Use .Slice when getting a buffer from a memory pool.

Author: electricessence

source/Extensions.Subsets.cs

@@ -84,7 +84,7 @@ static IEnumerable<Memory<T>> SubsetsCore(IReadOnlyList<T> source, int count, Me
 	public static IEnumerable<ReadOnlyMemory<T>> SubsetsBuffered<T>(this IReadOnlyList<T> source, int count)
 	{
 		using var lease = MemoryPool<T>.Shared.Rent(count);
-		Memory<T> buffer = lease.Memory;
+		Memory<T> buffer = lease.Memory.Slice(0, count);
 		ReadOnlyMemory<T> readBuffer = buffer;
 		foreach (Memory<T> _ in Subsets(source, count, buffer))
 			yield return readBuffer;
@@ -99,7 +99,7 @@ public static IEnumerable<ReadOnlyMemory<T>> SubsetsBuffered<T>(this IReadOnlyLi
 	public static IEnumerable<T[]> Subsets<T>(this IReadOnlyList<T> source, int count)
 	{
 		using var lease = MemoryPool<T>.Shared.Rent(count);
-		Memory<T> buffer = lease.Memory;
+		Memory<T> buffer = lease.Memory.Slice(0, count);
 		foreach (Memory<T> _ in Subsets(source, count, buffer))
 		{
 			var a = new T[count];
@@ -192,7 +192,7 @@ static IEnumerable<Memory<T>> SubsetsCore(ReadOnlyMemory<T> source, int count, M
 	public static IEnumerable<ReadOnlyMemory<T>> SubsetsBuffered<T>(this ReadOnlyMemory<T> source, int count)
 	{
 		using var lease = MemoryPool<T>.Shared.Rent(count);
-		Memory<T> buffer = lease.Memory;
+		Memory<T> buffer = lease.Memory.Slice(0, count);
 		ReadOnlyMemory<T> readBuffer = buffer;
 		foreach (Memory<T> _ in Subsets(source, count, buffer))
 			yield return readBuffer;
@@ -202,7 +202,7 @@ public static IEnumerable<ReadOnlyMemory<T>> SubsetsBuffered<T>(this ReadOnlyMem
 	public static IEnumerable<T[]> Subsets<T>(this ReadOnlyMemory<T> source, int count)
 	{
 		using var lease = MemoryPool<T>.Shared.Rent(count);
-		Memory<T> buffer = lease.Memory;
+		Memory<T> buffer = lease.Memory.Slice(0, count);
 		foreach (Memory<T> _ in Subsets(source, count, buffer))
 		{
 			var a = new T[count];

source/Open.Collections.csproj

@@ -18,7 +18,7 @@
 		<PackageProjectUrl>https://github.com/Open-NET-Libraries/Open.Collections/</PackageProjectUrl>
 		<RepositoryUrl>https://github.com/Open-NET-Libraries/Open.Collections/</RepositoryUrl>
 		<RepositoryType>git</RepositoryType>
-		<Version>3.1.4</Version>
+		<Version>3.1.5</Version>
 		<PackageReleaseNotes></PackageReleaseNotes>
 		<PackageLicenseExpression>MIT</PackageLicenseExpression>
 		<PublishRepositoryUrl>true</PublishRepositoryUrl>

testing/Open.Collections.Tests/SubsetTests.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Buffers;
 using System.Collections.Immutable;
 using System.Linq;
@@ -24,6 +25,9 @@ public void TestSubset1_2()
 		int[][] actual = Set1.Subsets(2).ToArray();
 		Assert.Equal(expected, actual);
 
+		ReadOnlyMemory<int> mem = Set1.ToArray();
+		Assert.Equal(expected, mem.Subsets(2).ToArray());
+
 		int[][] progressive = Set1.SubsetsProgressive(2).ToArray();
 		Assert.Equal(expected, progressive);
 	}