Use spaces in snippets in the guide

doc/src/guide/constraints.asciidoc

@@ -74,11 +74,11 @@ to an integer:
 [source,erlang]
 ----
 fun (Value0) when is_binary(Value0) ->
-	try binary_to_integer(Value0) of
-		Value -> {true, Value}
-	catch _:_ ->
-		false
-	end.
+    try binary_to_integer(Value0) of
+        Value -> {true, Value}
+    catch _:_ ->
+        false
+    end.
 ----
 
 Constraint functions should only crash because the programmer

doc/src/guide/cookies.asciidoc

@@ -50,7 +50,7 @@ They can also be set for a duration in seconds:
 ----
 SessionID = generate_session_id(),
 Req = cowboy_req:set_resp_cookie(<<"sessionid">>, SessionID,
-	#{max_age => 3600}, Req0).
+    #{max_age => 3600}, Req0).
 ----
 
 To delete cookies, set `max_age` to 0:
@@ -59,7 +59,7 @@ To delete cookies, set `max_age` to 0:
 ----
 SessionID = generate_session_id(),
 Req = cowboy_req:set_resp_cookie(<<"sessionid">>, SessionID,
-	#{max_age => 0}, Req0).
+    #{max_age => 0}, Req0).
 ----
 
 To restrict cookies to a specific domain and path, the options
@@ -68,7 +68,7 @@ of the same name can be used:
 [source,erlang]
 ----
 Req = cowboy_req:set_resp_cookie(<<"inaccount">>, <<"1">>,
-	#{domain => "my.example.org", path => "/account"}, Req0).
+    #{domain => "my.example.org", path => "/account"}, Req0).
 ----
 
 Cookies will be sent with requests to this domain and all
@@ -82,7 +82,7 @@ available over HTTPS):
 ----
 SessionID = generate_session_id(),
 Req = cowboy_req:set_resp_cookie(<<"sessionid">>, SessionID,
-	#{secure => true}, Req0).
+    #{secure => true}, Req0).
 ----
 
 To prevent client-side scripts from accessing a cookie:
@@ -91,7 +91,7 @@ To prevent client-side scripts from accessing a cookie:
 ----
 SessionID = generate_session_id(),
 Req = cowboy_req:set_resp_cookie(<<"sessionid">>, SessionID,
-	#{http_only => true}, Req0).
+    #{http_only => true}, Req0).
 ----
 
 Cookies may also be set client-side, for example using

doc/src/guide/getting_started.asciidoc

@@ -91,14 +91,14 @@ code to the `start/2` function to make it look like this:
 [source,erlang]
 ----
 start(_Type, _Args) ->
-	Dispatch = cowboy_router:compile([
-		{'_', [{"/", hello_handler, []}]}
-	]),
-	{ok, _} = cowboy:start_clear(my_http_listener, 100,
-		[{port, 8080}],
-		#{env => #{dispatch => Dispatch}}
-	),
-	hello_erlang_sup:start_link().
+    Dispatch = cowboy_router:compile([
+        {'_', [{"/", hello_handler, []}]}
+    ]),
+    {ok, _} = cowboy:start_clear(my_http_listener, 100,
+        [{port, 8080}],
+        #{env => #{dispatch => Dispatch}}
+    ),
+    hello_erlang_sup:start_link().
 ----
 
 Routes are explained in details in the xref:routing[Routing]
@@ -127,11 +127,11 @@ the `init/2` function like this to send a reply.
 [source,erlang]
 ----
 init(Req0, State) ->
-	Req = cowboy_req:reply(200,
-		#{<<"content-type">> => <<"text/plain">>},
-		<<"Hello Erlang!">>,
-		Req0),
-	{ok, Req, State}.
+    Req = cowboy_req:reply(200,
+        #{<<"content-type">> => <<"text/plain">>},
+        <<"Hello Erlang!">>,
+        Req0),
+    {ok, Req, State}.
 ----
 
 What the above code does is send a `200 OK` reply, with the

doc/src/guide/handlers.asciidoc

@@ -65,7 +65,7 @@ following snippet switches to a Websocket handler:
 [source,erlang]
 ----
 init(Req, State) ->
-	{cowboy_websocket, Req, State}.
+    {cowboy_websocket, Req, State}.
 ----
 
