RecyclableLongListExtensions & ListExtensions cleaned up

2023-06-17 13:09:19 +02:00
1 parent 45edb9d8fb
commit c5406b04b7
@@ -0,0 +1,90 @@
+namespace Recyclable.Collections
+{
+	public partial class RecyclableLongList<T>
+	{
+		internal class RecyclableLongListHelpers
+		{
+			public static void CopyTo(T[][] sourceMemoryBlocks, long startingIndex, int blockSize, long itemsCount, T[] destinationArray, int destinationArrayIndex)
+			{
+				if (itemsCount <= 0)
+				{
+					return;
+				}
+
+				Span<T> sourceBlockMemory;
+				Span<T> destinationArrayMemory;
+				int startingBlockIndex = (int)(startingIndex / blockSize);
+				int lastBlockIndex = (int)((itemsCount / blockSize) + (itemsCount % blockSize > 0 ? 1 : 0)) - 1;
+				Span<T[]> sourceMemoryBlocksSpan = new(sourceMemoryBlocks, startingBlockIndex, lastBlockIndex + 1);
+				destinationArrayMemory = new Span<T>(destinationArray, destinationArrayIndex, (int)Math.Min(destinationArray.Length - destinationArrayIndex, itemsCount));
+				int memoryBlockIndex;
+				for (memoryBlockIndex = 0; memoryBlockIndex < lastBlockIndex; memoryBlockIndex++)
+				{
+					sourceBlockMemory = new(sourceMemoryBlocksSpan[memoryBlockIndex], 0, blockSize);
+					sourceBlockMemory.CopyTo(destinationArrayMemory);
+					destinationArrayMemory = destinationArrayMemory[blockSize..];
+				}
+
+				if (itemsCount - (lastBlockIndex * blockSize) > 0)
+				{
+					sourceBlockMemory = new(sourceMemoryBlocksSpan[lastBlockIndex], 0, (int)(itemsCount - (lastBlockIndex * blockSize)));
+					sourceBlockMemory.CopyTo(destinationArrayMemory);
+				}
+			}
+
+			public static void CopyTo(T[][] sourceMemoryBlocks, long startingIndex, int blockSize, long itemsCount, Array destinationArray, int destinationArrayIndex)
+			{
+				if (itemsCount <= 0)
+				{
+					return;
+				}
+
+				int startingBlockIndex = (int)(startingIndex / blockSize);
+				int lastBlockIndex = (int)((itemsCount / blockSize) + (itemsCount % blockSize > 0 ? 1 : 0)) - 1;
+
+				var destinationIndex = destinationArrayIndex;
+				Span<T[]> sourceMemoryBlocksSpan = new(sourceMemoryBlocks, startingBlockIndex, lastBlockIndex + 1);
+				for (int memoryBlockIndex = 0; memoryBlockIndex < lastBlockIndex; memoryBlockIndex++)
+				{
+					Array.ConstrainedCopy(sourceMemoryBlocksSpan[memoryBlockIndex], 0, destinationArray, destinationIndex, blockSize);
+					destinationIndex += blockSize;
+				}
+
+				if (itemsCount - destinationIndex > 0)
+				{
+					Array.ConstrainedCopy(sourceMemoryBlocksSpan[lastBlockIndex], 0, destinationArray, destinationIndex, (int)(itemsCount - destinationIndex));
+				}
+			}
+
+			public static IEnumerable<T> Enumerate(T[][] arrays, int chunkSize, long totalCount)
+			{
+				long currentCount = 0;
+				for (var arrayIdx = 0; arrayIdx < arrays.Length && currentCount < totalCount; arrayIdx++)
+				{
+					var array = arrays[arrayIdx];
+					currentCount += chunkSize;
+					switch (currentCount < totalCount)
+					{
+						case true:
+							for (var valueIdx = 0; valueIdx < chunkSize; valueIdx++)
+							{
+								yield return array[valueIdx];
+							}
+
+							break;
+
+						case false:
+							var partialCount = (int)(totalCount % chunkSize);
+							int maxCount = partialCount > 0 ? partialCount : chunkSize;
+							for (var valueIdx = 0; valueIdx < maxCount; valueIdx++)
+							{
+								yield return array[valueIdx];
+							}
+
+							break;
+					}
+				}
+			}
+		}
+	}
+}