VBE的状态栏

Question

VBE (VBA的IDE)最烦人的地方之一是它没有状态栏。

Rubber达克2.0引入了RubberduckCommandBar，ab使用msoControlButton控件就好像它们是标签一样--命令栏会随着文本的变化而不断调整大小，但至少我们可以显示有关当前选择的上下文敏感信息：

由于Rubber鸭加载所有引用的COM类型并解析引用，而不管标识符是否内置，因此“状态栏”还在选择的标识符引用上显示内置声明的类型信息，例如Excel.ListObject：

...or甚至还内置了VBA标准库中的函数：

如果这是一个很棒的特性，那么它的代码就不那么“精彩”了。下面是整个RubberduckCommandBar类，我对SetSelectionText实现尤其不感兴趣--如何编写得更好呢？

public class RubberduckCommandBar
{
    private readonly RubberduckParserState _state;
    private readonly VBE _vbe;
    private readonly IShowParserErrorsCommand _command;

    private CommandBarButton _refreshButton;
    private CommandBarButton _statusButton;
    private CommandBarButton _selectionButton;

    public RubberduckCommandBar(RubberduckParserState state, VBE vbe, IShowParserErrorsCommand command)
    {
        _state = state;
        _vbe = vbe;
        _command = command;
        _state.StateChanged += State_StateChanged;
        Initialize();
    }

    private void _statusButton_Click(CommandBarButton Ctrl, ref bool CancelDefault)
    {
        if (_state.Status == ParserState.Error)
        {
            _command.Execute(null);
        }
    }

    public void SetStatusText(string value = null)
    {
        UiDispatcher.Invoke(() => _statusButton.Caption = value ?? RubberduckUI.ResourceManager.GetString("ParserState_" + _state.Status));
    }

    public void SetSelectionText(Declaration declaration)
    {
        if (declaration == null && _vbe.ActiveCodePane != null)
        {
            var selection = _vbe.ActiveCodePane.GetSelection();
            SetSelectionText(selection);
        }
        else if (declaration != null && !declaration.IsBuiltIn && declaration.DeclarationType != DeclarationType.Class && declaration.DeclarationType != DeclarationType.Module)
        {
            _selectionButton.Caption = string.Format("{0} ({1}): {2} ({3})", 
                declaration.QualifiedName.QualifiedModuleName,
                declaration.QualifiedSelection.Selection,
                declaration.IdentifierName,
                RubberduckUI.ResourceManager.GetString("DeclarationType_" + declaration.DeclarationType));
        }
        else if (declaration != null)
        {
            var selection = _vbe.ActiveCodePane.GetSelection();
            _selectionButton.Caption = string.Format("{0}: {1} ({2}) {3}",
                declaration.QualifiedName.QualifiedModuleName,
                declaration.IdentifierName,
                RubberduckUI.ResourceManager.GetString("DeclarationType_" + declaration.DeclarationType),
                selection.Selection);
        }
    }

    private void SetSelectionText(QualifiedSelection selection)
    {
        UiDispatcher.Invoke(() => _selectionButton.Caption = selection.ToString());
    }

    private void State_StateChanged(object sender, EventArgs e)
    {
        Debug.WriteLine("RubberduckCommandBar handles StateChanged...");
        SetStatusText(RubberduckUI.ResourceManager.GetString("ParserState_" + _state.Status));
    }

    public event EventHandler Refresh;

    private void OnRefresh()
    {
        var handler = Refresh;
        if (handler != null)
        {
            handler.Invoke(this, EventArgs.Empty);
        }
    }

    public void Initialize()
    {
        var commandbar = _vbe.CommandBars.Add("Rubberduck", MsoBarPosition.msoBarTop, false, true);

        _refreshButton = (CommandBarButton)commandbar.Controls.Add(MsoControlType.msoControlButton);
        ParentMenuItemBase.SetButtonImage(_refreshButton, Resources.arrow_circle_double, Resources.arrow_circle_double_mask);
        _refreshButton.Style = MsoButtonStyle.msoButtonIcon;
        _refreshButton.Tag = "Refresh";
        _refreshButton.TooltipText =RubberduckUI.RubberduckCommandbarRefreshButtonTooltip;
        _refreshButton.Click += refreshButton_Click;

        _statusButton = (CommandBarButton)commandbar.Controls.Add(MsoControlType.msoControlButton);
        _statusButton.Style = MsoButtonStyle.msoButtonCaption;
        _statusButton.Tag = "Status";
        _statusButton.Click += _statusButton_Click;

        _selectionButton = (CommandBarButton)commandbar.Controls.Add(MsoControlType.msoControlButton);
        _selectionButton.Style = MsoButtonStyle.msoButtonCaption;
        _selectionButton.BeginGroup = true;
        _selectionButton.Enabled = false;

        commandbar.Visible = true;
    }

    private void refreshButton_Click(CommandBarButton Ctrl, ref bool CancelDefault)
    {
        OnRefresh();
    }
}

还有什么地方不对劲吗？

在鼠标和键盘钩子事件处理程序中，从App类调用该代码：

private void HandleMouseMessage()
{
    RefreshSelection();
}

private void HandleKeyboardMessage()
{
    RefreshSelection();
}

private void RefreshSelection()
{
    _stateBar.SetSelectionText(_parser.State.FindSelectedDeclaration(_vbe.ActiveCodePane));
    _appMenus.EvaluateCanExecute(_parser.State);
}

