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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
using System.Collections;
using System.Collections.Generic;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Reactive.Subjects;
namespace System.Reactive
{
/// <summary>
/// Represents an object that retains the elements of the observable sequence and signals the end of the sequence.
/// </summary>
/// <typeparam name="T">The type of elements received from the source sequence.</typeparam>
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1710:IdentifiersShouldHaveCorrectSuffix", Justification = "By design; Observable suffix takes precedence.")]
[Experimental]
public class ListObservable<T> : IList<T>, IObservable<object>
{
IDisposable subscription;
AsyncSubject<object> subject = new AsyncSubject<object>();
List<T> results = new List<T>();
/// <summary>
/// Constructs an object that retains the values of source and signals the end of the sequence.
/// </summary>
/// <param name="source">The observable sequence whose elements will be retained in the list.</param>
/// <exception cref="ArgumentNullException"><paramref name="source"/> is null.</exception>
public ListObservable(IObservable<T> source)
{
if (source == null)
throw new ArgumentNullException("source");
subscription = source.Subscribe(results.Add, subject.OnError, subject.OnCompleted);
}
void Wait()
{
subject.DefaultIfEmpty().Wait();
}
/// <summary>
/// Returns the last value of the observable sequence.
/// </summary>
public T Value
{
get
{
Wait();
if (results.Count == 0)
throw new InvalidOperationException(Strings_Linq.NO_ELEMENTS);
return results[results.Count - 1];
}
}
/// <summary>
/// Determines the index of a specific item in the ListObservable.
/// </summary>
/// <param name="item">The element to determine the index for.</param>
/// <returns>The index of the specified item in the list; -1 if not found.</returns>
public int IndexOf(T item)
{
Wait();
return results.IndexOf(item);
}
/// <summary>
/// Inserts an item to the ListObservable at the specified index.
/// </summary>
/// <param name="index">The index to insert the item at.</param>
/// <param name="item">The item to insert in the list.</param>
public void Insert(int index, T item)
{
Wait();
results.Insert(index, item);
}
/// <summary>
/// Removes the ListObservable item at the specified index.
/// </summary>
/// <param name="index">The index of the item to remove.</param>
public void RemoveAt(int index)
{
Wait();
results.RemoveAt(index);
}
/// <summary>
/// Gets or sets the element at the specified index.
/// </summary>
/// <param name="index">The index of the item to retrieve or set.</param>
public T this[int index]
{
get
{
Wait();
return results[index];
}
set
{
Wait();
results[index] = value;
}
}
/// <summary>
/// Adds an item to the ListObservable.
/// </summary>
/// <param name="item">The item to add to the list.</param>
public void Add(T item)
{
Wait();
results.Add(item);
}
/// <summary>
/// Removes all items from the ListObservable.
/// </summary>
public void Clear()
{
Wait();
results.Clear();
}
/// <summary>
/// Determines whether the ListObservable contains a specific value.
/// </summary>
/// <param name="item">The item to search for in the list.</param>
/// <returns>true if found; false otherwise.</returns>
public bool Contains(T item)
{
Wait();
return results.Contains(item);
}
/// <summary>
/// Copies the elements of the ListObservable to an System.Array, starting at a particular System.Array index.
/// </summary>
/// <param name="array">The array to copy elements to.</param>
/// <param name="arrayIndex">The start index in the array to start copying elements to.</param>
public void CopyTo(T[] array, int arrayIndex)
{
Wait();
results.CopyTo(array, arrayIndex);
}
/// <summary>
/// Gets the number of elements contained in the ListObservable.
/// </summary>
public int Count
{
get
{
Wait();
return results.Count;
}
}
/// <summary>
/// Gets a value that indicates whether the ListObservable is read-only.
/// </summary>
public bool IsReadOnly
{
get { return false; }
}
/// <summary>
/// Removes the first occurrence of a specific object from the ListObservable.
/// </summary>
/// <param name="item">The item to remove from the list.</param>
/// <returns>true if the item was found; false otherwise.</returns>
public bool Remove(T item)
{
Wait();
return results.Remove(item);
}
/// <summary>
/// Returns an enumerator that iterates through the collection.
/// </summary>
/// <returns>Enumerator over the list.</returns>
public IEnumerator<T> GetEnumerator()
{
Wait();
return results.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return this.GetEnumerator();
}
/// <summary>
/// Subscribes an observer to the ListObservable which will be notified upon completion.
/// </summary>
/// <param name="observer">The observer to send completion or error messages to.</param>
/// <returns>The disposable resource that can be used to unsubscribe.</returns>
/// <exception cref="ArgumentNullException"><paramref name="observer"/> is null.</exception>
public IDisposable Subscribe(IObserver<object> observer)
{
if (observer == null)
throw new ArgumentNullException("observer");
return new CompositeDisposable(subscription, subject.Subscribe(observer));
}
}
}
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