New: Add interface-filtered object references

Add native hard and soft reference types for scene objects that implement
a scripting interface:

- ScriptingObjectInterfaceReference<T>
- SoftObjectInterfaceReference<T>

Source/Engine/Scripting/ScriptingObjectInterfaceReference.h

@@ -0,0 +1,195 @@
+// Copyright (c) Wojciech Figat. All rights reserved.
+
+#pragma once
+
+#include "Engine/Scripting/ScriptingObjectInterfaceReferenceUtils.h"
+
+/// <summary>
+/// The scene object interface reference.
+/// </summary>
+/// <typeparam name="T">The type of the scripting interface.</typeparam>
+template<typename T>
+API_CLASS(InBuild) class ScriptingObjectInterfaceReference : public ScriptingObjectReferenceBase
+{
+    typedef ScriptingObjectInterfaceReferenceHelper<T> Helper;
+
+public:
+    typedef ScriptingObjectInterfaceReference<T> Type;
+
+public:
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    ScriptingObjectInterfaceReference()
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="obj">The object to link.</param>
+    ScriptingObjectInterfaceReference(SceneObject* obj)
+        : ScriptingObjectReferenceBase(Helper::IsValidObject(obj) ? obj : nullptr)
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="interfaceObj">The interface object to link.</param>
+    ScriptingObjectInterfaceReference(T* interfaceObj)
+        : ScriptingObjectReferenceBase(Helper::GetSceneObject(interfaceObj))
+    {
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    /// <param name="other">The other property.</param>
+    ScriptingObjectInterfaceReference(const ScriptingObjectInterfaceReference& other)
+        : ScriptingObjectReferenceBase(other._object)
+    {
+    }
+
+    ScriptingObjectInterfaceReference(ScriptingObjectInterfaceReference&& other) noexcept
+        : ScriptingObjectReferenceBase(MoveTemp(other))
+    {
+    }
+
+    /// <summary>
+    /// Finalizes an instance of the <see cref="ScriptingObjectInterfaceReference"/> class.
+    /// </summary>
+    ~ScriptingObjectInterfaceReference()
+    {
+    }
+
+public:
+    FORCE_INLINE bool operator==(SceneObject* other) const
+    {
+        return _object == other;
+    }
+
+    FORCE_INLINE bool operator!=(SceneObject* other) const
+    {
+        return _object != other;
+    }
+
+    FORCE_INLINE bool operator==(T* other) const
+    {
+        return Get() == other;
+    }
+
+    FORCE_INLINE bool operator!=(T* other) const
+    {
+        return Get() != other;
+    }
+
+    FORCE_INLINE bool operator==(const ScriptingObjectInterfaceReference& other) const
+    {
+        return _object == other._object;
+    }
+
+    FORCE_INLINE bool operator!=(const ScriptingObjectInterfaceReference& other) const
+    {
+        return _object != other._object;
+    }
+
+    FORCE_INLINE ScriptingObjectInterfaceReference& operator=(SceneObject* other)
+    {
+        OnSet(Helper::IsValidObject(other) ? other : nullptr);
+        return *this;
+    }
+
+    FORCE_INLINE ScriptingObjectInterfaceReference& operator=(T* other)
+    {
+        OnSet(Helper::GetSceneObject(other));
+        return *this;
+    }
+
+    ScriptingObjectInterfaceReference& operator=(const ScriptingObjectInterfaceReference& other)
+    {
+        OnSet(other._object);
+        return *this;
+    }
+
+    ScriptingObjectInterfaceReference& operator=(ScriptingObjectInterfaceReference&& other) noexcept
+    {
+        ScriptingObjectReferenceBase::operator=(MoveTemp(other));
+        return *this;
+    }
+
+    FORCE_INLINE ScriptingObjectInterfaceReference& operator=(const Guid& id)
+    {
+        OnSet(Helper::FindSceneObject(id));
+        return *this;
+    }
+
+    /// <summary>
+    /// Implicit conversion to the interface.
+    /// </summary>
+    FORCE_INLINE operator T*() const
+    {
+        return Get();
+    }
+
+    /// <summary>
+    /// Implicit conversion to boolean value.
+    /// </summary>
+    FORCE_INLINE operator bool() const
+    {
+        return _object != nullptr;
+    }
+
+    /// <summary>
+    /// Interface accessor.
+    /// </summary>
+    FORCE_INLINE T* operator->() const
+    {
+        return Get();
+    }
+
+    /// <summary>
+    /// Gets the interface pointer.
+    /// </summary>
+    FORCE_INLINE T* Get() const
+    {
+        return ScriptingObject::ToInterface<T>(_object);
+    }
+
+    /// <summary>
+    /// Gets the referenced object.
+    /// </summary>
+    FORCE_INLINE SceneObject* GetObject() const
+    {
+        return static_cast<SceneObject*>(_object);
+    }
+
+    /// <summary>
+    /// Copies the object ID into the raw storage.
+    /// </summary>
+    FORCE_INLINE void CopyID(uint32 id[4]) const
+    {
+        memset(id, 0, sizeof(uint32) * 4);
+        if (_object)
+        {
+            const Guid value = GetID();
+            memcpy(id, &value, sizeof(uint32) * 4);
+        }
+    }
+
+    /// <summary>
+    /// Gets the object as a given type (static cast).
+    /// </summary>
+    template<typename U>
+    FORCE_INLINE U* As() const
+    {
+        return static_cast<U*>(_object);
+    }
+
+};
+
+template<typename T>
+uint32 GetHash(const ScriptingObjectInterfaceReference<T>& key)
+{
+    return GetHash(key.GetID());
+}