gh-145239: Colorize case + in the REPL (#150979)

Author: johnslavik

Lib/_pyrepl/utils.py

@@ -274,7 +274,7 @@ def is_soft_keyword_used(*tokens: TI | None) -> bool:
             None | TI(T.NEWLINE) | TI(T.INDENT) | TI(T.DEDENT) | TI(string=":"),
             TI(string="case"),
             TI(T.NUMBER | T.STRING | T.FSTRING_START | T.TSTRING_START)
-            | TI(T.OP, string="(" | "*" | "-" | "[" | "{")
+            | TI(T.OP, string="(" | "*" | "-" | "+" | "[" | "{")
         ):
             return True
         case (

Lib/test/test_pyrepl/test_utils.py

@@ -125,6 +125,14 @@ def test_gen_colors_keyword_highlighting(self):
                     ("import", "keyword"),
                 ],
             ),
+            (
+                "case +1",
+                [
+                    ("case", "soft_keyword"),
+                    ("+", "op"),
+                    ("1", "number"),
+                ],
+            ),
         ]
         for code, expected_highlights in cases:
             with self.subTest(code=code):