This is a 'formatexpr' plugin.

License:
  public domain

Usage:
  :set runtimepath+=/path/to/autofmt/
  :set formatexpr=autofmt#compat#formatexpr()

Following method can be used:
  autofmt#compat#formatexpr():    Vim compatible
  autofmt#uax14#formatexpr():     Implementation of UAX #14
  autofmt#japanese#formatexpr():  Japanese

See doc/autofmt.txt for more information.