Chores needed for stepper functionality

gui.rkt

@@ -64,13 +64,19 @@
   ; run the program
   (execute-content
    (lambda (ps)
-     (define out (prog-state-output ps))
-     ; update data tape inspector
-     (make-tape-cells ps)
-     ; set output and change color to ended
-     (send RUN-OUTPUT set-value out)
+     (update-state-gui ps)
      (send RUN-OUTPUT set-field-background end-col))))
 
+; update-state-gui: ProgState -> _
+; Given a prog-state, updates the data tape inspector and the output window with
+; the contents of that prog-state.
+(define (update-state-gui ps)
+  (define out (prog-state-output ps))
+  ; update data tape inspector
+  (make-tape-cells ps)
+  ; set output and change color to ended
+  (send RUN-OUTPUT set-value out))
+  
 ; Definition of the run button widget
 (define RUN-BTN (new button% [parent F]
                      [label "Run"]
@@ -218,7 +224,7 @@
 (define INPUT-DONE-BTN (new button%
                             [parent input-panel]
                             [label "Confirm"]
-                            [callback (lambda (btn ev) (input-done-cb btn ev))]))
+                            [callback (lambda (b ev) (input-done-cb b ev))]))
 
 ; The run output text object
 (define RUN-OUTPUT (new text-field%

interpreter.rkt

@@ -8,14 +8,8 @@
          racket/struct
          rackunit)
 
-(provide prog-state
-         prog-state?
-         prog-state-tape
-         prog-state-tape-len
-         prog-state-dp
-         prog-state-output
-         prog-state-program
-         prog-state-ip
+(provide (struct-out prog-state)
+         execute-instr
          execute
          string->program
          program->prog-state)
@@ -379,12 +373,12 @@
   (lambda (done) (done 50))
   (lambda (w) (check-equal? w (prog-state (list 50) 0 1 "," "" 1 #f)))))
 
-; execute: ProgState (ProgState -> _) ((Byte -> _) -> _) -> _
-; Given an initial ProgState state,
-; calls done when the final ProgState has been
-; computed by executing the program
-(define (execute prog done get-input)
-  
+; execute-instr: ProgState (ProgState -> _) ((Byte -> _) -> _) -> _
+; Given an initial ProgState state, an async function to get input and a "done"
+; callback, calls done with the ProgState updated after executing one
+; instruction.
+(define (execute-instr prog done get-input)
+
   ; execute-sync: Char ProgState -> ProgState
   ; Given a synchronous instruction as a Char and the current ProgState,
   ; returns the new ProgState by executing the instruction.
@@ -396,6 +390,20 @@
           [(char=? inst #\[) (exec-loop-start w)]
           [(char=? inst #\]) (exec-loop-end w)]
           [(char=? inst #\.) (exec-out w)]))
+
+  ; Fetch current instruction
+  (define inst (string-ref (prog-state-program prog) (prog-state-ip prog)))
+
+  ; Execute asynchr. if ",", otherwise call callback with results of
+  ; execute-sync
+  (cond [(char=? inst #\,) (exec-in prog get-input done)]
+        [else (done (execute-sync inst prog))]))
+
+; execute: ProgState (ProgState -> _) ((Byte -> _) -> _) -> _
+; Given an initial ProgState state,
+; calls done when the final ProgState has been
+; computed by executing the program
+(define (execute prog done get-input)
   
   ; The program length in characters
   (define program-len (string-length (prog-state-program prog)))
@@ -406,13 +414,7 @@
   ; when the final ProgState is ready.
   (define (execute-help w)
     (cond [(>= (prog-state-ip w) program-len) (done w)]
-          [else
-           ; Fetch current instruction
-           (define inst (string-ref (prog-state-program w) (prog-state-ip w)))
-           (cond [(char=? inst #\,)
-                  (exec-in w get-input
-                           (lambda (ps) (execute ps done get-input)))]
-                 [else (execute (execute-sync inst w) done get-input)])]))
+          [else (execute-instr w execute-help get-input)]))
 
   (execute-help prog))