namespace ReactiveUI

{

using System;

using System.Collections;

using System.Collections.Generic;

using System.Collections.Specialized;

using System.Reactive.Linq;

public static class CollectionExtensions

{

/// <summary>

/// Returns an observable sequence of the source collection change notifications.

/// Returns Observable.Never for collections not implementing INCC.

/// </summary>

/// <param name="source">Collection to observe.</param>

/// <returns>Observable sequence.</returns>

public static IObservable<NotifyCollectionChangedEventArgs> ObserveCollectionChanged(

this IEnumerable source)

{

var notifying = source as INotifyCollectionChanged;

if (notifying != null) {

return Observable.FromEventPattern<

NotifyCollectionChangedEventHandler,

NotifyCollectionChangedEventArgs>(

ev => notifying.CollectionChanged += ev,

ev => notifying.CollectionChanged -= ev)

.Select(x => x.EventArgs);

}

return Observable.Never<NotifyCollectionChangedEventArgs>();

}

/// <summary>

/// Returns an observable sequence of the source collection item property change notifications.

/// Returns Observable.Never for collections not implementing INCC.

/// </summary>

/// <param name="source">Collection to observe.</param>

/// <returns>Observable sequence.</returns>

public static IObservable<IObservedChange<T, object>> ObserveCollectionItemChanged<T>(

this IEnumerable source)

{

var notifying = source as IReactiveCollection<T>;

if (notifying != null)

{

return notifying.ItemChanged;

}

return Observable.Never<IObservedChange<T, object>>();

}

/// <summary>

/// Sorts the specified list in place using the comparer.

/// </summary>

/// <param name="list">List to sort.</param>

/// <param name="comparer">Comparer to use. If null, default comparer is used.</param>

public static void Sort<T>(

this IList<T> list,

IComparer<T> comparer = null)

{

comparer = comparer ?? Comparer<T>.Default;

var array = new T[list.Count];

list.CopyTo(array, 0);

Array.Sort(array, comparer);

for (var i = 0; i < array.Length; i++) {

list[i] = array[i];

}

}

/// <summary>

/// Finds an index of the specified value in the specified collection.

/// </summary>

public static int BinarySearch<T>(

this ICollection<T> collection,

T value,

IComparer<T> comparer = null)

{

var array = new T[collection.Count];

collection.CopyTo(array, 0);

return Array.BinarySearch(array, value, comparer);

}

}

}