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

lib/geef/reference.ex

@@ -1,15 +1,21 @@
 defrecord Geef.Reference, Record.extract(:geef_reference, from: "src/geef_records.hrl") do
   import Geef
   alias Geef.Reference
+  alias Geef.Oid
+  import Oid, only: :macros
 
-  defmacrop rebind(obj) do
-    quote do
-      set_elem(unquote(obj), 0, :geef_reference)
+  def from_erl(ref) do
+    case set_elem(ref, 0, Geef.Reference) do
+      ref = Reference[type: :symbolic] -> ref
+      ref = Reference[type: :oid, target: oid] -> ref.target(set_elem(oid, 0, Geef.Oid))
     end
   end
 
-  def from_erl(ref) do
-    set_elem(ref, 0, Geef.Reference)
+  def to_erl(ref = Reference[type: :symbolic]) do
+    set_elem(ref, 0, :geef_reference)
+  end
+  def to_erl(ref = Reference[type: :oid, target: oid]) do
+    ref |> set_elem(0, :geef_reference) |> set_elem(4, set_elem(oid, 0, :geef_oid))
   end
 
   defp maybe_ref({:ok, ref}), do: {:ok, Reference.from_erl ref}
@@ -18,7 +24,7 @@ defrecord Geef.Reference, Record.extract(:geef_reference, from: "src/geef_record
   def lookup(repo, name), do: :geef_ref.lookup(repo, name) |> maybe_ref
   def lookup!(repo, name), do: lookup(repo, name) |> assert_ok
 
-  def resolve(ref = Reference[]), do: :geef_ref.resolve(rebind(ref)) |> maybe_ref
+  def resolve(ref = Reference[]), do: :geef_ref.resolve(to_erl(ref)) |> maybe_ref
   def resolve!(ref =Reference[]), do: resolve(ref) |> assert_ok
 
   def dwim(repo, name), do: :geef_ref.dwim(repo, name) |> maybe_ref