 You can also switch to your own custom handler type:
@@ -73,7 +73,7 @@ You can also switch to your own custom handler type:
 [source,erlang]
 ----
 init(Req, State) ->
-	{my_handler_type, Req, State}.
+    {my_handler_type, Req, State}.
 ----
 
 How to implement a custom handler type is described in the

doc/src/guide/listeners.asciidoc

@@ -28,14 +28,14 @@ on port 8080:
 [source,erlang]
 ----
 start(_Type, _Args) ->
-	Dispatch = cowboy_router:compile([
-		{'_', [{"/", hello_handler, []}]}
-	]),
-	{ok, _} = cowboy:start_clear(my_http_listener, 100,
-		[{port, 8080}],
-		#{env => #{dispatch => Dispatch}}
-	),
-	hello_erlang_sup:start_link().
+    Dispatch = cowboy_router:compile([
+        {'_', [{"/", hello_handler, []}]}
+    ]),
+    {ok, _} = cowboy:start_clear(my_http_listener, 100,
+        [{port, 8080}],
+        #{env => #{dispatch => Dispatch}}
+    ),
+    hello_erlang_sup:start_link().
 ----
 
 The xref:getting_started[Getting Started] chapter uses a
@@ -72,18 +72,18 @@ used directly to setup a custom listener.
 [source,erlang]
 ----
 start(_Type, _Args) ->
-	Dispatch = cowboy_router:compile([
-		{'_', [{"/", hello_handler, []}]}
-	]),
-	{ok, _} = cowboy:start_tls(my_http_listener, 100,
-		[
-			{port, 8443},
-			{certfile, "/path/to/certfile"},
-			{keyfile, "/path/to/keyfile"}
-		],
-		#{env => #{dispatch => Dispatch}}
-	),
-	hello_erlang_sup:start_link().
+    Dispatch = cowboy_router:compile([
+        {'_', [{"/", hello_handler, []}]}
+    ]),
+    {ok, _} = cowboy:start_tls(my_http_listener, 100,
+        [
+            {port, 8443},
+            {certfile, "/path/to/certfile"},
+            {keyfile, "/path/to/keyfile"}
+        ],
+        #{env => #{dispatch => Dispatch}}
+    ),
+    hello_erlang_sup:start_link().
 ----
 
 Clients connecting to Cowboy on the secure listener are

doc/src/guide/req.asciidoc

@@ -32,15 +32,15 @@ otherwise.
 [source,erlang]
 ----
 init(Req0=#{method := <<"GET">>}, State) ->
-	Req = cowboy_req:reply(200, #{
-		<<"content-type">> => <<"text/plain">>
-	}, <<"Hello world!">>, Req0),
-	{ok, Req, State};
+    Req = cowboy_req:reply(200, #{
+        <<"content-type">> => <<"text/plain">>
+    }, <<"Hello world!">>, Req0),
+    {ok, Req, State};
 init(Req0, State) ->
-	Req = cowboy_req:reply(405, #{
-		<<"allow">> => <<"GET">>
-	}, Req0),
-	{ok, Req, State}.
+    Req = cowboy_req:reply(405, #{
+        <<"allow">> => <<"GET">>
+    }, Req0),
+    {ok, Req, State}.
 ----
 
 Any other field is internal and should not be accessed.
@@ -135,11 +135,11 @@ of the effective request URI can all be retrieved directly:
 [source,erlang]
 ----
 #{
-	scheme := Scheme,
-	host := Host,
-	port := Port,
-	path := Path,
-	qs := Qs
+    scheme := Scheme,
+    host := Host,
+    port := Port,
+    path := Path,
+    qs := Qs
 } = Req.
 ----
 
@@ -348,7 +348,7 @@ directly:
 [source,erlang]
 ----
 ParsedVal = cowboy_req:parse_header(<<"content-type">>, Req,
-	{<<"text">>, <<"plain">>, []}).
+    {<<"text">>, <<"plain">>, []}).
 ----
 
 === Peer

doc/src/guide/req_body.asciidoc

@@ -71,7 +71,7 @@ only up to 1MB for up to 5 seconds:
 [source,erlang]
 ----
 {ok, Data, Req} = cowboy_req:read_body(Req0,
-	#{length => 1000000, period => 5000}).
+    #{length => 1000000, period => 5000}).
 ----
 
