Make PyText compatible with Any type

Summary:
As discussed in https://fb.workplace.com/groups/300451907202972/permalink/566773450570815/, it seems like there is no support for the following:
 - `Any` or `Dict[str, Any]`: PyText serailize.py complains
 - `Dict[str, Union[str, float]]`: bad support of Union in Dict at flow level

 Anyway, this is blocking and I don't see stark downside of adding interim support for `Any` in `serialize.py`. This typing issue is blocking the large stack.

Reviewed By: kmalik22

Differential Revision: D19699214

fbshipit-source-id: 370a7d138aae3c9a96d0e302e1657585242098e6

pytext/config/serialize.py

@@ -2,7 +2,7 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
 
 from enum import Enum
-from typing import Dict, List, Tuple, Union
+from typing import Any, Dict, List, Tuple, Union
 
 from pytext.common.utils import eprint
 
@@ -94,6 +94,19 @@ def _union_from_json(subclasses, json_obj):
         ) from e
 
 
+def _any_from_json(cls, json_obj):
+    if _is_dict(json_obj):
+        if len(json_obj) == 1:
+            type_name, value = list(json_obj.keys())[0], list(json_obj.values())[0]
+            assert (
+                type_name == type(value).__name__
+            ), f"type of value mismatches: {type_name} vs. {type(value).__name__} from {value}"
+            return value
+        else:
+            raise TypeError("PyText Config currently don't support this")
+    return json_obj
+
+
 def _is_optional(cls):
     return _get_class_type(cls) == Union and type(None) in cls.__args__
 
@@ -118,6 +131,8 @@ def _value_from_json(cls, value):
     # nested config
     elif hasattr(cls, "_fields"):
         return config_from_json(cls, value)
+    elif cls_type == Any:
+        return _any_from_json(cls, value)
     elif cls_type == Union:
         return _union_from_json(cls.__args__, value)
     elif issubclass(cls_type, Enum):
@@ -221,7 +236,7 @@ def _value_to_json(cls, value):
     elif _is_optional(cls) and len(cls.__args__) == 2:
         sub_cls = cls.__args__[0] if type(None) != cls.__args__[0] else cls.__args__[1]
         return _value_to_json(sub_cls, value)
-    elif cls_type == Union or getattr(cls, "__EXPANSIBLE__", False):
+    elif cls_type == Any or cls_type == Union or getattr(cls, "__EXPANSIBLE__", False):
         real_cls = type(value)
         if hasattr(real_cls, "_fields"):
             value = config_to_json(real_cls, value)

pytext/config/test/serialize_test.py

@@ -2,14 +2,22 @@
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
 
 import unittest
-from typing import Union
+from typing import Any, Dict, Union
 
 from pytext.config import serialize
 
 
 SAMPLE_INT_JSON = {"int": 6}
 SAMPLE_UNION_CLS = Union[str, int]
 
+SAMPLE_DICT_WITH_ANY_CLS = Dict[str, Any]
+DICT_WITH_ANY: SAMPLE_DICT_WITH_ANY_CLS = {"lr": 0.1, "type": "FedAvg"}
+SAMPLE_DICT_WITH_ANY_JSON = {"lr": {"float": 0.1}, "type": {"str": "FedAvg"}}
+
+SAMPLE_ANY_CLS = Any
+MULTI_TYPE_LIST: Any = [1, "test", 0.01]
+SAMPLE_ANY: Any = {"list": MULTI_TYPE_LIST}
+
 
 class SerializeTest(unittest.TestCase):
     def test_value_from_json(self):
@@ -21,3 +29,19 @@ def test_value_to_json(self):
         print()
         json = serialize._value_to_json(Union[str, int], 6)
         self.assertEqual(SAMPLE_INT_JSON, json)
+
+    def test_value_to_json_for_class_type_any(self):
+        json = serialize._value_to_json(Dict[str, Any], DICT_WITH_ANY)
+        self.assertEqual(json, SAMPLE_DICT_WITH_ANY_JSON)
+
+        json = serialize._value_to_json(Any, [1, "test", 0.01])
+        self.assertEqual(json, SAMPLE_ANY)
+
+    def test_value_from_json_for_class_type_any(self):
+        value = serialize._value_from_json(
+            SAMPLE_DICT_WITH_ANY_CLS, SAMPLE_DICT_WITH_ANY_JSON
+        )
+        self.assertEqual(DICT_WITH_ANY, value)
+
+        value = serialize._value_from_json(SAMPLE_ANY_CLS, SAMPLE_ANY)
+        self.assertEqual([1, "test", 0.01], value)