From bbdb35ae03e83bf1a7b73e005b194fd101a16809 Mon Sep 17 00:00:00 2001
From: martinsumner <martin.sumner@adaptip.co.uk>
Date: Thu, 5 Jan 2017 14:09:39 +0000
Subject: [PATCH] Add ordered_set conversion

Can we go from an ets table to a skiplist
---
 src/leveled_skiplist.erl | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/leveled_skiplist.erl b/src/leveled_skiplist.erl
index 5824829..8870609 100644
--- a/src/leveled_skiplist.erl
+++ b/src/leveled_skiplist.erl
@@ -20,6 +20,8 @@
         from_list/2,
         from_sortedlist/1,
         from_sortedlist/2,
+        from_orderedset/1,
+        from_orderedset/2,
         to_list/1,
         enter/3,
         enter/4,
@@ -71,6 +73,12 @@ enter_nolookup(Key, Value, SkipList) ->
                 element(2, SkipList),
                 ?SKIP_WIDTH, ?LIST_HEIGHT)}.
 
+from_orderedset(Table) ->
+    from_orderedset(Table, false).
+
+from_orderedset(Table, Bloom) ->
+    from_sortedlist(ets:tab2list(Table), Bloom).
+
 from_list(UnsortedKVL) ->
     from_list(UnsortedKVL, false).
 
@@ -405,7 +413,15 @@ skiplist_nobloom_test() ->
 skiplist_tester(Bloom) ->
     N = 4000,
     KL = generate_randomkeys(1, N, 1, N div 5),
-                
+    
+    OS = ets:new(test, [ordered_set, private]),
+    ets:insert(OS, KL),
+    SWaETS = os:timestamp(),
+    SkipList = from_orderedset(OS, Bloom),
+    io:format(user, "Generating skip list with ~w keys in ~w microseconds " ++
+                        "from ordered set~n",
+                [N, timer:now_diff(os:timestamp(), SWaETS)]),
+    
     SWaGSL = os:timestamp(),
     SkipList = from_list(lists:reverse(KL), Bloom),
     io:format(user, "Generating skip list with ~w keys in ~w microseconds~n" ++