Add separation with nullability

Author: inputfalken

…onverters/Internal/StringSetConverter.cs …ternal/NoneNullableStringSetConverter.cssrc/DynamoDBGenerator/Converters/Internal/StringSetConverter.cs renamed to src/DynamoDBGenerator/Converters/Internal/NoneNullableStringSetConverter.cs src/DynamoDBGenerator/Converters/Internal/StringSetConverter.cs renamed to src/DynamoDBGenerator/Converters/Internal/NoneNullableStringSetConverter.cs

@@ -1,51 +1,79 @@
+using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using Amazon.DynamoDBv2.Model;
 using DynamoDBGenerator.Internal;
 
 namespace DynamoDBGenerator.Converters.Internal;
 
-internal sealed class StringSetConverter :
+internal sealed class NoneNullableStringSetConverter :
     IReferenceTypeConverter<IReadOnlySet<string>>,
     IReferenceTypeConverter<HashSet<string>>,
     IReferenceTypeConverter<ISet<string>>,
     IReferenceTypeConverter<SortedSet<string>>,
-    IStaticSingleton<StringSetConverter>
+    IStaticSingleton<NoneNullableStringSetConverter>
 {
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static HashSet<string>? ToHashSet(AttributeValue attributeValue)
+    private static TSet? ToSet<TSet>(
+        AttributeValue attributeValue,
+        Func<int, TSet> factory
+    )
+        where TSet : class, ISet<string>
     {
-        return attributeValue.IsSSSet
-            ? new HashSet<string>(attributeValue.SS)
-            : null;
+        if (attributeValue.IsSSSet is false)
+            return null;
+
+        var span = CollectionsMarshal.AsSpan(attributeValue.SS);
+        var set = factory(span.Length);
+        foreach (var item in span)
+        {
+            if (item is null)
+                throw ExceptionHelper.NotNull(null);
+
+            set.Add(item);
+        }
+
+        return set;
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static AttributeValue ToAttributeValue(IEnumerable<string> enumerable)
     {
-        return new AttributeValue { SS = new List<string>(enumerable) };
+        var ss = enumerable.TryGetNonEnumeratedCount(out var count)
+            ? new List<string>(capacity: count)
+            : new List<string>();
+
+        foreach (var item in enumerable)
+        {
+            if (item is null) // TODO need datamember
+                throw ExceptionHelper.NotNull(null);
+
+            ss.Add(item);
+        }
+
+        return new AttributeValue { SS = ss };
     }
 
     IReadOnlySet<string>? IReferenceTypeConverter<IReadOnlySet<string>>.Read(AttributeValue attributeValue)
     {
-        return ToHashSet(attributeValue);
+        return ToSet(attributeValue, x => new HashSet<string>(x));
     }
 
     ISet<string>? IReferenceTypeConverter<ISet<string>>.Read(AttributeValue attributeValue)
     {
-        return ToHashSet(attributeValue);
+        return ToSet(attributeValue, x => new HashSet<string>(x));
     }
 
     HashSet<string>? IReferenceTypeConverter<HashSet<string>>.Read(AttributeValue attributeValue)
     {
-        return ToHashSet(attributeValue);
+        return ToSet(attributeValue, x => new HashSet<string>(x));
     }
 
     SortedSet<string>? IReferenceTypeConverter<SortedSet<string>>.Read(AttributeValue attributeValue)
     {
-        return attributeValue.IsSSSet
-            ? new SortedSet<string>(attributeValue.SS)
-            : null;
+        return ToSet(attributeValue, _ => new SortedSet<string>());
     }
 
     AttributeValue IReferenceTypeConverter<SortedSet<string>>.Write(SortedSet<string> element)

src/DynamoDBGenerator/Options/AttributeValueConverters.cs

@@ -121,20 +121,20 @@ public class AttributeValueConverters
     /// <summary>
     /// The <see cref="ISet{T}"/> converter for <see cref="string"/> sets.
     /// </summary>
-    public IReferenceTypeConverter<ISet<string>> ISetConverter { get; protected init; } = Singleton.Static<StringSetConverter>();
+    public IReferenceTypeConverter<ISet<string>> NoneNullableStringISetConverter { get; protected init; } = Singleton.Static<NoneNullableStringSetConverter>();
 
     /// <summary>
     /// The <see cref="IReadOnlySet{T}"/> converter for <see cref="string"/> sets.
     /// </summary>
-    public IReferenceTypeConverter<IReadOnlySet<string>> IReadOnlySetConverter { get; protected init; } = Singleton.Static<StringSetConverter>();
+    public IReferenceTypeConverter<IReadOnlySet<string>> NoneNullableStringIReadOnlySetConverter { get; protected init; } = Singleton.Static<NoneNullableStringSetConverter>();
 
     /// <summary>
     /// The <see cref="HashSet{T}"/> converter for <see cref="string"/> sets.
     /// </summary>
-    public IReferenceTypeConverter<HashSet<string>> HashSetConverter { get; protected init; } = Singleton.Static<StringSetConverter>();
+    public IReferenceTypeConverter<HashSet<string>> NoneNullableStringhashSetConverter { get; protected init; } = Singleton.Static<NoneNullableStringSetConverter>();
 
     /// <summary>
     /// The <see cref="SortedSet{T}"/> converter for <see cref="string"/> sets.
     /// </summary>
-    public IReferenceTypeConverter<SortedSet<string>> SortedSetConverter { get; protected init; } = Singleton.Static<StringSetConverter>();
+    public IReferenceTypeConverter<SortedSet<string>> NoneNullableStringSortedSetConverter { get; protected init; } = Singleton.Static<NoneNullableStringSetConverter>();
 }