Merge pull request #18 from spawngrid/alterline

Adds rule tracing capabilities (hooks & currently fired rule)

src/internal.hrl

@@ -1 +1 @@
--record(seresye, {kb, alfa, join, agenda, pending_actions, client_state}).
+-record(seresye, {kb, alfa, join, agenda, pending_actions, client_state, fired_rule, hooks = []}).

src/seresye.erl

@@ -15,6 +15,7 @@
 -export([start/0, start/1, start/2, stop/1, get_engine/1,
          add_rules/2, add_rule/2, add_rule/3, assert/2, get_kb/1,
          get_rules_fired/1, get_client_state/1,
+         set_hooks/2, get_fired_rule/1,
          set_client_state/2, query_kb/2, remove_rule/2, retract/2]).
 
 %% gen_server callbacks
@@ -33,6 +34,9 @@ start(Name) ->
 start(Name, ClientState) ->
     seresye_sup:start_engine(Name, ClientState).
 
+set_hooks(Name, Hooks) when is_list(Hooks) ->
+    gen_server:cast(Name, {set_hooks, Hooks}).
+
 set_client_state(Name, NewState) ->
     gen_server:cast(Name, {set_client_state, NewState}).
 
@@ -72,6 +76,9 @@ remove_rule(Name, Rule) ->
 get_rules_fired(Name) ->
     gen_server:call(Name, get_rules_fired).
 
+get_fired_rule(Name) ->
+    gen_server:call(Name, get_fired_rule).    
+
 get_kb(Name) ->
     gen_server:call(Name, get_kb).
 
@@ -172,6 +179,15 @@ handle_call(get_rules_fired, _From, State0) ->
                 {error, {Type, Reason}}
         end,
     {reply, Reply, State0};
+handle_call(get_fired_rule, _From, State0) ->
+    Reply =
+        try
+            seresye_engine:get_fired_rule(State0)
+        catch
+            Type:Reason ->
+                {error, {Type, Reason}}
+        end,
+    {reply, Reply, State0};
 handle_call(get_engine, _From, State0) ->
     {reply, State0, State0};
 handle_call(get_kb, _From, State0) ->
@@ -193,6 +209,9 @@ handle_call({query_kb, Pattern}, _From, State0) ->
         end,
     {reply, Reply, State0}.
 
+handle_cast({set_hooks, Hooks}, State) ->
+    {noreply, seresye_engine:set_hooks(State, Hooks)};
+
 handle_cast({set_client_state, CS}, State) ->
     {noreply, seresye_engine:set_client_state(State, CS)}.
 

src/seresye_agenda.erl

@@ -314,4 +314,18 @@ execute_rule(EngineState, {{M,F}, Args, X1, X2}) ->
     L = length(Args) + 1,
     execute_rule(EngineState, {fun M:F/L, Args, X1, X2});
 execute_rule(EngineState, {Fun, Args, _, _}) when is_function(Fun) ->
-    apply(Fun, [EngineState | Args]).
+    case proplists:get_value(before_rule, EngineState#seresye.hooks) of
+        BF when is_function(BF) ->
+            BF(EngineState, Fun, Args);
+        _ ->
+            ignore
+    end,
+    Result = apply(Fun, [EngineState#seresye { fired_rule = {Fun, Args} } | Args]),
+    case proplists:get_value(after_rule, EngineState#seresye.hooks) of
+        AF when is_function(AF) ->
+            AF(Result, Fun, Args);
+        _ ->
+            ignore
+    end,
+    Result#seresye{ fired_rule = undefined }.
+

src/seresye_engine.erl

@@ -25,6 +25,7 @@
 %%====================================================================
 
 -export([new/0, new/1,
+         set_hooks/2, get_fired_rule/1,
          add_rules/2, add_rule/2, add_rule/3, assert/2, get_kb/1,
          get_rules_fired/1, get_client_state/1, set_client_state/2,
          query_kb/2, remove_rule/2, retract/2]).
@@ -41,6 +42,9 @@ new(ClientState) ->
                               pending_actions=[],
                               client_state=ClientState}).
 
+set_hooks(EngineState, Hooks) when is_list(Hooks) ->
+    EngineState#seresye{ hooks = Hooks }.
+
 set_client_state(EngineState, NewState) ->
     EngineState#seresye{client_state=NewState}.
 
@@ -130,6 +134,9 @@ add_rule(EngineState0, {Module, Fun}, ClauseID, Salience) ->
 remove_rule(EngineState0, Rule) ->
     execute_pending(remove_prod(seresye_agenda:delete_rule(EngineState0, Rule), Rule)).
 
+get_fired_rule(#seresye{ fired_rule = Rule }) ->
+    Rule.
+
 get_rules_fired(EngineState) ->
     seresye_agenda:get_rules_fired(EngineState).