103 lines
3.7 KiB
C#
103 lines
3.7 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;
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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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using CommunityToolkit.Mvvm.Collections.Internals;
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namespace CommunityToolkit.Mvvm.Collections;
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/// <summary>
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/// An observable group.
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/// It associates a <see cref="Key"/> to an <see cref="ObservableCollection{T}"/>.
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/// </summary>
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/// <typeparam name="TKey">The type of the group key.</typeparam>
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/// <typeparam name="TElement">The type of elements in the group.</typeparam>
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[DebuggerDisplay("Key = {Key}, Count = {Count}")]
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public sealed class ObservableGroup<TKey, TElement> : ObservableCollection<TElement>, IReadOnlyObservableGroup<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="ObservableGroup{TKey, TValue}"/> class.
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/// </summary>
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/// <param name="key">The key for the group.</param>
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/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="key"/> is <see langword="null"/>.</exception>
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public ObservableGroup(TKey key)
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{
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ArgumentNullException.For<TKey>.ThrowIfNull(key);
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this.key = key;
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ObservableGroup{TKey, TValue}"/> class.
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/// </summary>
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/// <param name="grouping">The grouping to fill the group.</param>
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/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="grouping"/> is <see langword="null"/>.</exception>
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public ObservableGroup(IGrouping<TKey, TElement> grouping)
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: base(grouping)
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{
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this.key = grouping.Key;
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ObservableGroup{TKey, TValue}"/> class.
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/// </summary>
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/// <param name="key">The key for the group.</param>
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/// <param name="collection">The initial collection of data to add to the group.</param>
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/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="key"/> or <paramref name="collection"/> are <see langword="null"/>.</exception>
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public ObservableGroup(TKey key, IEnumerable<TElement> collection)
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: base(collection)
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{
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ArgumentNullException.For<TKey>.ThrowIfNull(key);
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this.key = key;
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}
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private TKey key;
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/// <summary>
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/// Gets or sets the key of the group.
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/// </summary>
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/// <exception cref="System.ArgumentNullException">Thrown if <paramref name="value"/> is <see langword="null"/>.</exception>
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public TKey Key
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{
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get => this.key;
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set
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{
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ArgumentNullException.For<TKey>.ThrowIfNull(value);
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if (!EqualityComparer<TKey>.Default.Equals(this.key!, value))
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{
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this.key = value;
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OnPropertyChanged(ObservableGroupHelper.KeyChangedEventArgs);
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}
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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<TElement>? list)
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{
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list = Items as List<TElement>;
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return list is not null;
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}
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/// <inheritdoc/>
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object IReadOnlyObservableGroup.Key => Key;
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/// <inheritdoc/>
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object? IReadOnlyObservableGroup.this[int index] => this[index];
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}
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