TextBox, PropertyChangeHandler

src/Library/TerminalUI/PropertyChangedHandler.cs

@@ -0,0 +1,45 @@
+using System.Linq.Expressions;
+
+namespace TerminalUI;
+
+public sealed class PropertyChangedHandler<TItem, TExpressionResult> : PropertyTrackerBase<TItem, TExpressionResult>, IDisposable
+{
+    private readonly TItem _dataSource;
+    private readonly Action<string, bool, TExpressionResult?> _handler;
+    private readonly PropertyTrackTreeItem? _propertyTrackTreeItem;
+    private readonly Func<TItem, TExpressionResult> _propertyValueGenerator;
+
+    public PropertyChangedHandler(
+        TItem dataSource,
+        Expression<Func<TItem, TExpressionResult>> dataSourceExpression,
+        Action<string, bool, TExpressionResult?> handler
+    ) : base(() => dataSource, dataSourceExpression)
+    {
+        _dataSource = dataSource;
+        _handler = handler;
+        ArgumentNullException.ThrowIfNull(dataSource);
+        ArgumentNullException.ThrowIfNull(dataSourceExpression);
+        ArgumentNullException.ThrowIfNull(handler);
+
+        _propertyTrackTreeItem = CreateTrackingTree(dataSourceExpression);
+        _propertyValueGenerator = dataSourceExpression.Compile();
+        UpdateTrackers();
+    }
+
+    protected override void Update(string propertyPath)
+    {
+        TExpressionResult? value = default;
+        var parsed = false;
+
+        try
+        {
+            value = _propertyValueGenerator(_dataSource);
+            parsed = true;
+        }
+        catch
+        {
+        }
+
+        _handler(propertyPath, parsed, value);
+    }
+}