Intermediate changes

1 files changed, 72 insertions, 0 deletions

diff --git a/library/cpp/yt/misc/optional.h b/library/cpp/yt/misc/optional.h
new file mode 100644
index 0000000000..cfae5c36d5
--- /dev/null
+++ b/library/cpp/yt/misc/optional.h
@@ -0,0 +1,72 @@
+#pragma once
+
+#include <util/string/cast.h>
+
+#include <optional>
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <class T>
+struct TOptionalTraits
+{
+    using TOptional = std::optional<T>;
+    using TValue = T;
+};
+
+template <class T>
+struct TOptionalTraits<std::optional<T>>
+{
+    using TOptional = std::optional<T>;
+    using TValue = T;
+};
+
+template <class T>
+struct TOptionalTraits<T*>
+{
+    using TOptional = T*;
+    using TValue = T*;
+};
+
+template <class T>
+struct TOptionalTraits<TIntrusivePtr<T>>
+{
+    using TOptional = TIntrusivePtr<T>;
+    using TValue = TIntrusivePtr<T>;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+template <class T>
+struct TStdOptionalTraits
+{
+    static constexpr bool IsStdOptional = false;
+    using TValueType = T;
+};
+
+template <class T>
+struct TStdOptionalTraits<std::optional<T>>
+{
+    static constexpr bool IsStdOptional = true;
+    using TValueType = T;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT
+
+template <class T>
+TString ToString(const std::optional<T>& nullable)
+{
+    return nullable ? ToString(*nullable) : "<Null>";
+}
+
+template <class T>
+struct THash<std::optional<T>>
+{
+    size_t operator()(const std::optional<T>& nullable) const
+    {
+        return nullable ? THash<T>()(*nullable) : 0;
+    }
+};