Intermediate changes

commit_hash:ec4f52d7356d9851e370b5086e73fc1c2299884f

3 files changed, 170 insertions, 13 deletions

diff --git a/yt/yt/core/ytree/polymorphic_yson_struct-inl.h b/yt/yt/core/ytree/polymorphic_yson_struct-inl.h
index b9ea6afaf45..ed0352c2438 100644
--- a/yt/yt/core/ytree/polymorphic_yson_struct-inl.h
+++ b/yt/yt/core/ytree/polymorphic_yson_struct-inl.h
@@ -18,10 +18,10 @@ TIntrusivePtr<TBase> TMappingLeaf<TEnum, Value, TBase, TDerived>::CreateInstance
     return New<TDerived>();
 }
 
-template <class TEnum, TEnum BaseValue, CYsonStructDerived TBase, TEnum... Values, class... TDerived>
+template <class TEnum, TEnum... DefaultValue, TEnum BaseValue, CYsonStructDerived TBase, TEnum... Values, class... TDerived>
     requires (CHierarchy<TBase, TDerived...>)
 TIntrusivePtr<TBase>
-TPolymorphicMapping<TEnum, TLeafTag<BaseValue, TBase>, TLeafTag<Values, TDerived>...>::
+TPolymorphicMapping<TEnum, TOptionalValue<TEnum, DefaultValue...>, TLeafTag<BaseValue, TBase>, TLeafTag<Values, TDerived>...>::
 CreateInstance(TEnum value)
 {
     if (value == BaseValue) {
@@ -84,10 +84,12 @@ void TPolymorphicYsonStruct<TMapping>::Load(
 
     auto key = map->FindChildValue<TKey>("type");
     THROW_ERROR_EXCEPTION_UNLESS(
-        key.has_value(),
-        "Concrete type must be specified! Use \"type\": \"concrete_type\"");
+        key.has_value() || DefaultType_,
+        "Concrete type must be specified! Use \"type\": \"concrete_type\" or specify default type");
 
-    auto type = *key;
+    auto type = key
+        ? *key
+        : *DefaultType_;
     if (!Storage_ || HeldType_ != type) {
         // NB: We will try to merge configs if types match.
         HeldType_ = type;
@@ -207,7 +209,9 @@ void Deserialize(TPolymorphicYsonStruct<TMapping>& value, TSource source)
 ////////////////////////////////////////////////////////////////////////////////
 
 #undef DEFINE_POLYMORPHIC_YSON_STRUCT
+#undef DEFINE_POLYMORPHIC_YSON_STRUCT_WITH_DEFAULT
 #undef DEFINE_POLYMORPHIC_YSON_STRUCT_FOR_ENUM
+#undef DEFINE_POLYMORPHIC_YSON_STRUCT_FOR_ENUM_WITH_DEFAULT
 
 #define POLYMORPHIC_YSON_STRUCT_IMPL__GET_ENUM_SEQ_ELEM(item) \
     PP_LEFT_PARENTHESIS PP_ELEMENT(item, 0) PP_RIGHT_PARENTHESIS
@@ -231,11 +235,21 @@ void Deserialize(TPolymorphicYsonStruct<TMapping>& value, TSource source)
     PP_COMMA() ::NYT::NYTree::NDetail::TLeafTag<EType:: PP_ELEMENT(item, 0), PP_ELEMENT(item, 1)>
 
 #define POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_CLASS(Struct, seq) \
-    using TMapping = ::NYT::NYTree::TPolymorphicEnumMapping<EType PP_FOR_EACH(POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_LEAF_FROM_ETYPE, seq)>
+    using TMapping = ::NYT::NYTree::TPolymorphicEnumMapping< \
+        EType, \
+        ::NYT::NYTree::NDetail::TOptionalValue<EType> \
+        PP_FOR_EACH(POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_LEAF_FROM_ETYPE, seq) \
+    >
+
+#define POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_CLASS_WITH_DEFAULT(Struct, default, seq) \
+    using TMapping = ::NYT::NYTree::TPolymorphicEnumMapping< \
+        EType, \
+        ::NYT::NYTree::NDetail::TOptionalValue<EType, default> \
+        PP_FOR_EACH(POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_LEAF_FROM_ETYPE, seq) \
+    >
 
