Added a LWW register

src/lww_register.erl

@@ -0,0 +1,50 @@
+-module(lww_register).
+-export([new/1, new/2, merge/2, value/1]).
+-import(crdt_misc, [sorted_id/0]).
+
+-ifdef(TEST).
+-include_lib("eunit/include/eunit.hrl").
+-endif.
+
+-record(lwwregister, {value, ts}).
+
+new(Value) ->
+    new(Value, sorted_id()).
+
+new(Value, TS) ->
+    #lwwregister{value=Value, ts=TS}.
+
+value(#lwwregister{value=Value}) ->
+    Value.
+
+merge(V1=#lwwregister{ts=TS1}, #lwwregister{ts=TS2}) when TS1 > TS2 ->
+    V1;
+merge(_, V2) ->
+    V2.
+
+
+
+-ifdef(TEST).
+
+value_test() ->
+    R = new("hello"),
+    ?assertEqual("hello", value(R)).
+
+merge1_test() ->
+    R1 = new("hello"),
+    timer:sleep(1),
+    R2 = new("goodbye"),
+
+    R3 = merge(R1, R2),
+
+    ?assertEqual("goodbye", value(R3)).
+
+merge2_test() ->
+    R2 = new("goodbye", 2),
+    R1 = new("hello", 1),
+
+    R3 = merge(R1, R2),
+
+    ?assertEqual("goodbye", value(R3)).
+
+-endif.