uppercase hex in strings

Author: Joshix-1

src/black/__init__.py

@@ -318,6 +318,11 @@ def validate_regex(
     is_flag=True,
     help="Don't normalize string quotes or prefixes.",
 )
+@click.option(
+    "--uppercase-unicode-escapes",
+    is_flag=True,
+    help="Make unicode escapes uppercase."
+)
 @click.option(
     "-C",
     "--skip-magic-trailing-comma",
@@ -549,6 +554,7 @@ def main(
     python_cell_magics: Sequence[str],
     skip_source_first_line: bool,
     skip_string_normalization: bool,
+    uppercase_unicode_escapes: bool,
     skip_magic_trailing_comma: bool,
     preview: bool,
     unstable: bool,
@@ -657,6 +663,7 @@ def main(
         skip_source_first_line=skip_source_first_line,
         string_normalization=not skip_string_normalization,
         magic_trailing_comma=not skip_magic_trailing_comma,
+        uppercase_unicode_escapes=uppercase_unicode_escapes,
         preview=preview,
         unstable=unstable,
         python_cell_magics=set(python_cell_magics),

src/black/linegen.py

@@ -465,7 +465,10 @@ def foo(a: (int), b: (float) = 7): ...
         yield from self.visit_default(node)
 
     def visit_STRING(self, leaf: Leaf) -> Iterator[Line]:
-        normalize_unicode_escape_sequences(leaf)
+        normalize_unicode_escape_sequences(
+            leaf,
+            str.upper if self.mode.uppercase_unicode_escapes else str.lower,
+        )
 
         if is_docstring(leaf) and not re.search(r"\\\s*\n", leaf.value):
             # We're ignoring docstrings with backslash newline escapes because changing

src/black/mode.py

@@ -248,6 +248,7 @@ class Mode:
     target_versions: set[TargetVersion] = field(default_factory=set)
     line_length: int = DEFAULT_LINE_LENGTH
     string_normalization: bool = True
+    uppercase_unicode_escapes: bool = False
     is_pyi: bool = False
     is_ipynb: bool = False
     skip_source_first_line: bool = False
@@ -295,6 +296,7 @@ def get_cache_key(self) -> str:
             version_str,
             str(self.line_length),
             str(int(self.string_normalization)),
+            str(int(self.uppercase_unicode_escapes)),
             str(int(self.is_pyi)),
             str(int(self.is_ipynb)),
             str(int(self.skip_source_first_line)),
@@ -310,6 +312,7 @@ def __hash__(self) -> int:
             frozenset(self.target_versions),
             self.line_length,
             self.string_normalization,
+            self.uppercase_unicode_escapes,
             self.is_pyi,
             self.is_ipynb,
             self.skip_source_first_line,

src/black/resources/black.schema.json

@@ -14,6 +14,11 @@
       "description": "How many characters per line to allow.",
       "default": 88
     },
+    "uppercase-unicode-escapes": {
+      "type": "boolean",
+      "description": "Wether to make unicode escapes upper case.",
+      "default": false
+    },
     "target-version": {
       "type": "array",
       "items": {

src/black/strings.py

@@ -4,6 +4,7 @@
 
 import re
 import sys
+from collections.abc import Callable
 from functools import lru_cache
 from re import Match, Pattern
 from typing import Final
@@ -306,7 +307,7 @@ def normalize_fstring_quotes(
     return middles, new_quote
 
 
-def normalize_unicode_escape_sequences(leaf: Leaf) -> None:
+def normalize_unicode_escape_sequences(leaf: Leaf, _fix_hex: Callable[[str], str]) -> None:
     """Replace hex codes in Unicode escape sequences with lowercase representation."""
     text = leaf.value
     prefix = get_string_prefix(text)
@@ -322,13 +323,13 @@ def replace(m: Match[str]) -> str:
 
         if groups["u"]:
             # \u
-            return back_slashes + "u" + groups["u"].lower()
+            return back_slashes + "u" + _fix_hex(groups["u"])
         elif groups["U"]:
             # \U
-            return back_slashes + "U" + groups["U"].lower()
+            return back_slashes + "U" + _fix_hex(groups["U"])
         elif groups["x"]:
             # \x
-            return back_slashes + "x" + groups["x"].lower()
+            return back_slashes + "x" + _fix_hex(groups["x"])
         else:
             assert groups["N"], f"Unexpected match: {m}"
             # \N{}