error_logger_tty_h: Refactor and modernize code

Refactor, simplify, and modernize the code to facilitate future
improvements in the following commits.

1 files changed, 97 insertions, 83 deletions

diff --git a/lib/stdlib/src/error_logger_tty_h.erl b/lib/stdlib/src/error_logger_tty_h.erl
index 5307dac6d0..5dd8b0caa0 100644
--- a/lib/stdlib/src/error_logger_tty_h.erl
+++ b/lib/stdlib/src/error_logger_tty_h.erl
@@ -35,33 +35,40 @@
 
 -export([write_event/2]).
 
+-record(st,
+	{user,
+	 prev_handler,
+	 io_mod=io}).
+
 %% This one is used when we takeover from the simple error_logger.
 init({[], {error_logger, Buf}}) ->
     User = set_group_leader(),
-    write_events(Buf,io),
-    {ok, {User, error_logger}};
+    State = #st{user=User,prev_handler=error_logger},
+    write_events(State, Buf),
+    {ok, State};
 %% This one is used if someone took over from us, and now wants to
 %% go back.
 init({[], {error_logger_tty_h, PrevHandler}}) ->
     User = set_group_leader(),
-    {ok, {User, PrevHandler}};
+    {ok, #st{user=User,prev_handler=PrevHandler}};
 %% This one is used when we are started directly.
 init([]) ->
     User = set_group_leader(),
-    {ok, {User, []}}.
+    {ok, #st{user=User,prev_handler=[]}}.
     
 handle_event({_Type, GL, _Msg}, State) when node(GL) =/= node() ->
     {ok, State};
 handle_event(Event, State) ->
-    ok = write_event(tag_event(Event),io),
+    ok = do_write_event(State, tag_event(Event)),
     {ok, State}.
 
-handle_info({'EXIT', User, _Reason}, {User, PrevHandler}) ->
+handle_info({'EXIT', User, _Reason},
+	    #st{user=User,prev_handler=PrevHandler}=State) ->
     case PrevHandler of
 	[] ->
 	    remove_handler;
 	_ -> 
-	    {swap_handler, install_prev, {User, PrevHandler}, 
+	    {swap_handler, install_prev, State,
 	     PrevHandler, go_back}
     end;
 handle_info(_, State) ->
@@ -69,80 +76,95 @@ handle_info(_, State) ->
 
 handle_call(_Query, State) -> {ok, {error, bad_query}, State}.
 
-% unfortunately, we can't unlink from User - links are not counted!
-%    if pid(User) -> unlink(User); true -> ok end,
 terminate(install_prev, _State) ->
     [];
-terminate(_Reason, {_User, PrevHandler}) ->
+terminate(_Reason, #st{prev_handler=PrevHandler}) ->
     {error_logger_tty_h, PrevHandler}.
 
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
+%% Exported (but unoffical) API.
+write_event(Event, IoMod) ->
+    do_write_event(#st{io_mod=IoMod}, Event).
+
+
 %%% ------------------------------------------------------
 %%% Misc. functions.
 %%% ------------------------------------------------------
 
 set_group_leader() ->
     case whereis(user) of
-	User when is_pid(User) -> link(User), group_leader(User,self()), User;
-	_                      -> false
+	User when is_pid(User) ->
+	    link(User),
+	    group_leader(User,self()),
+	    User;
+	_ ->
+	    false
     end.
 
 tag_event(Event) ->    
     {erlang:universaltime(), Event}.
 
-%% IOMOd is always 'io'
-write_events(Events,IOMod) -> write_events1(lists:reverse(Events),IOMod).
-
-write_events1([Event|Es],IOMod) ->
-    ok = write_event(Event,IOMod),
-    write_events1(Es,IOMod);
-write_events1([],_IOMod) ->
+write_events(State, [Ev|Es]) ->
+    %% Write the events in reverse order.
+    _ = write_events(State, Es),
+    _ = do_write_event(State, Ev),
+    ok;
+write_events(_State, []) ->
     ok.
 
-write_event({Time, {error, _GL, {Pid, Format, Args}}},IOMod) ->
-    T = write_time(maybe_utc(Time)),
-    case catch io_lib:format(add_node(Format,Pid), Args) of
-	S when is_list(S) ->
-	    format(IOMod, T ++ S);
-	_ ->
-	    F = add_node("ERROR: ~p - ~p~n", Pid),
-	    format(IOMod, T ++ F, [Format,Args])
+do_write_event(State, {Time0, Event}) ->
+    case parse_event(Event) of
+	ignore ->
+	    ok;
+	{Head,Pid,FormatList} ->
+	    Time = maybe_utc(Time0),
+	    Header = write_time(Time, Head),
+	    Body = format_body(State, FormatList),
+	    AtNode = if
+			 node(Pid) =/= node() ->
+			     ["** at node ",atom_to_list(node(Pid))," **\n"];
+			 true ->
+			     []
+		     end,
+	    Str = [Header,Body,AtNode],
+	    case State#st.io_mod of
+		io_lib ->
+		    Str;
+		io ->
+		    io:put_chars(user, Str)
+	    end
     end;
-write_event({Time, {error_report, _GL, {Pid, std_error, Rep}}},IOMod) ->
-    T = write_time(maybe_utc(Time)),
-    S = format_report(Rep),
-    format(IOMod, T ++ S ++ add_node("", Pid));
-write_event({Time, {info_report, _GL, {Pid, std_info, Rep}}},IOMod) ->
-    T = write_time(maybe_utc(Time), "INFO REPORT"),
-    S = format_report(Rep),
-    format(IOMod, T ++ S ++ add_node("", Pid));
-write_event({Time, {info_msg, _GL, {Pid, Format, Args}}},IOMod) ->
-    T = write_time(maybe_utc(Time), "INFO REPORT"),
-    case catch io_lib:format(add_node(Format,Pid), Args) of
-	S when is_list(S) ->
-	    format(IOMod, T ++ S);
-	_ ->
-	    F = add_node("ERROR: ~p - ~p~n", Pid),
-	    format(IOMod, T ++ F, [Format,Args])
-    end;
-write_event({Time, {warning_report, _GL, {Pid, std_warning, Rep}}},IOMod) ->
-    T = write_time(maybe_utc(Time), "WARNING REPORT"),
-    S = format_report(Rep),
-    format(IOMod, T ++ S ++ add_node("", Pid));
-write_event({Time, {warning_msg, _GL, {Pid, Format, Args}}},IOMod) ->
-    T = write_time(maybe_utc(Time), "WARNING REPORT"),
-    case catch io_lib:format(add_node(Format,Pid), Args) of
-	S when is_list(S) ->
-	    format(IOMod, T ++ S);
-	_ ->
-	    F = add_node("ERROR: ~p - ~p~n", Pid),
-	    format(IOMod, T ++ F, [Format,Args])
-    end;
-write_event({_Time, _Error},_IOMod) ->
+do_write_event(_, _) ->
     ok.
 
