Reconfigure AST to convert all blocks with the role SLIDE into sections and transferring the content to those new sections.

slide-transformer.rb

require 'asciidoctor/extensions' unless RUBY_ENGINE == 'opal'
require 'pp'

Asciidoctor::Extensions.register do
  treeprocessor do
    process do |doc|

      doc.blocks.replace (doc.find_by role: 'SLIDE').map {|slide|
        slide.parent.blocks.delete slide
        sect = Asciidoctor::Section.new doc, 1, false
        sect.title = '!'
        sect.id = slide.id
        sect.set_attr "id", ""
        slide.id = nil
        slide.roles.each {|r|
          if r != 'SLIDE'
            sect.add_role r
          end
        }
        if slide.blocks?
          slide.blocks.each do |child|
            child.remove_role 'SLIDE'
            child.parent = sect
            sect << child
          end
        else
          slide.remove_role 'SLIDE'
          slide.parent = sect
          sect << slide
        end
        sect
      }
      nil

    end
  end
end