C++ Template functions to find the best (e.g. max/min) of something.

best.cpp

template<typename Iterator, typename Value>
struct Position
{
	Position(const Iterator& iterator_, const Value& value_)
	: iterator(iterator_)
	, value(value_)
	{ }

	Iterator iterator;
	
	Value value;
};

template<typename Iterator, typename Projection, typename Compare>
auto best(Iterator begin,
		  Iterator end,
		  Projection projection,
		  Compare compare)
{
	using Output = decltype(projection(*begin));
	
	auto best_iterator = begin;

	auto best_value = projection(*begin);
	
	for (++begin; begin != end; ++begin)
	{
		auto&& value = projection(*begin);
		
		if (compare(std::forward<Output>(value), best_value))
		{
			best_value = std::forward<Output>(value);
			
			best_iterator = begin;
		}
	}
	
	return Position<Iterator, Output>{best_iterator, best_value};
}

template<typename Iterator, typename Projection>
auto maximum(Iterator begin, Iterator end, Projection projection)
{
	using Output = decltype(projection(*begin));

	return best(begin, end, projection, std::greater<Output>());
}

template<typename Iterator, typename Projection>
auto minimum(Iterator begin, Iterator end, Projection projection)
{
	using Output = decltype(projection(*begin));

	return best(begin, end, projection, std::less<Output>());
}