Intermediate changes

commit_hash:50996f174ea1b659bc41e9f4e9f27328060af2ca

Author: robot-piglet

yql/essentials/udfs/common/python/bindings/py_cast.cpp

@@ -814,6 +814,27 @@ NUdf::TUnboxedValue FromPyDict(
     throw yexception() << "Can't cast "<< PyObjectRepr(value) << " to dict.";
 }
 
+TPyObjectPtr ToPyNull(
+    const TPyCastContext::TPtr& ctx,
+    const NUdf::TType* type,
+    const NUdf::TUnboxedValuePod& value)
+{
+    if (!value.HasValue()) {
+        return TPyObjectPtr(Py_None, TPyObjectPtr::ADD_REF);
+    }
+    throw yexception() << "Value is not null";
+}
+
+NUdf::TUnboxedValue FromPyNull(
+        const TPyCastContext::TPtr& ctx,
+        const NUdf::TType* type, PyObject* value)
+{
+    if (value == Py_None) {
+        return NYql::NUdf::TUnboxedValuePod();
+    }
+    throw yexception() << "Can't cast " << PyObjectRepr(value) << " to null.";
+}
+
 } // namespace
 
 TPyObjectPtr ToPyObject(
@@ -832,6 +853,7 @@ TPyObjectPtr ToPyObject(
         case NUdf::ETypeKind::Void: return ToPyVoid(ctx, type, value);
         case NUdf::ETypeKind::Stream: return ToPyStream(ctx, type, value);
         case NUdf::ETypeKind::Variant: return ToPyVariant(ctx, type, value);
+        case NUdf::ETypeKind::Null: return ToPyNull(ctx, type, value);
         default: {
             ::TStringBuilder sb;
             sb << "Failed to export: ";
@@ -857,6 +879,7 @@ NUdf::TUnboxedValue FromPyObject(
         case NUdf::ETypeKind::Void: return FromPyVoid(ctx, type, value);
         case NUdf::ETypeKind::Stream: return FromPyStream(ctx, type, TPyObjectPtr(value, TPyObjectPtr::ADD_REF), nullptr, nullptr, nullptr);
         case NUdf::ETypeKind::Variant: return FromPyVariant(ctx, type, value);
+        case NUdf::ETypeKind::Null: return FromPyNull(ctx, type, value);
         default: {
             ::TStringBuilder sb;
             sb << "Failed to import: ";