;;;; LOADS THE EXPLICIT-CONTROL EVALUATOR FROM SECTION 5.4 OF
;;;; STRUCTURE AND INTERPRETATION OF COMPUTER PROGRAMS, WITH
;;;; ALL THE SUPPORTING CODE IT NEEDS IN ORDER TO RUN.

;(load "syntax")			;section 4.1.2 syntax procedures
;(load "compiler")               ;compiler
;(load "regsim")			;reg machine simulator
;(load "ecevsup")		;simulation of machine operations
;(load "ecevcomp")		;eceval itself
				;and interface to compiled code

(define the-global-environment (setup-environment))

(define standard-primitives
  `((+ ,+) (- ,-) (* ,*) (/ ,/) (inc ,inc) (dec ,dec) (= ,=) (< ,<)
    (> ,>) (zero? ,zero?) (not ,not) (true ,true) (false ,false)
    (nil ,nil) (cons ,cons) (car ,car) (cdr ,cdr) (pair? ,pair?)
    (null? ,null?) (list ,list) (eq? ,eq?) (symbol? ,symbol?)
    (write-line ,write-line)))

(define (compile-and-display expression)
  (fluid-let ((*unparser-list-breadth-limit* #f)
	      (*unparse-uninterned-symbols-by-name?* #T))
    (newline)
    (for-each
     (lambda (statement)
       (newline)
       (if (pair? statement) (display "  "))
       (display statement))
     (statements (compile expression 'val 'return)))))

(define (continue-eceval)
  (set-register-contents! eceval 'flag false)
  (start eceval))

;;;; To start, can use compile-and-go as in section 5.5.7
;;;;  or start-eceval as in the section 5.5.7 footnote.

;;;; To resume the machine without reinitializing the global environment
;;;; if you have somehow interrupted out of the machine back to Scheme, do

;;;; (set-register-contents! eceval 'flag false)
;;;; (start eceval)

;;; Now the following things should work:

;; (define gcd-machine
;;   (make-machine
;;    '(a b t)
;;    (list (list 'rem remainder) (list '= =))
;;    '(test-b
;;        (test (op =) (reg b) (const 0))
;;        (branch (label gcd-done))
;;        (assign t (op rem) (reg a) (reg b))
;;        (assign a (reg b))
;;        (assign b (reg t))
;;        (goto (label test-b))
;;      gcd-done)))
;;
;; (set-register-contents! gcd-machine 'a 206)
;;
;; (set-register-contents! gcd-machine 'b 40)
;;
;; (start gcd-machine)
;;
;; (get-register-contents gcd-machine 'a)
;;  ... should return 2 

;; (start-eceval)
;; 
;; ;;; EC-Eval input:
;; (define (append x y)
;;   (if (null? x)
;;       y
;;       (cons (car x)
;;             (append (cdr x) y))))
;; (total-pushes = 3 maximum-depth = 3)
;;; EC-Eval value:
;; ok
;; 
;; ;;; EC-Eval input:
;; (append '(a b c) '(d e f))
;; (total-pushes = 118 maximum-depth = 17)
;; ;;; EC-Eval value:
;; (a b c d e f)