+format_body(State, [{Format,Args}|T]) ->
+    S = try io_lib:format(Format, Args) of
+	    S0 ->
+		S0
+	catch
+	    _:_ ->
+		io_lib:format("ERROR: ~p - ~p\n", [Format,Args])
+	end,
+    [S|format_body(State, T)];
+format_body(_State, []) ->
+    [].
+
+parse_event({error, _GL, {Pid, Format, Args}}) ->
+    {"ERROR REPORT",Pid,[{Format,Args}]};
+parse_event({info_msg, _GL, {Pid, Format, Args}}) ->
+    {"INFO REPORT",Pid,[{Format, Args}]};
+parse_event({warning_msg, _GL, {Pid, Format, Args}}) ->
+    {"WARNING REPORT",Pid,[{Format,Args}]};
+parse_event({error_report, _GL, {Pid, std_error, Args}}) ->
+    {"ERROR REPORT",Pid,format_term(Args)};
+parse_event({info_report, _GL, {Pid, std_info, Args}}) ->
+    {"INFO REPORT",Pid,format_term(Args)};
+parse_event({warning_report, _GL, {Pid, std_warning, Args}}) ->
+    {"WARNING REPORT",Pid,format_term(Args)};
+parse_event(_) -> ignore.
+
 maybe_utc(Time) ->
     UTC = case application:get_env(sasl, utc_log) of
               {ok, Val} -> Val;
@@ -158,33 +180,26 @@ maybe_utc(Time) ->
 maybe_utc(Time, true) -> {utc, Time};
 maybe_utc(Time, _) -> {local, calendar:universal_time_to_local_time(Time)}.
 
-format(IOMod, String)       -> format(IOMod, String, []).
-format(io_lib, String, Args) -> io_lib:format(String, Args);
-format(io, String, Args) -> io:format(user, String, Args).
-
-format_report(Rep) when is_list(Rep) ->
-    case string_p(Rep) of
+format_term(Term) when is_list(Term) ->
+    case string_p(Term) of
 	true ->
-	    io_lib:format("~s~n",[Rep]);
-	_ ->
-	    format_rep(Rep)
+	    [{"~s\n",[Term]}];
+	false ->
+	    format_term_list(Term)
     end;
-format_report(Rep) ->
-    io_lib:format("~p~n",[Rep]).
-
-format_rep([{Tag,Data}|Rep]) ->
-    io_lib:format("    ~p: ~p~n",[Tag,Data]) ++ format_rep(Rep);
-format_rep([Other|Rep]) ->
-    io_lib:format("    ~p~n",[Other]) ++ format_rep(Rep);
-format_rep(_) ->
-    [].
+format_term(Term) ->
+    [{"~p\n",[Term]}].
 
-add_node(X, Pid) when is_atom(X) ->
-    add_node(atom_to_list(X), Pid);
-add_node(X, Pid) when node(Pid) =/= node() ->
-    lists:concat([X,"** at node ",node(Pid)," **~n"]);
-add_node(X, _) ->
-    X.
+format_term_list([{Tag,Data}|T]) ->
+    [{"    ~p: ~p\n",[Tag,Data]}|format_term_list(T)];
+format_term_list([Data|T]) ->
+    [{"    ~p\n",[Data]}|format_term_list(T)];
+format_term_list([]) ->
+    [];
+format_term_list(_) ->
+    %% Continue to allow non-proper lists for now.
+    %% FIXME: Remove this clause in OTP 19.
+    [].
 
 string_p([]) ->
     false;
@@ -208,7 +223,6 @@ string_p1([H|T]) when is_list(H) ->
 string_p1([]) -> true;
 string_p1(_) ->  false.
 
-write_time(Time) -> write_time(Time, "ERROR REPORT").
 write_time({utc,{{Y,Mo,D},{H,Mi,S}}},Type) ->
     io_lib:format("~n=~s==== ~p-~s-~p::~s:~s:~s UTC ===~n",
 		  [Type,D,month(Mo),Y,t(H),t(Mi),t(S)]);