Introduce TEnumIndexedArray as a refurbished version of TEnumIndexedVector

1 files changed, 64 insertions, 0 deletions

diff --git a/library/cpp/yt/misc/enum_indexed_array.h b/library/cpp/yt/misc/enum_indexed_array.h
new file mode 100644
index 0000000000..8992456277
--- /dev/null
+++ b/library/cpp/yt/misc/enum_indexed_array.h
@@ -0,0 +1,64 @@
+#pragma once
+
+#include "enum.h"
+
+namespace NYT {
+
+////////////////////////////////////////////////////////////////////////////////
+
+//! A statically sized vector with elements of type |T| indexed by
+//! the items of enumeration type |E|.
+/*!
+ *  By default, valid indexes are in range from the minimum declared value of |E|
+ *  to the maximum declared value of |E|.
+ *
+ *  Items are value-initialized on construction.
+ */
+template <
+    class E,
+    class T,
+    E Min = TEnumTraits<E>::GetMinValue(),
+    E Max = TEnumTraits<E>::GetMaxValue()
+>
+class TEnumIndexedArray
+{
+public:
+    static_assert(Min <= Max);
+
+    using TIndex = E;
+    using TValue = T;
+
+    constexpr TEnumIndexedArray() = default;
+    TEnumIndexedArray(std::initializer_list<std::pair<E, T>> elements);
+
+    constexpr TEnumIndexedArray(const TEnumIndexedArray&) = default;
+    constexpr TEnumIndexedArray(TEnumIndexedArray&&) = default;
+
+    constexpr TEnumIndexedArray& operator=(const TEnumIndexedArray&) = default;
+    constexpr TEnumIndexedArray& operator=(TEnumIndexedArray&&) = default;
+
+    T& operator[] (E index);
+    const T& operator[] (E index) const;
+
+    // STL interop.
+    T* begin();
+    const T* begin() const;
+    T* end();
+    const T* end() const;
+
+    constexpr size_t size() const;
+
+    static bool IsValidIndex(E index);
+
+private:
+    static constexpr size_t Size = static_cast<size_t>(Max) - static_cast<size_t>(Min) + 1;
+    std::array<T, Size> Items_{};
+};
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NYT
+
+#define ENUM_INDEXED_ARRAY_INL_H_
+#include "enum_indexed_array-inl.h"
+#undef ENUM_INDEXED_ARRAY_INL_H_