Skip colour for non-Python <repr>

Author: hugovk

Lib/pprint.py

@@ -145,7 +145,13 @@ def _colorize_output(text):
         # (for example, from a custom __repr__),
         # return as-is to avoid breaking their color.
         return text
-    colors = list(gen_colors(text))
+    # Skip coloring inside <...> reprs (for example, <built-in function print>),
+    # they're placeholders, not Python source.
+    skip = [m.span() for m in re.finditer(r"<[^<>\n]*>", text)]
+    colors = [
+        c for c in gen_colors(text)
+        if not any(start <= c.span.start < end for start, end in skip)
+    ]
     chars, _ = disp_str(text, colors=colors, force_color=True, escape=False)
     return "".join(chars)
 

Lib/test/test_pprint.py

@@ -269,6 +269,24 @@ def __repr__(self):
         expected = "{'a': \x1b[31mred\x1b[0m, 'b': 42, 'c': 'hello'}\n"
         self.assertEqual(result, expected)
 
+    def test_color_skips_placeholder_reprs(self):
+        """<...> reprs are non-literal placeholders, not Python source,
+        so their contents must not be tokenized and colored."""
+        recursive = [1, "two", None]
+        recursive.append(recursive)
+
+        with unittest.mock.patch.dict(
+            "os.environ", {"FORCE_COLOR": "1", "NO_COLOR": ""}
+        ):
+            stream = io.StringIO()
+            pprint.pprint(recursive, stream=stream, color=True)
+            result = stream.getvalue()
+
+        self.assertIn("\x1b[", result)  # surrounding output is still colored
+        match = re.search(r"<[^<>\n]*>", result)
+        self.assertIsNotNone(match)
+        self.assertNotIn("\x1b[", match.group(0))
+
     def test_basic(self):
         # Verify .isrecursive() and .isreadable() w/o recursion
         pp = pprint.PrettyPrinter()