Browse Source

Async variants of TakeWhile and SkipWhile.

Bart De Smet 8 years ago
parent
commit
c89ae4f52e

+ 179 - 1
Ix.NET/Source/System.Interactive.Async/Skip.cs

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Threading;
 using System.Threading.Tasks;
 
 namespace System.Linq
@@ -71,6 +70,26 @@ namespace System.Linq
             return new SkipWhileWithIndexAsyncIterator<TSource>(source, predicate);
         }
 
+        public static IAsyncEnumerable<TSource> SkipWhile<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, Task<bool>> predicate)
+        {
+            if (source == null)
+                throw new ArgumentNullException(nameof(source));
+            if (predicate == null)
+                throw new ArgumentNullException(nameof(predicate));
+
+            return new SkipWhileAsyncIteratorWithTask<TSource>(source, predicate);
+        }
+
+        public static IAsyncEnumerable<TSource> SkipWhile<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, int, Task<bool>> predicate)
+        {
+            if (source == null)
+                throw new ArgumentNullException(nameof(source));
+            if (predicate == null)
+                throw new ArgumentNullException(nameof(predicate));
+
+            return new SkipWhileWithIndexAsyncIteratorWithTask<TSource>(source, predicate);
+        }
+
         private sealed class SkipAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly int count;
@@ -366,5 +385,164 @@ namespace System.Linq
                 return false;
             }
         }
+
+        private sealed class SkipWhileAsyncIteratorWithTask<TSource> : AsyncIterator<TSource>
+        {
+            private readonly Func<TSource, Task<bool>> predicate;
+            private readonly IAsyncEnumerable<TSource> source;
+
+            private bool doMoveNext;
+            private IAsyncEnumerator<TSource> enumerator;
+
+            public SkipWhileAsyncIteratorWithTask(IAsyncEnumerable<TSource> source, Func<TSource, Task<bool>> predicate)
+            {
+                Debug.Assert(predicate != null);
+                Debug.Assert(source != null);
+
+                this.source = source;
+                this.predicate = predicate;
+            }
+
+            public override AsyncIterator<TSource> Clone()
+            {
+                return new SkipWhileAsyncIteratorWithTask<TSource>(source, predicate);
+            }
+
+            public override async Task DisposeAsync()
+            {
+                if (enumerator != null)
+                {
+                    await enumerator.DisposeAsync().ConfigureAwait(false);
+                    enumerator = null;
+                }
+
+                await base.DisposeAsync().ConfigureAwait(false);
+            }
+
+            protected override async Task<bool> MoveNextCore()
+            {
+                switch (state)
+                {
+                    case AsyncIteratorState.Allocated:
+                        enumerator = source.GetAsyncEnumerator();
+
+                        // skip elements as requested
+                        while (await enumerator.MoveNextAsync()
+                                               .ConfigureAwait(false))
+                        {
+                            var element = enumerator.Current;
+                            if (!await predicate(element).ConfigureAwait(false))
+                            {
+                                doMoveNext = false;
+                                state = AsyncIteratorState.Iterating;
+                                goto case AsyncIteratorState.Iterating;
+                            }
+                        }
+                        break;
+
+                    case AsyncIteratorState.Iterating:
+                        if (doMoveNext && await enumerator.MoveNextAsync()
+                                                          .ConfigureAwait(false))
+                        {
+                            current = enumerator.Current;
+                            return true;
+                        }
+                        if (!doMoveNext)
+                        {
+                            current = enumerator.Current;
+                            doMoveNext = true;
+                            return true;
+                        }
+
+                        break;
+                }
+
+                await DisposeAsync().ConfigureAwait(false);
+                return false;
+            }
+        }
+
+        private sealed class SkipWhileWithIndexAsyncIteratorWithTask<TSource> : AsyncIterator<TSource>
+        {
+            private readonly Func<TSource, int, Task<bool>> predicate;
+            private readonly IAsyncEnumerable<TSource> source;
+
+            private bool doMoveNext;
+            private IAsyncEnumerator<TSource> enumerator;
+            private int index;
+
+            public SkipWhileWithIndexAsyncIteratorWithTask(IAsyncEnumerable<TSource> source, Func<TSource, int, Task<bool>> predicate)
+            {
+                Debug.Assert(predicate != null);
+                Debug.Assert(source != null);
+
+                this.source = source;
+                this.predicate = predicate;
+            }
+
+            public override AsyncIterator<TSource> Clone()
+            {
+                return new SkipWhileWithIndexAsyncIteratorWithTask<TSource>(source, predicate);
+            }
+
+            public override async Task DisposeAsync()
+            {
+                if (enumerator != null)
+                {
+                    await enumerator.DisposeAsync().ConfigureAwait(false);
+                    enumerator = null;
+                }
+
+                await base.DisposeAsync().ConfigureAwait(false);
+            }
+
+            protected override async Task<bool> MoveNextCore()
+            {
+                switch (state)
+                {
+                    case AsyncIteratorState.Allocated:
+                        enumerator = source.GetAsyncEnumerator();
+                        index = -1;
+
+                        // skip elements as requested
+                        while (await enumerator.MoveNextAsync()
+                                               .ConfigureAwait(false))
+                        {
+                            checked
+                            {
+                                index++;
+                            }
+
+                            var element = enumerator.Current;
+                            if (!await predicate(element, index).ConfigureAwait(false))
+                            {
+                                doMoveNext = false;
+                                state = AsyncIteratorState.Iterating;
+                                goto case AsyncIteratorState.Iterating;
+                            }
+                        }
+                        break;
+
+                    case AsyncIteratorState.Iterating:
+                        if (doMoveNext && await enumerator.MoveNextAsync()
+                                                          .ConfigureAwait(false))
+                        {
+                            current = enumerator.Current;
+                            return true;
+                        }
+                        if (!doMoveNext)
+                        {
+                            current = enumerator.Current;
+                            doMoveNext = true;
+                            return true;
+                        }
+
+                        break;
+                }
+
+                await DisposeAsync().ConfigureAwait(false);
+                return false;
+            }
+        }
     }
 }

