Implement set equality.

src/util-string.scm

@@ -30,6 +30,7 @@
  (
   string-repeat
   string-first+rest
+  string-utf8?
   )
 
  (import scheme
@@ -57,6 +58,12 @@
 		(val (irregex-replace (irregex "^[ \\t]*" 'u) sep+val "")))
 	   (cons key-str val))
 	 (cons str ""))))
+
+ ;; Returns true, if given string contains UTF-8 characters
+ (define (string-utf8? str)
+   (let ((asciilen (string-length str))
+	 (utf8len (length (irregex-extract (irregex "." 'u)))))
+     (not (= asciilen utf8len))))
 	 
  ;; Performs utils module self-tests.
  (define (utils-tests!)
@@ -77,6 +84,8 @@
     (test-equal? string-first+rest
 		 (string-first+rest "asdf")
 		 '("asdf" . ""))
+    (test-true string-utf8? (string-utf8? "ěščř"))
+    (test-false string-utf8? (string-utf8? "Hello World!"))
     ))
 
  )