ParseTree is a C extension (using RubyInline) that extracts the parse
tree for an entire class or a specific method and returns it as a
s-expression (aka sexp) using ruby's arrays, strings, symbols, and
integers.

As an example:

def conditional1(arg1)
if arg1 == 0 then
return 1
end
return 0
end

becomes:

[:defn,
:conditional1,
[:scope,
[:block,
[:args, :arg1],
[:if,
[:call, [:lvar, :arg1], :==, [:array, [:lit, 0]]],
[:return, [:lit, 1]],
nil],
[:return, [:lit, 0]]]]]

** FEATURES/PROBLEMS:

+ Uses RubyInline, so it just drops in.
+ Includes SexpProcessor and CompositeSexpProcessor.
+ Allows you to write very clean filters.
+ Includes show.rb, which lets you quickly snoop code.
+ Includes abc.rb, which lets you get abc metrics on code.
+ abc metrics = numbers of assignments, branches, and calls.
+ whitespace independent metric for method complexity.
+ Only works on methods in classes/modules, not arbitrary code.
+ Does not work on the core classes, as they are not ruby (yet).

Changes:

+ 2 bug fixes
+ bug:1459: Cleaned up and corrected superclass naming code.
+ bug:1458: Fixed while to support post-conditional while/until nodes.