DescendantOverDescendantQuery.cs

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using System.Xml.XPath;
 
namespace MS.Internal.Xml.XPath;
 
internal sealed class DescendantOverDescendantQuery : DescendantBaseQuery
{
    private int _level;
 
    public DescendantOverDescendantQuery(Query qyParent, bool matchSelf, string name, string prefix, XPathNodeType typeTest, bool abbrAxis)
        : base(qyParent, name, prefix, typeTest, matchSelf, abbrAxis)
    {
    }
 
    private DescendantOverDescendantQuery(DescendantOverDescendantQuery other)
        : base(other)
    {
        _level = other._level;
    }
 
    public override void Reset()
    {
        _level = 0;
        base.Reset();
    }
 
    public override XPathNavigator Advance()
    {
        while (true)
        {
            if (_level == 0)
            {
                currentNode = qyInput.Advance();
                position = 0;
                if (currentNode == null)
                {
                    return null;
                }
                if (matchSelf && matches(currentNode))
                {
                    break;
                }
                currentNode = currentNode.Clone();
                if (!MoveToFirstChild())
                {
                    continue;
                }
            }
            else if (!MoveUpUntilNext())
            {
                continue;
            }
            do
            {
                if (matches(currentNode))
                {
                    position++;
                    return currentNode;
                }
            }
            while (MoveToFirstChild());
        }
        position = 1;
        return currentNode;
    }
 
    private bool MoveToFirstChild()
    {
        if (currentNode.MoveToFirstChild())
        {
            _level++;
            return true;
        }
        return false;
    }
 
    private bool MoveUpUntilNext()
    {
        while (!currentNode.MoveToNext())
        {
            _level--;
            if (_level == 0)
            {
                return false;
            }
            bool flag = currentNode.MoveToParent();
        }
        return true;
    }
 
    public override XPathNodeIterator Clone()
    {
        return new DescendantOverDescendantQuery(this);
    }
}