html_output_stripper.rb

# Rack middleware. Strips unecessary whitespaces from HTML output.
class HtmlOutputStripper
  def initialize(app, options = {})
    @app = app
  end

  def call(env)
    status, headers, response = @app.call(env)
    if headers["Content-Type"] =~ /text\/html|application\/xhtml\+xml/
      body = ""
      response.each { |part| body << part }
      body = body.gsub(/>\s+([^\s])/, '> \1').
                  gsub(/([^\s])\s+</, '\1 <').
                  gsub(/>[ \t\n]+</, '><')
      headers["Content-Length"] = body.length.to_s
      response = [body]
    end

    [status, headers, response]
  end
end