From 581b6954d344eaca2bfcdab663019796e852c778 Mon Sep 17 00:00:00 2001
From: Jan Uhlig <juhlig@hnc-agency.org>
Date: Wed, 1 Sep 2021 14:01:47 +0200
Subject: Update docs and modernize examples

* Use the map form for transport options everywhere
* Remove mentions of the list form for transport options
* Use a state enter call instead of gen_statem:enter_loop/4 and
  proc_lib:start_link/3 in the tcp_reverse example
* Take care of different EOLs in the tcp_reverse example
* Mention state enter calls, the next_event action, and {continue, ...}
  in the docs for how to use gen_statem and gen_server
---
 examples/tcp_reverse/src/reverse_protocol.erl | 38 ++++++++++++++++++---------
 1 file changed, 25 insertions(+), 13 deletions(-)

(limited to 'examples')

diff --git a/examples/tcp_reverse/src/reverse_protocol.erl b/examples/tcp_reverse/src/reverse_protocol.erl
index d274b3a..73d7aff 100644
--- a/examples/tcp_reverse/src/reverse_protocol.erl
+++ b/examples/tcp_reverse/src/reverse_protocol.erl
@@ -16,28 +16,29 @@
 
 -define(TIMEOUT, 60000).
 
--record(state, {socket, transport}).
+-record(state, {ref, transport, socket}).
 
 %% API.
 
 start_link(Ref, Transport, Opts) ->
-	{ok, proc_lib:spawn_link(?MODULE, init, [{Ref, Transport, Opts}])}.
+	gen_statem:start_link(?MODULE, {Ref, Transport, Opts}, []).
 
 %% gen_statem.
 
 callback_mode() ->
-	state_functions.
+	[state_functions, state_enter].
 
 init({Ref, Transport, _Opts = []}) ->
+	{ok, connected, #state{ref=Ref, transport=Transport}, ?TIMEOUT}.
+
+connected(enter, connected, StateData=#state{
+		ref=Ref, transport=Transport}) ->
 	{ok, Socket} = ranch:handshake(Ref),
 	ok = Transport:setopts(Socket, [{active, once}, {packet, line}]),
-	gen_statem:enter_loop(?MODULE, [], connected,
-		#state{socket=Socket, transport=Transport},
-		[?TIMEOUT]).
-
+	{keep_state, StateData#state{socket=Socket}};
 connected(info, {tcp, Socket, Data}, _StateData=#state{
 		socket=Socket, transport=Transport})
-		when byte_size(Data) > 1 ->
+		when byte_size(Data) >= 1 ->
 	Transport:setopts(Socket, [{active, once}]),
 	Transport:send(Socket, reverse_binary(Data)),
 	{keep_state_and_data, ?TIMEOUT};
@@ -57,7 +58,7 @@ connected(_EventType, _Msg, _StateData) ->
 
 terminate(Reason, StateName, StateData=#state{
 		socket=Socket, transport=Transport})
-		when Socket=/=undefined andalso Transport=/=undefined ->
+		when Socket=/=undefined, Transport=/=undefined ->
 	catch Transport:close(Socket),
 	terminate(Reason, StateName,
 		StateData#state{socket=undefined, transport=undefined});
@@ -69,7 +70,18 @@ code_change(_OldVsn, StateName, StateData, _Extra) ->
 
 %% Internal.
 
-reverse_binary(B) when is_binary(B) ->
-	[list_to_binary(lists:reverse(binary_to_list(
-		binary:part(B, {0, byte_size(B)-2})
-	))), "\r\n"].
+reverse_binary(B0) when is_binary(B0) ->
+	Size = bit_size(B0),
+	<<B1:Size/integer-little>> = B0,
+	case <<B1:Size/integer-big>> of
+		%% Take care of different possible line terminators.
+		<<$\n, $\r, B2/binary>> ->
+			%% CR/LF (Windows)
+			<<B2/binary, $\r, $\n>>;
+		<<$\n, B2/binary>> ->
+			%% LF (Linux, Mac OS X and later)
+			<<B2/binary, $\n>>;
+		<<$\r, B2/binary>> ->
+			%% CR (Mac Classic, ie prior to Mac OS X)
+			<<B2/binary, $\r>>
+	end.
-- 
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