module-navigation-tool/Editor/History/Utilities/HistoryUtility.cs

using System.Collections.Generic;

namespace Game.NavigationTool.Editor.History
{
    internal static class HistoryUtility
    {
        private static HistoryList HISTORY_LIST;

        static HistoryUtility()
        {
            HISTORY_LIST = null;
        }
        
        public static HistoryList GetHistoryList()
        {
            return HISTORY_LIST ?? (HISTORY_LIST = new HistoryList());
        }

        public static bool IsLoaded()
        {
            return HISTORY_LIST != null;
        }

        public static void RefreshAll()
        {
            if (HISTORY_LIST == null)
                return;

            List<HistoryList.Entry> entries = HISTORY_LIST.entries;

            for (var i = 0; i < entries.Count; i++)
            {
                entries[i].Refresh();
            }
        }
    }
}