ReadOnlyMemoryConverter<T>
using System.Collections.Generic;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
namespace System.Text.Json.Serialization.Converters
{
internal sealed class ReadOnlyMemoryConverter<T> : JsonCollectionConverter<ReadOnlyMemory<T>, T>
{
internal override bool CanHaveMetadata => false;
public override bool HandleNull => true;
internal sealed override bool IsConvertibleCollection => true;
internal override bool OnTryRead(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options, [System.Runtime.CompilerServices.ScopedRef] ref ReadStack state, out ReadOnlyMemory<T> value)
{
if (reader.TokenType == JsonTokenType.Null) {
value = default(ReadOnlyMemory<T>);
return true;
}
return base.OnTryRead(ref reader, typeToConvert, options, ref state, out value);
}
protected override void Add([In] [System.Runtime.CompilerServices.IsReadOnly] T value, ref ReadStack state)
{
((List<T>)state.Current.ReturnValue).Add(value);
}
protected override void CreateCollection(ref Utf8JsonReader reader, [System.Runtime.CompilerServices.ScopedRef] ref ReadStack state, JsonSerializerOptions options)
{
state.Current.ReturnValue = new List<T>();
}
protected override void ConvertCollection(ref ReadStack state, JsonSerializerOptions options)
{
ReadOnlyMemory<T> readOnlyMemory = MemoryExtensions.AsMemory<T>(((List<T>)state.Current.ReturnValue).ToArray());
state.Current.ReturnValue = readOnlyMemory;
}
protected override bool OnWriteResume(Utf8JsonWriter writer, ReadOnlyMemory<T> value, JsonSerializerOptions options, ref WriteStack state)
{
return OnWriteResume(writer, value.Span, options, ref state);
}
internal static bool OnWriteResume(Utf8JsonWriter writer, ReadOnlySpan<T> value, JsonSerializerOptions options, ref WriteStack state)
{
int i = state.Current.EnumeratorIndex;
JsonConverter<T> elementConverter = JsonCollectionConverter<ReadOnlyMemory<T>, T>.GetElementConverter(ref state);
if (!elementConverter.CanUseDirectReadOrWrite || state.Current.NumberHandling.HasValue) {
for (; i < value.Length; i++) {
if (!elementConverter.TryWrite(writer, ref value[i], options, ref state)) {
state.Current.EnumeratorIndex = i;
return false;
}
state.Current.EndCollectionElement();
if (JsonConverter.ShouldFlush(ref state, writer)) {
i = (state.Current.EnumeratorIndex = i + 1);
return false;
}
}
} else {
for (; i < value.Length; i++) {
elementConverter.Write(writer, value[i], options);
}
}
return true;
}
}
}