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Assets/Textus/SerializeReferenceUI/Core/ManagedReferenceUtility.cs

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+#if UNITY_EDITOR
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using UnityEditor;
+using UnityEngine;
+using Object = UnityEngine.Object;
+
+public static class ManagedReferenceUtility
+{
+    /// Creates instance of passed type and assigns it to managed reference
+    public static object AssignNewInstanceOfTypeToManagedReference(this SerializedProperty serializedProperty, Type type)
+    {
+        var instance = Activator.CreateInstance(type);
+        
+        serializedProperty.serializedObject.Update(); 
+        serializedProperty.managedReferenceValue = instance;
+        serializedProperty.serializedObject.ApplyModifiedProperties(); 
+        
+        return instance;
+    }
+
+    /// Sets managed reference to null
+    public static void SetManagedReferenceToNull(this SerializedProperty serializedProperty)
+    {
+        serializedProperty.serializedObject.Update();
+        serializedProperty.managedReferenceValue = null;
+        serializedProperty.serializedObject.ApplyModifiedProperties(); 
+    }
+
+    /// Collects appropriate types based on managed reference field type and filters. Filters all derive
+    public static IEnumerable<Type> GetAppropriateTypesForAssigningToManagedReference(this SerializedProperty property, List<Func<Type, bool>> filters = null)
+    {
+        var fieldType = property.GetManagedReferenceFieldType();
+        return GetAppropriateTypesForAssigningToManagedReference(fieldType, filters);
+    }
+
+    /// Filters derived types of field typ parameter and finds ones whose are compatible with managed reference and filters.
+    public static IEnumerable<Type> GetAppropriateTypesForAssigningToManagedReference(Type fieldType, List<Func<Type, bool>> filters = null)
+    {
+        var appropriateTypes = new List<Type>();
+
+        // Get and filter all appropriate types
+        var derivedTypes = TypeCache.GetTypesDerivedFrom(fieldType);
+        foreach (var type in derivedTypes)
+        {
+            // Skips unity engine Objects (because they are not serialized by SerializeReference)
+            if (type.IsSubclassOf(typeof(Object)))
+                continue;
+            // Skip abstract classes because they should not be instantiated
+            if (type.IsAbstract)
+                continue;
+            // Skip types that has no public empty constructors (activator can not create them)    
+            if (type.IsClass && type.GetConstructor(Type.EmptyTypes) == null) // Structs still can be created (strangely)
+                continue;
+            // Filter types by provided filters if there is ones
+            if (filters != null && filters.All(f => f == null || f.Invoke(type)) == false) 
+                continue;
+
+            appropriateTypes.Add(type);
+        }
+
+        return appropriateTypes;
+    }
+    
+    /// Gets real type of managed reference
+    public static Type GetManagedReferenceFieldType(this SerializedProperty property)
+    {
+        var realPropertyType = GetRealTypeFromTypename(property.managedReferenceFieldTypename);
+        if (realPropertyType != null) 
+            return realPropertyType;
+        
+        Debug.LogError($"Can not get field type of managed reference : {property.managedReferenceFieldTypename}");
+        return null;
+    }
+    
+    /// Gets real type of managed reference's field typeName
+    public static Type GetRealTypeFromTypename(string stringType)
+    {
+        var names = GetSplitNamesFromTypename(stringType);
+        var realType = Type.GetType($"{names.ClassName}, {names.AssemblyName}");
+        return realType;
+    }
+    
+    /// Get assembly and class names from typeName
+    public static (string AssemblyName, string ClassName) GetSplitNamesFromTypename(string typename)
+    {
+        if (string.IsNullOrEmpty(typename))  
+            return ("","");
+        
+        var typeSplitString = typename.Split(char.Parse(" "));
+        var typeClassName = typeSplitString[1];
+        var typeAssemblyName = typeSplitString[0];
+        return (typeAssemblyName,  typeClassName); 
+    }
+}
+#endif