我想匹配（从.cs文件中选择）属性名，字段名和使用正则表达式的地方。
这是示例类：

using System;
... // usings
using Grpc.Net.Client;
using UI = Gtk.Builder.ObjectAttribute;

namespace DummyProject;

public class MainWindow : Window
{
    [UI] private readonly MenuItem _aboutMenuItem;
    [UI] private readonly MenuItem _openFolderItem;
    [UI] private readonly MenuItem _openFileItem;
    [UI] private readonly Viewport _fileViewport;
    [UI] private readonly Notebook _codeNotebook;
    private readonly SourceView _codeSourceView;
    private readonly FileViewer _fileViewer;
    private readonly Files.FilesClient _filesClient;
    
    public FileSystemViewer FileSystemViewer { get; }
    
    public MainWindow() 
    {
        _fileViewer = new FileViewer();
        // some code
    }

    // methods

结果将是：_aboutMenuItem、_openFolderItem、_openFileItem、_fileViewport、_codeNotebook、_codeSourceView、_fileViewer、_filesClient、FileSystemViewer
我试过这个正则表达式：^(?:(?=[^()]*$))?(?:(?!.*\b(namespace|return|using|class)\b))[\t \b]*(?:[\[\]a-zA-Z0-9_.]+\s+)?(?:(?:private|public|protected|internal)\s+)?(?:(?:static readonly|static|const|readonly|volatile|virtual|override)\s+)?(?:(?:[a-zA-Z0-9\.]+)\s+)?(\w+)\s*
但此正则表达式匹配不正确（请参见https://regex101.com/r/ZbctGa/3）
有什么建议吗？