feat(lib): add equiv.hpp C++ header, see commit details.

Signed-off-by: Amlal <amlal@nekernel.org>

1 files changed, 101 insertions, 0 deletions

diff --git a/lib/astdx/equiv.hpp b/lib/astdx/equiv.hpp
new file mode 100644
index 0000000..73e63b3
--- /dev/null
+++ b/lib/astdx/equiv.hpp
@@ -0,0 +1,101 @@
+/*
+ * File: equiv.hpp
+ * Purpose: equivalence runtime c++ header.
+ * Author: Amlal El Mahrouss (amlal@nekernel.org)
+ * Copyright 2025, Amlal El Mahrouss all rights reserved.
+ */
+
+#pragma once
+
+namespace astdx
+{
+	template <typename T>
+	struct basic_hash_trait
+	{
+		/// @brief hash from T's result.
+		static typename T::result hash()
+		{
+			static T val;
+			return val.hash();
+		}
+	};
+
+	template <typename T, typename U>
+	struct is_same
+	{
+		static constexpr bool value = false;
+
+		/// @brief check if hash matches what we expect.
+		constexpr bool operator()() noexcept
+		{
+			return T::hash() == U::hash();
+		}
+	};
+
+	template <typename T>
+	struct is_same<T, T>
+	{
+		static constexpr bool value = true;
+	};
+
+	template <typename T, typename U>
+	struct is_not_same
+	{
+		static constexpr bool value = true;
+
+		constexpr bool operator()() noexcept
+		{
+			return T::hash() != U::hash();
+		}
+	};
+	template <typename T>
+	struct is_not_same<T, T>
+	{
+		static constexpr bool value = false;
+	};
+
+	template <typename T>
+	struct equiv_is_int8
+	{
+	private:
+		T left_ = 255, right_ = 255;
+
+	public:
+		using result = T;
+
+		constexpr result hash()
+		{
+			return (left_ + right_) < 1;
+		}
+	};
+
+	template <typename T>
+	struct equiv_not_int8
+	{
+	private:
+		T left_ = 255, right_ = 255;
+
+	public:
+		using result = T;
+
+		constexpr result hash()
+		{
+			return (left_ + right_) > 0;
+		}
+	};
+
+	template <typename T>
+	struct equiv_is_real
+	{
+	private:
+		T left_ = 5, right_ = 3;
+
+	public:
+		using result = T;
+
+		constexpr result hash()
+		{
+			return left_ / right_;
+		}
+	};
+} // namespace astdx
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