 You may also disable the length limit:
@@ -126,5 +126,5 @@ read for up to 64KB and up to 5 seconds. They can be modified:
 [source,erlang]
 ----
 {ok, KeyValues, Req} = cowboy_req:read_urlencoded_body(Req0,
-	#{length => 4096, period => 3000}).
+    #{length => 4096, period => 3000}).
 ----

doc/src/guide/resp.asciidoc

@@ -71,7 +71,7 @@ Body = <<"Hats off!">>,
 Req = cowboy_req:reply(200, #{
     <<"content-type">> => <<"text/html">>
 }, ["<html><head><title>", Title, "</title></head>",
-	"<body><p>", Body, "</p></body></html>"], Req0).
+    "<body><p>", Body, "</p></body></html>"], Req0).
 ----
 
 This method of building responses is more efficient than
@@ -247,7 +247,7 @@ To send a file while replying:
 [source,erlang]
 ----
 Req = cowboy_req:reply(200, #{
-	<<"content-type">> => "image/png"
+    <<"content-type">> => "image/png"
 }, {sendfile, 0, 12345, "path/to/logo.png"}, Req0).
 ----
 
@@ -289,13 +289,13 @@ in the response:
 [source,erlang]
 ----
 cowboy_req:push("/static/style.css", #{
-	<<"accept">> => <<"text/css">>
+    <<"accept">> => <<"text/css">>
 }, Req0),
 Req = cowboy_req:reply(200, #{
-	<<"content-type">> => <<"text/html">>
+    <<"content-type">> => <<"text/html">>
 }, ["<html><head><title>My web page</title>",
-	"<link rel='stylesheet' type='text/css' href='/static/style.css'>",
-	"<body><p>Welcome to Erlang!</p></body></html>"], Req0).
+    "<link rel='stylesheet' type='text/css' href='/static/style.css'>",
+    "<body><p>Welcome to Erlang!</p></body></html>"], Req0).
 ----
 
 To override the method, scheme, host, port or query string,
@@ -305,7 +305,7 @@ uses a different host name:
 [source,erlang]
 ----
 cowboy_req:push("/static/style.css", #{
-	<<"accept">> => <<"text/css">>
+    <<"accept">> => <<"text/css">>
 }, #{host => <<"cdn.example.org">>}, Req),
 ----
 

doc/src/guide/sub_protocols.asciidoc

@@ -17,7 +17,7 @@ is handled by the sub protocol.
 [source,erlang]
 ----
 init(Req, State) ->
-	{cowboy_websocket, Req, State}.
+    {cowboy_websocket, Req, State}.
 ----
 
 The return value may also have a `Timeout` value and/or the
@@ -34,7 +34,7 @@ hibernation:
 [source,erlang]
 ----
 init(Req, State) ->
-	{my_protocol, Req, State, 5000, hibernate}.
+    {my_protocol, Req, State, 5000, hibernate}.
 ----
 
 If a sub protocol does not make use of these options, it should
@@ -59,7 +59,7 @@ timeout and hibernate values.
 [source,erlang]
 ----
 upgrade(Req, Env, Handler, HandlerOpts, Timeout, Hibernate) ->
-	%% Sub protocol code here.
+    %% Sub protocol code here.
 ----
 
 This callback is expected to behave like a middleware and to

doc/src/guide/ws_handlers.asciidoc

@@ -21,7 +21,7 @@ To establish a Websocket connection, you must switch to the
 [source,erlang]
 ----
 init(Req, State) ->
-	{cowboy_websocket, Req, State}.
+    {cowboy_websocket, Req, State}.
 ----
 
 Cowboy will perform the Websocket handshake immediately. Note
@@ -58,19 +58,19 @@ be:
 [source,erlang]
 ----
 init(Req, State) ->
-	case cowboy_req:parse_header(<<"sec-websocket-protocol">>, Req) of
-		undefined ->
-			{ok, Req, State};
-		Subprotocols ->
-			case lists:keymember(<<"mqtt">>, 1, Subprotocols) of
-				true ->
-					Req2 = cowboy_req:set_resp_header(<<"sec-websocket-protocol">>,
-						<<"mqtt">>, Req),
-					{ok, Req2, State};
-				false ->
-					{stop, Req, State}
-			end
-	end.
+    case cowboy_req:parse_header(<<"sec-websocket-protocol">>, Req) of
+        undefined ->
+            {ok, Req, State};
+        Subprotocols ->
+            case lists:keymember(<<"mqtt">>, 1, Subprotocols) of
+                true ->
+                    Req2 = cowboy_req:set_resp_header(<<"sec-websocket-protocol">>,
+                        <<"mqtt">>, Req),
+                    {ok, Req2, State};
+                false ->
+                    {stop, Req, State}
+            end
+    end.
 ----
 
