force_espace_single_quote_in_html_attribute.rb

module Rack #:nodoc:
  class ForceEscapeSingleQuoteInHTMLAttribute
    def initialize(app, options = {})
      @app = app
    end

    def call(env)
      status, headers, response = @app.call(env)
      if headers['Content-Type'] =~ %r!text/html|application/xhtml\+xml!
        body = build_response_body(response)
        body.gsub!(/<.+?>/) do |i|
          i.gsub(/(\w+)=".*?"/){|attribute| $1 =~ /^on/ ? attribute : attribute.gsub(/'/, '&#39;') }
        end
        headers['Content-Length'] = body.length.to_s
        response = [body]
      end
      [status, headers, response]
    end

    private
    def build_response_body(response)
      body = ''
      response.each{|part| body << part }
      body
    end
  end
end