Fast path to measure width of ASCII strings

See also: psf#3445 (comment)
dahlia · Feb 10, 2023 · 52e1406 · 52e1406
1 parent 9646c4c
commit 52e1406
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/src/black/strings.py b/src/black/strings.py
@@ -298,6 +298,9 @@ def str_width(line_str: str) -> int:
     You could utilize this function to determine, for example, if a string
     is too wide to display in a terminal or editor.
     """
+    if line_str.isascii():
+        # Fast path for most of strings which contains only characters in ASCII:
+        return len(line_str)
     return sum(map(char_width, line_str))