Expose getStandardImmutableDefaultValueForType to python

Summary: The motivation is that in Thrift Patch, we want to be able to ensure a field to the default value. We need a way to get the standard default value in python.

Reviewed By: praihan

Differential Revision: D66269102

fbshipit-source-id: 0a033a5d2e931bb88f6fc25f978758a67daf5404

third-party/thrift/src/thrift/lib/python/test/typeinfo_test.py

@@ -30,6 +30,7 @@
 from thrift.python.types import (
     AdaptedTypeInfo,
     EnumTypeInfo,
+    get_standard_immutable_default_value_for_type,
     IntegerTypeInfo,
     IOBufTypeInfo,
     ListTypeInfo,
@@ -38,6 +39,15 @@
     StringTypeInfo,
     StructTypeInfo,
     TypeInfo,
+    typeinfo_binary,
+    typeinfo_bool,
+    typeinfo_byte,
+    typeinfo_double,
+    typeinfo_float,
+    typeinfo_i16,
+    typeinfo_i32,
+    typeinfo_i64,
+    typeinfo_string,
 )
 
 # This python file serves as a boilerplate code for executing tests written
@@ -125,3 +135,43 @@ def test_MutableMapTypeInfo(self) -> None:
 
     def test_MutableStructTypeInfo(self) -> None:
         CTests(self).test_MutableStructTypeInfo()
+
+    def test_StandardDefaultValue(self) -> None:
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(typeinfo_bool), False
+        )
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(typeinfo_byte), 0
+        )
+        self.assertEqual(get_standard_immutable_default_value_for_type(typeinfo_i16), 0)
+        self.assertEqual(get_standard_immutable_default_value_for_type(typeinfo_i32), 0)
+        self.assertEqual(get_standard_immutable_default_value_for_type(typeinfo_i64), 0)
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(typeinfo_float), 0.0
+        )
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(typeinfo_double), 0.0
+        )
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(typeinfo_string), ""
+        )
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(typeinfo_binary), b""
+        )
+
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(
+                ListTypeInfo(typeinfo_string)
+            ),
+            [],
+        )
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(SetTypeInfo(typeinfo_string)),
+            set(),
+        )
+        self.assertEqual(
+            get_standard_immutable_default_value_for_type(
+                MapTypeInfo(typeinfo_string, typeinfo_string)
+            ),
+            {},
+        )

third-party/thrift/src/thrift/lib/python/types.cpp

@@ -1692,6 +1692,16 @@ const detail::TypeInfo iobufTypeInfo{
     /* .typeExt */ &ioBufFieldType,
 };
 
+PyObject* getStandardImmutableDefaultValuePtrForType(
+    const detail::TypeInfo& typeInfo) {
+  auto ret = getStandardImmutableDefaultValueForType(typeInfo);
+  return std::get<0>(ret).release();
+}
+PyObject* getStandardMutableDefaultValuePtrForType(
+    const detail::TypeInfo& typeInfo) {
+  auto ret = getStandardMutableDefaultValueForType(typeInfo);
+  return std::get<0>(ret).release();
+}
 } // namespace apache::thrift::python
 
 namespace apache::thrift::python::capi {

third-party/thrift/src/thrift/lib/python/types.h

@@ -838,6 +838,45 @@ inline const PyObject* getListObjectItemBase(const void* pyList) {
   return reinterpret_cast<PyObject*>(&PyList_GET_ITEM(pyList, 0));
 }
 
+/**
+ * Returns the appropriate standard immutable default value for the given
+ * `typeInfo`.
+ *
+ * The standard default values are as follows:
+ *   * `0L` for integral numbers.
+ *   * `0d` for floating-point numbers.
+ *   * `false` for booleans.
+ *   * `""` (i.e., the empty string) for strings and `binary` fields (or an
+ *      empty `IOBuf` if applicable).
+ *   * An empty `tuple` for lists and maps.
+ *   * An empty `frozenset` for sets.
+ *   * A recursively default-initialized instance for structs and unions.
+ *
+ * @throws if there is no standard default value
+ */
+PyObject* getStandardImmutableDefaultValuePtrForType(
+    const detail::TypeInfo& typeInfo);
+
+/**
+ * Returns the appropriate standard mutable default value for the given
+ * `typeInfo`.
+ *
+ * The standard default values are as follows:
+ *   * `0L` for integral numbers.
+ *   * `0d` for floating-point numbers.
+ *   * `false` for booleans.
+ *   * `""` (i.e., the empty string) for strings and `binary` fields (or an
+ *      empty `IOBuf` if applicable).
+ *   * An empty `list` for lists.
+ *   * An empty `dict` for maps.
+ *   * An empty `set` for sets.
+ *   * A recursively default-initialized instance for structs and unions.
+ *
+ * @throws if there is no standard default value
+ */
+PyObject* getStandardMutableDefaultValuePtrForType(
+    const detail::TypeInfo& typeInfo);
+
 } // namespace apache::thrift::python
 
 namespace apache::thrift::python::capi {

third-party/thrift/src/thrift/lib/python/types.pxd

@@ -82,6 +82,9 @@ cdef extern from "<thrift/lib/python/types.h>" namespace "::apache::thrift::pyth
         const cDynamicStructInfo& structInfo
     ) except+
     cdef void setStructIsset(object, int index, bint set) except+
+    cdef object getStandardImmutableDefaultValuePtrForType(
+        const cTypeInfo& typeInfo
+    ) except+
 
     cdef const cTypeInfo& boolTypeInfo
     cdef const cTypeInfo& byteTypeInfo

third-party/thrift/src/thrift/lib/python/types.pyi

@@ -16,6 +16,9 @@
 
 import enum
 import typing
+from typing import Never
+
+from folly.iobuf import IOBuf
 
 from thrift.python.adapter import Adapter
 from thrift.python.exceptions import GeneratedError
@@ -197,6 +200,26 @@ def update_nested_field(
     obj: sT, path_to_values: typing.Mapping[str, typing.Any]
 ) -> sT: ...
 
+_DefaultFieldValue = typing.Union[
+    bool,
+    int,
+    float,
+    str,
+    bytes,
+    IOBuf,
+    Enum,
+    Struct,
+    Union,
+    GeneratedError,
+    typing.Sequence[Never],
+    typing.AbstractSet[Never],
+    typing.Mapping[Never, Never],
+]
+
+def get_standard_immutable_default_value_for_type(
+    type_info: AnyTypeInfo,
+) -> _DefaultFieldValue: ...
+
 class _fbthrift_ResponseStreamResult(Struct, typing.Generic[TChunk]):
     success: typing.Final[TChunk]
 

third-party/thrift/src/thrift/lib/python/types.pyx

@@ -2539,3 +2539,7 @@ cdef class ServiceInterface:
 
     async def onStopRequested(self):
         pass
+
+
+def get_standard_immutable_default_value_for_type(TypeInfoBase typeinfo):
+    return typeinfo.to_python_value(getStandardImmutableDefaultValuePtrForType(typeinfo.get_cTypeInfo()[0]))