From 137013265ea10fd8a99ae76e9d075592bc05d953 Mon Sep 17 00:00:00 2001
From: babenko <babenko@yandex-team.com>
Date: Fri, 3 Jul 2026 16:17:12 +0300
Subject: Add TAnyObject::Holds<T> and rename IsCurrentlyStored to HoldsType
 commit_hash:5f0c248f2c24b501b04777fb0300693b0e942c89

---
 library/cpp/yt/memory/type_erasure.h               | 18 ++++++++++++----
 library/cpp/yt/memory/type_erasure_detail.h        |  6 +++---
 .../cpp/yt/memory/unittests/type_erasure_ut.cpp    | 24 ++++++++++++++++++++++
 3 files changed, 41 insertions(+), 7 deletions(-)

(limited to 'library/cpp')

diff --git a/library/cpp/yt/memory/type_erasure.h b/library/cpp/yt/memory/type_erasure.h
index 8d87a347b45..3b2dbe34015 100644
--- a/library/cpp/yt/memory/type_erasure.h
+++ b/library/cpp/yt/memory/type_erasure.h
@@ -94,7 +94,7 @@ public:
     T& AnyCast() &
     {
         const auto& vtable = GetVTable();
-        if (!vtable.IsValid() || !vtable.template IsCurrentlyStored<T>()) {
+        if (!vtable.IsValid() || !vtable.template HoldsType<T>()) {
             throw TBadAnyCast{};
         }
 
@@ -106,7 +106,7 @@ public:
     const T& AnyCast() const &
     {
         const auto& vtable = Holder_.GetVTable();
-        if (!vtable.IsValid() || !vtable.template IsCurrentlyStored<T>()) {
+        if (!vtable.IsValid() || !vtable.template HoldsType<T>()) {
             throw TBadAnyCast{};
         }
 
@@ -306,7 +306,7 @@ public:
         using TWrapped = TOwningWrapper<TDecayed, TStorage, EnableCopy, TCpos...>;
 
         const auto& vtable = GetVTable();
-        if (!vtable.IsValid() || !vtable.template IsCurrentlyStored<TWrapped>()) {
+        if (!vtable.IsValid() || !vtable.template HoldsType<TWrapped>()) {
             throw TBadAnyCast{};
         }
 
@@ -320,13 +320,23 @@ public:
         using TWrapped = TOwningWrapper<TDecayed, TStorage, EnableCopy, TCpos...>;
 
         const auto& vtable = GetVTable();
-        if (!vtable.IsValid() || !vtable.template IsCurrentlyStored<TWrapped>()) {
+        if (!vtable.IsValid() || !vtable.template HoldsType<TWrapped>()) {
             throw TBadAnyCast{};
         }
 
         return Storage_.template As<TWrapped>().Unwrap();
     }
 
+    template <class T>
+    Y_FORCE_INLINE bool Holds() const
+    {
+        using TDecayed = std::remove_cvref_t<T>;
+        using TWrapped = TOwningWrapper<TDecayed, TStorage, EnableCopy, TCpos...>;
+
+        const auto& vtable = GetVTable();
+        return vtable.IsValid() && vtable.template HoldsType<TWrapped>();
+    }
+
     Y_FORCE_INLINE bool IsValid() const
     {
         return Holder_.IsValid();
diff --git a/library/cpp/yt/memory/type_erasure_detail.h b/library/cpp/yt/memory/type_erasure_detail.h
index 92904573d01..76b611a2d67 100644
--- a/library/cpp/yt/memory/type_erasure_detail.h
+++ b/library/cpp/yt/memory/type_erasure_detail.h
@@ -304,7 +304,7 @@ public:
     // NB(arkady-e1ppa): This method may or may not work correctly
     // for dynamically-linked libraries.
     template <class T>
-    Y_FORCE_INLINE bool IsCurrentlyStored() const noexcept
+    Y_FORCE_INLINE bool HoldsType() const noexcept
     {
         return Function_ == &TVTableEntry::StaticInvoke<T>;
     }
@@ -358,9 +358,9 @@ public:
     }
 
     template <class T>
-    Y_FORCE_INLINE bool IsCurrentlyStored() const noexcept
+    Y_FORCE_INLINE bool HoldsType() const noexcept
     {
-        return TVTableEntry<TStorage, TCpo>::template IsCurrentlyStored<T>();
+        return TVTableEntry<TStorage, TCpo>::template HoldsType<T>();
     }
 
 private:
diff --git a/library/cpp/yt/memory/unittests/type_erasure_ut.cpp b/library/cpp/yt/memory/unittests/type_erasure_ut.cpp
index b33ab368023..c923ec29a11 100644
--- a/library/cpp/yt/memory/unittests/type_erasure_ut.cpp
+++ b/library/cpp/yt/memory/unittests/type_erasure_ut.cpp
@@ -23,6 +23,14 @@ struct TCustomized
     }
 };
 
+struct TOtherCustomized
+{
+    friend int TagInvoke(TTagInvokeTag<TestCpo>, const TOtherCustomized&)
+    {
+        return 0;
+    }
+};
+
 ////////////////////////////////////////////////////////////////////////////////
 
 // 2 CPOs won't trigger static vtable.
@@ -253,6 +261,22 @@ TEST(TAnyObjectTest, EmptyAny)
     EXPECT_EQ(conc.Value, 11);
 }
 
+TEST(TAnyObjectTest, Holds)
+{
+    using TAnyObject = TAnyObject<TOverload<TestCpo, int(const TErasedThis&)>>;
+
+    TAnyObject any{TCustomized{.Value = 42}};
+    EXPECT_TRUE(any.Holds<TCustomized>());
+    EXPECT_FALSE(any.Holds<TOtherCustomized>());
+
+    TAnyObject other{TOtherCustomized{}};
+    EXPECT_TRUE(other.Holds<TOtherCustomized>());
+    EXPECT_FALSE(other.Holds<TCustomized>());
+
+    TAnyObject empty;
+    EXPECT_FALSE(empty.Holds<TCustomized>());
+}
+
 TEST(TAnyObjectTest, CvRefCorrectness)
 {
     using TAnyObject = TAnyObject<
-- 
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