From f98e80b6e39882e46caa850ea10a4869418d30ae Mon Sep 17 00:00:00 2001
From: Stefan Boberg <stefan@boberg.org>
Date: Tue, 5 Oct 2021 21:06:44 +0200
Subject: Added Ref<> constructor which allows casting from derived types to
 parent types

---
 zencore/include/zencore/refcount.h | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'zencore')

diff --git a/zencore/include/zencore/refcount.h b/zencore/include/zencore/refcount.h
index 320718f5b..7167ab3b5 100644
--- a/zencore/include/zencore/refcount.h
+++ b/zencore/include/zencore/refcount.h
@@ -4,6 +4,8 @@
 #include "atomic.h"
 #include "zencore.h"
 
+#include <concepts>
+
 namespace zen {
 
 /**
@@ -114,6 +116,10 @@ public:
 	inline Ref(T* Ptr) : m_Ref(Ptr) { m_Ref && m_Ref->AddRef(); }
 	inline ~Ref() { m_Ref && m_Ref->Release(); }
 
+	template<typename DerivedType>
+	requires std::derived_from<DerivedType, T>
+	inline Ref(const Ref<DerivedType>& Rhs) : Ref(Rhs.m_Ref) {}
+
 	[[nodiscard]] inline bool IsNull() const { return m_Ref == nullptr; }
 	inline explicit			  operator bool() const { return m_Ref != nullptr; }
 	inline T*				  operator->() const { return m_Ref; }
@@ -152,6 +158,9 @@ public:
 
 private:
 	T* m_Ref = nullptr;
+
+	template<class T>
+	friend class Ref;
 };
 
 void refcount_forcelink();
-- 
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