class Asciidoctor::Converter::TemplateConverter

def scan_dir template_dir, pattern, template_cache = nil
  result, helpers = {}, nil
  # Grab the files in the top level of the directory (do not recurse)
  ::Dir.glob(pattern).keep_if {|match| ::File.file? match }.each do |file|
    if (basename = ::File.basename file) == 'helpers.rb'
      helpers = file
      next
    elsif (path_segments = basename.split '.').size < 2
      next
    end
    if (name = path_segments[0]) == 'block_ruler'
      name = 'thematic_break'
    elsif name.start_with? 'block_'
      name = name.slice 6, name.length
    end
    unless template_cache && (template = template_cache[file])
      template_class, extra_engine_options, extsym = ::Tilt, {}, path_segments[-1].to_sym
      case extsym
      when :slim
        unless @active_engines[extsym]
          # NOTE slim doesn't get automatically loaded by Tilt
          Helpers.require_library 'slim' unless defined? ::Slim::Engine
          require 'slim/include' unless defined? ::Slim::Include
          ::Slim::Engine.define_options asciidoc: {}
          # align safe mode of AsciiDoc embedded in Slim template with safe mode of current document
          # NOTE safe mode won't get updated if using template cache and changing safe mode
          (@engine_options[extsym][:asciidoc] ||= {})[:safe] ||= @safe if @safe
          @active_engines[extsym] = true
        end
      when :haml
        unless @active_engines[extsym]
          Helpers.require_library 'haml' unless defined? ::Haml::Engine
          # NOTE Haml 5 dropped support for pretty printing
          @engine_options[extsym].delete :ugly if defined? ::Haml::TempleEngine
          @engine_options[extsym][:attr_quote] = @engine_options[extsym].delete :attr_wrapper unless defined? ::Haml::Options
          @active_engines[extsym] = true
        end
      when :erb
        template_class, extra_engine_options = (@active_engines[extsym] ||= (load_eruby @eruby))
      when :rb
        next
      else
        next unless ::Tilt.registered? extsym.to_s
      end
      template = template_class.new file, 1, (@engine_options[extsym] ||= {}).merge(extra_engine_options)
    end
    result[name] = template
  end
  if helpers || ::File.file?(helpers = %(#{template_dir}/helpers.rb))
    require helpers
  end
  result
end