421 lines
16 KiB
C#
421 lines
16 KiB
C#
// Cascader.cs
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using System.Collections;
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using System.Windows.Controls.Primitives;
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using System.Windows.Input;
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using Melskin.Utilities;
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namespace Melskin.Controls;
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/// <summary>
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/// 用于实现级联选择器功能的控件类。该控件允许用户从多层级的数据源中选择一个值，通常应用于需要按类别或层级进行选择的场景。
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/// </summary>
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[TemplatePart(Name = "PART_Popup", Type = typeof(Popup))]
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public class Cascader : Control
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{
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private static readonly DependencyPropertyKey FilteredItemsSourcePropertyKey = DependencyProperty.RegisterReadOnly("FilteredItemsSource", typeof(IEnumerable), typeof(Cascader), new PropertyMetadata(null));
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/// <summary>
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/// 用于获取经过筛选后的项集合。此属性为只读，其值由控件内部逻辑根据当前搜索条件自动更新。
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/// </summary>
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public static readonly DependencyProperty FilteredItemsSourceProperty = FilteredItemsSourcePropertyKey.DependencyProperty;
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/// <summary>
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/// 控制是否启用搜索功能的开关
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/// </summary>
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public static readonly DependencyProperty IsSearchableProperty =
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DependencyProperty.Register(nameof(IsSearchable), typeof(bool), typeof(Cascader), new PropertyMetadata(true));
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/// <summary>
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/// 定义一个依赖属性，用于接收来自 XAML 的 ListBox 样式
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/// </summary>
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public static readonly DependencyProperty PanelStyleProperty =
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DependencyProperty.Register(nameof(PanelStyle), typeof(Style), typeof(Cascader), new PropertyMetadata(null));
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/// <summary>
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/// 用于存储或获取搜索框中的文本，支持双向数据绑定。
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/// </summary>
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public static readonly DependencyProperty SearchTextProperty = DependencyProperty.Register(nameof(SearchText), typeof(string), typeof(Cascader), new FrameworkPropertyMetadata("", FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnSearchTextChanged));
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private readonly List<object> selectedPath = [];
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static Cascader()
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{
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DefaultStyleKeyProperty.OverrideMetadata(typeof(Cascader), new FrameworkPropertyMetadata(typeof(Cascader)));
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}
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/// <summary>
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/// Cascader 控件用于在用户界面中显示级联选择菜单。该控件支持从数据源动态加载选项，并允许用户通过多级菜单进行选择。
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/// </summary>
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/// <remarks>
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/// 该控件包含多个依赖属性，如 ItemsSource、SelectedValue 和 DisplayMemberPath 等，以支持数据绑定和自定义显示。
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/// 另外，Cascader 控件还支持搜索功能（通过 IsSearchable 属性控制），并且可以自定义弹出面板的样式（通过 PanelStyle 属性）。
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/// </remarks>
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public Cascader()
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{
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SelectSearchResultCommand = new RelayCommand<CascaderSearchResult>(ExecuteSelectSearchResult);
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}
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private ListBox CreateItemsControl(IEnumerable items)
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{
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var itemsControl = new ListBox
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{
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Style = PanelStyle,
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ItemsSource = items,
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//DisplayMemberPath = DisplayMemberPath
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};
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itemsControl.SelectionChanged += OnSelectionChanged;
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return itemsControl;
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}
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private void ExecuteSelectSearchResult(CascaderSearchResult? result)
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{
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if (result == null) return;
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selectedPath.Clear();
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selectedPath.AddRange(result.FullPath);
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SelectedValue = result.TargetItem;
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UpdateSelectedText();
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IsDropDownOpen = false;
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SearchText = "";
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}
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private IEnumerable? GetChildren(object? item)
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{
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if (item == null || string.IsNullOrEmpty(SubmenuMemberPath)) return null;
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var property = item.GetType().GetProperty(SubmenuMemberPath);
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return property?.GetValue(item) as IEnumerable;
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}
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private string GetObjectDisplayText(object? item)
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{
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if (item == null) return string.Empty;
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if (!string.IsNullOrEmpty(DisplayMemberPath))
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{
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var prop = item.GetType().GetProperty(DisplayMemberPath);
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return prop?.GetValue(item)?.ToString() ?? string.Empty;
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}
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return item.ToString()!;
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}
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// 创建了完整的、非空的 CascadingPanel
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private void InitializeCascadingPanel()
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{
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selectedPath.Clear();
