79 lines
2.8 KiB
C#
79 lines
2.8 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System.Collections.Generic;
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using System.Collections.ObjectModel;
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using System.Diagnostics.CodeAnalysis;
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using System.Linq;
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using System.Runtime.CompilerServices;
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namespace CommunityToolkit.Mvvm.Collections;
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/// <summary>
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/// An observable list of observable groups.
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/// </summary>
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/// <typeparam name="TKey">The type of the group keys.</typeparam>
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/// <typeparam name="TElement">The type of elements in the collection.</typeparam>
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public sealed class ObservableGroupedCollection<TKey, TElement> : ObservableCollection<ObservableGroup<TKey, TElement>>, ILookup<TKey, TElement>
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where TKey : notnull
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{
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/// <summary>
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/// Initializes a new instance of the <see cref="ObservableGroupedCollection{TKey, TValue}"/> class.
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/// </summary>
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public ObservableGroupedCollection()
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ObservableGroupedCollection{TKey, TValue}"/> class.
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/// </summary>
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/// <param name="collection">The initial data to add in the grouped collection.</param>
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/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="collection"/> is <see langword="null"/>.</exception>
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public ObservableGroupedCollection(IEnumerable<IGrouping<TKey, TElement>> collection)
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: base(collection?.Select(static group => new ObservableGroup<TKey, TElement>(group))!)
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{
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}
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/// <inheritdoc/>
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IEnumerable<TElement> ILookup<TKey, TElement>.this[TKey key]
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{
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get
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{
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IEnumerable<TElement>? result = null;
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if (key is not null)
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{
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result = this.FirstGroupByKeyOrDefault(key);
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}
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return result ?? Enumerable.Empty<TElement>();
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}
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}
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/// <summary>
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/// Tries to get the underlying <see cref="List{T}"/> instance, if present.
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/// </summary>
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/// <param name="list">The resulting <see cref="List{T}"/>, if one was in use.</param>
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/// <returns>Whether or not a <see cref="List{T}"/> instance has been found.</returns>
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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internal bool TryGetList([NotNullWhen(true)] out List<ObservableGroup<TKey, TElement>>? list)
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{
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list = Items as List<ObservableGroup<TKey, TElement>>;
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return list is not null;
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}
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/// <inheritdoc/>
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bool ILookup<TKey, TElement>.Contains(TKey key)
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{
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return key is not null && this.FirstGroupByKey(key) is not null;
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}
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/// <inheritdoc/>
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IEnumerator<IGrouping<TKey, TElement>> IEnumerable<IGrouping<TKey, TElement>>.GetEnumerator()
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{
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return GetEnumerator();
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}
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}
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