Avoid boxing when writing list to appender.

Author: Giorgi

DuckDB.NET.Data/Internal/Writer/ListVectorDataWriter.cs

@@ -1,35 +1,72 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Numerics;
 using DuckDB.NET.Native;
 
 namespace DuckDB.NET.Data.Internal.Writer;
 
 internal sealed unsafe class ListVectorDataWriter : VectorDataWriterBase
 {
     private ulong offset = 0;
-    private readonly VectorDataWriterBase listDataWriter;
+    private readonly VectorDataWriterBase listItemWriter;
 
     public ListVectorDataWriter(IntPtr vector, void* vectorData, DuckDBType columnType, DuckDBLogicalType logicalType) : base(vector, vectorData, columnType)
     {
         using var childType = NativeMethods.LogicalType.DuckDBListTypeChildType(logicalType);
         var childVector = NativeMethods.Vectors.DuckDBListVectorGetChild(vector);
-        listDataWriter = VectorDataWriterFactory.CreateWriter(childVector, childType);
+        listItemWriter = VectorDataWriterFactory.CreateWriter(childVector, childType);
     }
 
     internal override bool AppendCollection(IList value, int rowIndex)
     {
-        var index = 0;
-
-        foreach (var item in value)
+        _ = value switch
         {
-            listDataWriter.AppendValue(item, (int)offset + (index++));
-        }
+            IEnumerable<bool> items => WriteItems(items),
+
+            IEnumerable<sbyte> items => WriteItems(items),
+            IEnumerable<short> items => WriteItems(items),
+            IEnumerable<int> items => WriteItems(items),
+            IEnumerable<long> items => WriteItems(items),
+            IEnumerable<byte> items => WriteItems(items),
+            IEnumerable<ushort> items => WriteItems(items),
+            IEnumerable<uint> items => WriteItems(items),
+            IEnumerable<ulong> items => WriteItems(items),
+            
+            IEnumerable<decimal> items => WriteItems(items),
+            IEnumerable<BigInteger> items => WriteItems(items),
+            
+            IEnumerable<string> items => WriteItems(items),
+            IEnumerable<Guid> items => WriteItems(items),
+            IEnumerable<DateTime> items => WriteItems(items),
+            IEnumerable<TimeSpan> items => WriteItems(items),
+            IEnumerable<DuckDBDateOnly> items => WriteItems(items),
+            IEnumerable<DuckDBTimeOnly> items => WriteItems(items),
+#if NET6_0_OR_GREATER
+            IEnumerable<DateOnly> items => WriteItems(items),
+            IEnumerable<TimeOnly> items => WriteItems(items),
+#endif
+            IEnumerable<DateTimeOffset> items => WriteItems(items),
+            
+            _ => WriteItems<object>((IEnumerable<object>)value)
+        };
 
         var result = AppendValueInternal(new DuckDBListEntry(offset, (ulong)value.Count), rowIndex);
 
         offset += (ulong)value.Count;
 
         return result;
+
+        int WriteItems<T>(IEnumerable<T> items)
+        {
+            var index = 0;
+
+            foreach (var item in items)
+            {
+                listItemWriter.AppendValue(item, (int)offset + (index++));
+            }
+
+            return 0;
+        }
     }
 }