shoulder-specs-doc/script/exstension/nofollow_processor.rb

require 'asciidoctor/extensions'

class NofollowProcessor < Asciidoctor::Extensions::InlineMacroProcessor
  use_dsl

  named :nofollow
  name_positional_attributes 'target', 'text'

  def process(parent, target, attrs)
    text = attrs['text'] || target
    (create_anchor parent, text, type: :link, target: target).tap |node|
      node.set_attr 'rel', 'nofollow'
    end
  end
end

Asciidoctor::Extensions.register do
  inline_macro NofollowProcessor
end