Allow getting a tree entry by position

src/geef_tree.erl

@@ -4,19 +4,22 @@
 -include_lib("eunit/include/eunit.hrl").
 -endif.
 
--export([get/2, lookup/2]).
+-export([get/2, nth/2, lookup/2]).
 
 -include("geef_records.hrl").
 
+from_nif({ok, Mode, Type, Oid, Name}) ->
+    {ok, #geef_tree_entry{mode=Mode, type=Type, id=#geef_oid{oid=Oid}, name=Name}};
+from_nif(Err = {error, _}) ->
+    Err.
+
 -spec get(geef_object(), iolist()) -> {ok, geef_tree_entry()} | {error, term()}.
 get(#geef_object{type=tree,handle=Handle}, Path) ->
-    case geef_nif:tree_bypath(Handle, Path) of
-	{ok, Mode, Type, Geef_Oid, Name} ->
-	    {ok, #geef_tree_entry{mode=Mode, type=Type,
-				  id=#geef_oid{oid=Geef_Oid}, name=Name}};
-	Other ->
-	    Other
-    end.
+    from_nif(geef_nif:tree_bypath(Handle, Path)).
+
+-spec nth(geef_object(), non_neg_integer()) -> {ok, geef_tree_entry()} | {error, term()}.
+nth(#geef_object{type=tree,handle=Handle}, Nth) ->
+    from_nif(geef_nif:tree_nth(Handle, Nth)).
 
 -spec lookup(pid(), geef_oid() | iolist()) -> {ok, geef_object()} | {error, term()}.
 lookup(Repo, Id) ->
@@ -26,11 +29,13 @@ lookup(Repo, Id) ->
 
 %% This is somewhat hacky, assuming that this is running under .eunit,
 %% but it's good enough for now
-bypath_test() ->
+access_test() ->
     {ok, Repo} = geef_repo:open(".."),
     {ok, Tree} = geef_obj:lookup(Repo, geef_oid:parse("395e1c39cb203640b78da8458a42afdb92bef7aa")),
     Id = geef_oid:parse("80d5c15a040c93a4f98f4496a05ebf30cdd58650"),
     Expected = #geef_tree_entry{mode=8#100644, type=blob, id=Id, name = <<"README.md">>},
-    {ok, Actual}= geef_tree:get(Tree, "README.md"),
-    ?assertEqual(Expected, Actual).
+    {ok, ActualByPath}= geef_tree:get(Tree, "README.md"),
+    {ok, ActualNth} = geef_tree:nth(Tree, 2),
+    ?assertEqual(Expected, ActualByPath),
+    ?assertEqual(Expected, ActualNth).
 -endif.