metal: initial support

third_party/metal-cpp/Foundation/NSSharedPtr.hpp

@@ -0,0 +1,311 @@
+//-------------------------------------------------------------------------------------------------------------------------------------------------------------
+//
+// Foundation/NSSharedPtr.hpp
+//
+// Copyright 2020-2023 Apple Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+//-------------------------------------------------------------------------------------------------------------------------------------------------------------
+
+#pragma once
+
+#include "NSDefines.hpp"
+
+namespace NS
+{
+template <class _Class>
+class SharedPtr
+{
+public:
+    /**
+     * Create a new null pointer.
+     */
+    SharedPtr();
+
+    /**
+     * Destroy this SharedPtr, decreasing the reference count.
+     */
+    ~SharedPtr();
+
+    /**
+     * SharedPtr copy constructor.
+     */
+    SharedPtr(const SharedPtr<_Class>& other) noexcept;
+
+    /**
+     * Construction from another pointee type.
+     */
+    template <class _OtherClass>
+    SharedPtr(const SharedPtr<_OtherClass>& other, typename std::enable_if_t<std::is_convertible_v<_OtherClass *, _Class *>> * = nullptr) noexcept;
+
+    /**
+     * SharedPtr move constructor.
+     */
+    SharedPtr(SharedPtr<_Class>&& other) noexcept;
+
+    /**
+     * Move from another pointee type.
+     */
+    template <class _OtherClass>
+    SharedPtr(SharedPtr<_OtherClass>&& other, typename std::enable_if_t<std::is_convertible_v<_OtherClass *, _Class *>> * = nullptr) noexcept;
+
+    /**
+     * Copy assignment operator.
+     * Copying increases reference count. Only releases previous pointee if objects are different.
+     */
+    SharedPtr& operator=(const SharedPtr<_Class>& other);
+
+    /**
+     * Copy-assignment from different pointee.
+     * Copying increases reference count. Only releases previous pointee if objects are different.
+     */
+    template <class _OtherClass>
+    typename std::enable_if_t<std::is_convertible_v<_OtherClass *, _Class *>, SharedPtr &>
+    operator=(const SharedPtr<_OtherClass>& other);
+
+    /**
+     * Move assignment operator.
+     * Move without affecting reference counts, unless pointees are equal. Moved-from object is reset to nullptr.
+     */
+    SharedPtr& operator=(SharedPtr<_Class>&& other);
+
+    /**
+     * Move-asignment from different pointee.
+     * Move without affecting reference counts, unless pointees are equal. Moved-from object is reset to nullptr.
+     */
+    template <class _OtherClass>
+    typename std::enable_if_t<std::is_convertible_v<_OtherClass *, _Class *>, SharedPtr &>
+    operator=(SharedPtr<_OtherClass>&& other);
+
+    /**
+     * Access raw pointee.
+     * @warning Avoid wrapping the returned value again, as it may lead double frees unless this object becomes detached.
+     */
+    _Class* get() const;
+
+    /**
+     * Call operations directly on the pointee.
+     */
+    _Class* operator->() const;
+
+    /**
+     * Implicit cast to bool.
+     */
+    explicit operator bool() const;
+
+    /**
+     * Reset this SharedPtr to null, decreasing the reference count.
+     */
+    void reset();
+
+    /**
+     * Detach the SharedPtr from the pointee, without decreasing the reference count.
+     */
+    void detach();
+
+    template <class _OtherClass>
+    friend SharedPtr<_OtherClass> RetainPtr(_OtherClass* ptr);
+
+    template <class _OtherClass>
+    friend SharedPtr<_OtherClass> TransferPtr(_OtherClass* ptr);
+
+private:
+    _Class* m_pObject;
+};
+
+/**
+ * Create a SharedPtr by retaining an existing raw pointer.
+ * Increases the reference count of the passed-in object.
+ * If the passed-in object was in an AutoreleasePool, it will be removed from it.
+ */
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class> RetainPtr(_Class* pObject)
+{
+    NS::SharedPtr<_Class> ret;
+    ret.m_pObject = pObject->retain();
+    return ret;
+}
+
+/*
+ * Create a SharedPtr by transfering the ownership of an existing raw pointer to SharedPtr.
+ * Does not increase the reference count of the passed-in pointer, it is assumed to be >= 1.
+ * This method does not remove objects from an AutoreleasePool.
