Function difft::parse::guess_language::from_emacs_mode_header

fn from_emacs_mode_header(src: &str) -> Option<Language>

Try to guess the language based on an Emacs mode comment at the beginning of the file.

https://www.gnu.org/software/emacs/manual/html_node/emacs/Choosing-Modes.html https://www.gnu.org/software/emacs/manual/html_node/emacs/Specifying-File-Variables.html