get_chars with test

youknowone · youknowone · commit 04d0ee8152c2 · 2020-07-25T22:08:09.000+09:00
diff --git a/vm/src/obj/objstr.rs b/vm/src/obj/objstr.rs
@@ -1272,6 +1272,19 @@ fn char_is_printable(c: char) -> bool {
     !(cat.is_other() || cat.is_separator())
 }
 
+fn str_get_chars(s: &str, range: std::ops::Range<usize>) -> &str {
+    let mut chars = s.chars();
+    for _ in 0..range.start {
+        let _ = chars.next();
+    }
+    let start = chars.as_str();
+    for _ in range {
+        let _ = chars.next();
+    }
+    let end = chars.as_str();
+    &start[..start.len() - end.len()]
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -1350,6 +1363,19 @@ mod tests {
             "TypeError".to_owned()
         );
     }
+
+    #[test]
+    fn test_get_chars() {
+        let s = "0123456789";
+        assert_eq!(str_get_chars(s, 3..7), "3456");
+        assert_eq!(str_get_chars(s, 3..7), &s[3..7]);
+
+        let s = "0유니코드 문자열9";
+        assert_eq!(str_get_chars(s, 3..7), "코드 문");
+
+        let s = "0😀😃😄😁😆😅😂🤣9";
+        assert_eq!(str_get_chars(s, 3..7), "😄😁😆😅");
+    }
 }
 
 impl PyCommonStringWrapper<str> for PyStringRef {
@@ -1406,16 +1432,7 @@ impl<'s> PyCommonString<'s, char> for str {
     }
 
     fn get_chars<'a>(&'a self, range: std::ops::Range<usize>) -> &'a Self {
-        let mut chars = self.chars();
-        for _ in 0..range.start {
-            let _ = chars.next();
-        }
-        let start = chars.as_str();
-        for _ in range {
-            let _ = chars.next();
-        }
-        let end = chars.as_str();
-        &start[..start.len() - end.len()]
+        str_get_chars(self, range)
     }
 
     fn is_empty(&self) -> bool {