 #define DEFINE_POLYMORPHIC_YSON_STRUCT(name, seq) \
 namespace NPolymorphicYsonStructFor##name { \
- \
     POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_ENUM(seq); \
     POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_CLASS(name, seq); \
 } /*NPolymorphicYsonStructFor##name*/ \
@@ -243,6 +257,15 @@ using POLYMORPHIC_YSON_STRUCT_IMPL__ENUM_NAME(name) = NPolymorphicYsonStructFor#
 using T##name = ::NYT::NYTree::TPolymorphicYsonStruct<NPolymorphicYsonStructFor##name::TMapping>; \
 static_assert(true)
 
+#define DEFINE_POLYMORPHIC_YSON_STRUCT_WITH_DEFAULT(name, default, seq) \
+namespace NPolymorphicYsonStructFor##name { \
+    POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_ENUM(seq); \
+    POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_CLASS_WITH_DEFAULT(name, EType::default, seq); \
+} /*NPolymorphicYsonStructFor##name*/ \
+using POLYMORPHIC_YSON_STRUCT_IMPL__ENUM_NAME(name) = NPolymorphicYsonStructFor##name::EType; \
+using T##name = ::NYT::NYTree::TPolymorphicYsonStruct<NPolymorphicYsonStructFor##name::TMapping>; \
+static_assert(true)
+
 #define DEFINE_POLYMORPHIC_YSON_STRUCT_FOR_ENUM(name, enum, seq) \
 namespace NPolymorphicYsonStructFor##name { \
     POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_ENUM_ALIAS(enum); \
@@ -251,6 +274,14 @@ namespace NPolymorphicYsonStructFor##name { \
 using T##name = ::NYT::NYTree::TPolymorphicYsonStruct<NPolymorphicYsonStructFor##name::TMapping>; \
 static_assert(true)
 
+#define DEFINE_POLYMORPHIC_YSON_STRUCT_FOR_ENUM_WITH_DEFAULT(name, enum, default, seq) \
+namespace NPolymorphicYsonStructFor##name { \
+    POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_ENUM_ALIAS(enum); \
+    POLYMORPHIC_YSON_STRUCT_IMPL__MAKE_MAPPING_CLASS_WITH_DEFAULT(name, EType::default, seq); \
+} /*NPolymorphicYsonStructFor##name*/ \
+using T##name = ::NYT::NYTree::TPolymorphicYsonStruct<NPolymorphicYsonStructFor##name::TMapping>; \
+static_assert(true)
+
 ////////////////////////////////////////////////////////////////////////////////
 
 } // namespace NYT::NYTree
diff --git a/yt/yt/core/ytree/polymorphic_yson_struct.h b/yt/yt/core/ytree/polymorphic_yson_struct.h
index ee4732fa8e7..50c4b206380 100644
--- a/yt/yt/core/ytree/polymorphic_yson_struct.h
+++ b/yt/yt/core/ytree/polymorphic_yson_struct.h
@@ -59,12 +59,27 @@ struct TMappingLeaf
     friend TDerived EnumToDerivedMethod(TFactoryTag<Value>, TMappingLeaf*);
 };
 
-template <class TEnum, class... TLeafTags>
+template <class T, T... Value>
+struct TOptionalValue;
+
+template <class T>
+struct TOptionalValue<T>
+{
+    static constexpr std::optional<T> OptionalValue;
+};
+
+template <class T, T Value>
+struct TOptionalValue<T, Value>
+{
+    static constexpr std::optional<T> OptionalValue = Value;
+};
+
+template <class TEnum, class TDefaultEnumValue, class... TLeafTags>
 struct TPolymorphicMapping;
 
-template <class TEnum, TEnum BaseValue, CYsonStructDerived TBase, TEnum... Values, class... TDerived>
+template <class TEnum, TEnum... DefaultValue, TEnum BaseValue, CYsonStructDerived TBase, TEnum... Values, class... TDerived>
     requires (CHierarchy<TBase, TDerived...>)
-struct TPolymorphicMapping<TEnum, TLeafTag<BaseValue, TBase>, TLeafTag<Values, TDerived>...>
+struct TPolymorphicMapping<TEnum, TOptionalValue<TEnum, DefaultValue...>, TLeafTag<BaseValue, TBase>, TLeafTag<Values, TDerived>...>
     : public TMappingLeaf<TEnum, BaseValue, TBase, TBase>
     , public TMappingLeaf<TEnum, Values, TBase, TDerived>...
 {
@@ -77,6 +92,8 @@ struct TPolymorphicMapping<TEnum, TLeafTag<BaseValue, TBase>, TLeafTag<Values, T
     using TKey = TEnum;
     using TBaseClass = TBase;
 