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UpdateSelectedText();
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// 1. 创建一个水平 StackPanel 作为根容器。这就是 CascadingPanel 的实体。
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var panel = new StackPanel { Orientation = Orientation.Horizontal };
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if (ItemsSource != null && ItemsSource.Cast<object>().Any())
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{
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// 2. 创建第一级菜单 (ListBox)
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var firstLevelMenu = CreateItemsControl(ItemsSource);
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// 3. 将第一级菜单添加到 Panel 中
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panel.Children.Add(firstLevelMenu);
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}
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// 4. 将这个构建好的、包含内容的 Panel 赋值给依赖属性，让 XAML 可以找到它。
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CascadingPanel = panel;
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}
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private static void OnItemsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
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{
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var control = (Cascader)d;
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control.InitializeCascadingPanel();
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control.UpdateFilteredItems();
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}
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private static void OnSearchTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
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{
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var control = (Cascader)d;
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control.UpdateFilteredItems();
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}
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private void OnSelectionChanged(object sender, SelectionChangedEventArgs e)
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{
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if (e.AddedItems.Count == 0) return;
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var selectedItem = e.AddedItems[0]!;
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var currentMenu = sender as ItemsControl;
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var parentPanel = CascadingPanel;
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if (parentPanel == null) return;
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var currentIndex = parentPanel.Children.IndexOf(currentMenu);
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while (selectedPath.Count > currentIndex) selectedPath.RemoveAt(selectedPath.Count - 1);
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selectedPath.Add(selectedItem);
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while (parentPanel.Children.Count > currentIndex + 1) parentPanel.Children.RemoveAt(parentPanel.Children.Count - 1);
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var children = GetChildren(selectedItem);
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if (children != null && children.Cast<object>().Any())
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{
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var newMenu = CreateItemsControl(children);
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parentPanel.Children.Add(newMenu);
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UpdateSelectedText();
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}
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else
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{
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SelectedValue = selectedItem;
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UpdateSelectedText();
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IsDropDownOpen = false;
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}
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}
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private void SearchRecursive(IEnumerable? nodes, List<object> currentPath, List<CascaderSearchResult> results)
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{
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if (nodes == null) return;
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foreach (var node in nodes)
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{
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var newPath = new List<object>(currentPath) { node };
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var displayText = GetObjectDisplayText(node);
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if (displayText.IndexOf(SearchText, StringComparison.OrdinalIgnoreCase) >= 0)
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{
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var fullPathText = string.Join(Separator, newPath.Select(GetObjectDisplayText));
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results.Add(new CascaderSearchResult(fullPathText, node, newPath));
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}
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var children = GetChildren(node);
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if (children != null)
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{
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SearchRecursive(children, newPath, results);
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}
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}
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}
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private void UpdateFilteredItems()
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{
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if (string.IsNullOrWhiteSpace(SearchText) || ItemsSource == null)
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{
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FilteredItemsSource = null;
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return;
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}
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var results = new List<CascaderSearchResult>();
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SearchRecursive(ItemsSource, [], results);
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FilteredItemsSource = results;
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}
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private void UpdateSelectedText()
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{
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SelectedText = string.Join(Separator, selectedPath.Select(GetObjectDisplayText));
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}
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/// <inheritdoc />
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public override void OnApplyTemplate()
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{
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base.OnApplyTemplate();
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InitializeCascadingPanel();
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}
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/// <summary>
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///
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/// </summary>
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public IEnumerable? FilteredItemsSource { get => (IEnumerable)GetValue(FilteredItemsSourceProperty); protected set => SetValue(FilteredItemsSourcePropertyKey, value); }
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/// <summary>
