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using System;
using System.Collections.Generic;
using System.Collections.Specialized;
namespace Xamarin.Forms
{
internal static class NotifyCollectionChangedEventArgsExtensions
{
public static void Apply<TFrom>(this NotifyCollectionChangedEventArgs self, IList<TFrom> from, IList<object> to)
{
self.Apply((o, i, b) => to.Insert(i, o), (o, i) => to.RemoveAt(i), () =>
{
to.Clear();
for (var i = 0; i < from.Count; i++)
to.Add(from[i]);
});
}
public static NotifyCollectionChangedAction Apply(this NotifyCollectionChangedEventArgs self, Action<object, int, bool> insert, Action<object, int> removeAt, Action reset)
{
if (self == null)
throw new ArgumentNullException("self");
if (reset == null)
throw new ArgumentNullException("reset");
if (insert == null)
throw new ArgumentNullException("insert");
if (removeAt == null)
throw new ArgumentNullException("removeAt");
switch (self.Action)
{
case NotifyCollectionChangedAction.Add:
if (self.NewStartingIndex < 0)
goto case NotifyCollectionChangedAction.Reset;
for (var i = 0; i < self.NewItems.Count; i++)
insert(self.NewItems[i], i + self.NewStartingIndex, true);
break;
case NotifyCollectionChangedAction.Move:
if (self.NewStartingIndex < 0 || self.OldStartingIndex < 0)
goto case NotifyCollectionChangedAction.Reset;
for (var i = 0; i < self.OldItems.Count; i++)
removeAt(self.OldItems[i], self.OldStartingIndex);
int insertIndex = self.NewStartingIndex;
if (self.OldStartingIndex < self.NewStartingIndex)
insertIndex -= self.OldItems.Count - 1;
for (var i = 0; i < self.OldItems.Count; i++)
insert(self.OldItems[i], insertIndex + i, false);
break;
case NotifyCollectionChangedAction.Remove:
if (self.OldStartingIndex < 0)
goto case NotifyCollectionChangedAction.Reset;
for (var i = 0; i < self.OldItems.Count; i++)
removeAt(self.OldItems[i], self.OldStartingIndex);
break;
case NotifyCollectionChangedAction.Replace:
if (self.OldStartingIndex < 0)
goto case NotifyCollectionChangedAction.Reset;
for (var i = 0; i < self.OldItems.Count; i++)
{
removeAt(self.OldItems[i], i + self.OldStartingIndex);
insert(self.OldItems[i], i + self.OldStartingIndex, true);
}
break;
case NotifyCollectionChangedAction.Reset:
reset();
return NotifyCollectionChangedAction.Reset;
}
return self.Action;
}
public static NotifyCollectionChangedEventArgsEx WithCount(this NotifyCollectionChangedEventArgs e, int count)
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
return new NotifyCollectionChangedEventArgsEx(count, NotifyCollectionChangedAction.Add, e.NewItems, e.NewStartingIndex);
case NotifyCollectionChangedAction.Remove:
return new NotifyCollectionChangedEventArgsEx(count, NotifyCollectionChangedAction.Remove, e.OldItems, e.OldStartingIndex);
case NotifyCollectionChangedAction.Move:
return new NotifyCollectionChangedEventArgsEx(count, NotifyCollectionChangedAction.Move, e.OldItems, e.NewStartingIndex, e.OldStartingIndex);
case NotifyCollectionChangedAction.Replace:
return new NotifyCollectionChangedEventArgsEx(count, NotifyCollectionChangedAction.Replace, e.NewItems, e.OldItems, e.OldStartingIndex);
default:
return new NotifyCollectionChangedEventArgsEx(count, NotifyCollectionChangedAction.Reset);
}
}
}
}
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