stepping_iota.h

#pragma once

#include <numeric>

namespace impl_details
{
	template <typename T, typename UnaryAdvanceOp>
	class proxy
	{
		T value;
		UnaryAdvanceOp op;
	public:
		proxy(T init_value, UnaryAdvanceOp op_) :
			value(init_value),
			op(op_)
		{

		}

		operator T()
		{
			return value;
		}

		T operator++()
		{
			value = op(value);
			return value;
		}

		T operator++(int)
		{
			T old = value;
			value = op(value);
			return old;
		}
	};
}

template <typename OutputIterator, typename T, typename UnaryAdavanceOp>
void stepping_iota(OutputIterator first, OutputIterator last, T init_value, UnaryAdavanceOp op)
{
	impl_details::proxy<T, UnaryAdavanceOp> p(init_value, op);
	std::iota(first, last, p);
}