+    static constexpr auto DefaultEnumValue = TOptionalValue<TEnum, DefaultValue...>::OptionalValue;
+
     static TIntrusivePtr<TBase> CreateInstance(TEnum value);
 };
 
@@ -84,7 +101,7 @@ struct TPolymorphicMapping<TEnum, TLeafTag<BaseValue, TBase>, TLeafTag<Values, T
 
 template <class T>
 constexpr bool IsMapping = requires (T t) {
-    [] <class TEnum, class... TLeafTags> (TPolymorphicMapping<TEnum, TLeafTags...>) {
+    [] <class TEnum, class TDefaultEnumValue, class... TLeafTags> (TPolymorphicMapping<TEnum, TDefaultEnumValue, TLeafTags...>) {
     } (t);
 };
 
@@ -97,8 +114,8 @@ constexpr bool IsMapping = requires (T t) {
 template <class TBase, class... TDerived>
 concept CHierarchy = NDetail::CHierarchy<TBase, TDerived...>;
 
-template <class TEnum, class... TLeafTags>
-using TPolymorphicEnumMapping = NDetail::TPolymorphicMapping<TEnum, TLeafTags...>;
+template <class TEnum, class TDefaultEnumValue, class... TLeafTags>
+using TPolymorphicEnumMapping = NDetail::TPolymorphicMapping<TEnum, TDefaultEnumValue, TLeafTags...>;
 
 template <class T>
 concept CPolymorphicEnumMapping = NDetail::IsMapping<T>;
@@ -182,6 +199,8 @@ private:
     INodePtr SerializedStorage_;
     TKey HeldType_;
 
+    static constexpr auto DefaultType_ = TMapping::DefaultEnumValue;
+
     void PrepareInstance(INodePtr& node);
 };
 
@@ -202,6 +221,13 @@ void Deserialize(TPolymorphicYsonStruct<TMapping>& value, TSource source);
         ((Derived1) (TDerivedStruct1))
         ((Derived2) (TDerivedStruct2))
     );
+    or
+    DEFINE_POLYMORPHIC_YSON_STRUCT_WITH_DEFAULT(Struct, Derived1,
+        ((Base)     (TBaseStruct))
+        ((Derived1) (TDerivedStruct1))
+        ((Derived2) (TDerivedStruct2))
+    );
+
     .....TypeName.....ActualTypeName
 
     Macro generates two names:
@@ -211,6 +237,7 @@ void Deserialize(TPolymorphicYsonStruct<TMapping>& value, TSource source);
     hierarchy members. They are keys in serialization.
 */
 #define DEFINE_POLYMORPHIC_YSON_STRUCT(name, seq)
+#define DEFINE_POLYMORPHIC_YSON_STRUCT_WITH_DEFAULT(name, default, seq)
 
 //! Usage:
 /*
@@ -223,6 +250,11 @@ void Deserialize(TPolymorphicYsonStruct<TMapping>& value, TSource source);
         ((Pear)  (TPearClass))
         ((Apple) (TAppleClass))
     )
+    or
+    DEFINE_POLYMORPHIC_YSON_STRUCT_FOR_ENUM_WITH_DEFAULT(Struct, EMyEnum, Apple,
+        ((Pear)  (TPearClass))
+        ((Apple) (TAppleClass))
+    )
 
     // NB(arkady-e1ppa): enum names in the list must be unqualified! E.g.
 
