From 2d2362d85c9e05e4b5660904b9fb5a7794bad079 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Wed, 23 Aug 2023 00:04:05 +0300
Subject: [PATCH] More util::uuid functions: create from string, check
 for/convert to RFC 4122

---
 libs/util/include/psemek/util/uuid.hpp | 53 +++++++++++++++++++++++++-
 libs/util/source/uuid.cpp              | 24 ++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)
 create mode 100644 libs/util/source/uuid.cpp

diff --git a/libs/util/include/psemek/util/uuid.hpp b/libs/util/include/psemek/util/uuid.hpp
index 980ea8b8..e4b6881b 100644
--- a/libs/util/include/psemek/util/uuid.hpp
+++ b/libs/util/include/psemek/util/uuid.hpp
@@ -4,15 +4,66 @@
 
 #include <array>
 #include <cstdint>
+#include <string_view>
+#include <iostream>
 
 namespace psemek::util
 {
 
-	using uuid = std::array<std::uint64_t, 2>;
+	struct uuid
+	{
+		std::uint64_t values[2];
+
+		constexpr std::uint64_t & operator[](std::size_t i)
+		{
+			return values[i];
+		}
+
+		constexpr std::uint64_t const & operator[](std::size_t i) const
+		{
+			return values[i];
+		}
+
+		constexpr friend bool operator == (uuid const &, uuid const &) = default;
+		constexpr friend std::strong_ordering operator <=> (uuid const &, uuid const &) = default;
+	};
 
 	static_assert(sizeof(uuid) == 16);
 	static_assert(alignof(uuid) == 8);
 
+	constexpr bool is_rfc_4122(uuid const & uuid)
+	{
+		return ((uuid[0] & 0x00f0000000000000ull) == 0x0040000000000000ull)
+			&& ((uuid[1] & 0x00000000000000c0ull) == 0x0000000000000080ull);
+	}
+
+	constexpr uuid make_rfc_4122(uuid uuid)
+	{
+		uuid[0] = (uuid[0] & 0xff0fffffffffffffull) | 0x0040000000000000ull;
+		uuid[1] = (uuid[1] & 0xffffffffffffff3full) | 0x0000000000000080ull;
+		return uuid;
+	}
+
+	// TODO: use SHA-1 or something like that?
+	constexpr uuid make_uuid(std::string_view str)
+	{
+		struct char_hash
+		{
+			constexpr std::size_t operator()(char c) const noexcept
+			{
+				return static_cast<std::size_t>(c);
+			}
+		};
+
+		uuid result{0x6eb49abceae6db24ull, 0x476c4c69fd7925a7ull};
+		hash_sequence(result[0], str.begin(), str.end(), char_hash{});
+		hash_sequence(result[1], str.begin(), str.end(), char_hash{});
+		make_rfc_4122(result);
+		return result;
+	}
+
+	std::ostream & operator << (std::ostream & os, uuid const & uuid);
+
 }
 
 namespace std
diff --git a/libs/util/source/uuid.cpp b/libs/util/source/uuid.cpp
new file mode 100644
index 00000000..1505ebf6
--- /dev/null
+++ b/libs/util/source/uuid.cpp
@@ -0,0 +1,24 @@
+#include <psemek/util/uuid.hpp>
+
+#include <iomanip>
+
+namespace psemek::util
+{
+
+	std::ostream & operator << (std::ostream & os, uuid const & uuid)
+	{
+		os << std::hex << std::setfill('0') << std::left;
+		os << std::setw(8)  <<  (uuid[0] & 0x00000000ffffffffull);
+		os << std::setw(1) << '-';
+		os << std::setw(4)  << ((uuid[0] & 0x0000ffff00000000ull) >> 32);
+		os << std::setw(1) << '-';
+		os << std::setw(4)  << ((uuid[0] & 0xffff000000000000ull) >> 48);
+		os << std::setw(1) << '-';
+		os << std::setw(4)  <<  (uuid[1] & 0x000000000000ffffull);
+		os << std::setw(1) << '-';
+		os << std::setw(12) << ((uuid[1] & 0xffffffffffff0000ull) >> 16);
+
+		return os;
+	}
+
+}