Commit 6c54fb04 authored by Yuanle Song's avatar Yuanle Song
Browse files

add javascript fifo implementation

parent 44dc983d

calc.html

+2 −1
Original line number Diff line number Diff line
@@ -117,7 +117,8 @@ 
      </div>

    </div>

    <script type="text/javascript" src="vendor/jquery.min.js"></script>

    <script type="text/javascript" src="fsm.js"></script>

    <script type="text/javascript" src="fifo.js"></script>

    <script type="text/javascript" src="fsm.js"></script> <!-- fifo.js is required by fsm.js -->

    <script type="text/javascript">

      (function () {

	  /**

fifo.js

0 → 100644
+77 −0
Original line number Diff line number Diff line 
var fifo = function () {

    /**

     * an unbounded fifo queue.

     */

    const Queue = function () {

	this.data = [];

	this.push = function (e) {

	    this.data.push(e);

	};

	/**

	 * note: pop() will return undefined when there is not enough element.

	 */

	this.pop = function () {

	    return this.data.shift();

	};

    };



    /**

     * a bounded fifo queue.

     */

    const BoundedQueue = function (capacity) {

	this.capacity = capacity;

	this.data = [];

	/**

	 * push new element to the BoundedQueue. if there is no room for it,

	 * remove the oldest element from the queue.

	 */

	this.push = function (e) {

	    console.assert(this.data.length <= this.capacity, "bounded queue data size is invalid");

	    if (this.data.length === this.capacity) {

		this.data.shift();

	    }

	    this.data.push(e);

	};

	/**

	 * note: pop() will return undefined when there is not enough element.

	 */

	this.pop = function () {

	    return this.data.shift();

	};

    };



    const testFIFO = function () {

	var q = new Queue();

	q.push(1);

	q.push(2);

	q.push(3);

	console.assert(q.pop() === 1);

	console.assert(q.pop() === 2);

	console.assert(q.pop() === 3);



	q = new BoundedQueue(3);

	q.push(1);

	q.push(2);

	q.push(3);

	console.assert(q.pop() === 1);

	console.assert(q.pop() === 2);

	console.assert(q.pop() === 3);



	q = new BoundedQueue(3);

	q.push(1);

	q.push(2);

	q.push(3);

	q.push(4);

	console.assert(q.pop() === 2);

	console.assert(q.pop() === 3);

	console.assert(q.pop() === 4);

    };



    // run all tests

    testFIFO();



    return {

	Queue: Queue,

	BoundedQueue: BoundedQueue,

    };

}();

operational

+19 −1
Original line number Diff line number Diff line
@@ -48,8 +48,26 @@ the parent DOM. 


* current                                                             :entry:

** 

** 2017-01-27 make trail work

- when is trail being updated?

  - when a number is committed to number stack. return.

  - when a new number is pushed to stack as an op result. plus, change-sign.

  - swap doesn't change trail.

- this should be part of the FSM.

  what data should I store?

  it's a queue of [(Maybe op, number)].



  as mentioned previously, this data can be made persistent across

  pages/sessions.

- first write a bounded fifo queue in javascript.

- load persistent data for trails when init the FSM.

- update the persistent data when trails has changed.



  // is updating local storage a heavy operation? I hope it doesn't sync to

  disk everytime I update a key.



** 2017-01-26 make trail persistent

trail is a sized fifo queue, it just store recent 1k entries.

trail is a bounded fifo queue, it just store recent 1k entries.

when multiple instances of calculator is working. they all write to a single

trail cache. it's not a problem.