Lesson Plan - 6.001 SP04 - recitation 12

ADTs - tables

truth tables
lookup


(define (lookup t1 t2 lookup-table)
  (second (assoc (list t1 t2) lookup-table)))

(define and-table
  '(((#t #t) #t)
    ((#t #f) #f)
    ((#f #t) #f)
    ((#f #f) #f)))

(define or-table
  '(((#t #t) #t)
    ((#t #f) #t)
    ((#f #t) #t)
    ((#f #f) #f)))

(define nand-table
  '(((#t #t) #f)
    ((#t #f) #t)
    ((#f #t) #t)
    ((#f #f) #t)))

(lookup #t #f nand-table)


; component
(define (make-component lookup-table)
  (let ((num (get-counter))
	(table (make-eq-hash-table)))
    (hash-table/put! table 'lookup-table lookup-table)
    (component-table-put! num table)
    (inc-counter)
    num))

(define (component-get num property)
  (hash-table/get (component-table-get num) property 'empty))

(define (component-connect! cnum1 cnum2 side)
  (let ((c1table (component-table-get cnum1)))
    (hash-table/put! c1table 'output cnum2)
    (hash-table/put! c1table 'output-side side)
    'connected))

(define (component-output! cnum)
  (hash-table/put! (component-table-get cnum) 'output 'output)
  (hash-table/put! (component-table-get cnum) 'output-side 'output)
  'will-output)

(define (component-output-data num data)
  (let ((output (component-output-num num))
	(output-side (component-output-side num)))
    (cond ((or (eq? output 'empty) (eq? output-side 'empty))
	   (error "unconnected component output" num))
	  ((eq? output 'output)
	   (display "Result: ")
	   (display data)
	   (newline)
	   #t)
	  (else
	   (hash-table/put! (component-table-get output)
			    output-side
			    data)
	   #f))))

(define (component-process num)
  (let ((inp1 (component-input1 num))
	(inp2 (component-input2 num)))
    (if (or (eq? inp1 'empty) (eq? inp2 'empty))
	#f
	(component-output-data
	 num
	 (lookup inp1 inp2 (component-lookup-table num))))))

(define (simulate)
  (let ((results (map component-process (component-table-keys))))
    (if (fold-right boolean/or #f results)
	'simulation-complete
	(simulate))))