// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.Runtime.Serialization.DataContracts;
using System.Xml;
 
using DataContractDictionary = System.Collections.Generic.Dictionary<System.Xml.XmlQualifiedName, System.Runtime.Serialization.DataContracts.DataContract>;
 
namespace System.Runtime.Serialization
{
    internal struct ScopedKnownTypes
    {
        internal DataContractDictionary[] dataContractDictionaries;
        private int _count;
        internal void Push(DataContractDictionary dataContractDictionary)
        {
            if (dataContractDictionaries == null)
            {
                dataContractDictionaries = new DataContractDictionary[4];
            }
            else if (_count == dataContractDictionaries.Length)
            {
                Array.Resize<DataContractDictionary>(ref dataContractDictionaries, dataContractDictionaries.Length * 2);
            }
 
            dataContractDictionaries[_count++] = dataContractDictionary;
        }
 
        internal void Pop()
        {
            _count--;
        }
 
        internal DataContract? GetDataContract(XmlQualifiedName qname)
        {
            for (int i = (_count - 1); i >= 0; i--)
            {
                DataContractDictionary dataContractDictionary = dataContractDictionaries[i];
                DataContract? dataContract;
                if (dataContractDictionary.TryGetValue(qname, out dataContract))
                    return dataContract;
            }
            return null;
        }
    }
}