Add ManyPtr which tracks specified subclasses

This removes the need to repeated dynamic_cast the pointer.
Provides interface which enforces the fastest option for the required
types.

2 files changed, 88 insertions, 1 deletions

diff --git a/lib/manyPtr.h b/lib/manyPtr.h
new file mode 100644
index 0000000..9e08452
--- /dev/null
+++ b/lib/manyPtr.h
@@ -0,0 +1,86 @@
+#pragma once
+
+#include <memory>
+#include <tuple>
+
+template<typename Primary, typename... Others> class ManyPtr : Primary {
+public:
+	using element_type = typename Primary::element_type;
+
+	template<typename... Params> ManyPtr(Params &&... params) : Primary {std::forward<Params>(params)...}
+	{
+		updatePtrs();
+	}
+
+	using Primary::operator->;
+	using Primary::operator*;
+	using Primary::operator bool;
+	using Primary::get;
+
+	template<typename... Params>
+	void
+	reset(Params &&... params)
+	{
+		Primary::reset(std::forward<Params>(params)...);
+		updatePtrs();
+	}
+
+	template<typename Other>
+	[[nodiscard]] consteval static bool
+	couldBe()
+	{
+		return (std::is_convertible_v<Others *, Other *> || ...);
+	}
+
+	template<typename Other>
+		requires(couldBe<Other>())
+	[[nodiscard]] auto
+	getAs() const
+	{
+		return std::get<idx<Other>()>(others);
+	}
+
+	template<typename Other>
+		requires(!couldBe<Other>() && requires { std::dynamic_pointer_cast<Other>(std::declval<Primary>()); })
+	[[nodiscard]] auto
+	dynamicCast() const
+	{
+		return std::dynamic_pointer_cast<Other>(*this);
+	}
+
+	template<typename Other>
+		requires(!couldBe<Other>() && !requires { std::dynamic_pointer_cast<Other>(std::declval<Primary>()); })
+	[[nodiscard]] auto
+	dynamicCast() const
+	{
+		return dynamic_cast<Other *>(get());
+	}
+
+private:
+	using OtherPtrs = std::tuple<Others *...>;
+
+	template<typename Other>
+		requires(couldBe<Other>())
+	[[nodiscard]] consteval static bool
+	idx()
+	{
+		size_t typeIdx = 0;
+		return ((typeIdx++ && std::is_convertible_v<Others *, Other *>) || ...);
+	}
+
+	void
+	updatePtrs()
+	{
+		if (*this) {
+			others = {dynamic_cast<Others *>(get())...};
+		}
+		else {
+			others = {};
+		}
+	}
+
+	OtherPtrs others;
+};
+
+template<typename Primary, typename... Others> using ManySharedPtr = ManyPtr<std::shared_ptr<Primary>, Others...>;
+template<typename Primary, typename... Others> using ManyUniquePtr = ManyPtr<std::unique_ptr<Primary>, Others...>;
diff --git a/lib/persistence.h b/lib/persistence.h
index e385b20..75bcea6 100644
--- a/lib/persistence.h
+++ b/lib/persistence.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "manyPtr.h"
 #include <charconv>
 #include <format>
 #include <functional>
@@ -200,7 +201,7 @@ namespace Persistence {
 		}
 
 		[[nodiscard]] virtual NameActionSelection setName(const std::string_view key, SelectionFactory &&) = 0;
-		virtual void selHandler() {};
+		virtual void selHandler() { };
 		virtual void setType(const std::string_view, const Persistable *) = 0;
 
 		SelectionPtr sel {};