Add new shared pointer and make use of it

arm9/source/core/WeakPtr.h

@@ -0,0 +1,158 @@
+#pragma once
+#include <type_traits>
+#include "RefCount.h"
+#include "SharedPtr.h"
+
+class WeakPtrBase
+{
+public:
+    ~WeakPtrBase()
+    {
+        Reset();
+    }
+
+    void Reset()
+    {
+        if (_refCount)
+        {
+            Reset();
+        }
+    }
+
+protected:
+    RefCount* _refCount;
+
+    WeakPtrBase()
+        : _refCount(nullptr) { }
+
+    explicit WeakPtrBase(RefCount* refCount)
+        : _refCount(refCount) { }
+
+    void ResetIntern();
+    bool LockIntern() const;
+};
+
+template <class T>
+class WeakPtr : public WeakPtrBase
+{
+    template <class Y> friend class WeakPtr;
+    template <class Y> friend class EnableSharedFromThis;
+
+public:
+    WeakPtr() { }
+
+    WeakPtr(std::nullptr_t) { }
+
+    WeakPtr(const WeakPtr& other)
+        : WeakPtrBase(other._refCount), _object(other._object)
+    {
+        if (_refCount)
+        {
+            shared_ptr_increase_ref_count(_refCount->weakRefCount);
+        }
+    }
+
+    WeakPtr(WeakPtr&& other)
+        : WeakPtrBase(other._refCount), _object(other._object)
+    {
+        other._refCount = nullptr;
+        other._object = nullptr;
+    }
+
+    template <class Y> requires std::assignable_from<T*&, Y*>
+    WeakPtr(const SharedPtr<Y>& sharedPtr)
+        : WeakPtrBase(sharedPtr._refCount), _object(static_cast<T*>(sharedPtr.GetPointer()))
+    {
+        if (_refCount)
+        {
+            shared_ptr_increase_ref_count(_refCount->weakRefCount);
+        }
+    }
+
+    template <class Y>
+    explicit WeakPtr(const SharedPtr<Y>& sharedPtr)
+        : WeakPtrBase(sharedPtr._refCount), _object(static_cast<T*>(sharedPtr.GetPointer()))
+    {
+        if (_refCount)
+        {
+            shared_ptr_increase_ref_count(_refCount->weakRefCount);
+        }
+    }
+
+    WeakPtr& operator=(const WeakPtr& other)
+    {
+        Reset();
+        _object = other._object;
+        _refCount = other._refCount;
+        if (_refCount)
+        {
+            shared_ptr_increase_ref_count(_refCount->weakRefCount);
+        }
+        return *this;
+    }
+
+    template <class Y> requires std::assignable_from<T*&, Y*>
+    WeakPtr<T>& operator=(const WeakPtr<Y>& other)
+    {
+        Reset();
+        _object = static_cast<T*>(static_cast<Y*>(other._object));
+        _refCount = other._refCount;
+        if (_refCount)
+        {
+            shared_ptr_increase_ref_count(_refCount->weakRefCount);
+        }
+        return *this;
+    }
+
+    template <class Y> requires std::assignable_from<T*&, Y*>
+    WeakPtr<T>& operator=(const SharedPtr<Y>& sharedPtr)
+    {
+        Reset();
+        _object = static_cast<T*>(sharedPtr.GetPointer());
+        _refCount = sharedPtr._refCount;
+        if (_refCount)
+        {
+            shared_ptr_increase_ref_count(_refCount->weakRefCount);
+        }
+        return *this;
+    }
+
+    WeakPtr& operator=(WeakPtr&& other)
+    {
+        Reset();
+        _object = other._object;
+        _refCount = other._refCount;
+        other._object = nullptr;
+        other._refCount = nullptr;
+        return *this;
+    }
+
+    template <class Y> requires std::assignable_from<T*&, Y*>
+    WeakPtr<T>& operator=(WeakPtr<Y>&& other)
+    {
+        Reset();
+        _object = static_cast<T*>(static_cast<Y*>(other._object));
+        _refCount = other._refCount;
+        other._object = nullptr;
+        other._refCount = nullptr;
+        return *this;
+    }
+
+    SharedPtr<T> Lock() const
+    {
+        if (_refCount && LockIntern())
+        {
+            return SharedPtr<T>(_object, _refCount);
+        }
+        else
+        {
+            return SharedPtr<T>();
+        }
+    }
+
+private:
+    T* _object;
+
+    WeakPtr(T* object, RefCount* refCount)
+        : WeakPtrBase(refCount), _object(object) { }
+};