xNode/Scripts/Editor/NodeEditorReflection.cs

using System.Collections.Generic;
using System.Reflection;
using System.Linq; 
using System;
using UnityEngine;

/// <summary> Contains reflection-related info </summary>
public partial class NodeEditorWindow {
    [NonSerialized] private static Dictionary<Type, NodeEditor> customNodeEditor;
    public static Type[] nodeTypes { get { return _nodeTypes != null ? _nodeTypes : _nodeTypes = GetNodeTypes(); } }
    [NonSerialized] private static Type[] _nodeTypes = null;

    public static NodeEditor GetNodeEditor(Type node) {
        if (customNodeEditor == null) CacheCustomNodeEditors();
        if (customNodeEditor.ContainsKey(node)) return customNodeEditor[node];
        return customNodeEditor[typeof(Node)];
    }

    public static Type[] GetNodeTypes() {
        //Get all classes deriving from Node via reflection
        return GetDerivedTypes(typeof(Node));
    }

    public static void CacheCustomNodeEditors(){
        customNodeEditor = new Dictionary<Type, NodeEditor>();
        customNodeEditor.Add(typeof(Node), new NodeEditor());
        //Get all classes deriving from NodeEditor via reflection
        Type[] nodeEditors = GetDerivedTypes(typeof(NodeEditor));
        for (int i = 0; i < nodeEditors.Length; i++) {
            var attribs = nodeEditors[i].GetCustomAttributes(typeof(CustomNodeEditorAttribute), false);
            if (attribs == null || attribs.Length == 0) continue;
            if (nodeEditors[i].IsAbstract) continue;
            CustomNodeEditorAttribute attrib = attribs[0] as CustomNodeEditorAttribute;
            customNodeEditor.Add(attrib.inspectedType, Activator.CreateInstance(nodeEditors[i]) as NodeEditor);
        }
    }

    public static Type[] GetDerivedTypes(Type baseType) {
        //Get all classes deriving from baseType via reflection
        Assembly assembly = Assembly.GetAssembly(baseType);
        return assembly.GetTypes().Where(t =>
            !t.IsAbstract &&
            baseType.IsAssignableFrom(t)
            ).ToArray();
    }

    public static object ObjectFromType(Type type) {
        return Activator.CreateInstance(type);
    }
}