antlr-mode

The Emacs package ANTLR-Mode provides: syntax highlighting for ANTLR grammar
files, automatic indentation, menus containing rule/token definitions and
supported options and various other things like running ANTLR from within
Emacs.  It works for ANTLR v2, v3 and v4.

For details, check <https://antlr-mode.sourceforge.net/> or, if you prefer
the manual style, follow all commands mentioned in the documentation of
`antlr-mode'.  ANTLR is a LL(k)-based recognition tool which generates
lexers, parsers and tree transformers in Java, C++ or other languages and
can be found at <https://www.antlr.org/>.

Topics for 3.2 or later:

 * Special support for `indent-region': faster and better for Python ELP
   profiling in a class init action shows half the time is spent in
   `antlr-next-rule', the other half in `c-guess-basic-syntax'.
   Do not define a indent command, just a function to be put into
   indent-line/region-function.
 * In v4, highlight lexer commands after "->"
 * Test: in `antlr-imenu-create-index-function', can we use
     (or antlr-skip-line-regexp antlr-grammar-header-regexp)
 * Use native menu bindings instead easymenu (and use :help)
 * Support v4 rule element options
 * Define minor mode for `antlr-hide-actions' functionality.
 * [C-c C-u].  *Help* for current rule / all rules: used-By list (at least
   for single-file grammars)
 * [C-c C-j].  Jump to generated coding.

Eventually:

 * Support for one of the multi-mode imenu extensions mentioned in
   https://www.emacswiki.org/emacs-test/ImenuMode - if necessary
 * [C-c C-w].  Produce HTML document with syntax highlighted and
   hyper-links.  With htmfontify: invisible actions did not really work
   (only w/o spaces?, default invisible would be better anyway) - we need to
   set <a> tags afterwards ourselves...  Firefox does not understand
   encoding via XML declaration - use HTML meta tag.
 * Support for outline-minor-mode.

The following topics and suggestions are unlikely to be implemented:

 * Some constructs of languages (in actions) which are highly un-C-ish might
   bring Emacs (and ANTLR!) out of sync: e.g. regexp literals in Perl,
   character and percent literals in Ruby.
 * Faster syntax highlighting: sectionize the buffer into Antlr and action
   code and run special highlighting functions on these regions.  UNLIKELY
   due to: code size, this mode would depend on font-lock internals.
 * Set the syntax-table of the inner mode before calling the indentation
   engine of the inner mode (possible? - BUT: actions should still end at
   the same place!).  Probably not worth the effort.

Bug fixes, bug reports, improvements, and suggestions for the newest version
are strongly appreciated.