Backtracking parser generator based on byacc

 btyacc is a hacked version of the original Berkeley "byacc". The main
 change to byacc is the addition of backtracking code, allowing you to
 try both alternatives in case of shift-reduce or reduce-reduce
 conflicts. As long as no backtracking takes place, speed is comparable
 to bison.
 .
 Additional features:
  - enhanced support for storing of text position information for tokens
  - closes the potential *yacc/bison memory leak during error recovery
  - preprocessor directives like %ifdef, %include
  - C++ friendly
 .
 Related packages: bison, byacc, antlr