Support the creation of pg.typing.Enum from typing.Literal annotation.

PiperOrigin-RevId: 565168139

Author: daiyip

pyglove/core/typing/annotation_conversion.py

@@ -118,10 +118,13 @@ def _value_spec_from_type_annotation(
         return vs.Tuple(_value_spec_from_type_annotation(args[0], False))
       return vs.Tuple([_value_spec_from_type_annotation(arg, False)
                        for arg in args])
-  # Handle sequence.
+  # Handling sequence.
   elif origin in (collections.abc.Sequence,):
     elem = _value_spec_from_annotation(args[0], True) if args else vs.Any()
     return vs.Union([vs.List(elem), vs.Tuple(elem)])
+  # Handling literals.
+  elif origin is typing.Literal:
+    return vs.Enum(object_utils.MISSING_VALUE, args)
   # Handling dict.
   elif origin in (dict, typing.Dict, collections.abc.Mapping):
     if not args:

pyglove/core/typing/annotation_conversion_test.py

@@ -200,6 +200,11 @@ def test_sequence(self):
         ValueSpec.from_annotation(typing.Sequence[int], True),
         vs.Union([vs.List(vs.Int()), vs.Tuple(vs.Int())]))
 
+  def test_enum(self):
+    self.assertEqual(
+        ValueSpec.from_annotation(typing.Literal[None, 1, 'foo'], True),
+        vs.Enum[None, 1, 'foo'])
+
   def test_dict(self):
     self.assertEqual(ValueSpec.from_annotation(dict, True), vs.Dict())
     self.assertEqual(ValueSpec.from_annotation(typing.Dict, True), vs.Dict())