class Middleman::CoreExtensions::InlineURLRewriter::Rack

def initialize(app, options={})
  @rack_app = app
  @middleman_app = options.fetch(:middleman_app)
  @rewriters = options.fetch(:rewriters)
  all_source_exts = @rewriters
                    .reduce([]) { |sum, rewriter| sum + rewriter[:source_extensions] }
                    .flatten
                    .uniq
  @source_exts_regex_text = Regexp.union(all_source_exts).to_s
  @all_asset_exts = @rewriters
                    .reduce([]) { |sum, rewriter| sum + rewriter[:url_extensions] }
                    .flatten
                    .uniq
end