Fixed to support non-ascii strings

Author: schultetwin1

src/string.rs

@@ -255,7 +255,7 @@ impl<const N: usize> String<N> {
         Some(ch)
     }
 
-    /// Removes a [`u8`] from this `String` at a byte position and returns it.
+    /// Removes a [`char`] from this `String` at a byte position and returns it.
     ///
     /// Note: Because this shifts over the remaining elements, it has a
     /// worst-case performance of *O*(*n*).
@@ -274,13 +274,28 @@ impl<const N: usize> String<N> {
     ///
     /// let mut s: String<8> = String::from("foo");
     ///
-    /// assert_eq!(s.remove(0), b'f');
-    /// assert_eq!(s.remove(1), b'o');
-    /// assert_eq!(s.remove(0), b'o');
+    /// assert_eq!(s.remove(0), 'f');
+    /// assert_eq!(s.remove(1), 'o');
+    /// assert_eq!(s.remove(0), 'o');
     /// ```
     #[inline]
-    pub fn remove(&mut self, index: usize) -> u8 {
-        self.vec.remove(index)
+    pub fn remove(&mut self, index: usize) -> char {
+        let ch = match self[index..].chars().next() {
+            Some(ch) => ch,
+            None => panic!("cannot remove a char from the end of a string"),
+        };
+
+        let next = index + ch.len_utf8();
+        let len = self.len();
+        unsafe {
+            core::ptr::copy(
+                self.vec.as_ptr().add(next),
+                self.vec.as_mut_ptr().add(index),
+                len - next,
+            );
+            self.vec.set_len(len - (next - index));
+        }
+        ch
     }
 
     /// Truncates this `String`, removing all contents.
@@ -740,7 +755,23 @@ mod tests {
     #[test]
     fn remove() {
         let mut s: String<8> = String::from("foo");
-        assert_eq!(b'f', s.remove(0));
-        assert_eq!("oo", s.as_str());
+        assert_eq!(s.remove(0), 'f');
+        assert_eq!(s.as_str(), "oo");
+    }
+
+    #[test]
+    fn remove_uenc() {
+        let mut s: String<8> = String::from("ĝėēƶ");
+        assert_eq!(s.remove(2), 'ė');
+        assert_eq!(s.remove(2), 'ē');
+        assert_eq!(s.remove(2), 'ƶ');
+        assert_eq!(s.as_str(), "ĝ");
+    }
+
+    #[test]
+    fn remove_uenc_combo_characters() {
+        let mut s: String<8> = String::from("héy");
+        assert_eq!(s.remove(2), '\u{0301}');
+        assert_eq!(s.as_str(), "hey");
     }
 }