Vhdl_parser is a project mainly written in OCAML and C++, it's free.
VHDL port extractor in C++ using boost::spirit (2.x)
A minimal VHDL parser to extract VHDL port definitions.
requires boost 1.43.
Doesn't do a whole lot just yet... Still learning boost::spirit (version 2.x)
To compare with a different PEG parser I've added an Aurochs directory here that contains an implementation using the Aurochs PEG parser generator for OCaml. See the README in the aurochs directory for more info.