Using the information extracted from an AST Tree, so we can do something meaningful with it.

using_ast_tree.rb

# Using the information extracted from an AST Tree, so we can do something meaningful with it.
# this needs https://github.com/whitequark/parser
require 'parser/current'

op = "(a > 3) or (a == b) or ((b > 3.months) and (c =~ 'd')) or jojo?"
parsed = Parser::CurrentRuby.parse(op)

def clean_begin(node)
  return node unless node.type == :begin
  raise "begin has more than one children!" if node.children.length > 1
  node.children.first
end

def process_node(node)
  raise "object is not a AST::Node" unless node.is_a?(Parser::AST::Node)

  node = clean_begin(node)
  children = node.children

  case node.type
  when :int
    children.first
  when :str
    "'%s'" % children.first
  when :send
    case children.length
    when 2
      if children.first.nil? then # method or local variable
        children.last
      else # method on (method or local variable)
        left = process_node(children.first)
        right = children.last
        "#{left}.#{right}"
      end
    when 3 # ==, <, >, <=, >=, =~, etc operations
      left, op, right = process_node(children[0]), children[1], process_node(children[2])
      "(#{left} #{op} #{right})"
    else
      raise "send has weird children. #{children.length}"
    end
  when :or, :and
    left, right = children.map{|child| clean_begin(child)}
    return "(#{process_node(left)} #{node.type} #{process_node(right)})"
  else
    raise "Found another type of node! #{node.type}"
  end
end

puts op             # => (a > 3) or (a == b) or ((b > 3.months) and (c =~ 'd')) or jojo?
puts debug(parsed)  # => ((((a > 3) or (a == b)) or ((b > 3.months) and (c =~ 'd'))) or jojo?)
# p parsed

this is the first version.
i'm keeping an "updated" version in https://gist.github.com/eljojo/53f145473c1d30244efa