+ 154 - 1
Ix.NET/Source/System.Interactive.Async/Take.cs

@@ -4,7 +4,6 @@
 
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Threading;
 using System.Threading.Tasks;
 
 namespace System.Linq
@@ -57,6 +56,26 @@ namespace System.Linq
             return new TakeWhileWithIndexAsyncIterator<TSource>(source, predicate);
         }
 
+        public static IAsyncEnumerable<TSource> TakeWhile<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, Task<bool>> predicate)
+        {
+            if (source == null)
+                throw new ArgumentNullException(nameof(source));
+            if (predicate == null)
+                throw new ArgumentNullException(nameof(predicate));
+
+            return new TakeWhileAsyncIteratorWithTask<TSource>(source, predicate);
+        }
+
+        public static IAsyncEnumerable<TSource> TakeWhile<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, int, Task<bool>> predicate)
+        {
+            if (source == null)
+                throw new ArgumentNullException(nameof(source));
+            if (predicate == null)
+                throw new ArgumentNullException(nameof(predicate));
+
+            return new TakeWhileWithIndexAsyncIteratorWithTask<TSource>(source, predicate);
+        }
+
         private sealed class TakeAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly int count;
@@ -345,5 +364,139 @@ namespace System.Linq
                 return false;
             }
         }
+
+        private sealed class TakeWhileAsyncIteratorWithTask<TSource> : AsyncIterator<TSource>
+        {
+            private readonly Func<TSource, Task<bool>> predicate;
+            private readonly IAsyncEnumerable<TSource> source;
+
+            private IAsyncEnumerator<TSource> enumerator;
+
+            public TakeWhileAsyncIteratorWithTask(IAsyncEnumerable<TSource> source, Func<TSource, Task<bool>> predicate)
+            {
+                Debug.Assert(predicate != null);
+                Debug.Assert(source != null);
+
+                this.source = source;
+                this.predicate = predicate;
+            }
+
+            public override AsyncIterator<TSource> Clone()
+            {
+                return new TakeWhileAsyncIteratorWithTask<TSource>(source, predicate);
+            }
+
+            public override async Task DisposeAsync()
+            {
+                if (enumerator != null)
+                {
+                    await enumerator.DisposeAsync().ConfigureAwait(false);
+                    enumerator = null;
+                }
+
+                await base.DisposeAsync().ConfigureAwait(false);
+            }
+
+            protected override async Task<bool> MoveNextCore()
+            {
+                switch (state)
+                {
+                    case AsyncIteratorState.Allocated:
+                        enumerator = source.GetAsyncEnumerator();
+
+                        state = AsyncIteratorState.Iterating;
+                        goto case AsyncIteratorState.Iterating;
+
+
+                    case AsyncIteratorState.Iterating:
+                        if (await enumerator.MoveNextAsync()
+                                            .ConfigureAwait(false))
+                        {
+                            var item = enumerator.Current;
+                            if (!await predicate(item).ConfigureAwait(false))
+                            {
+                                break;
+                            }
+                            current = item;
+                            return true;
+                        }
+
+                        break;
+                }
+
+                await DisposeAsync().ConfigureAwait(false);
+                return false;
+            }
+        }
+
+        private sealed class TakeWhileWithIndexAsyncIteratorWithTask<TSource> : AsyncIterator<TSource>
+        {
+            private readonly Func<TSource, int, Task<bool>> predicate;
+            private readonly IAsyncEnumerable<TSource> source;
+
+            private IAsyncEnumerator<TSource> enumerator;
+            private int index;
+
+            public TakeWhileWithIndexAsyncIteratorWithTask(IAsyncEnumerable<TSource> source, Func<TSource, int, Task<bool>> predicate)
+            {
+                Debug.Assert(predicate != null);
+                Debug.Assert(source != null);
+
+                this.source = source;
+                this.predicate = predicate;
+            }
+
+            public override AsyncIterator<TSource> Clone()
+            {
+                return new TakeWhileWithIndexAsyncIteratorWithTask<TSource>(source, predicate);
+            }
+
+            public override async Task DisposeAsync()
+            {
+                if (enumerator != null)
+                {
+                    await enumerator.DisposeAsync().ConfigureAwait(false);
+                    enumerator = null;
+                }
+
+                await base.DisposeAsync().ConfigureAwait(false);
+            }
+
+            protected override async Task<bool> MoveNextCore()
+            {
+                switch (state)
+                {
+                    case AsyncIteratorState.Allocated:
+                        enumerator = source.GetAsyncEnumerator();
+                        index = -1;
+                        state = AsyncIteratorState.Iterating;
+                        goto case AsyncIteratorState.Iterating;
+
+
+                    case AsyncIteratorState.Iterating:
+                        if (await enumerator.MoveNextAsync()
+                                            .ConfigureAwait(false))
+                        {
+                            var item = enumerator.Current;
+                            checked
+                            {
+                                index++;
+                            }
+
+                            if (!await predicate(item, index).ConfigureAwait(false))
+                            {
+                                break;
+                            }
+                            current = item;
+                            return true;
+                        }
+
+                        break;
+                }
+
+                await DisposeAsync().ConfigureAwait(false);
+                return false;
+            }
+        }
     }
 }

