ObjectIDGenerator.cs

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using System.Collections;
using System.Runtime.CompilerServices;
 
namespace System.Runtime.Serialization;
 
public class ObjectIDGenerator
{
    internal int _currentCount;
 
    private int _currentSize;
 
    private long[] _ids;
 
    private object[] _objs;
 
    public ObjectIDGenerator()
    {
        _currentCount = 1;
        _currentSize = 3;
        _ids = new long[_currentSize * 4];
        _objs = new object[_currentSize * 4];
    }
 
    private int FindElement(object obj, out bool found)
    {
        int num = RuntimeHelpers.GetHashCode(obj);
        int num2 = 1 + (num & 0x7FFFFFFF) % (_currentSize - 2);
        while (true)
        {
            int num3 = (num & 0x7FFFFFFF) % _currentSize * 4;
            for (int i = num3; i < num3 + 4; i++)
            {
                if (_objs[i] == null)
                {
                    found = false;
                    return i;
                }
                if (_objs[i] == obj)
                {
                    found = true;
                    return i;
                }
            }
            num += num2;
        }
    }
 
    public virtual long GetId(object obj, out bool firstTime)
    {
        if (obj == null)
        {
            throw new ArgumentNullException("obj");
        }
        bool found;
        int num = FindElement(obj, out found);
        long result;
        if (!found)
        {
            _objs[num] = obj;
            _ids[num] = _currentCount++;
            result = _ids[num];
            if (_currentCount > _currentSize * 4 / 2)
            {
                Rehash();
            }
        }
        else
        {
            result = _ids[num];
        }
        firstTime = !found;
        return result;
    }
 
    public virtual long HasId(object obj, out bool firstTime)
    {
        if (obj == null)
        {
            throw new ArgumentNullException("obj");
        }
        bool found;
        int num = FindElement(obj, out found);
        if (found)
        {
            firstTime = false;
            return _ids[num];
        }
        firstTime = true;
        return 0L;
    }
 
    private void Rehash()
    {
        int currentSize = _currentSize;
        int num = System.Collections.HashHelpers.ExpandPrime(currentSize);
        if (num == currentSize)
        {
            throw new SerializationException(System.SR.Serialization_TooManyElements);
        }
        _currentSize = num;
        long[] ids = new long[_currentSize * 4];
        object[] objs = new object[_currentSize * 4];
        long[] ids2 = _ids;
        object[] objs2 = _objs;
        _ids = ids;
        _objs = objs;
        for (int i = 0; i < objs2.Length; i++)
        {
            if (objs2[i] != null)
            {
                bool found;
                int num2 = FindElement(objs2[i], out found);
                _objs[num2] = objs2[i];
                _ids[num2] = ids2[i];
            }
        }
    }
}