fungus/Assets/Fungus/Scripts/Editor/EditorExtensions.cs

// This code is part of the Fungus library (http://fungusgames.com) maintained by Chris Gregan (http://twitter.com/gofungus).
// It is released for free under the MIT open source license (https://github.com/snozbot/fungus/blob/master/LICENSE)

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

namespace Fungus.EditorUtils
{
    public static class EditorExtensions
    {
        /// <summary>
        /// FindDerivedTypesFromAssembly allows a user to query all of types derived from a
        /// particular Type at runtime.
        /// Example usage:
        ///     foreach (System.Type st in EditorUtility.FindDerivedTypesFromAssembly(System.Reflection.Assembly.GetAssembly(typeof(BaseTimelineEvent)), typeof(BaseTimelineEvent), true))
        /// </summary>
        /// <param name="assembly">The assembly to search in</param>
        /// <param name="baseType">The base Type from which all returned Types derive</param>
        /// <param name="classOnly">If true, only class Types will be returned</param>
        /// <returns></returns>
        public static System.Type[] FindDerivedTypesFromAssembly(this System.Reflection.Assembly assembly, System.Type baseType, bool classOnly = true)
        {
            if (assembly == null)
                Debug.LogError("Assembly must be defined");
            if (baseType == null)
                Debug.LogError("Base type must be defined");

            // Iterate through all available types in the assembly
            var types = assembly.GetTypes().Where(type =>
                {
                    if (classOnly && !type.IsClass)
                        return false;
                    
                    if (baseType.IsInterface)
                    {
                        var it = type.GetInterface(baseType.FullName);

                        if (it != null)
                            return true;
                    }
                    else if (type.IsSubclassOf(baseType))
                    {
                        return true;
                    }

                    return false;
                }
            );

            return types.ToArray();
        }

        /// <summary>
        /// A convenient method for calling the above.
        /// Example usage:
        ///     List<System.Type> subTypes = EditorUtility.FindDerivedTypes(typeof(BaseTimelineEvent)).ToList();
        /// </summary>
        /// <param name="baseType"></param>
        /// <param name="classOnly"></param>
        /// <returns></returns>
        public static System.Type[] FindDerivedTypes(System.Type baseType, bool classOnly = true)
        {
            return FindDerivedTypesFromAssembly(System.Reflection.Assembly.GetAssembly(baseType), baseType, classOnly);
        }
    }
}