RedParse is a ruby parser (and parser-compiler) written in pure ruby. Instead of YACC or ANTLR, it's parse tool is a home-brewed language. (The tool is (at least) LALR(1)-equivalent and the 'parse language' is pretty nice, even in it's current form.) My intent is to have a completely correct parser for ruby, in 100% ruby. And I think I've more or less succeeded. Aside from some fairly minor quibbles (see below), RedParse can parse all known ruby 1.8 and 1.9 constructions correctly. Input text may be encoded in ascii, binary, utf-8, iso-8859-1, and the euc-* family of encodings. Sjis is not yet supported.
RubyMacros is a lisp-like macro pre-processor for Ruby. More than just a purely textual substitution scheme, RubyMacros can manipulate and morph Ruby parse trees (in the form of RedParse Nodes) at parse time in just about any way you see fit. Macros are programmed in ruby itself. And since parse trees are represented in RedParse format, they're easier to use (programatically) and more object- oriented than other available ruby parsetree formats. (RedParse Node format is actually designed to be straightforward to use and to represent the structure of ruby source code very closely.)