add missing exercies for reverse-string #364

config.json

@@ -364,7 +364,7 @@
         "uuid": "59c6319b-2799-4e4c-bef1-e28626878446",
         "practices": [],
         "prerequisites": [],
-        "difficulty": 2
+        "difficulty": 4
       },
       {
         "slug": "roman-numerals",

exercises/practice/reverse-string/.meta/config.json

@@ -2,6 +2,9 @@
   "authors": [
     "fapdash"
   ],
+  "contributors": [
+    "kmarker1101"
+  ],
   "files": {
     "solution": [
       "reverse-string.el"

exercises/practice/reverse-string/.meta/example.el

@@ -5,9 +5,33 @@
 ;;; Code:
 
 
-(defun reverse-string (value)
-  (reverse value))
+(require 'cl-lib)
+(require 'ucs-normalize)
+
+(defun combining-mark-p (char)
+  (let ((category (get-char-code-property char 'general-category)))
+    (or (string= category "Mn")  ; Nonspacing_Mark
+        (string= category "Mc")  ; Spacing_Mark
+        (string= category "Me")))) ; Enclosing_Mark
 
+(defun split-grapheme-clusters (str)
+  (let ((clusters '())
+        (i 0)
+        (len (length str)))
+    (while (< i len)
+      (let ((start i)
+            (char (aref str i)))
+        (setq i (1+ i))
+        (while (and (< i len)
+                    (combining-mark-p (aref str i)))
+          (setq i (1+ i)))
+        (push (substring str start i) clusters)))
+    (nreverse clusters)))
+
+(defun reverse-string (value)
+  (let* ((decomposed (ucs-normalize-NFD-string value))
+         (clusters (split-grapheme-clusters decomposed)))
+    (apply #'concat (reverse clusters))))
 
 (provide 'reverse-string)
 ;;; reverse-string.el ends here

exercises/practice/reverse-string/.meta/tests.toml

@@ -26,3 +26,12 @@ description = "a palindrome"
 
 [b9e7dec1-c6df-40bd-9fa3-cd7ded010c4c]
 description = "an even-sized word"
+
+[1bed0f8a-13b0-4bd3-9d59-3d0593326fa2]
+description = "wide characters"
+
+[93d7e1b8-f60f-4f3c-9559-4056e10d2ead]
+description = "grapheme cluster with pre-combined form"
+
+[1028b2c1-6763-4459-8540-2da47ca512d9]
+description = "grapheme clusters"

exercises/practice/reverse-string/reverse-string-test.el

@@ -32,6 +32,15 @@
 (ert-deftest an-even-sized-word ()
   (should (string= (reverse-string "drawer") "reward")))
 
+(ert-deftest wide-characters ()
+  (should (string= (reverse-string "子猫") "猫子")))
+
+(ert-deftest grapheme-cluster-with-pre-combined-form ()
+  (should (string= (reverse-string "Würstchenstand") "dnatsnehctsrüW")))
+
+(ert-deftest grapheme-cluster ()
+  (should (string= (reverse-string "ผู้เขียนโปรแกรม") "มรกแรปโนยขีเผู้")))
+
 
 (provide 'reverse-string-test)
 ;;; reverse-string-test.el ends here