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namespace System.Collections.ObjectModel
{
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
/// <summary>
/// Implementation of a dynamic data collection based on generic Collection<T>,
/// implementing INotifyCollectionChanged to notify listeners
/// when items get added, removed or the whole list is refreshed.
/// </summary>
public class RangeObservableCollection<T> : ObservableCollection<T>
{
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
#region Private Fields
[NonSerialized]
private DeferredEventsCollection? _deferredEvents;
#endregion Private Fields
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
/// <summary>
/// Initializes a new instance of ObservableCollection that is empty and has default initial capacity.
/// </summary>
public RangeObservableCollection() { }
/// <summary>
/// Initializes a new instance of the ObservableCollection class that contains
/// elements copied from the specified collection and has sufficient capacity
/// to accommodate the number of elements copied.
/// </summary>
/// <param name="collection">The collection whose elements are copied to the new list.</param>
/// <remarks>
/// The elements are copied onto the ObservableCollection in the
/// same order they are read by the enumerator of the collection.
/// </remarks>
/// <exception cref="ArgumentNullException"> collection is a null reference </exception>
public RangeObservableCollection(IEnumerable<T> collection) : base(collection) { }
/// <summary>
/// Initializes a new instance of the ObservableCollection class
/// that contains elements copied from the specified list
/// </summary>
/// <param name="list">The list whose elements are copied to the new list.</param>
/// <remarks>
/// The elements are copied onto the ObservableCollection in the
/// same order they are read by the enumerator of the list.
/// </remarks>
/// <exception cref="ArgumentNullException"> list is a null reference </exception>
public RangeObservableCollection(List<T> list) : base(list) { }
#endregion Constructors
//------------------------------------------------------
//
// Public Properties
//
//------------------------------------------------------
#region Public Properties
EqualityComparer<T>? _Comparer;
public EqualityComparer<T> Comparer
{
get => _Comparer ??= EqualityComparer<T>.Default;
private set => _Comparer = value;
}
/// <summary>
/// Gets or sets a value indicating whether this collection acts as a <see cref="HashSet{T}"/>,
/// disallowing duplicate items, based on <see cref="Comparer"/>.
/// This might indeed consume background performance, but in the other hand,
/// it will pay off in UI performance as less required UI updates are required.
/// </summary>
public bool AllowDuplicates { get; set; } = true;
#endregion Public Properties
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
#region Public Methods
/// <summary>
/// Clear the list and set a collection in place
/// </summary>
/// <param name="collection">
/// The collection whose elements should be added to the end of the <see cref="ObservableCollection{T}"/>.
/// The collection itself cannot be null, but it can contain elements that are null, if type T is a reference type.
/// </param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
public void ReplaceCollection(IEnumerable<T> collection)
{
Clear();
AddRange(collection);
}
/// <summary>
/// Adds the elements of the specified collection to the end of the <see cref="ObservableCollection{T}"/>.
/// </summary>
/// <param name="collection">
/// The collection whose elements should be added to the end of the <see cref="ObservableCollection{T}"/>.
/// The collection itself cannot be null, but it can contain elements that are null, if type T is a reference type.
/// </param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
public void AddRange(IEnumerable<T> collection)
{
InsertRange(Count, collection);
}
/// <summary>
/// Inserts the elements of a collection into the <see cref="ObservableCollection{T}"/> at the specified index.
/// </summary>
/// <param name="index">The zero-based index at which the new elements should be inserted.</param>
/// <param name="collection">The collection whose elements should be inserted into the List<T>.
/// The collection itself cannot be null, but it can contain elements that are null, if type T is a reference type.</param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is not in the collection range.</exception>
public void InsertRange(int index, IEnumerable<T> collection)
{
if (collection == null)
throw new ArgumentNullException(nameof(collection));
if (index < 0)
throw new ArgumentOutOfRangeException(nameof(index));
if (index > Count)
throw new ArgumentOutOfRangeException(nameof(index));
if (!AllowDuplicates)
collection =
collection
.Distinct(Comparer)
.Where(item => !Items.Contains(item, Comparer))
.ToList();
if (collection is ICollection<T> countable)
{
if (countable.Count == 0)
return;
}
else if (!collection.Any())
return;
CheckReentrancy();
//expand the following couple of lines when adding more constructors.
var target = (List<T>)Items;
target.InsertRange(index, collection);
OnEssentialPropertiesChanged();
/*if (!(collection is IList list))
list = new List<T>(collection);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset, list, index));*/
OnCollectionReset();
}
/// <summary>
/// Removes the first occurence of each item in the specified collection from the <see cref="ObservableCollection{T}"/>.
