feat: add config parameter to choose type of line ending (#15)

* feat: config switch for line ending type

* doc: document line_ending_type config parameter

Author: cdyb-kivra

README.md

@@ -39,6 +39,20 @@ To print each json object to a new line, set `new_line` to `true`:
 #{formatter => {jsonformat, #{ new_line => true }}}
 ```
 
+To specify which kind of line ending to use, set `new_line_type` to
+one of `nl`, `crlf`, `cr`, `unix`, `windows` or `macos9`. These
+correspond to:
+
+ * `nl` or `unix` means `\n`, ASCII character 0x0A
+ * `crlf` or `windows` means `\r\n`, ASCII characters 0x0D 0x0A
+ * `cr` or `macos9` means `\r`, ASCII character 0x0D
+
+The default line ending if none is specified is `nl`.
+
+```erlang
+#{formatter => {jsonformat, #{ new_line => true, new_line_type => crlf }}}
+```
+
 To control what is being included in the log object from the metadata, there
 are two ways. One can opt-out from fields. Default opts out is `[report_cb]`.
 

src/jsonformat.erl

@@ -28,6 +28,7 @@
 
 %%%_* Types ============================================================
 -type config() :: #{ new_line => boolean()
+                   , new_line_type => nl | crlf | cr | unix | windows | macos9
                    , key_mapping => #{atom() => atom()}
                    , format_funs => #{atom() => fun((_) -> _)}}.
 
@@ -90,7 +91,7 @@ merge_meta(Msg, Meta0, Config) ->
 encode(Data, Config) ->
   Json = jsx:encode(Data),
   case new_line(Config) of
-    true -> [Json, <<"\n">>];
+    true -> [Json, new_line_type(Config)];
     false -> Json
   end.
 
@@ -133,6 +134,14 @@ apply_key_mapping(Data, _) ->
 
 new_line(Config) -> maps:get(new_line, Config, ?NEW_LINE).
 
+new_line_type(#{new_line_type := nl})      -> <<"\n">>;
+new_line_type(#{new_line_type := unix})    -> <<"\n">>;
+new_line_type(#{new_line_type := crlf})    -> <<"\r\n">>;
+new_line_type(#{new_line_type := windows}) -> <<"\r\n">>;
+new_line_type(#{new_line_type := cr})      -> <<"\r">>;
+new_line_type(#{new_line_type := macos9})  -> <<"\r">>;
+new_line_type(_Default)                    -> <<"\n">>.
+
 meta_without(Meta, Config) ->
     maps:without(maps:get(meta_without, Config, [report_cb]), Meta).
 
@@ -224,6 +233,16 @@ meta_with_test() ->
         jsx:decode(format(Error, Config2))),
     ok.
 
+newline_test() ->
+    ConfigDefault = #{ new_line => true },
+    ?assertEqual( [<<"{\"level\":\"alert\",\"text\":\"derp\"}">>, <<"\n">>]
+                , format(#{level => alert, msg => {string, "derp"}, meta => #{}}, ConfigDefault) ),
+    ConfigCRLF = #{ new_line_type => crlf
+                  , new_line => true
+                  },
+    ?assertEqual( [<<"{\"level\":\"alert\",\"text\":\"derp\"}">>, <<"\r\n">>]
+                , format(#{level => alert, msg => {string, "derp"}, meta => #{}}, ConfigCRLF) ).
+
 -endif.
 
 %%%_* Emacs ============================================================