QilCloneVisitor.cs

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namespace System.Xml.Xsl.Qil;
 
internal class QilCloneVisitor : QilScopedVisitor
{
    private readonly QilFactory _fac;
 
    private readonly SubstitutionList _subs;
 
    public QilCloneVisitor(QilFactory fac)
        : this(fac, new SubstitutionList())
    {
    }
 
    public QilCloneVisitor(QilFactory fac, SubstitutionList subs)
    {
        _fac = fac;
        _subs = subs;
    }
 
    public QilNode Clone(QilNode node)
    {
        QilDepthChecker.Check(node);
        return VisitAssumeReference(node);
    }
 
    protected override QilNode Visit(QilNode oldNode)
    {
        QilNode qilNode = null;
        if (oldNode == null)
        {
            return null;
        }
        if (oldNode is QilReference)
        {
            qilNode = FindClonedReference(oldNode);
        }
        if (qilNode == null)
        {
            qilNode = oldNode.ShallowClone(_fac);
        }
        return base.Visit(qilNode);
    }
 
    protected override QilNode VisitChildren(QilNode parent)
    {
        for (int i = 0; i < parent.Count; i++)
        {
            QilNode qilNode = parent[i];
            if (IsReference(parent, i))
            {
                parent[i] = VisitReference(qilNode);
                if (parent[i] == null)
                {
                    parent[i] = qilNode;
                }
            }
            else
            {
                parent[i] = Visit(qilNode);
            }
        }
        return parent;
    }
 
    protected override QilNode VisitReference(QilNode oldNode)
    {
        QilNode qilNode = FindClonedReference(oldNode);
        return base.VisitReference((qilNode == null) ? oldNode : qilNode);
    }
 
    protected override void BeginScope(QilNode node)
    {
        _subs.AddSubstitutionPair(node, node.ShallowClone(_fac));
    }
 
    protected override void EndScope(QilNode node)
    {
        _subs.RemoveLastSubstitutionPair();
    }
 
    protected QilNode FindClonedReference(QilNode node)
    {
        return _subs.FindReplacement(node);
    }
}