module Jekyll
  class LinkableTitleTag < Liquid::Tag
    def initialize(tag_name, text, token)
      super
      @title = text
    end

    def render(context)
      title = Liquid::Template.parse(@title).render context
      slug = title.downcase.strip.gsub(' ', '-').gsub(/[^\w-]/, '')
      "<a class='title-link' name='#{slug}' href='\##{slug}'></a> #{title}"
    end
  end
end

Liquid::Template.register_tag('linkable_title', Jekyll::LinkableTitleTag)