/// </summary>
/// <param name="collection">The items to remove.</param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
public void RemoveRange(IEnumerable<T> collection)
{
if (collection == null)
throw new ArgumentNullException(nameof(collection));
if (Count == 0)
return;
else if (collection is ICollection<T> countable)
{
switch (countable.Count)
{
case 0:
return;
case 1:
{
using IEnumerator<T> enumerator = countable.GetEnumerator();
enumerator.MoveNext();
Remove(enumerator.Current);
return;
}
}
}
else if (!collection.Any())
return;
CheckReentrancy();
//var clusters = new Dictionary<int, List<T>>();
//var lastIndex = -1;
//List<T>? lastCluster = null;
foreach (T item in collection)
{
var index = IndexOf(item);
if (index < 0)
continue;
Items.RemoveAt(index);
/*if (lastIndex == index && lastCluster != null)
lastCluster.Add(item);
else
clusters[lastIndex = index] = lastCluster = new List<T> { item };*/
}
OnEssentialPropertiesChanged();
OnCollectionReset();
/*if (Count == 0)
OnCollectionReset();
else
foreach (var cluster in clusters)
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, cluster.Value, cluster.Key));*/
}
/// <summary>
/// Iterates over the collection and removes all items that satisfy the specified match.
/// </summary>
/// <remarks>The complexity is O(n).</remarks>
/// <param name="match"></param>
/// <returns>Returns the number of elements that where </returns>
/// <exception cref="ArgumentNullException"><paramref name="match"/> is null.</exception>
public int RemoveAll(Predicate<T> match)
{
return RemoveAll(0, Count, match);
}
/// <summary>
/// Iterates over the specified range within the collection and removes all items that satisfy the specified match.
/// </summary>
/// <remarks>The complexity is O(n).</remarks>
/// <param name="index">The index of where to start performing the search.</param>
/// <param name="count">The number of items to iterate on.</param>
/// <param name="match"></param>
/// <returns>Returns the number of elements that where </returns>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is out of range.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="count"/> is out of range.</exception>
/// <exception cref="ArgumentNullException"><paramref name="match"/> is null.</exception>
public int RemoveAll(int index, int count, Predicate<T> match)
{
if (index < 0)
throw new ArgumentOutOfRangeException(nameof(index));
if (count < 0)
throw new ArgumentOutOfRangeException(nameof(count));
if (index + count > Count)
throw new ArgumentOutOfRangeException(nameof(index));
if (match == null)
throw new ArgumentNullException(nameof(match));
if (Count == 0)
return 0;
//List<T>? cluster = null;
var clusterIndex = -1;
var removedCount = 0;
using (BlockReentrancy())
using (DeferEvents())
{
for (var i = 0; i < count; i++, index++)
{
T item = Items[index];
if (match(item))
{
Items.RemoveAt(index);
removedCount++;
/*if (clusterIndex == index)
{
Debug.Assert(cluster != null);
cluster!.Add(item);
}
else
{
cluster = new List<T> { item };
clusterIndex = index;
}*/
index--;
}
/*else if (clusterIndex > -1)
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, cluster, clusterIndex));
clusterIndex = -1;
cluster = null;
}*/
}
//if (clusterIndex > -1)
// OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, cluster, clusterIndex));
}
if (removedCount > 0)
{
OnEssentialPropertiesChanged();
OnCollectionReset();
}
return removedCount;
}
/// <summary>
/// Removes a range of elements from the <see cref="ObservableCollection{T}"/>>.
/// </summary>
/// <param name="index">The zero-based starting index of the range of elements to remove.</param>
/// <param name="count">The number of elements to remove.</param>
/// <exception cref="ArgumentOutOfRangeException">The specified range is exceeding the collection.</exception>
public void RemoveRange(int index, int count)
{
if (index < 0)
throw new ArgumentOutOfRangeException(nameof(index));
if (count < 0)
throw new ArgumentOutOfRangeException(nameof(count));
if (index + count > Count)
throw new ArgumentOutOfRangeException(nameof(index));
if (count == 0)
return;
if (count == 1)
{
RemoveItem(index);
return;
}
//Items will always be List<T>, see constructors
var items = (List<T>)Items;
List<T> removedItems = items.GetRange(index, count);
CheckReentrancy();
items.RemoveRange(index, count);
OnEssentialPropertiesChanged();
if (Count == 0)
OnCollectionReset();
else
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removedItems, index));
}
/// <summary>
/// Clears the current collection and replaces it with the specified collection,
/// using <see cref="Comparer"/>.
