From eb425792eb5f32ce0db85a766d68e950dc3dbac1 Mon Sep 17 00:00:00 2001
From: Magnus Klaar <klaar@ninenines.fr>
Date: Tue, 24 Apr 2012 03:05:21 +0200
Subject: [PATCH] Add runtime context module

---
 src/gr_context.erl | 71 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 src/gr_context.erl

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.