augroup filetypedetect
    au BufNewFile,BufRead *.i       set filetype=swig
    au BufNewFile,BufRead *.swg     set filetype=swig
    au BufNewFile,BufRead *.g       set filetype=antlr3
    au BufNewFile,BufRead *.g4      set filetype=antlr4
    au BufNewFile,BufRead *.gv      set filetype=dot
    au BufNewFile,BufRead *.tikz    set filetype=tex
    au BufRead,BufNewFile *.tex     set filetype=tex
augroup END