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/// 获取或设置一个值，指示是否允许搜索功能。当设置为 true 时，用户可以使用搜索框来过滤选项；如果设置为 false，则禁用搜索功能。
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/// </summary>
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public bool IsSearchable { get => (bool)GetValue(IsSearchableProperty); set => SetValue(IsSearchableProperty, value); }
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/// <summary>
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/// 用于设置或获取级联控件面板的样式
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/// </summary>
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public Style PanelStyle
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{
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get => (Style)GetValue(PanelStyleProperty);
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set => SetValue(PanelStyleProperty, value);
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}
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/// <summary>
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/// 用于存储或获取当前搜索框中的文本，支持双向绑定。
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/// </summary>
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public string SearchText { get => (string)GetValue(SearchTextProperty); set => SetValue(SearchTextProperty, value); }
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/// <summary>
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/// 用于选择搜索结果的命令。此命令绑定到UI元素上，当用户触发时，将执行与选择搜索结果相关的操作。
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/// </summary>
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public ICommand SelectSearchResultCommand { get; private set; }
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#region 依赖属性
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/// <summary>
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/// 用于设置或获取级联选择器的数据源。
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/// </summary>
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public static readonly DependencyProperty ItemsSourceProperty =
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DependencyProperty.Register(
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nameof(ItemsSource),
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typeof(IEnumerable),
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typeof(Cascader),
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new PropertyMetadata(null, OnItemsSourceChanged));
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/// <summary>
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/// 获取或设置用于显示的项集合。
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/// </summary>
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public IEnumerable ItemsSource
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{
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get => (IEnumerable)GetValue(ItemsSourceProperty);
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set => SetValue(ItemsSourceProperty, value);
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}
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/// <summary>
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/// 用于获取或设置当前选中的值。此属性支持双向数据绑定。
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/// </summary>
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public static readonly DependencyProperty SelectedValueProperty =
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DependencyProperty.Register(
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nameof(SelectedValue),
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typeof(object),
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typeof(Cascader),
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new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
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/// <summary>
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/// 获取或设置当前选中的值。
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/// 该属性支持双向数据绑定，可以用于在Cascader控件与其数据源之间同步选定的项。
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/// </summary>
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public object SelectedValue
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{
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get => GetValue(SelectedValueProperty);
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set => SetValue(SelectedValueProperty, value);
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}
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/// <summary>
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/// 用于指定在显示项时使用的属性路径。
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/// </summary>
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public static readonly DependencyProperty DisplayMemberPathProperty =
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DependencyProperty.Register(nameof(DisplayMemberPath), typeof(string), typeof(Cascader), new PropertyMetadata(""));
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/// <summary>
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/// 用于指定在显示项时，用来表示对象的属性路径。当设置此属性后，控件将使用该属性的值来展示列表中的每个项目。
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/// </summary>
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public string DisplayMemberPath
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{
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get => (string)GetValue(DisplayMemberPathProperty);
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set => SetValue(DisplayMemberPathProperty, value);
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}
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/// <summary>
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/// 用于指定子菜单成员路径的属性，该属性指示了在数据源中如何查找子项。
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/// </summary>
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public static readonly DependencyProperty SubmenuMemberPathProperty =
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DependencyProperty.Register(
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nameof(SubmenuMemberPath),
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typeof(string),
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typeof(Cascader),
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new PropertyMetadata("Children"));
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/// <summary>
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/// 用于指定子菜单项的属性路径，该属性路径指向的数据应为可枚举类型，表示当前项下的子项集合。
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/// </summary>
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public string SubmenuMemberPath
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{
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get => (string)GetValue(SubmenuMemberPathProperty);
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set => SetValue(SubmenuMemberPathProperty, value);
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}
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/// <summary>
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/// 用于获取或设置与控件关联的输入绑定集合
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/// </summary>
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public static readonly DependencyProperty InputBindingsProperty =
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DependencyProperty.RegisterAttached("InputBindings", typeof(InputBindingCollection), typeof(Cascader),
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new FrameworkPropertyMetadata(new InputBindingCollection(), OnInputBindingsChanged));
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/// <summary>
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/// 获取指定元素的输入绑定集合。
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/// </summary>