 === Post-upgrade initialization
@@ -93,8 +93,8 @@ The optional `websocket_init/1` can be used instead:
 [source,erlang]
 ----
 websocket_init(State) ->
-	erlang:start_timer(1000, self(), <<"Hello!">>),
-	{ok, State}.
+    erlang:start_timer(1000, self(), <<"Hello!">>),
+    {ok, State}.
 ----
 
 All Websocket callbacks share the same return values. This
@@ -104,7 +104,7 @@ the upgrade:
 [source,erlang]
 ----
 websocket_init(State) ->
-	{reply, {text, <<"Hello!">>}, State}.
+    {reply, {text, <<"Hello!">>}, State}.
 ----
 
 === Receiving frames
@@ -121,9 +121,9 @@ ignores all others:
 [source,erlang]
 ----
 websocket_handle(Frame = {text, _}, State) ->
-	{reply, Frame, State};
+    {reply, Frame, State};
 websocket_handle(_Frame, State) ->
-	{ok, State}.
+    {ok, State}.
 ----
 
 Note that ping and pong frames require no action from the
@@ -144,9 +144,9 @@ and ignores all others:
 [source,erlang]
 ----
 websocket_info({log, Text}, State) ->
-	{reply, {text, Text}, State};
+    {reply, {text, Text}, State};
 websocket_info(_Info, State) ->
-	{ok, State}.
+    {ok, State}.
 ----
 
 === Sending frames
@@ -161,7 +161,7 @@ To send nothing, just return an ok tuple:
 [source,erlang]
 ----
 websocket_info(_Info, State) ->
-	{ok, State}.
+    {ok, State}.
 ----
 
 To send one frame, return a reply tuple with the frame to send:
@@ -169,7 +169,7 @@ To send one frame, return a reply tuple with the frame to send:
 [source,erlang]
 ----
 websocket_info(_Info, State) ->
-	{reply, {text, <<"Hello!">>}, State}.
+    {reply, {text, <<"Hello!">>}, State}.
 ----
 
 You can send frames of any type: text, binary, ping, pong
@@ -181,11 +181,11 @@ list of frames to send:
 [source,erlang]
 ----
 websocket_info(_Info, State) ->
-	{reply, [
-		{text, "Hello"},
-		{text, <<"world!">>},
-		{binary, <<0:8000>>}
-	], State}.
+    {reply, [
+        {text, "Hello"},
+        {text, <<"world!">>},
+        {binary, <<0:8000>>}
+    ], State}.
 ----
 
 They are sent in the given order.
@@ -215,7 +215,7 @@ close connections idle for more than 60 seconds:
 [source,erlang]
 ----
 init(Req, State) ->
-	{cowboy_websocket, Req, State, 60000}.
+    {cowboy_websocket, Req, State, 60000}.
 ----
 
 This value cannot be changed once it is set. It defaults to
@@ -233,13 +233,13 @@ Simply add an `hibernate` field to the ok or reply tuples:
 [source,erlang]
 ----
 websocket_init(State) ->
-	{ok, State, hibernate}.
+    {ok, State, hibernate}.
 
 websocket_handle(_Frame, State) ->
-	{ok, State, hibernate}.
+    {ok, State, hibernate}.
 
 websocket_info(_Info, State) ->
-	{reply, {text, <<"Hello!">>}, State, hibernate}.
+    {reply, {text, <<"Hello!">>}, State, hibernate}.
 ----
 
 It is highly recommended to write your handlers with
@@ -258,7 +258,7 @@ To tell Cowboy to close the connection, use a stop tuple:
 [source,erlang]
 ----
 websocket_info(_Info, State) ->
-	{stop, State}.
+    {stop, State}.
 ----
 
 Sending a `close` frame will immediately initiate the closing