#lang scheme/base

(require (planet chongkai/sml/ml-package)
         scheme/match
         (only-in (planet chongkai/sml/ml-primitives)
                  SOME? SOME SOME-content
                  NONE? NONE
                  Subscript? Subscript
                  LESS? LESS
                  EQUAL? EQUAL
                  GREATER? GREATER))

(provide CharVector-struct)

(define-package CharVector-struct
  (maxLen fromList tabulate length sub extract concat app
          map foldl foldr appi mapi foldli foldri)
  
  
  (define maxLen +inf.0)
  
  (define tabulate
    (match-lambda
      ((vector n f)
       (build-string n f))))
  
  (define sub
    (match-lambda
      ((vector s i)
       (call-with-exception-handler
        (lambda (e)
          (if (exn:break? e)
              e
              (Subscript (current-continuation-marks))))
        (lambda () (string-ref s i))))))
  
  (define extract
    (match-lambda
      ((vector s i (? NONE?))
       (call-with-exception-handler
        (lambda (e)
          (if (exn:break? e)
              e
              (Subscript (current-continuation-marks))))
        (lambda () (substring s i))))
      ((vector s i (? SOME? (app SOME-content j)))
       (call-with-exception-handler
        (lambda (e)
          (if (exn:break? e)
              e
              (Subscript (current-continuation-marks))))
        (lambda () (substring s i j))))))
  
  (define (concat l)
    (apply string-append l))
  
  (define ((app f) s)
    (for-each f (string->list s)))
  
  (define ((map f) s)
    (list->string (map f (string->list s))))
  
  (define ((appi f) s)
    (let ((stop (string-length s)))
      (let lp ((i 0))
        (when (< i stop)
          (f (vector-immutable i (string-ref s i)))
          (lp (add1 i))))))
  
  (define ((mapi f) s)
    (let* ((stop (string-length s))
           (newstr (make-string stop)))
      (let lp ((j 0))
        (when (< j stop)
          (string-set! newstr j (f (vector j (string-ref s j))))
          (lp (add1 j))))
      (string->immutable-string newstr)))
  
  (define (((foldli f) init) s)
    (let ((stop (string-length s)))
      (let lp ((i 0)
               (acc init))
        (if (< i stop)
            (lp (add1 i)
                (f (vector-immutable i (string-ref s i) acc)))
            acc))))
  
  (define (((foldri f) init) s)
    (let lp ((j (sub1 (string-length s)))
             (acc init))
      (if (<= 0 j)
          (lp (sub1 j)
              (f (vector-immutable j (string-ref s j) acc)))
          acc)))
  
  (define (((foldl f) init) v)
    (let ((end (string-length v)))
      (let lp ((i 0)
               (acc init))
        (if (< i end)
            (lp (add1 i)
                (f (vector (string-ref v i) acc)))
            acc))))
  
  (define (((foldr f) init) v)
    (let lp ((i (sub1 (string-length v)))
             (acc init))
      (if (negative? i)
          acc
          (lp (sub1 i)
              (f (vector (string-ref v i) acc))))))
  
  (define fromList list->string)
  (define* length string-length)
  )