# File lib/webby/link_validator.rb, line 83
  def validate_uri( uri, dir, doc )
    # do not retry external uris that have already been validated
    return if @valid_uris.include? uri.to_s

    return validate_relative_uri(uri, dir, doc) if uri.relative?
    return validate_external_uri(uri, dir, doc) if uri.respond_to? :open

    # otherwise, post a warning that the URI could not be validated
    @log.warn "could not validate URI '#{uri.to_s}'"
  end