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* Update BindingBase.Instance signature. - Swap `target` and `targetProperty` order to make it consistent with other similar methods - Make `targetProperty` nullable as it will need to be null for `MultiBinding` * IBinding2.Instance needs to accept a null target property. It will need to be null for `MultiBinding`. * Attach needs to accept a null target property. It will need to be null for `MultiBinding`. * Initial implementation of MultiBindingExpression. * Fix failing template binding test. Only publish unset value if we've already published a value. * Enabled nullability annotations. * Added passing test for #16084. * Remove obsolete API usages. * Bind to Tag not Text. Prevents test passing when it shouldn't. See https://github.com/AvaloniaUI/Avalonia/pull/16219#discussion_r1665466968 * Handle DoNothing in MultiBindingExpression.pull/16620/head
Steven Kirk
2 years ago
committed by
GitHub
GitHub
13 changed files with 259 additions and 98 deletions
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using System; |
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using System.Collections.Generic; |
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using System.Collections.ObjectModel; |
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using System.Diagnostics; |
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using System.Globalization; |
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using Avalonia.Data.Converters; |
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namespace Avalonia.Data.Core; |
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internal class MultiBindingExpression : UntypedBindingExpressionBase, IBindingExpressionSink |
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{ |
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private static readonly object s_uninitialized = new object(); |
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private readonly IBinding[] _bindings; |
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private readonly IMultiValueConverter? _converter; |
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private readonly CultureInfo? _converterCulture; |
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private readonly object? _converterParameter; |
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private readonly UntypedBindingExpressionBase?[] _expressions; |
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private readonly object? _fallbackValue; |
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private readonly object? _targetNullValue; |
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private readonly object?[] _values; |
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private readonly ReadOnlyCollection<object?> _valuesView; |
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public MultiBindingExpression( |
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BindingPriority priority, |
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IList<IBinding> bindings, |
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IMultiValueConverter? converter, |
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CultureInfo? converterCulture, |
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object? converterParameter, |
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object? fallbackValue, |
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object? targetNullValue) |
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: base(priority) |
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{ |
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_bindings = [.. bindings]; |
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_converter = converter; |
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_converterCulture = converterCulture; |
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_converterParameter = converterParameter; |
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_expressions = new UntypedBindingExpressionBase[_bindings.Length]; |
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_fallbackValue = fallbackValue; |
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_targetNullValue = targetNullValue; |
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_values = new object?[_bindings.Length]; |
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_valuesView = new(_values); |
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#if NETSTANDARD2_0
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for (var i = 0; i < _bindings.Length; ++i) |
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_values[i] = s_uninitialized; |
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#else
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Array.Fill(_values, s_uninitialized); |
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#endif
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} |
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public override string Description => "MultiBinding"; |
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protected override void StartCore() |
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{ |
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if (!TryGetTarget(out var target)) |
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throw new AvaloniaInternalException("MultiBindingExpression has no target."); |
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for (var i = 0; i < _bindings.Length; ++i) |
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{ |
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var binding = _bindings[i]; |
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if (binding is not IBinding2 b) |
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throw new NotSupportedException($"Unsupported IBinding implementation '{binding}'."); |
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var expression = b.Instance(target, null, null); |
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if (expression is not UntypedBindingExpressionBase e) |
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throw new NotSupportedException($"Unsupported BindingExpressionBase implementation '{expression}'."); |
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_expressions[i] = e; |
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e.AttachAndStart(this, target, null, Priority); |
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} |
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} |
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protected override void StopCore() |
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{ |
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for (var i = 0; i < _expressions.Length; ++i) |
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{ |
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_expressions[i]?.Dispose(); |
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_expressions[i] = null; |
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_values[i] = s_uninitialized; |
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} |
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} |
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void IBindingExpressionSink.OnChanged( |
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UntypedBindingExpressionBase instance, |
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bool hasValueChanged, |
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bool hasErrorChanged, |
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object? value, |
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BindingError? error) |
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{ |
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var i = Array.IndexOf(_expressions, instance); |
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Debug.Assert(i != -1); |
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_values[i] = BindingNotification.ExtractValue(value); |
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PublishValue(); |
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} |
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void IBindingExpressionSink.OnCompleted(UntypedBindingExpressionBase instance) |
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{ |
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// Nothing to do here.
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} |
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private void PublishValue() |
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{ |
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foreach (var v in _values) |
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{ |
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if (v == s_uninitialized) |
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return; |
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} |
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if (_converter is not null) |
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{ |
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var culture = _converterCulture ?? CultureInfo.CurrentCulture; |
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var converted = _converter.Convert(_valuesView, TargetType, _converterParameter, culture); |
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converted = BindingNotification.ExtractValue(converted); |
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if (converted != BindingOperations.DoNothing) |
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{ |
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if (converted == null) |
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converted = _targetNullValue; |
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if (converted == AvaloniaProperty.UnsetValue) |
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converted = _fallbackValue; |
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PublishValue(converted); |
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} |
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} |
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else |
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{ |
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PublishValue(_valuesView); |
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} |
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} |
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} |
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