下面是FindSelectedDeclaration实现，可以在RubberduckParserState类中找到：

private QualifiedSelection _lastSelection;
private Declaration _selectedDeclaration;

public Declaration FindSelectedDeclaration(CodePane activeCodePane)
{
    var selection = activeCodePane.GetSelection();
    if (selection.Equals(_lastSelection))
    {
        return _selectedDeclaration;
    }

    _lastSelection = selection;
    _selectedDeclaration = null;

    if (!selection.Equals(default(QualifiedSelection)))
    {
        var matches = AllDeclarations
            .Where(item => item.DeclarationType != DeclarationType.Project &&
                           item.DeclarationType != DeclarationType.ModuleOption &&
                           item.DeclarationType != DeclarationType.Class &&
                           item.DeclarationType != DeclarationType.Module &&
                           (IsSelectedDeclaration(selection, item) ||
                            item.References.Any(reference => IsSelectedReference(selection, reference))));
        try
        {
            var match = matches.SingleOrDefault() ?? AllUserDeclarations
                .SingleOrDefault(item => (item.DeclarationType == DeclarationType.Class || item.DeclarationType == DeclarationType.Module)
                        && item.QualifiedName.QualifiedModuleName.Equals(selection.QualifiedName));
            _selectedDeclaration = match;
        }
        catch (InvalidOperationException exception)
        {
            Debug.WriteLine(exception);
        }
    }

    if (_selectedDeclaration != null)
    {
        Debug.WriteLine("Current selection ({0}) is '{1}' ({2})", selection, _selectedDeclaration.IdentifierName, _selectedDeclaration.DeclarationType);
    }

    return _selectedDeclaration;
}

private static bool IsSelectedDeclaration(QualifiedSelection selection, Declaration declaration)
{
    return declaration.QualifiedSelection.QualifiedName.Equals(selection.QualifiedName)
           && (declaration.QualifiedSelection.Selection.ContainsFirstCharacter(selection.Selection));
}

private static bool IsSelectedReference(QualifiedSelection selection, IdentifierReference reference)
{
    return reference.QualifiedModuleName.Equals(selection.QualifiedName)
           && reference.Selection.ContainsFirstCharacter(selection.Selection);
}

Answer 1

通过在第一个if语句中添加一个小嵌套，您可以跳过对declaration != null的多次检查，这将使代码更具可读性，如下所示

public void SetSelectionText(Declaration declaration)
{
    if (declaration == null)
    {
        if(_vbe.ActiveCodePane == null)
        {
            return;
        }

        var selection = _vbe.ActiveCodePane.GetSelection();
        SetSelectionText(selection);
    }
    else if (!declaration.IsBuiltIn && declaration.DeclarationType != DeclarationType.Class && declaration.DeclarationType != DeclarationType.Module)
    {
        _selectionButton.Caption = string.Format("{0} ({1}): {2} ({3})",
            declaration.QualifiedName.QualifiedModuleName,
            declaration.QualifiedSelection.Selection,
            declaration.IdentifierName,
            RubberduckUI.ResourceManager.GetString("DeclarationType_" + declaration.DeclarationType));
    }
    else
    {
        var selection = _vbe.ActiveCodePane.GetSelection();
        _selectionButton.Caption = string.Format("{0}: {1} ({2}) {3}",
            declaration.QualifiedName.QualifiedModuleName,
            declaration.IdentifierName,
            RubberduckUI.ResourceManager.GetString("DeclarationType_" + declaration.DeclarationType),
            selection.Selection);
    }
}  

可以将else if的条件检查提取为有意义的名称的方法。虽然它只使用一次，但可以提高当前方法的可读性。

FindSelectedDeclaration()类的RubberduckParserState方法也可以使用剪裁。如果您使用这里的条件，if (!selection.Equals(default(QualifiedSelection)))，您可以提前返回并保存一个缩进级别，如下所示

public Declaration FindSelectedDeclaration(CodePane activeCodePane)
{
    var selection = activeCodePane.GetSelection();
    if (selection.Equals(_lastSelection))
    {
        return _selectedDeclaration;
    }

    _lastSelection = selection;
    _selectedDeclaration = null;

    if (selection.Equals(default(QualifiedSelection)))
    {
        return null;
    }

    var matches = AllDeclarations
        .Where(item => item.DeclarationType != DeclarationType.Project &&
                       item.DeclarationType != DeclarationType.ModuleOption &&
                       item.DeclarationType != DeclarationType.Class &&
                       item.DeclarationType != DeclarationType.Module &&
                       (IsSelectedDeclaration(selection, item) ||
                        item.References.Any(reference => IsSelectedReference(selection, reference))));
    try
    {
        var match = matches.SingleOrDefault() ?? AllUserDeclarations
            .SingleOrDefault(item => (item.DeclarationType == DeclarationType.Class || item.DeclarationType == DeclarationType.Module)
                    && item.QualifiedName.QualifiedModuleName.Equals(selection.QualifiedName));
        _selectedDeclaration = match;
    }
        catch (InvalidOperationException exception)
        {
            Debug.WriteLine(exception);
        }

    if (_selectedDeclaration != null)
    {
        Debug.WriteLine("Current selection ({0}) is '{1}' ({2})", selection, _selectedDeclaration.IdentifierName, _selectedDeclaration.DeclarationType);
    }

    return _selectedDeclaration;
}

但是，如果我阅读var matches或var match，我总是会考虑正则表达式，所以我倾向于将这些变量重命名为foundDeclarations和foundDeclaration。