ObjectToIdCache.cs

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using System.Runtime.CompilerServices;
 
namespace System.Runtime.Serialization;
 
internal sealed class ObjectToIdCache
{
    internal int m_currentCount;
 
    internal int[] m_ids;
 
    internal object[] m_objs;
 
    internal bool[] m_isWrapped;
 
    internal static readonly int[] primes = new int[30]
    {
        3, 7, 17, 37, 89, 197, 431, 919, 1931, 4049,
        8419, 17519, 36353, 75431, 156437, 324449, 672827, 1395263, 2893249, 5999471,
        11998949, 23997907, 47995853, 95991737, 191983481, 383966977, 767933981, 1535867969, 2146435069, 2147483591
    };
 
    public ObjectToIdCache()
    {
        m_currentCount = 1;
        m_ids = new int[GetPrime(1)];
        m_objs = new object[m_ids.Length];
        m_isWrapped = new bool[m_ids.Length];
    }
 
    public int GetId(object obj, ref bool newId)
    {
        bool isEmpty;
        bool isWrapped;
        int num = FindElement(obj, out isEmpty, out isWrapped);
        if (!isEmpty)
        {
            newId = false;
            return m_ids[num];
        }
        if (!newId)
        {
            return -1;
        }
        int num2 = m_currentCount++;
        m_objs[num] = obj;
        m_ids[num] = num2;
        m_isWrapped[num] = isWrapped;
        if (m_currentCount >= m_objs.Length - 1)
        {
            Rehash();
        }
        return num2;
    }
 
    public int ReassignId(int oldObjId, object oldObj, object newObj)
    {
        int num = FindElement(oldObj, out var isEmpty, out var isWrapped);
        if (isEmpty)
        {
            return 0;
        }
        int num2 = m_ids[num];
        if (oldObjId > 0)
        {
            m_ids[num] = oldObjId;
        }
        else
        {
            RemoveAt(num);
        }
        num = FindElement(newObj, out isEmpty, out isWrapped);
        int result = 0;
        if (!isEmpty)
        {
            result = m_ids[num];
        }
        m_objs[num] = newObj;
        m_ids[num] = num2;
        m_isWrapped[num] = isWrapped;
        return result;
    }
 
    private int FindElement(object obj, out bool isEmpty, out bool isWrapped)
    {
        isWrapped = false;
        int num = ComputeStartPosition(obj);
        for (int i = num; i != num - 1; i++)
        {
            if (m_objs[i] == null)
            {
                isEmpty = true;
                return i;
            }
            if (m_objs[i] == obj)
            {
                isEmpty = false;
                return i;
            }
            if (i == m_objs.Length - 1)
            {
                isWrapped = true;
                i = -1;
            }
        }
        throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(XmlObjectSerializer.CreateSerializationException(System.SR.ObjectTableOverflow));
    }
 
    private void RemoveAt(int position)
    {
        int num = m_objs.Length;
        int num2 = position;
        for (int i = ((position != num - 1) ? (position + 1) : 0); i != position; i++)
        {
            if (m_objs[i] == null)
            {
                m_objs[num2] = null;
                m_ids[num2] = 0;
                m_isWrapped[num2] = false;
                return;
            }
            int num3 = ComputeStartPosition(m_objs[i]);
            bool flag = i < position && !m_isWrapped[i];
            bool flag2 = num2 < position;
            if ((num3 <= num2 && (!flag || flag2)) || (flag2 && !flag))
            {
                m_objs[num2] = m_objs[i];
                m_ids[num2] = m_ids[i];
                m_isWrapped[num2] = m_isWrapped[i] && i > num2;
                num2 = i;
            }
            if (i == num - 1)
            {
                i = -1;
            }
        }
        throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(XmlObjectSerializer.CreateSerializationException(System.SR.ObjectTableOverflow));
    }
 
    private int ComputeStartPosition(object o)
    {
        return (RuntimeHelpers.GetHashCode(o) & 0x7FFFFFFF) % m_objs.Length;
    }
 
    private void Rehash()
    {
        int prime = GetPrime(m_objs.Length + 1);
        int[] ids = m_ids;
        object[] objs = m_objs;
        m_ids = new int[prime];
        m_objs = new object[prime];
        m_isWrapped = new bool[prime];
        for (int i = 0; i < objs.Length; i++)
        {
            object obj = objs[i];
            if (obj != null)
            {
                bool isEmpty;
                bool isWrapped;
                int num = FindElement(obj, out isEmpty, out isWrapped);
                m_objs[num] = obj;
                m_ids[num] = ids[i];
                m_isWrapped[num] = isWrapped;
            }
        }
    }
 
    private static int GetPrime(int min)
    {
        for (int i = 0; i < primes.Length; i++)
        {
            int num = primes[i];
            if (num >= min)
            {
                return num;
            }
        }
        return min;
    }
}