class Ransack::Context

def traverse(str, base = @base)
  str ||= ''.freeze
  if (segments = str.split(Constants::UNDERSCORE)).size > 0
    remainder = []
    found_assoc = nil
    while !found_assoc && segments.size > 0 do
      # Strip the _of_Model_type text from the association name, but hold
      # onto it in klass, for use as the next base
      assoc, klass = unpolymorphize_association(
        segments.join(Constants::UNDERSCORE)
        )
      if found_assoc = get_association(assoc, base)
        base = traverse(
          remainder.join(Constants::UNDERSCORE), klass || found_assoc.klass
          )
      end
      remainder.unshift segments.pop
    end
    raise UntraversableAssociationError,
      "No association matches #{str}" unless found_assoc
  end
  klassify(base)
end