Add polymorphism support to Ref

src/reference.hpp

@@ -135,6 +135,18 @@ template <typename T> struct Ref {
     }
   }
 
+  /**
+   * @brief Converting copy constructor for polymorphism (Derived -> Base)
+   */
+  template <typename U>
+  Ref(const Ref<U> &other) noexcept
+    requires std::is_convertible_v<U *, T *>
+      : ptr(other.ptr), control_block(other.control_block) {
+    if (control_block) {
+      control_block->increment_strong();
+    }
+  }
+
   /**
    * @brief Copy assignment operator
    */
@@ -150,6 +162,22 @@ template <typename T> struct Ref {
     return *this;
   }
 
+  /**
+   * @brief Converting assignment operator for polymorphism (Derived -> Base)
+   */
+  template <typename U>
+  Ref &operator=(const Ref<U> &other) noexcept
+    requires std::is_convertible_v<U *, T *>
+  {
+    release();
+    ptr = other.ptr;
+    control_block = other.control_block;
+    if (control_block) {
+      control_block->increment_strong();
+    }
+    return *this;
+  }
+
   /**
    * @brief Move constructor - transfers ownership
    */
@@ -159,6 +187,17 @@ template <typename T> struct Ref {
     other.control_block = nullptr;
   }
 
+  /**
+   * @brief Converting move constructor for polymorphism (Derived -> Base)
+   */
+  template <typename U>
+  Ref(Ref<U> &&other) noexcept
+    requires std::is_convertible_v<U *, T *>
+      : ptr(other.ptr), control_block(other.control_block) {
+    other.ptr = nullptr;
+    other.control_block = nullptr;
+  }
+
   /**
    * @brief Move assignment operator
    */
@@ -173,6 +212,22 @@ template <typename T> struct Ref {
     return *this;
   }
 
+  /**
+   * @brief Converting move assignment operator for polymorphism (Derived ->
+   * Base)
+   */
+  template <typename U>
+  Ref &operator=(Ref<U> &&other) noexcept
+    requires std::is_convertible_v<U *, T *>
+  {
+    release();
+    ptr = other.ptr;
+    control_block = other.control_block;
+    other.ptr = nullptr;
+    other.control_block = nullptr;
+    return *this;
+  }
+
   /**
    * @brief Reset to empty state
    */
@@ -233,6 +288,7 @@ private:
   friend Ref<U> make_ref(Args &&...args);
 
   template <typename U> friend struct WeakRef;
+  template <typename U> friend struct Ref;
 };
 
 /**
@@ -302,6 +358,83 @@ template <typename T> struct WeakRef {
     }
   }
 
+  /**
+   * @brief Converting copy constructor from WeakRef for polymorphism
+   */
+  template <typename U>
+  WeakRef(const WeakRef<U> &other) noexcept
+    requires std::is_convertible_v<U *, T *>
+      : control_block(other.control_block) {
+    if (control_block) {
+      control_block->increment_weak();
+    }
+  }
+
+  /**
+   * @brief Converting copy constructor from Ref for polymorphism
+   */
+  template <typename U>
+  WeakRef(const Ref<U> &ref) noexcept
+    requires std::is_convertible_v<U *, T *>
+      : control_block(ref.control_block) {
+    if (control_block) {
+      control_block->increment_weak();
+    }
+  }
+
+  /**
+   * @brief Converting copy assignment from WeakRef for polymorphism
+   */
+  template <typename U>
+  WeakRef &operator=(const WeakRef<U> &other) noexcept
+    requires std::is_convertible_v<U *, T *>
+  {
+    release();
+    control_block = other.control_block;
+    if (control_block) {
+      control_block->increment_weak();
+    }
+    return *this;
+  }
+
+  /**
+   * @brief Converting copy assignment from Ref for polymorphism
+   */
+  template <typename U>
+  WeakRef &operator=(const Ref<U> &ref) noexcept
+    requires std::is_convertible_v<U *, T *>
+  {
+    release();
+    control_block = ref.control_block;
+    if (control_block) {
+      control_block->increment_weak();
+    }
+    return *this;
+  }
+
+  /**
+   * @brief Converting move constructor from WeakRef for polymorphism
+   */
+  template <typename U>
+  WeakRef(WeakRef<U> &&other) noexcept
+    requires std::is_convertible_v<U *, T *>
+      : control_block(other.control_block) {
+    other.control_block = nullptr;
+  }
+
+  /**
+   * @brief Converting move assignment from WeakRef for polymorphism
+   */
+  template <typename U>
+  WeakRef &operator=(WeakRef<U> &&other) noexcept
+    requires std::is_convertible_v<U *, T *>
+  {
+    release();
+    control_block = other.control_block;
+    other.control_block = nullptr;
+    return *this;
+  }
+
   /**
    * @brief Copy assignment from WeakRef
    */
@@ -393,6 +526,7 @@ private:
   }
 
   template <typename U> friend struct Ref;
+  template <typename U> friend struct WeakRef;
 };
 
 /**