#!/usr/bin/env ruby

# https://cirosantilli.com/linux-kernel-module-cheat#asciidoctor-extract-header-ids

require 'asciidoctor'
require 'asciidoctor/extensions'

class Main < Asciidoctor::Extensions::TreeProcessor
  def process document
    return unless document.blocks?
    (document.find_by context: :section).each do |section|
      if section.id
        puts section.id
      end
    end
    nil
  end
end

Asciidoctor::Extensions.register do
  treeprocessor Main
end

(Asciidoctor.load_file(ARGV[0])).convert