@@ -234,6 +266,7 @@ void Deserialize(TPolymorphicYsonStruct<TMapping>& value, TSource source);
     Will not compile
 */
 #define DEFINE_POLYMORPHIC_YSON_STRUCT_FOR_ENUM(name, enum, seq)
+#define DEFINE_POLYMORPHIC_YSON_STRUCT_FOR_ENUM_WITH_DEFAULT(name, enum, default, seq)
 
 ////////////////////////////////////////////////////////////////////////////////
 
diff --git a/yt/yt/core/ytree/unittests/yson_struct_ut.cpp b/yt/yt/core/ytree/unittests/yson_struct_ut.cpp
index aaed3fd853b..8e708cc2ed0 100644
--- a/yt/yt/core/ytree/unittests/yson_struct_ut.cpp
+++ b/yt/yt/core/ytree/unittests/yson_struct_ut.cpp
@@ -3459,6 +3459,99 @@ TEST(TYsonStructTest, TestPolymorphicYsonStructMergeIfPossible)
     EXPECT_EQ(drv1Ptr->Field1, 18);
 }
 
+DEFINE_POLYMORPHIC_YSON_STRUCT_WITH_DEFAULT(MyPolyDefault, Drv1,
+    ((Base) (TPolyBase))
+    ((Drv1) (TPolyDerived1))
+    ((Drv2) (TPolyDerived2))
+);
+
+TEST(TYsonStructTest, TestPolymorphicYsonStructDefault)
+{
+    TMyPolyDefault poly;
+
+    auto node = BuildYsonNodeFluently()
+        .BeginMap()
+            .Item("base_field").Value(11)
+            .Item("field1").Value(123)
+        .EndMap();
+
+    Deserialize(poly, node->AsMap());
+    EXPECT_EQ(poly.GetCurrentType(), EMyPolyDefaultType::Drv1);
+
+    auto drv1Ptr = poly.TryGetConcrete<TPolyDerived1>();
+    EXPECT_TRUE(drv1Ptr.operator bool());
+    EXPECT_EQ(drv1Ptr->BaseField, 11);
+    EXPECT_EQ(drv1Ptr->Field1, 123);
+
+    node = BuildYsonNodeFluently()
+        .BeginMap()
+            .Item("type").Value("drv2")
+            .Item("base_field").Value(14)
+            .Item("field2").Value(111)
+        .EndMap();
+
+    Deserialize(poly, node->AsMap());
+    EXPECT_EQ(poly.GetCurrentType(), EMyPolyDefaultType::Drv2);
+
+    node = BuildYsonNodeFluently()
+    .BeginMap()
+        .Item("base_field").Value(11)
+        .Item("field1").Value(123)
+    .EndMap();
+
+    Deserialize(poly, node->AsMap());
+    EXPECT_EQ(poly.GetCurrentType(), EMyPolyDefaultType::Drv1);
+}
+
+DEFINE_ENUM(EMyPolyDefaultEnum,
+    (Base)
+    (Drv1)
+    (Drv2)
+);
+
+DEFINE_POLYMORPHIC_YSON_STRUCT_FOR_ENUM_WITH_DEFAULT(MyPolyDefaultEnum, EMyPolyDefaultEnum, Base,
+    ((Base) (TPolyBase))
+    ((Drv1) (TPolyDerived1))
+    ((Drv2) (TPolyDerived2))
+);
+
+TEST(TYsonStructTest, TestPolymorphicYsonStructDefaultEnum)
+{
+    TMyPolyDefaultEnum poly;
+
+    auto node = BuildYsonNodeFluently()
+        .BeginMap()
+            .Item("base_field").Value(11)
+            .Item("field1").Value(123)
+        .EndMap();
+
+    Deserialize(poly, node->AsMap());
+    EXPECT_EQ(poly.GetCurrentType(), EMyPolyDefaultEnum::Base);
+
+    auto basePtr = poly.TryGetConcrete<TPolyBase>();
+    EXPECT_TRUE(basePtr.operator bool());
+    EXPECT_EQ(basePtr->BaseField, 11);
+
+    node = BuildYsonNodeFluently()
+        .BeginMap()
+            .Item("type").Value("drv1")
+            .Item("base_field").Value(14)
+            .Item("field1").Value(111)
+        .EndMap();
+
+    Deserialize(poly, node->AsMap());
+    EXPECT_EQ(poly.GetCurrentType(), EMyPolyDefaultEnum::Drv1);
+
+    node = BuildYsonNodeFluently()
+    .BeginMap()
+        .Item("base_field").Value(11)
+        .Item("field1").Value(123)
+    .EndMap();
+
+    Deserialize(poly, node->AsMap());
+    EXPECT_EQ(poly.GetCurrentType(), EMyPolyDefaultEnum::Base);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 struct TPolyHolder