Middleware Stack

MiddlewareStack.coffee

`
Object.isObject = function(_obj) {
  var _test  = _obj;
  return (  typeof _obj !== 'object' || _obj === null ?
              false :  
              (
                (function () {
                  while (!false) {
                    if (  Object.getPrototypeOf( _test = Object.getPrototypeOf(_test)  ) === null) {
                      break;
                    }      
                  }
                  return Object.getPrototypeOf(_obj) === _test;
                })()
              )
          );
}

if(!Array.isArray) {
  Array.isArray = function (vArg) {
    return Object.prototype.toString.call(vArg) === "[object Array]";
  };
}
`


class MiddlewareStack
    constructor: ->
        @stack = []

    use: (fn) ->
        if Array.isArray fn
            @stack.push fn...
        else
            @stack[@stack.length] = fn

        @

    walk: (initial) ->
        if not Array.isArray(initial) and not Object.isObject(initial)
            throw new Error 'Initial value must be an array or an object'

        i = 0
        next = () =>
            return if i == @stack.length

            @stack[i++].call initial, initial, next

        next()

        initial


plus    = (ø, next) -> @.d += 2; next()
minus   = (ø, next) -> @.d -= 0.5; next()
times   = (ø, next) -> @.d *= 10; next()


s = new MiddlewareStack()

s.use plus
s.use [minus, times]

alert s.walk 10