Introduce an elixir OID type

This is still fairly experimental.

lib/geef/oid.ex

@@ -0,0 +1,31 @@
+defrecord Geef.Oid, Record.extract(:geef_oid, from: "src/geef_records.hrl") do
+  alias Geef.Oid
+
+  @doc false
+  defmacro to_erl(oid) do
+    quote do
+      set_elem(unquote(oid), 0, :geef_oid)
+    end
+  end
+
+  @doc false
+  defmacro from_erl(oid) do
+    quote do
+      set_elem(unquote(oid), 0, Geef.Oid)
+    end
+  end
+
+  defp maybe_oid({:ok, oid}), do: from_erl(oid)
+  defp maybe_oid(error = {:error, _}), do: error
+
+  @spec parse(iolist) :: t
+  def parse(str) do
+    :geef_oid.parse(str)
+  end
+
+  @spec hex(t) :: String.t
+  def hex(oid = Oid[]) do
+    :geef_oid.hex(to_erl(oid))
+  end
+
+end