cont, fun);
}

#include <iostream>
#include <vector>
#include <array>

int main() {
	//std::array<std::vector<std::vector<int>>, 2> arr = {{{{1,2},{3,4}},{{4,5}}}};
	std::vector<std::vector<int>> arr = {{1,2}, {3}};
	deep_for_each<1>(arr, [](int i){ std::cout << i << '\n'; });
	std::cout << std::endl;
}