ParseTree 2.1.0 Released

ParseTree version 2.1.0 has been released!

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

As an example:

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


[:args, :arg1],
[:call, [:lvar, :arg1], :==, [:array, [:lit, 0]]],
[:return, [:lit, 1]],
[:return, [:lit, 0]]]]]

  • Uses RubyInline, so it just drops in.
  • Includes SexpProcessor and CompositeSexpProcessor.
    • Allows you to write very clean filters.
  • Includes UnifiedRuby, allowing you to automatically rewrite ruby
  • ParseTree#parse_tree_for_string lets you parse arbitrary strings of
  • Includes parse_tree_show, which lets you quickly snoop code.
    • echo “1+1” | parse_tree_show -f for quick snippet output.
  • Includes parse_tree_abc, which lets you get abc metrics on code.
    • abc metrics = numbers of assignments, branches, and calls.
    • whitespace independent metric for method complexity.
  • Includes parse_tree_deps, which shows you basic class level
  • Does not work on the core classes, as they are not ruby (yet).


  • 13 minor enhancements:

    • Added (partial) regexp flag support, currently numerical. ugh.
    • Added -a flag to parse_tree_show to turn on newline (all) nodes.
    • Added -r to parse_tree_show for raw arrays instead of sexps.
    • Added Unifier (SexpProcessor) class to unified_ruby.rb.
    • Added a ton of tests while working on ruby_parser.
    • Added ability to tell proc {} (nil arg slot) from proc {||} (0
      arg slot)
    • Added context tracking to rewriting phase… slightly broken.
    • Added evstr support. (I hate evan)
    • Added usage for parse_tree_show.
    • Changed verbose to be true all the time in parse_tree_for_string.
    • Removed process_level from SexpProcessor… just look at context
      size instead.
    • Revamped ParseTree. No more passing around newline. Pass around
      self instead.
    • I’m starting to dislike ruby’s AST. It is REALLY inconsistent.
  • 6 bug fix:

    • SexpProcessor#assert_type now a bit safer with bad values.
    • Uncovered a bug in ruby (AST changes when -v used), added handler
    • Fixed NODE_BLOCK and massively simplified in the process.
    • Fixed rewrite_defs to deal with non-block asts.
    • Fixed test/unit hack so it does not die under miniunit.
    • Found a bug in PT where parse_tree_for_string had some shadowed