DescendantMergeIterator.cs

Go to the documentation of this file.

using System.ComponentModel;
using System.Xml.XPath;
 
namespace System.Xml.Xsl.Runtime;
 
[EditorBrowsable(EditorBrowsableState.Never)]
public struct DescendantMergeIterator
{
    private enum IteratorState
    {
        NoPrevious,
        NeedCurrent,
        NeedDescendant
    }
 
    private XmlNavigatorFilter _filter;
 
    private XPathNavigator _navCurrent;
 
    private XPathNavigator _navRoot;
 
    private XPathNavigator _navEnd;
 
    private IteratorState _state;
 
    private bool _orSelf;
 
    public XPathNavigator Current => _navCurrent;
 
    public void Create(XmlNavigatorFilter filter, bool orSelf)
    {
        _filter = filter;
        _state = IteratorState.NoPrevious;
        _orSelf = orSelf;
    }
 
    public IteratorResult MoveNext(XPathNavigator input)
    {
        if (_state != IteratorState.NeedDescendant)
        {
            if (input == null)
            {
                return IteratorResult.NoMoreNodes;
            }
            if (_state != 0 && _navRoot.IsDescendant(input))
            {
                return IteratorResult.NeedInputNode;
            }
            _navCurrent = XmlQueryRuntime.SyncToNavigator(_navCurrent, input);
            _navRoot = XmlQueryRuntime.SyncToNavigator(_navRoot, input);
            _navEnd = XmlQueryRuntime.SyncToNavigator(_navEnd, input);
            _navEnd.MoveToNonDescendant();
            _state = IteratorState.NeedDescendant;
            if (_orSelf && !_filter.IsFiltered(input))
            {
                return IteratorResult.HaveCurrentNode;
            }
        }
        if (_filter.MoveToFollowing(_navCurrent, _navEnd))
        {
            return IteratorResult.HaveCurrentNode;
        }
        _state = IteratorState.NeedCurrent;
        return IteratorResult.NeedInputNode;
    }
}