Adding SequenceEqual.

AsyncRx.NET/System.Reactive.Async/System/Reactive/Linq/Operators/SequenceEqual.cs

@@ -0,0 +1,219 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information. 
+
+using System.Collections.Generic;
+using System.Reactive.Disposables;
+using System.Threading;
+
+namespace System.Reactive.Linq
+{
+    partial class AsyncObservable
+    {
+        public static IAsyncObservable<bool> SequenceEqual<TSource>(this IAsyncObservable<TSource> first, IAsyncObservable<TSource> second)
+        {
+            if (first == null)
+                throw new ArgumentNullException(nameof(first));
+            if (second == null)
+                throw new ArgumentNullException(nameof(second));
+
+            return Create<bool>(async observer =>
+            {
+                var (firstObserver, secondObserver) = AsyncObserver.SequenceEqual<TSource>(observer);
+
+                var firstTask = first.SubscribeAsync(firstObserver);
+                var secondTask = second.SubscribeAsync(secondObserver);
+
+                var d1 = await firstTask.ConfigureAwait(false);
+                var d2 = await secondTask.ConfigureAwait(false);
+
+                return StableCompositeAsyncDisposable.Create(d1, d2);
+            });
+        }
+
+        public static IAsyncObservable<bool> SequenceEqual<TSource>(this IAsyncObservable<TSource> first, IAsyncObservable<TSource> second, IEqualityComparer<TSource> comparer)
+        {
+            if (first == null)
+                throw new ArgumentNullException(nameof(first));
+            if (second == null)
+                throw new ArgumentNullException(nameof(second));
+            if (comparer == null)
+                throw new ArgumentNullException(nameof(comparer));
+
+            return Create<bool>(async observer =>
+            {
+                var (firstObserver, secondObserver) = AsyncObserver.SequenceEqual<TSource>(observer, comparer);
+
+                var firstTask = first.SubscribeAsync(firstObserver);
+                var secondTask = second.SubscribeAsync(secondObserver);
+
+                var d1 = await firstTask.ConfigureAwait(false);
+                var d2 = await secondTask.ConfigureAwait(false);
+
+                return StableCompositeAsyncDisposable.Create(d1, d2);
+            });
+        }
+    }
+
+    partial class AsyncObserver
+    {
+        public static (IAsyncObserver<TSource>, IAsyncObserver<TSource>) SequenceEqual<TSource>(IAsyncObserver<bool> observer)
+        {
+            if (observer == null)
+                throw new ArgumentNullException(nameof(observer));
+
+            return SequenceEqual(observer, EqualityComparer<TSource>.Default);
+        }
+
+        public static (IAsyncObserver<TSource>, IAsyncObserver<TSource>) SequenceEqual<TSource>(IAsyncObserver<bool> observer, IEqualityComparer<TSource> comparer)
+        {
+            if (observer == null)
+                throw new ArgumentNullException(nameof(observer));
+            if (comparer == null)
+                throw new ArgumentNullException(nameof(comparer));
+
+            var gate = new AsyncLock();
+
+            var queueLeft = new Queue<TSource>();
+            var queueRight = new Queue<TSource>();
+            var doneLeft = false;
+            var doneRight = false;
+
+            return
+                (
+                    Create<TSource>(
+                        async x =>
+                        {
+                            using (await gate.LockAsync().ConfigureAwait(false))
+                            {
+                                if (queueRight.Count > 0)
+                                {
+                                    var v = queueRight.Dequeue();
+
+                                    var equal = false;
+                                    try
+                                    {
+                                        equal = comparer.Equals(x, v);
+                                    }
+                                    catch (Exception ex)
+                                    {
+                                        await observer.OnErrorAsync(ex).ConfigureAwait(false);
+                                        return;
+                                    }
+
+                                    if (!equal)
+                                    {
+                                        await observer.OnNextAsync(false).ConfigureAwait(false);
+                                        await observer.OnCompletedAsync().ConfigureAwait(false);
+                                    }
+                                }
+                                else if (doneRight)
+                                {
+                                    await observer.OnNextAsync(false).ConfigureAwait(false);
+                                    await observer.OnCompletedAsync().ConfigureAwait(false);
+                                }
+                                else
+                                {
+                                    queueLeft.Enqueue(x);
+                                }
+                            }
+                        },
+                        async ex =>
+                        {
+                            using (await gate.LockAsync().ConfigureAwait(false))
+                            {
+                                await observer.OnErrorAsync(ex).ConfigureAwait(false);
+                            }
+                        },
+                        async () =>
+                        {
+                            using (await gate.LockAsync().ConfigureAwait(false))
+                            {
+                                doneLeft = true;
+
+                                if (queueLeft.Count == 0)
+                                {
+                                    if (queueRight.Count > 0)
+                                    {
+                                        await observer.OnNextAsync(false).ConfigureAwait(false);
+                                        await observer.OnCompletedAsync().ConfigureAwait(false);
+                                    }
+                                    else if (doneRight)
+                                    {
+                                        await observer.OnNextAsync(true).ConfigureAwait(false);
+                                        await observer.OnCompletedAsync().ConfigureAwait(false);
+                                    }
+                                }
+                            }
+                        }
+                    ),
+                    Create<TSource>(
+                        async x =>
+                        {
+                            using (await gate.LockAsync().ConfigureAwait(false))
+                            {
+                                if (queueLeft.Count > 0)
+                                {
+                                    var v = queueLeft.Dequeue();
+
+                                    var equal = false;
+                                    try
+                                    {
+                                        equal = comparer.Equals(v, x);
+                                    }
+                                    catch (Exception ex)
+                                    {
+                                        await observer.OnErrorAsync(ex).ConfigureAwait(false);
+                                        return;
+                                    }
+
+                                    if (!equal)
+                                    {
+                                        await observer.OnNextAsync(false).ConfigureAwait(false);
+                                        await observer.OnCompletedAsync().ConfigureAwait(false);
+                                    }
+                                }
+                                else if (doneLeft)
+                                {
+                                    await observer.OnNextAsync(false).ConfigureAwait(false);
+                                    await observer.OnCompletedAsync().ConfigureAwait(false);
+                                }
+                                else
+                                {
+                                    queueRight.Enqueue(x);
+                                }
+                            }
+                        },
+                        async ex =>
+                        {
+                            using (await gate.LockAsync().ConfigureAwait(false))
+                            {
+                                await observer.OnErrorAsync(ex).ConfigureAwait(false);
+                            }
+                        },
+                        async () =>
+                        {
+                            using (await gate.LockAsync().ConfigureAwait(false))
+                            {
+                                doneRight = true;
+
+                                if (queueRight.Count == 0)
+                                {
+                                    if (queueLeft.Count > 0)
+                                    {
+                                        await observer.OnNextAsync(false).ConfigureAwait(false);
+                                        await observer.OnCompletedAsync().ConfigureAwait(false);
+                                    }
+                                    else if (doneLeft)
+                                    {
+                                        await observer.OnNextAsync(true).ConfigureAwait(false);
+                                        await observer.OnCompletedAsync().ConfigureAwait(false);
+                                    }
+                                }
+                            }
+                        }
+                    )
+                );
+        }
+    }
+}