Add runtime context module
diff --git a/src/gr_context.erl b/src/gr_context.erl
new file mode 100644
index 0000000..c25899b
--- /dev/null
+++ b/src/gr_context.erl
@@ -0,0 +1,71 @@
+%% Copyright (c) 2012, Magnus Klaar <klaar@ninenines.eu>
+%%
+%% Permission to use, copy, modify, and/or distribute this software for any
+%% purpose with or without fee is hereby granted, provided that the above
+%% copyright notice and this permission notice appear in all copies.
+%%
+%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+%% @doc Runtime context for events.
+-module(gr_context).
+
+-export([
+ make/1
+]).
+
+make(Options) ->
+ make_(undefined, undefined, undefined, undefined, Options).
+
+make_(_Node, App, Pid, Time, [{'$n', Node}|T]) ->
+ make_(Node, App, Pid, Time, T);
+make_(Node, _App, Pid, Time, [{'$a', App}|T]) ->
+ make_(Node, App, Pid, Time, T);
+make_(Node, App, _Pid, Time, [{'$p', Pid}|T]) ->
+ make_(Node, App, Pid, Time, T);
+make_(Node, App, Pid, _Time, [{'$t', Time}|T]) ->
+ make_(Node, App, Pid, Time, T);
+make_(Node, App, Pid, Time, []) ->
+ Pid2 = case Pid of undefined -> self(); _ -> Pid end,
+ Node2 = case Node of undefined -> node(Pid2); _ -> Node end,
+ App2 = case App of undefined -> application(Pid2); _ -> App end,
+ Time2 = case Time of undefined -> os:timestamp(); _ -> Time end,
+ {Node2, App2, Pid2, Time2}.
+
+application(Pid) when Pid =:= self() ->
+ case application:get_application(group_leader()) of
+ {ok, App} -> App;
+ undefined -> undefined
+ end;
+application(Pid) ->
+ {_, GroupLeader} = erlang:process_info(Pid, group_leader),
+ case application:get_application(GroupLeader) of
+ {ok, App} -> App;
+ undefined -> undefined
+ end.
+
+-ifdef(TEST).
+-include_lib("eunit/include/eunit.hrl").
+
+make_defaults_test() ->
+ {Node, App, Pid, Time} = gr_context:make([]),
+ ?assertEqual(Node, node()),
+ ?assertEqual(Pid, self()),
+ ?assert(is_atom(App)),
+ ?assertMatch({_,_,_}, Time).
+
+
+make_override_test() ->
+ Pid = spawn(fun() -> ok end),
+ {Node, App, Pid, Time} = gr_context:make([
+ {'$n', nodename}, {'$a', appname}, {'$p', Pid}, {'$t', timeval}]),
+ ?assertEqual(nodename, Node),
+ ?assertEqual(appname, App),
+ ?assertEqual(timeval, Time).
+
+-endif.
