RegionIterator.cs

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using System.Diagnostics.CodeAnalysis;
using System.Text;
 
namespace System.Xml;
 
internal sealed class RegionIterator : BaseRegionIterator
{
    private readonly XmlBoundElement _rowElement;
 
    private XmlNode _currentNode;
 
    internal override XmlNode CurrentNode => _currentNode;
 
    internal RegionIterator(XmlBoundElement rowElement)
        : base(((XmlDataDocument)rowElement.OwnerDocument).Mapper)
    {
        _rowElement = rowElement;
        _currentNode = rowElement;
    }
 
    [MemberNotNullWhen(true, "CurrentNode")]
    internal override bool Next()
    {
        ElementState elementState = _rowElement.ElementState;
        XmlNode firstChild = _currentNode.FirstChild;
        if (firstChild != null)
        {
            _currentNode = firstChild;
            _rowElement.ElementState = elementState;
            return true;
        }
        return NextRight();
    }
 
    [MemberNotNullWhen(true, "CurrentNode")]
    internal override bool NextRight()
    {
        if (_currentNode == _rowElement)
        {
            _currentNode = null;
            return false;
        }
        ElementState elementState = _rowElement.ElementState;
        XmlNode nextSibling = _currentNode.NextSibling;
        if (nextSibling != null)
        {
            _currentNode = nextSibling;
            _rowElement.ElementState = elementState;
            return true;
        }
        nextSibling = _currentNode;
        while (nextSibling != _rowElement && nextSibling.NextSibling == null)
        {
            nextSibling = nextSibling.ParentNode;
        }
        if (nextSibling == _rowElement)
        {
            _currentNode = null;
            _rowElement.ElementState = elementState;
            return false;
        }
        _currentNode = nextSibling.NextSibling;
        _rowElement.ElementState = elementState;
        return true;
    }
 
    [MemberNotNullWhen(true, "CurrentNode")]
    internal bool NextInitialTextLikeNodes(out string value)
    {
        ElementState elementState = _rowElement.ElementState;
        XmlNode n = CurrentNode.FirstChild;
        value = GetInitialTextFromNodes(ref n);
        if (n == null)
        {
            _rowElement.ElementState = elementState;
            return NextRight();
        }
        _currentNode = n;
        _rowElement.ElementState = elementState;
        return true;
    }
 
    private static string GetInitialTextFromNodes(ref XmlNode n)
    {
        string text = null;
        if (n != null)
        {
            while (n.NodeType == XmlNodeType.Whitespace)
            {
                n = n.NextSibling;
                if (n == null)
                {
                    return string.Empty;
                }
            }
            if (XmlDataDocument.IsTextLikeNode(n) && (n.NextSibling == null || !XmlDataDocument.IsTextLikeNode(n.NextSibling)))
            {
                text = n.Value;
                n = n.NextSibling;
            }
            else
            {
                StringBuilder stringBuilder = new StringBuilder();
                while (n != null && XmlDataDocument.IsTextLikeNode(n))
                {
                    if (n.NodeType != XmlNodeType.Whitespace)
                    {
                        stringBuilder.Append(n.Value);
                    }
                    n = n.NextSibling;
                }
                text = stringBuilder.ToString();
            }
        }
        return text ?? string.Empty;
    }
}