NullableConverterFactory.cs

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using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using System.Text.Json.Reflection;
 
namespace System.Text.Json.Serialization.Converters;
 
internal sealed class NullableConverterFactory : JsonConverterFactory
{
    public override bool CanConvert(Type typeToConvert)
    {
        return typeToConvert.IsNullableOfT();
    }
 
    public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializerOptions options)
    {
        Type type = typeToConvert.GetGenericArguments()[0];
        JsonConverter converterInternal = options.GetConverterInternal(type);
        if (!converterInternal.TypeToConvert.IsValueType && type.IsValueType)
        {
            return converterInternal;
        }
        return CreateValueConverter(type, converterInternal);
    }
 
    public static JsonConverter CreateValueConverter(Type valueTypeToConvert, JsonConverter valueConverter)
    {
        return (JsonConverter)Activator.CreateInstance(GetNullableConverterType(valueTypeToConvert), BindingFlags.Instance | BindingFlags.Public, null, new object[1] { valueConverter }, null);
    }
 
    [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2055:MakeGenericType", Justification = "'NullableConverter<T> where T : struct' implies 'T : new()', so the trimmer is warning calling MakeGenericType here because valueTypeToConvert's constructors are not annotated. But NullableConverter doesn't call new T(), so this is safe.")]
    [return: DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
    private static Type GetNullableConverterType(Type valueTypeToConvert)
    {
        return typeof(NullableConverter<>).MakeGenericType(valueTypeToConvert);
    }
}