[utils] `traverse_obj`: Allow `re.Match` objects (#5174)

Authored by: Grub4K

test/test_utils.py

@@ -2,6 +2,7 @@
 
 # Allow direct execution
 import os
+import re
 import sys
 import unittest
 
@@ -2080,6 +2081,25 @@ Line 1
         with self.assertRaises(TypeError, msg='too many params should result in error'):
             traverse_obj(_IS_USER_INPUT_DATA, ('range8', ':::'), is_user_input=True)
 
+        # Test re.Match as input obj
+        mobj = re.fullmatch(r'0(12)(?P<group>3)(4)?', '0123')
+        self.assertEqual(traverse_obj(mobj, ...), [x for x in mobj.groups() if x is not None],
+                         msg='`...` on a `re.Match` should give its `groups()`')
+        self.assertEqual(traverse_obj(mobj, lambda k, _: k in (0, 2)), ['0123', '3'],
+                         msg='function on a `re.Match` should give groupno, value starting at 0')
+        self.assertEqual(traverse_obj(mobj, 'group'), '3',
+                         msg='str key on a `re.Match` should give group with that name')
+        self.assertEqual(traverse_obj(mobj, 2), '3',
+                         msg='int key on a `re.Match` should give group with that name')
+        self.assertEqual(traverse_obj(mobj, 'gRoUp', casesense=False), '3',
+                         msg='str key on a `re.Match` should respect casesense')
+        self.assertEqual(traverse_obj(mobj, 'fail'), None,
+                         msg='failing str key on a `re.Match` should return `default`')
+        self.assertEqual(traverse_obj(mobj, 'gRoUpS', casesense=False), None,
+                         msg='failing str key on a `re.Match` should return `default`')
+        self.assertEqual(traverse_obj(mobj, 8), None,
+                         msg='failing int key on a `re.Match` should return `default`')
+
 
 if __name__ == '__main__':
     unittest.main()

yt_dlp/utils.py

@@ -5305,13 +5305,14 @@ def traverse_obj(
 
     Each of the provided `paths` is tested and the first producing a valid result will be returned.
     The next path will also be tested if the path branched but no results could be found.
+    Supported values for traversal are `Mapping`, `Sequence` and `re.Match`.
     A value of None is treated as the absence of a value.
 
     The paths will be wrapped in `variadic`, so that `'key'` is conveniently the same as `('key', )`.
 
     The keys in the path can be one of:
         - `None`:           Return the current object.
-        - `str`/`int`:      Return `obj[key]`.
+        - `str`/`int`:      Return `obj[key]`. For `re.Match, return `obj.group(key)`.
         - `slice`:          Branch out and return all values in `obj[key]`.
         - `Ellipsis`:       Branch out and return a list of all values.
         - `tuple`/`list`:   Branch out and return a list of all matching values.
@@ -5322,7 +5323,7 @@ def traverse_obj(
         - `dict`            Transform the current object and return a matching dict.
                             Read as: `{key: traverse_obj(obj, path) for key, path in dct.items()}`.
 
-        `tuple`, `list`, and `dict` all support nested paths and branches
+        `tuple`, `list`, and `dict` all support nested paths and branches.
 
     @params paths           Paths which to traverse by.
     @param default          Value to return if the paths do not match.
@@ -5370,6 +5371,8 @@ def traverse_obj(
                 yield from obj.values()
             elif is_sequence(obj):
                 yield from obj
+            elif isinstance(obj, re.Match):
+                yield from obj.groups()
             elif traverse_string:
                 yield from str(obj)
 
@@ -5378,6 +5381,8 @@ def traverse_obj(
                 iter_obj = enumerate(obj)
             elif isinstance(obj, collections.abc.Mapping):
                 iter_obj = obj.items()
+            elif isinstance(obj, re.Match):
+                iter_obj = enumerate((obj.group(), *obj.groups()))
             elif traverse_string:
                 iter_obj = enumerate(str(obj))
             else:
@@ -5389,10 +5394,21 @@ def traverse_obj(
             yield {k: v if v is not None else default for k, v in iter_obj
                    if v is not None or default is not NO_DEFAULT}
 
-        elif isinstance(obj, dict):
+        elif isinstance(obj, collections.abc.Mapping):
             yield (obj.get(key) if casesense or (key in obj)
                    else next((v for k, v in obj.items() if casefold(k) == key), None))
 
+        elif isinstance(obj, re.Match):
+            if isinstance(key, int) or casesense:
+                with contextlib.suppress(IndexError):
+                    yield obj.group(key)
+                    return
+
+            if not isinstance(key, str):
+                return
+
+            yield next((v for k, v in obj.groupdict().items() if casefold(k) == key), None)
+
         else:
             if is_user_input:
                 key = (int_or_none(key) if ':' not in key