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/// <param name="element">要获取输入绑定集合的UI元素。</param>
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/// <returns>返回指定元素的输入绑定集合。</returns>
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public static InputBindingCollection GetInputBindings(UIElement element) => (InputBindingCollection)element.GetValue(InputBindingsProperty);
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/// <summary>
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/// 设置指定元素的输入绑定集合。
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/// </summary>
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/// <param name="element">要设置输入绑定的UI元素。</param>
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/// <param name="value">要分配给元素的输入绑定集合。</param>
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public static void SetInputBindings(UIElement element, InputBindingCollection value) => element.SetValue(InputBindingsProperty, value);
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private static void OnInputBindingsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
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{
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if (d is not UIElement uiElement) return;
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uiElement.InputBindings.Clear();
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if (e.NewValue is InputBindingCollection bindings)
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{
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uiElement.InputBindings.AddRange(bindings);
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}
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}
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/// <summary>
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/// 用于设置或获取分隔符字符串，该字符串用于在显示层级结构时分隔不同层级的文本。
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/// </summary>
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public static readonly DependencyProperty SeparatorProperty =
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DependencyProperty.Register(nameof(Separator), typeof(string), typeof(Cascader), new PropertyMetadata(" / "));
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/// <summary>
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/// 用于连接路径中各个元素的分隔符字符串
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/// </summary>
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public string Separator
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{ get => (string)GetValue(SeparatorProperty); set => SetValue(SeparatorProperty, value); }
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/// <summary>
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/// 控制下拉菜单是否展开的属性
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/// </summary>
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public static readonly DependencyProperty IsDropDownOpenProperty =
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DependencyProperty.Register(
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nameof(IsDropDownOpen),
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typeof(bool),
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typeof(Cascader),
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new FrameworkPropertyMetadata(false, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
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/// <summary>
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/// 获取或设置一个值，表示下拉菜单是否处于打开状态。此属性支持双向数据绑定。
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/// </summary>
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public bool IsDropDownOpen
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{
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get => (bool)GetValue(IsDropDownOpenProperty);
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set => SetValue(IsDropDownOpenProperty, value);
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}
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private static readonly DependencyPropertyKey SelectedTextPropertyKey =
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DependencyProperty.RegisterReadOnly("SelectedText", typeof(string), typeof(Cascader), new PropertyMetadata(""));
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/// <summary>
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/// 获取或设置当前选中的文本。
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/// </summary>
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public static readonly DependencyProperty SelectedTextProperty = SelectedTextPropertyKey.DependencyProperty;
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/// <summary>
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/// 获取或设置当前选中的文本，该文本通常由用户选择的级联项组成。
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/// </summary>
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public string SelectedText
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{
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get => (string)GetValue(SelectedTextProperty);
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protected set => SetValue(SelectedTextPropertyKey, value);
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}
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// 【核心概念】这里定义了 CascadingPanel 属性，它是一个“舞台”的蓝图
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internal static readonly DependencyProperty CascadingPanelProperty =
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DependencyProperty.Register(nameof(CascadingPanel), typeof(Panel), typeof(Cascader), new PropertyMetadata(null));
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internal Panel CascadingPanel
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{
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get => (Panel)GetValue(CascadingPanelProperty);
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set => SetValue(CascadingPanelProperty, value);
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}
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#endregion
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}
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/// <summary>
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/// 用于封装级联选择器搜索结果的类
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/// </summary>
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/// <remarks>
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/// 用于封装级联选择器搜索结果的类。此类包含了展示文本、目标项以及完整的路径信息。
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/// </remarks>
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public class CascaderSearchResult(string displayText, object targetItem, List<object> fullPath)
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{
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/// <summary>
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/// 用于在UI上显示的完整路径文本
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/// </summary>
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public string DisplayText { get; } = displayText;
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/// <summary>
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/// 构成完整路径的原始数据对象列表
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/// </summary>
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public List<object> FullPath { get; } = fullPath;
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/// <summary>
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/// 路径中的最后一项，即匹配到的原始数据对象
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/// </summary>
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public object TargetItem { get; } = targetItem;
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}
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