PreserveReferenceResolver.cs

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using System.Collections.Generic;
 
namespace System.Text.Json.Serialization;
 
internal sealed class PreserveReferenceResolver : ReferenceResolver
{
    private uint _referenceCount;
 
    private readonly Dictionary<string, object> _referenceIdToObjectMap;
 
    private readonly Dictionary<object, string> _objectToReferenceIdMap;
 
    public PreserveReferenceResolver(bool writing)
    {
        if (writing)
        {
            _objectToReferenceIdMap = new Dictionary<object, string>(ReferenceEqualityComparer.Instance);
        }
        else
        {
            _referenceIdToObjectMap = new Dictionary<string, object>();
        }
    }
 
    public override void AddReference(string referenceId, object value)
    {
        if (!_referenceIdToObjectMap.TryAdd(in referenceId, in value))
        {
            ThrowHelper.ThrowJsonException_MetadataDuplicateIdFound(referenceId);
        }
    }
 
    public override string GetReference(object value, out bool alreadyExists)
    {
        if (_objectToReferenceIdMap.TryGetValue(value, out var value2))
        {
            alreadyExists = true;
        }
        else
        {
            _referenceCount++;
            value2 = _referenceCount.ToString();
            _objectToReferenceIdMap.Add(value, value2);
            alreadyExists = false;
        }
        return value2;
    }
 
    public override object ResolveReference(string referenceId)
    {
        if (!_referenceIdToObjectMap.TryGetValue(referenceId, out var value))
        {
            ThrowHelper.ThrowJsonException_MetadataReferenceNotFound(referenceId);
        }
        return value;
    }
}