+ 4 - 4
Ix.NET/Source/Tests/AsyncTests.Single.cs

@@ -1006,7 +1006,7 @@ namespace Tests
         {
             var ex = new Exception("Bang");
             var xs = new[] { 1, 2, 3, 4 }.ToAsyncEnumerable();
-            var ys = xs.TakeWhile(x => { throw ex; });
+            var ys = xs.TakeWhile(new Func<int, bool>(x => { throw ex; }));
 
             var e = ys.GetAsyncEnumerator();
             AssertThrows(() => e.MoveNextAsync().Wait(WaitTimeoutMs), (Exception ex_) => ((AggregateException)ex_).Flatten().InnerExceptions.Single() == ex);
@@ -1053,7 +1053,7 @@ namespace Tests
         {
             var ex = new Exception("Bang");
             var xs = new[] { 1, 2, 3, 4 }.ToAsyncEnumerable();
-            var ys = xs.TakeWhile((x, i) => { throw ex; });
+            var ys = xs.TakeWhile(new Func<int, int, bool>((x, i) => { throw ex; }));
 
             var e = ys.GetAsyncEnumerator();
             AssertThrows(() => e.MoveNextAsync().Wait(WaitTimeoutMs), (Exception ex_) => ((AggregateException)ex_).Flatten().InnerExceptions.Single() == ex);
@@ -1215,7 +1215,7 @@ namespace Tests
         {
             var ex = new Exception("Bang");
             var xs = new[] { 1, 2, 3, 4 }.ToAsyncEnumerable();
-            var ys = xs.SkipWhile(x => { throw ex; });
+            var ys = xs.SkipWhile(new Func<int, bool>(x => { throw ex; }));
 
             var e = ys.GetAsyncEnumerator();
             AssertThrows(() => e.MoveNextAsync().Wait(WaitTimeoutMs), (Exception ex_) => ((AggregateException)ex_).Flatten().InnerExceptions.Single() == ex);
@@ -1262,7 +1262,7 @@ namespace Tests
         {
             var ex = new Exception("Bang");
             var xs = new[] { 1, 2, 3, 4 }.ToAsyncEnumerable();
-            var ys = xs.SkipWhile((x, i) => { throw ex; });
+            var ys = xs.SkipWhile(new Func<int, int, bool>((x, i) => { throw ex; }));
 
             var e = ys.GetAsyncEnumerator();
             AssertThrows(() => e.MoveNextAsync().Wait(WaitTimeoutMs), (Exception ex_) => ((AggregateException)ex_).Flatten().InnerExceptions.Single() == ex);