Added epilogue

include/tl/epilogue.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "tl/functional.h"
+
+namespace tl
+{
+class epilogue
+{
+	public:
+
+	epilogue(function<void()> i_function) noexcept
+		: m_function(std::move(i_function))
+	{
+	}
+
+	~epilogue() noexcept
+	{
+		m_function();
+	}
+private:
+	function<void()> m_function;
+};
+
+}

include/tl/identifier.h

@@ -7,43 +7,46 @@
 namespace tl
 {
 
-template<typename T, typename Tag>
+template<typename T, T invalid_value, typename Tag>
 struct identifier
 {
 	using underlying_type = T;
 
-	identifier() = delete;
+	constexpr identifier() noexcept = default;
 	explicit constexpr identifier(T value) noexcept : m_value(std::move(value)) {}
 
 	constexpr T value() const noexcept { return m_value; }
-	auto operator<=>(const identifier<T, Tag>& other) const noexcept { return m_value <=> other.value(); }
+	constexpr bool is_valid() const noexcept { return m_value != invalid_value; }
+	//inline static identifier<T, invalid_value, Tag> invalid() noexcept { return identifier<T, invalid_value, Tag>(); }
+
+	auto operator<=>(const identifier<T, invalid_value, Tag>& other) const noexcept { return m_value <=> other.value(); }
 	auto operator<=>(const T& other) const noexcept { return m_value <=> other; }
-	bool operator==(const identifier<T, Tag>& other) const noexcept { return m_value == other.value(); }
+	bool operator==(const identifier<T, invalid_value, Tag>& other) const noexcept { return m_value == other.value(); }
 	bool operator==(const T& other) const noexcept { return m_value == other; }
 
 private:
-	T m_value;
+	T m_value = invalid_value;
 };
 }
 
-#define TL_DECLARE_INTEGRAL_ID(NAME, TYPE) \
+#define TL_DECLARE_INTEGRAL_ID(NAME, TYPE, INVALID_VALUE) \
 struct NAME##_tag {};\
-using NAME = tl::identifier<TYPE, NAME##_tag>;
+using NAME = tl::identifier<TYPE, INVALID_VALUE, NAME##_tag>;
 
-template <typename T, typename Tag>
-struct std::formatter<tl::identifier<T, Tag>>
+template <typename T, T invalid_value, typename Tag>
+struct std::formatter<tl::identifier<T, invalid_value, Tag>>
 {
 	constexpr auto parse(format_parse_context& ctx) noexcept { return ctx.begin(); }
-	auto format(const tl::identifier<T, Tag>& id, std::format_context& ctx) const
+	auto format(const tl::identifier<T, invalid_value, Tag>& id, std::format_context& ctx) const
 	{
 		return format_to(ctx.out(), "{}", id.value());
 	}
 };
 
-template<typename T, typename Tag>
-struct eastl::hash<tl::identifier<T, Tag>>
+template<typename T, T invalid_value, typename Tag>
+struct eastl::hash<tl::identifier<T, invalid_value, Tag>>
 {
-	size_t operator()(tl::identifier<T, Tag> const& id) const
+	size_t operator()(tl::identifier<T, invalid_value, Tag> const& id) const
 	{
 		return hash<T>()(id.value());
 	}