Allow streaming from an iterator

lib/geef/iterator.ex

@@ -0,0 +1,29 @@
+defrecord Geef.Iterator, Record.extract(:geef_iterator, from: "src/geef_records.hrl") do
+  alias Geef.Iterator
+  alias Geef.Reference
+
+  @doc false
+  defmacro rebind(obj) do
+    quote do
+      set_elem(unquote(obj), 0, :geef_iterator)
+    end
+  end
+
+
+  def stream(iter = Iterator[]) do
+    &stream(iter, &1, &2)
+  end
+
+  def stream(iter = Iterator[type: ref], acc, fun) do
+    case :geef_ref.next(rebind(iter)) do
+      {:ok, ref} ->
+        stream(iter, fun.(Reference.new(ref), acc), fun)
+      {:error, :iterover} ->
+        acc
+      {:error, error} ->
+        raise Geef.IteratorError, message: error
+    end
+  end
+end
+
+defexception Geef.IteratorError, [message: nil]

lib/geef/reference.ex

@@ -31,4 +31,13 @@ defrecord Geef.Reference, Record.extract(:geef_reference, from: "src/geef_record
     :geef_ref.shorthand(name)
   end
 
+  def iterator(repo, regexp // :undefined) do
+    case :geef_ref.iterator(repo, regexp) do
+      {:ok, iter} ->
+        {:ok, Geef.Iterator.new iter}
+      other ->
+        other
+    end
+  end
+
 end