ruby_parser (RP) is a ruby parser written in pure ruby (utilizing
https://github.com/seattlerb/ruby_parser

ruby_parser (RP) is a ruby parser written in pure ruby (utilizing
racc--which does by default use a C extension). RP's output is
the same as ParseTree's output: s-expressions using ruby's arrays and
base types.
As an example:
def conditional1 arg1
return 1 if arg1 == 0
return 0
end
becomes:
s(:defn, :conditional1, s(:args, :arg1),
s(:if,
s(:call, s(:lvar, :arg1), :==, s(:lit, 0)),
s(:return, s(:lit, 1)),
nil),
s(:return, s(:lit, 0)))
Tested against 801,039 files from the latest of all rubygems (as of 2013-05):
* 1.8 parser is at 99.9739% accuracy, 3.651 sigma
* 1.9 parser is at 99.9940% accuracy, 4.013 sigma
* 2.0 parser is at 99.9939% accuracy, 4.008 sigma.