/// </summary>
/// <param name="collection">The items to fill the collection with, after clearing it.</param>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
public void ReplaceRange(IEnumerable<T> collection)
{
ReplaceRange(0, Count, collection);
}
/// <summary>
/// Removes the specified range and inserts the specified collection in its position, leaving equal items in equal positions intact.
/// </summary>
/// <param name="index">The index of where to start the replacement.</param>
/// <param name="count">The number of items to be replaced.</param>
/// <param name="collection">The collection to insert in that location.</param>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="index"/> is out of range.</exception>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="count"/> is out of range.</exception>
/// <exception cref="ArgumentNullException"><paramref name="collection"/> is null.</exception>
/// <exception cref="ArgumentNullException"><paramref name="comparer"/> is null.</exception>
public void ReplaceRange(int index, int count, IEnumerable<T> collection)
{
if (index < 0)
throw new ArgumentOutOfRangeException(nameof(index));
if (count < 0)
throw new ArgumentOutOfRangeException(nameof(count));
if (index + count > Count)
throw new ArgumentOutOfRangeException(nameof(index));
if (collection == null)
throw new ArgumentNullException(nameof(collection));
if (!AllowDuplicates)
collection =
collection
.Distinct(Comparer)
.ToList();
if (collection is ICollection<T> countable)
{
if (countable.Count == 0)
{
RemoveRange(index, count);
return;
}
}
else if (!collection.Any())
{
RemoveRange(index, count);
return;
}
if (index + count == 0)
{
InsertRange(0, collection);
return;
}
if (!(collection is IList<T> list))
list = new List<T>(collection);
using (BlockReentrancy())
using (DeferEvents())
{
var rangeCount = index + count;
var addedCount = list.Count;
var changesMade = false;
List<T>?
newCluster = null,
oldCluster = null;
int i = index;
for (; i < rangeCount && i - index < addedCount; i++)
{
//parallel position
T old = this[i], @new = list[i - index];
if (Comparer.Equals(old, @new))
{
OnRangeReplaced(i, newCluster!, oldCluster!);
continue;
}
else
{
Items[i] = @new;
if (newCluster == null)
{
Debug.Assert(oldCluster == null);
newCluster = new List<T> { @new };
oldCluster = new List<T> { old };
}
else
{
newCluster.Add(@new);
oldCluster!.Add(old);
}
changesMade = true;
}
}
OnRangeReplaced(i, newCluster!, oldCluster!);
//exceeding position
if (count != addedCount)
{
var items = (List<T>)Items;
if (count > addedCount)
{
var removedCount = rangeCount - addedCount;
T[] removed = new T[removedCount];
items.CopyTo(i, removed, 0, removed.Length);
items.RemoveRange(i, removedCount);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removed, i));
}
else
{
var k = i - index;
T[] added = new T[addedCount - k];
for (int j = k; j < addedCount; j++)
{
T @new = list[j];
added[j - k] = @new;
}
items.InsertRange(i, added);
OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, added, i));
}
OnEssentialPropertiesChanged();
}
else if (changesMade)
{
OnIndexerPropertyChanged();
}
}
}
public void Sort()
{
Sort(null);
}
public void Sort(Comparison<T> comparison)
{
if (Count == 0)
{
return;
}
var list = this.ToList();
list.Sort(comparison);
ReplaceCollection(list);
}
#endregion Public Methods
//------------------------------------------------------
//
// Protected Methods
//
//------------------------------------------------------
#region Protected Methods
/// <summary>
/// Called by base class Collection<T> when the list is being cleared;
/// raises a CollectionChanged event to any listeners.
