source: binary-improvements2/7dtd-server-fixes/src/PersistentData/Players.cs@ 385

using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace AllocsFixes.PersistentData {
        [Serializable]
        public class Players {
                public readonly Dictionary<PlatformUserIdentifierAbs, Player> Dict = new Dictionary<PlatformUserIdentifierAbs, Player> ();

                public Player this [PlatformUserIdentifierAbs _platformId, bool _create] {
                        get {
                                if (_platformId == null) {
                                        return null;
                                }

                                if (Dict.TryGetValue (_platformId, out Player pOld)) {
                                        return pOld;
                                }

                                if (!_create) {
                                        return null;
                                }

                                Log.Out ("Created new player entry for ID: " + _platformId);
                                Player p = new Player (_platformId);
                                Dict.Add (_platformId, p);
                                return p;
                        }
                }

                public int Count => Dict.Count;

                public PlatformUserIdentifierAbs GetSteamID (string _nameOrId, bool _ignoreColorCodes) {
                        if (string.IsNullOrEmpty (_nameOrId)) {
                                return null;
                        }

                        if (PlatformUserIdentifierAbs.TryFromCombinedString (_nameOrId, out PlatformUserIdentifierAbs userId)) {
                                return userId;
                        }

                        if (int.TryParse (_nameOrId, out int entityId)) {
                                foreach (KeyValuePair<PlatformUserIdentifierAbs, Player> kvp in Dict) {
                                        if (kvp.Value.IsOnline && kvp.Value.EntityID == entityId) {
                                                return kvp.Key;
                                        }
                                }
                        }

                        foreach (KeyValuePair<PlatformUserIdentifierAbs, Player> kvp in Dict) {
                                string name = kvp.Value.Name;
                                if (_ignoreColorCodes) {
                                        name = Regex.Replace (name, "\\[[0-9a-fA-F]{6}\\]", "");
                                }

                                if (kvp.Value.IsOnline && name.EqualsCaseInsensitive (_nameOrId)) {
                                        return kvp.Key;
                                }
                        }

                        return null;
                }
        }
}