[utils] `traverse_obj`: Allow unbranching using `all` and `any` (#9571)

Authored by: Grub4K

test/test_traversal.py

@@ -377,3 +377,35 @@ class TestTraversal:
             'special transformations should act on current element'
         assert traverse_obj(etree, ('country', 0, ..., 'text()', {int_or_none})) == [1, 2008, 141100], \
             'special transformations should act on current element'
+
+    def test_traversal_unbranching(self):
+        assert traverse_obj(_TEST_DATA, [(100, 1.2), all]) == [100, 1.2], \
+            '`all` should give all results as list'
+        assert traverse_obj(_TEST_DATA, [(100, 1.2), any]) == 100, \
+            '`any` should give the first result'
+        assert traverse_obj(_TEST_DATA, [100, all]) == [100], \
+            '`all` should give list if non branching'
+        assert traverse_obj(_TEST_DATA, [100, any]) == 100, \
+            '`any` should give single item if non branching'
+        assert traverse_obj(_TEST_DATA, [('dict', 'None', 100), all]) == [100], \
+            '`all` should filter `None` and empty dict'
+        assert traverse_obj(_TEST_DATA, [('dict', 'None', 100), any]) == 100, \
+            '`any` should filter `None` and empty dict'
+        assert traverse_obj(_TEST_DATA, [{
+            'all': [('dict', 'None', 100, 1.2), all],
+            'any': [('dict', 'None', 100, 1.2), any],
+        }]) == {'all': [100, 1.2], 'any': 100}, \
+            '`all`/`any` should apply to each dict path separately'
+        assert traverse_obj(_TEST_DATA, [{
+            'all': [('dict', 'None', 100, 1.2), all],
+            'any': [('dict', 'None', 100, 1.2), any],
+        }], get_all=False) == {'all': [100, 1.2], 'any': 100}, \
+            '`all`/`any` should apply to dict regardless of `get_all`'
+        assert traverse_obj(_TEST_DATA, [('dict', 'None', 100, 1.2), all, {float}]) is None, \
+            '`all` should reset branching status'
+        assert traverse_obj(_TEST_DATA, [('dict', 'None', 100, 1.2), any, {float}]) is None, \
+            '`any` should reset branching status'
+        assert traverse_obj(_TEST_DATA, [('dict', 'None', 100, 1.2), all, ..., {float}]) == [1.2], \
+            '`all` should allow further branching'
+        assert traverse_obj(_TEST_DATA, [('dict', 'None', 'urls', 'data'), any, ..., 'index']) == [0, 1], \
+            '`any` should allow further branching'

yt_dlp/utils/traversal.py

@@ -228,6 +228,15 @@ def traverse_obj(
             if not casesense and isinstance(key, str):
                 key = key.casefold()
 
+            if key in (any, all):
+                has_branched = False
+                filtered_objs = (obj for obj in objs if obj not in (None, {}))
+                if key is any:
+                    objs = (next(filtered_objs, None),)
+                else:
+                    objs = (list(filtered_objs),)
+                continue
+
             if __debug__ and callable(key):
                 # Verify function signature
                 inspect.signature(key).bind(None, None)