Based on https://relaxng.org/compact.html with the attempt to make the grammar more readable when avoid ambiguity.
This requires the Emacs 29 builtin treesit.el support.
Compile and install the libtree-sitter-rnc.$(LIBEXT)
to treesit search path, e.g. ~/.emacs.d/tree-sitter/.
$ cc -fPIC -c -Isrc src/parser.c
$ cc -fPIC -shared parser.o -o libtree-sitter-rnc.so
Copy emacs/rnc-ts-mode.el to Emacs load path.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU Lesser General Public License along with this program. If not, see https://www.gnu.org/licenses/.