(define-module (language python for)
  #:use-module (oop pf-objects)
  #:use-module (ice-9 control)
  #:export (for break))

(eval-when (compile eval load)
  (define (generate-temporaries2 x)
    (map (lambda (x) (generate-temporaries x)) x)))

(define-syntax-parameter break (lambda (x) #f))

(define-syntax for
  (lambda (x)
    (syntax-case x (:)
      ((for ((x ... : E) ...) ((c n) ...) code ... #:final fin)
       (with-syntax (((It ...)       (generate-temporaries #'(E ...)))
                     ((cc ...)       (generate-temporaries #'(c ...)))
                     (((x1 ...) ...) (generate-temporaries2 #'((x ...) ...)))
                     (((x2 ...) ...) (generate-temporaries2 #'((x ...) ...))))
         #'(let/ec lp-break
             (syntax-parameterize ((break (lambda (z)
                                            (syntax-case z ()
                                            ((_ . l)
                                             #'(lp-break . l))
                                            (_ #'lp-break)))))

               (let ((It E) ... (c n) ... (x 'None) ... ... (x1 #f) ... ...)
                 (catch StopIteration
                   (lambda ()
                     (let lp ((cc c) ...)                                
                       (set! c cc) ...
                       (call-with-values
                           (lambda () (next It))
                         (lambda (x2 ...)
                           (set! x1 x2) ...))
                       ...
                       (set! x x1)
                       ... ...
                       (call-with-values
                           (lambda () code ...)
                         lp)))
                   (lambda q fin)))))))

      ((for ((x ... : E) ...) ((c n) ...) code ...)
       (with-syntax (((It ...)       (generate-temporaries #'(E ...)))
                     ((cc ...)       (generate-temporaries #'(c ...)))
                     (((x1 ...) ...) (generate-temporaries2 #'((x ...) ...)))
                     (((x2 ...) ...) (generate-temporaries2 #'((x ...) ...))))
         #'(let/ec lp-break
             (syntax-parameterize ((break (lambda (z)
                                            (syntax-case z ()
                                              ((_ . l)
                                               #'(lp-break . l))
                                              (_ #'lp-break)))))

               (let ((It E) ... (c n) ... (x 'None) ... ... (x1 #f) ... ...)
                 (catch StopIteration
                   (lambda ()
                     (let lp ((cc c) ...)                                
                       (set! c cc) ...
                       (call-with-values
                           (lambda () (next It))
                         (lambda (x2 ...)
                           (set! x1 x2) ...))
                       ...
                       (set! x x1)
                       ... ...
                       (call-with-values
                           (lambda () code ...)
                         lp)))
                   (lambda q (values))))))))

      ((for lp ((x ... : E) ...) ((c n) ...) code ... #:final fin)
       (with-syntax (((It ...)       (generate-temporaries #'(E ...)))
                     ((cc ...)       (generate-temporaries #'(c ...)))
                     (((x1 ...) ...) (generate-temporaries2 #'((x ...) ...)))
                     (((x2 ...) ...) (generate-temporaries2 #'((x ...) ...))))
         #'(let/ec lp-break
             (syntax-parameterize ((break (lambda (z)
                                            (syntax-case z ()
                                              ((_ . l)
                                               #'(lp-break . l))
                                              (_ #'lp-break)))))
                                  
               (let ((It E) ... (c n) ... (x 'None) ... ... (x1 #f) ... ...)
                 (catch StopIteration
                   (lambda ()
                     (let lp ((cc c) ...)                                
                       (set! c cc) ...
                       (call-with-values
                           (lambda () (next It))
                         (lambda (x2 ...)
                           (set! x1 x2) ...))
                       ...
                       (set! x x1)
                       ... ...
                       (call-with-values
                           (lambda () (let/ec lp code ...))
                         lp)))
                   (lambda q fin)))))))

      ((for lp ((x ... : E) ...) ((c n) ...) code ...)
       (with-syntax (((It ...)       (generate-temporaries #'(E ...)))
                     ((cc ...)       (generate-temporaries #'(c ...)))
                     (((x1 ...) ...) (generate-temporaries2 #'((x ...) ...)))
                     (((x2 ...) ...) (generate-temporaries2 #'((x ...) ...))))
         #'(let/ec lp-break
             (syntax-parameterize ((break (lambda (z)
                                            (syntax-case z ()
                                              ((_ . l)
                                               #'(lp-break . l))
                                              (_ #'lp-break)))))

               (let ((It E) ... (c n) ... (x 'None) ... ... (x1 #f) ... ...)
                 (catch StopIteration
                   (lambda ()
                     (let lp ((cc c) ...)                                
                       (set! c cc) ...
                       (call-with-values
                           (lambda () (next It))
                         (lambda (x2 ...)
                           (set! x1 x2) ...))
                       ...
                       (set! x x1)
                       ... ...
                       (call-with-values
                           (lambda () (let/ec lp code ...))
                         lp)))
                   (lambda q (values)))))))))))


#;
(pk
 (for c ((x : (gen '(1 2 3)))) ((s 0))
      (pk x)
      (if (> x 2) (c s))
      (+ s x)

      #:final
      s))