fenollp / erlang-formatter Goto Github PK

When formatting code we get some strange results from the erlang-formatter.
Indifferent of using the makefile-method or via rebar3 fmt the following code example:

-module(parser).

parse(Token) ->
    case Token of
        <<"$", Rest/binary>> -> {done, Rest};
        <<"1", Rest/binary>> -> {done, Rest};
        <<"2", Rest/binary>> -> {done, Rest}
    end.

results in a bit skewed output:

-module(parser).

parse(Token) ->
    case Token of
        <<"$", Rest/binary>> -> {done, Rest};
        <<"1", Rest/binary>> -> {done, Rest};
          <<"2", Rest/binary>> -> {done, Rest}
        end.

By experimenting a bit it seems that "$" is to be blamed for the skewed lines further down (see line with <<"2" and end).

When opening the same file in emacs manually the fomatting can be restored by either the menu Erlang->Indent->Indent buffer or by M-x erlang-indent-current-buffer. Using tab will also correct the lines in emacs.
So there seem to be a difference using erlang-formatter and doing it manually.

Another finding is that when trying to break down what fmt.el was doing and reproducing it via an own test function in my emacs,
I found that the following function resulted in the same skewed output as from erlang-formatter.

(defun my-erlang-format ()
  (interactive)
  (erlang-mode)
  (erlang-indent-current-buffer))

while removing (erlang-mode) in the above function resulted in an ok output!

Any ideas what is happening?

Tested using GNU Emacs 28.1 and Emacs 26.3 emacs-nox 1:26.3+1, with and without newer erlang.el

Hi,

Thanks for this library, I was wondering if it is possible to add command line arguments to enable running formatting on a single file like below:

rebar3 fmt -f test.erl

It would be easier to integrate your plugin to other tools this way that might support format on save like VS Code. For example currently the erlang formatter plugin for VS Code supports 3 formatters erlfmt, rebar3_format, steamroller, I think emacs formatting would be a good addition to that list.

I have checked the emacs binary arguments and there is a --file flag along with --directory flag you are currently using. I. can submit a pull request with the proposed changes if you like.

Example: https://github.com/erlang/rebar3/blob/master/.editorconfig

Should read this file and if exists

• remove trailing whitespaces if told so
• use the specified amount of tabs/spaces