JSON Document Object Model for .NET Framework.

JsonNode.cs

namespace System.Runtime.Serialization.Json;

using System.IO;
using System.Xml;
using System.Linq;
using System.Text;
using System.Xml.Linq;
using System.Collections;
using System.Collections.Generic;

public readonly struct JsonNode : IEnumerable<JsonNode>
{
    public enum JsonType { Value, Array, Object }

    readonly XElement Element;

    readonly JsonType Type;

    public JsonNode() => throw new NotSupportedException();

    JsonNode(XElement _) => Type = (Element = _).Attribute("type").Value[0] switch
    {
        'a' => JsonType.Array,
        'o' => JsonType.Object,
        _ => JsonType.Value
    };

    public static JsonNode Parse(string value) => Parse(Encoding.Unicode.GetBytes(value));

    public static JsonNode Parse(byte[] value)
    {
        using var reader = JsonReaderWriterFactory.CreateJsonReader(value, XmlDictionaryReaderQuotas.Max);
        return new(XElement.Load(reader));
    }

    public static JsonNode Parse(Stream value)
    {
        using var reader = JsonReaderWriterFactory.CreateJsonReader(value, XmlDictionaryReaderQuotas.Max);
        return new(XElement.Load(reader));
    }

    public readonly string Value => 
    Type is JsonType.Value ? Element.Value : throw new InvalidOperationException();

    public readonly JsonNode this[string value, bool _ = false] => 
    new(Type is JsonType.Object ? (_ ? Element.Descendants() : Element.Elements()).First(_ => Name(_) == value) : throw new InvalidOperationException());

    public readonly JsonNode this[int value] => 
    new(Type is JsonType.Array ? Element.Elements().ElementAt(value) : throw new InvalidOperationException());

    static string Name(XElement _) => 
    string.IsNullOrEmpty(_.Name.NamespaceName) ? _.Name.LocalName : _.Attribute("item").Value;

    public IEnumerator<JsonNode> GetEnumerator() => 
    Element.Elements().Select(_ => new JsonNode(_)).GetEnumerator();

    IEnumerator IEnumerable.GetEnumerator() => 
    GetEnumerator();
}