Add std::optional serialization

libs/sir/include/psemek/sir/optional.hpp

@@ -0,0 +1,33 @@
+#pragma once
+
+#include <psemek/sir/platform.hpp>
+#include <psemek/sir/stream.hpp>
+#include <psemek/sir/trivial.hpp>
+
+#include <optional>
+
+namespace psemek::sir
+{
+
+	template <typename Stream, typename T>
+	requires (is_ostream_v<Stream> && !is_custom_v<std::optional<T>>)
+	void write(Stream & s, std::optional<T> const & x)
+	{
+		write(s, static_cast<bool>(x));
+		if (x) write(s, *x);
+	}
+
+	template <typename Stream, typename T>
+	requires (is_istream_v<Stream> && !is_custom_v<std::optional<T>>)
+	void read(Stream & s, std::optional<T> & x)
+	{
+		bool initialized = false;
+		read(s, initialized);
+		if (initialized)
+		{
+			x.emplace();
+			read(s, *x);
+		}
+	}
+
+}