/// </summary>
protected override void ClearItems()
{
if (Count == 0)
return;
//CheckReentrancy();
base.ClearItems();
//OnEssentialPropertiesChanged();
//OnCollectionReset();
}
/// <inheritdoc/>
protected override void InsertItem(int index, T item)
{
if (!AllowDuplicates && Items.Contains(item))
return;
base.InsertItem(index, item);
}
/// <inheritdoc/>
protected override void SetItem(int index, T item)
{
if (AllowDuplicates)
{
if (Comparer.Equals(this[index], item))
return;
}
else
if (Items.Contains(item, Comparer))
return;
CheckReentrancy();
T oldItem = this[index];
base.SetItem(index, item);
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Replace, oldItem!, item!, index);
}
/// <summary>
/// Raise CollectionChanged event to any listeners.
/// Properties/methods modifying this ObservableCollection will raise
/// a collection changed event through this virtual method.
/// </summary>
/// <remarks>
/// When overriding this method, either call its base implementation
/// or call <see cref="BlockReentrancy"/> to guard against reentrant collection changes.
/// </remarks>
protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
{
if (_deferredEvents != null)
{
_deferredEvents.Add(e);
return;
}
base.OnCollectionChanged(e);
}
protected virtual IDisposable DeferEvents() => new DeferredEventsCollection(this);
#endregion Protected Methods
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
#region Private Methods
/// <summary>
/// Helper to raise Count property and the Indexer property.
/// </summary>
void OnEssentialPropertiesChanged()
{
OnPropertyChanged(EventArgsCache.CountPropertyChanged);
OnIndexerPropertyChanged();
}
/// <summary>
/// /// Helper to raise a PropertyChanged event for the Indexer property
/// /// </summary>
void OnIndexerPropertyChanged() =>
OnPropertyChanged(EventArgsCache.IndexerPropertyChanged);
/// <summary>
/// Helper to raise CollectionChanged event to any listeners
/// </summary>
void OnCollectionChanged(NotifyCollectionChangedAction action, object oldItem, object newItem, int index) =>
OnCollectionChanged(new NotifyCollectionChangedEventArgs(action, newItem, oldItem, index));
/// <summary>
/// Helper to raise CollectionChanged event with action == Reset to any listeners
/// </summary>
void OnCollectionReset() =>
OnCollectionChanged(EventArgsCache.ResetCollectionChanged);
/// <summary>
/// Helper to raise event for clustered action and clear cluster.
/// </summary>
/// <param name="followingItemIndex">The index of the item following the replacement block.</param>
/// <param name="newCluster"></param>
/// <param name="oldCluster"></param>
//TODO should have really been a local method inside ReplaceRange(int index, int count, IEnumerable<T> collection, IEqualityComparer<T> comparer),
//move when supported language version updated.
void OnRangeReplaced(int followingItemIndex, ICollection<T> newCluster, ICollection<T> oldCluster)
{
if (oldCluster == null || oldCluster.Count == 0)
{
Debug.Assert(newCluster == null || newCluster.Count == 0);
return;
}
OnCollectionChanged(
new NotifyCollectionChangedEventArgs(
NotifyCollectionChangedAction.Replace,
new List<T>(newCluster),
new List<T>(oldCluster),
followingItemIndex - oldCluster.Count));
oldCluster.Clear();
newCluster.Clear();
}
#endregion Private Methods
//------------------------------------------------------
//
// Private Types
//
//------------------------------------------------------
#region Private Types
sealed class DeferredEventsCollection : List<NotifyCollectionChangedEventArgs>, IDisposable
{
readonly RangeObservableCollection<T> _collection;
public DeferredEventsCollection(RangeObservableCollection<T> collection)
{
Debug.Assert(collection != null);
Debug.Assert(collection._deferredEvents == null);
_collection = collection;
_collection._deferredEvents = this;
}
public void Dispose()
{
_collection._deferredEvents = null;
foreach (var args in this)
_collection.OnCollectionChanged(args);
}
}
#endregion Private Types
}
/// <remarks>
/// To be kept outside <see cref="ObservableCollection{T}"/>, since otherwise, a new instance will be created for each generic type used.
/// </remarks>
internal static class EventArgsCache
{
internal static readonly PropertyChangedEventArgs CountPropertyChanged = new PropertyChangedEventArgs("Count");
internal static readonly PropertyChangedEventArgs IndexerPropertyChanged = new PropertyChangedEventArgs("Item[]");
internal static readonly NotifyCollectionChangedEventArgs ResetCollectionChanged = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset);
}
}
|