+*/
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class> TransferPtr(_Class* pObject)
+{
+    NS::SharedPtr<_Class> ret;
+    ret.m_pObject = pObject;
+    return ret;
+}
+
+}
+
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class>::SharedPtr()
+    : m_pObject(nullptr)
+{
+}
+
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class>::~SharedPtr<_Class>()
+{
+    if (m_pObject)
+    {
+        m_pObject->release();
+    }
+}
+
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class>::SharedPtr(const NS::SharedPtr<_Class>& other) noexcept
+    : m_pObject(other.m_pObject->retain())
+{
+}
+
+template <class _Class>
+template <class _OtherClass>
+_NS_INLINE NS::SharedPtr<_Class>::SharedPtr(const NS::SharedPtr<_OtherClass>& other, typename std::enable_if_t<std::is_convertible_v<_OtherClass *, _Class *>> *) noexcept
+    : m_pObject(reinterpret_cast<_Class*>(other.get()->retain()))
+{
+}
+
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class>::SharedPtr(NS::SharedPtr<_Class>&& other) noexcept
+    : m_pObject(other.m_pObject)
+{
+    other.m_pObject = nullptr;
+}
+
+template <class _Class>
+template <class _OtherClass>
+_NS_INLINE NS::SharedPtr<_Class>::SharedPtr(NS::SharedPtr<_OtherClass>&& other, typename std::enable_if_t<std::is_convertible_v<_OtherClass *, _Class *>> *) noexcept
+    : m_pObject(reinterpret_cast<_Class*>(other.get()))
+{
+    other.detach();
+}
+
+template <class _Class>
+_NS_INLINE _Class* NS::SharedPtr<_Class>::get() const
+{
+    return m_pObject;
+}
+
+template <class _Class>
+_NS_INLINE _Class* NS::SharedPtr<_Class>::operator->() const
+{
+    return m_pObject;
+}
+
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class>::operator bool() const
+{
+    return nullptr != m_pObject;
+}
+
+template <class _Class>
+_NS_INLINE void NS::SharedPtr<_Class>::reset()
+{
+    m_pObject->release();
+    m_pObject = nullptr;
+}
+
+template <class _Class>
+_NS_INLINE void NS::SharedPtr<_Class>::detach()
+{
+    m_pObject = nullptr;
+}
+
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class>& NS::SharedPtr<_Class>::operator=(const SharedPtr<_Class>& other)
+{
+    if (m_pObject != other.m_pObject)
+    {
+        if (m_pObject)
+        {
+            m_pObject->release();
+        }
+        m_pObject = other.m_pObject->retain();
+    }
+    return *this;
+}
+
+template <class _Class>
+template <class _OtherClass>
+typename std::enable_if_t<std::is_convertible_v<_OtherClass *, _Class *>, NS::SharedPtr<_Class> &>
+_NS_INLINE NS::SharedPtr<_Class>::operator=(const SharedPtr<_OtherClass>& other)
+{
+    if (m_pObject != other.get())
+    {
+        if (m_pObject)
+        {
+            m_pObject->release();
+        }
+        m_pObject = reinterpret_cast<_Class*>(other.get()->retain());
+    }
+    return *this;
+}
+
+template <class _Class>
+_NS_INLINE NS::SharedPtr<_Class>& NS::SharedPtr<_Class>::operator=(SharedPtr<_Class>&& other)
+{
+    if (m_pObject != other.m_pObject)
+    {
+        if (m_pObject)
+        {
+            m_pObject->release();
+        }
+        m_pObject = other.m_pObject;
+    }
+    else
+    {
+        m_pObject = other.m_pObject;
+        other.m_pObject->release();
+    }
+    other.m_pObject = nullptr;
+    return *this;
+}
+
+template <class _Class>
+template <class _OtherClass>
+typename std::enable_if_t<std::is_convertible_v<_OtherClass *, _Class *>, NS::SharedPtr<_Class> &>
+_NS_INLINE NS::SharedPtr<_Class>::operator=(SharedPtr<_OtherClass>&& other)
+{
+    if (m_pObject != other.get())
+    {
+        if (m_pObject)
+        {
+            m_pObject->release();
+        }
+        m_pObject = reinterpret_cast<_Class*>(other.get());
+        other.detach();
+    }
+    else
+    {
+        m_pObject = other.get();
+        other.reset();
+    }
+    return *this;
+}
+
+template <class _ClassLhs, class _ClassRhs>
+_NS_INLINE bool operator==(const NS::SharedPtr<_ClassLhs>& lhs, const NS::SharedPtr<_ClassRhs>& rhs)
+{
+    return lhs.get() == rhs.get();
+}
+
+template <class _ClassLhs, class _ClassRhs>
+_NS_INLINE bool operator!=(const NS::SharedPtr<_ClassLhs>& lhs, const NS::SharedPtr<_ClassRhs>& rhs)
+{
+    return lhs.get() != rhs.get();
+}