in case you want to follow along with v4 dev: http://github.com/antlr/antlr4 Just finished phase 1 semantic checks: http://www.antlr.org/wiki/display/~admin/Enforcing+semantics summary: tree pattern matching kicks ass. here are general plans http://www.antlr.org/wiki/display/~admin/ANTLR+v4+plans Ter