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Adds Range Manipulation APIs for Collection<T> and ObservableCollection<T> #65101

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Adds Range Manipulation APIs for Collection<T> and ObservableCollection<T> #65101

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19ca559
Added range manipulation APIS for Collect<T> and ObservableCollection<T>
SkyeHoefling Feb 8, 2022
2a9612e
Added unit tests for Collection and ObservableCollection
SkyeHoefling Feb 9, 2022
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171 changes: 165 additions & 6 deletions src/libraries/System.ObjectModel/src/System/Collections/ObjectModel/ObservableCollection.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,9 @@ public class ObservableCollection<T> : Collection<T>, INotifyCollectionChanged,
[NonSerialized]
private int _blockReentrancyCount;

[NonSerialized]
private bool _skipRaisingEvents;

/// <summary>
/// Initializes a new instance of ObservableCollection that is empty and has default initial capacity.
/// </summary>
Expand Down Expand Up @@ -110,9 +113,115 @@ protected override void RemoveItem(int index)

base.RemoveItem(index);

OnCountPropertyChanged();
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Remove, removedItem, index);
if (!_skipRaisingEvents)
{
OnCountPropertyChanged();
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Remove, removedItem, index);
}
}

/// <summary>
/// Called by base class Collection&lt;T&gt; when a count of items is removed from the list;
/// raises a CollectionChanged event to any listeners.
/// </summary>
protected override void RemoveItemsRange(int index, int count)
{
CheckReentrancy();

T[] removedItems = Array.Empty<T>();

bool ignore = _skipRaisingEvents;
if (!ignore)
{
if (Items.IsReadOnly)
{
throw new NotSupportedException(SR.NotSupported_ReadOnlyCollection);
}

if ((uint)index > (uint)Items.Count)
{
throw new ArgumentOutOfRangeException(SR.ArgumentOutOfRange_InvalidThreshold);
}

if (count < 0)
{
throw new ArgumentOutOfRangeException(SR.ArgumentOutOfRange_NeedNonNegNum);
}

if (index > Items.Count - count)
{
throw new ArgumentException(SR.Argument_ItemNotExist);
}

_skipRaisingEvents = true;

if (count > 0)
{
removedItems = new T[count];
for (int i = 0; i < count; i++)
{
removedItems[i] = this[index + i];
}
}
}

try
{
base.RemoveItemsRange(index, count);
}
finally
{
if (!ignore)
{
_skipRaisingEvents = false;
}
}

if (count > 0 && !_skipRaisingEvents)
{
OnCountPropertyChanged();
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Remove, removedItems, index);
}
}

/// <summary>
/// Called by base class Collection&lt;T&gt; when a collection of items is added to list;
/// raises a CollectionChanged event to any listeners.
/// </summary>
protected override void ReplaceItemsRange(int index, int count, IEnumerable<T> collection)
{
CheckReentrancy();

_skipRaisingEvents = true;

T[] itemsToReplace = new T[count - index];
for (int i = index; i < count; i++)
{
itemsToReplace[i] = this[i];
}

try
{
base.ReplaceItemsRange(index, count, collection);
}
finally
{
_skipRaisingEvents = false;
}

if (!_skipRaisingEvents)
{
IList newItems = collection is IList list ? list : new List<T>(collection);

if (newItems.Count > 0)
{
OnCountPropertyChanged();
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Replace, itemsToReplace, newItems, index);
}
}
}

/// <summary>
Expand All @@ -124,9 +233,51 @@ protected override void InsertItem(int index, T item)
CheckReentrancy();
base.InsertItem(index, item);

OnCountPropertyChanged();
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Add, item, index);
if (!_skipRaisingEvents)
{
OnCountPropertyChanged();
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Add, item, index);
}
}

/// <summary>
/// Called by base class Collection&lt;T&gt; when a collection of items is added to list;
/// raises a CollectionChanged event to any listeners.
/// </summary>
protected override void InsertItemsRange(int index, IEnumerable<T> collection)
{
CheckReentrancy();

bool ignore = _skipRaisingEvents;
if (!ignore)
{
_skipRaisingEvents = true;
}

try
{
base.InsertItemsRange(index, collection);
}
finally
{
if (!ignore)
{
_skipRaisingEvents = false;
}
}

if (!_skipRaisingEvents)
{
IList newItems = collection is IList list ? list : new List<T>(collection);

if (newItems.Count > 0)
{
OnCountPropertyChanged();
OnIndexerPropertyChanged();
OnCollectionChanged(NotifyCollectionChangedAction.Add, newItems, index);
}
}
}

/// <summary>
Expand Down Expand Up @@ -262,6 +413,14 @@ private void OnCollectionChanged(NotifyCollectionChangedAction action, object? i
OnCollectionChanged(new NotifyCollectionChangedEventArgs(action, item, index, oldIndex));
}

/// <summary>
/// Helper to raise CollectionChanged event to any listeners
/// </summary>
private void OnCollectionChanged(NotifyCollectionChangedAction action, IList? items, int index)
{
OnCollectionChanged(new NotifyCollectionChangedEventArgs(action, items, index));
}

/// <summary>
/// Helper to raise CollectionChanged event to any listeners
/// </summary>
Expand Down
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