public static ReadOnlySpan<char> ParentDirectory(this ReadOnlySpan<char> filePath) { if (filePath.IsNullOrEmpty()) return TypeConstants.NullStringSpan; var dirSep = filePath.IndexOf(PclExport.Instance.DirSep) != -1 ? PclExport.Instance.DirSep : filePath.IndexOf(PclExport.Instance.AltDirSep) != -1 ? PclExport.Instance.AltDirSep : (char)0; if (dirSep == 0) return TypeConstants.NullStringSpan; MemoryExtensions.TrimEnd(filePath, dirSep).SplitOnLast(dirSep, out var first, out _); return first; }