Data commit

Task/Validate-International-Securities-Identification-Number/Racket/validate-international-securities-identification-number.rkt

@@ -0,0 +1,33 @@
+#lang racket
+
+;; convert a base36 character (#\0 - #\Z) to its equivalent
+;; in base 10 as a string ("0" - "35")
+(define (base36-char->base10-string c)
+  (let ([char-int (char->integer (char-upcase c))]
+        [zero-int (char->integer #\0)]
+        [nine-int (char->integer #\9)]
+        [A-int (char->integer #\A)]
+        [Z-int (char->integer #\Z)])
+    (cond [(and (>= char-int zero-int) (<= char-int nine-int)) (~a c)]
+          [(and (>= char-int A-int) (<= char-int Z-int)) (~a (+ (- char-int A-int) 10))]
+          [else null])))
+
+;; substitute equivalent base 10 numbers for base 36 characters in string
+;; this is a character-by-character substitution not a conversion
+;; of a base36 number to a base10 number
+(define (base36-string-characters->base10-string-characters s)
+  (for/fold ([joined ""])
+            ([tenstr (map base36-char->base10-string (string->list (string-upcase s)))])
+    (values (string-append joined tenstr))))
+
+;; This uses the Racket Luhn solution
+(define [isin-test? s]
+  (let ([RE (pregexp "^[A-Z]{2}[A-Z0-9]{9}[0-9]{1}$")])
+    (and
+     (regexp-match? RE s)
+     (luhn-test (string->number (base36-string-characters->base10-string-characters s))))))
+
+(define test-cases '("US0378331005" "US0373831005" "U50378331005" "US03378331005" "AU0000XVGZA3" "AU0000VXGZA3" "FR0000988040"))
+
+(map isin-test? test-cases)
+;; -> '(#t #f #f #f #t #t #t)