prints instance variable accesses inside a class methods.

split.rb

#!/usr/bin/env ruby

require 'ruby_parser'

class Graph
  def initialize
    @watch_lvars = []
  end
  
  def visit(tree)
    type, *rest = tree
    
    self.send("accept_#{type}", *rest)
  end
  
  def accept_block(*contents)
    contents.each do |entry|
      visit(entry)
    end
  end
  def accept_class(name, _, definition)
    name = visit(name)
    
    visit(definition)
  end
  def accept_colon2(mod, name)
    visit(mod) + "::" + name.to_s
  end
  def accept_const(name)
    name.to_s
  end
  def accept_scope(content)
    visit(content)
  end
  def accept_defn(name, args, content)
    # p name
    @ivars = []
    visit(args)
    visit(content)
    
    @ivars.each do |ivar|
      puts "#{name.to_s.inspect} -> #{ivar.to_s.inspect};"
    end
    # p [name, @ivars]
  end
  def accept_iasgn(var, value)
    @ivars << var
    visit(value)
  end
  def accept_ivar(name)
    @ivars << name
  end
  
  def accept_lvar(name)
    if @watch_lvars.include?(name.to_s)
      p name
    end
  end
  def accept_call(receiver, name, args)
    visit(receiver)
    visit(args)
    
    if name =~ /attr_/
      @watch_lvars += @syms
    end
  end
  def accept_arglist(*list)
    @syms = []
    list.each { |el| visit(el) }
  end
  def accept_lit(literal)
    if literal.respond_to?(:to_sym)
      @syms << literal.to_s
    end
  end
  
  
  
  DONTPRINT = [
    :args, :array, :arglist, :until, :if, 
    :str, :splat, :lit, :lasgn, :dstr, :evstr, 
    :and, :not, :iter, :return, :op_asgn_or, :or]
  def method_missing(sym, *args, &block)
    if sym =~ /accept_(.*)/
      return nil if args.size==0
      # p [sym, args.size, *args.map { |e| e && e.respond_to?(:to_ary) && [e.first, '...'] || e }] \
      #   unless DONTPRINT.include?($1.to_sym)
      args.each do |arg|
        next unless arg.respond_to?(:to_ary)
        visit(arg)
      end
      nil
    else
      super
    end
  end
end

tree = RubyParser.new.parse(ARGF.read)
graph = Graph.new

puts "digraph test {"
graph.visit(tree)
puts "}"