call

# File actionpack/lib/action_dispatch/middleware/static.rb, line 12
    def call(env)
      path   = env['PATH_INFO'].chomp('/')
      method = env['REQUEST_METHOD']

      if FILE_METHODS.include?(method)
        if file_exist?(path)
          return @file_server.call(env)
        else
          cached_path = directory_exist?(path) ? "#{path}/index" : path
          cached_path += ::ActionController::Base.page_cache_extension

          if file_exist?(cached_path)
            env['PATH_INFO'] = cached_path
            return @file_server.call(env)
          end
        end
      end

      @app.call(env)
    end