WhitespaceRuleReader.cs

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namespace System.Xml.Xsl.Runtime;
 
internal sealed class WhitespaceRuleReader : XmlWrappingReader
{
    private readonly WhitespaceRuleLookup _wsRules;
 
    private readonly BitStack _stkStrip;
 
    private bool _shouldStrip;
 
    private bool _preserveAdjacent;
 
    private string _val;
 
    public override string Value
    {
        get
        {
            if (_val != null)
            {
                return _val;
            }
            return base.Value;
        }
    }
 
    public static XmlReader CreateReader(XmlReader baseReader, WhitespaceRuleLookup wsRules)
    {
        if (wsRules == null)
        {
            return baseReader;
        }
        XmlReaderSettings settings = baseReader.Settings;
        if (settings != null)
        {
            if (settings.IgnoreWhitespace)
            {
                return baseReader;
            }
        }
        else
        {
            if (baseReader is XmlTextReader { WhitespaceHandling: WhitespaceHandling.None })
            {
                return baseReader;
            }
            if (baseReader is XmlTextReaderImpl { WhitespaceHandling: WhitespaceHandling.None })
            {
                return baseReader;
            }
        }
        return new WhitespaceRuleReader(baseReader, wsRules);
    }
 
    private WhitespaceRuleReader(XmlReader baseReader, WhitespaceRuleLookup wsRules)
        : base(baseReader)
    {
        _val = null;
        _stkStrip = new BitStack();
        _shouldStrip = false;
        _preserveAdjacent = false;
        _wsRules = wsRules;
        _wsRules.Atomize(baseReader.NameTable);
    }
 
    public override bool Read()
    {
        string text = null;
        _val = null;
        while (base.Read())
        {
            switch (base.NodeType)
            {
            case XmlNodeType.Element:
                if (!base.IsEmptyElement)
                {
                    _stkStrip.PushBit(_shouldStrip);
                    _shouldStrip = _wsRules.ShouldStripSpace(base.LocalName, base.NamespaceURI) && base.XmlSpace != XmlSpace.Preserve;
                }
                break;
            case XmlNodeType.EndElement:
                _shouldStrip = _stkStrip.PopBit();
                break;
            case XmlNodeType.Text:
            case XmlNodeType.CDATA:
                if (_preserveAdjacent)
                {
                    return true;
                }
                if (!_shouldStrip)
                {
                    break;
                }
                if (!XmlCharType.IsOnlyWhitespace(base.Value))
                {
                    if (text != null)
                    {
                        _val = text + base.Value;
                    }
                    _preserveAdjacent = true;
                    return true;
                }
                goto case XmlNodeType.Whitespace;
            case XmlNodeType.Whitespace:
            case XmlNodeType.SignificantWhitespace:
                if (_preserveAdjacent)
                {
                    return true;
                }
                if (_shouldStrip)
                {
                    text = ((text != null) ? (text + base.Value) : base.Value);
                    continue;
                }
                break;
            case XmlNodeType.EndEntity:
                continue;
            }
            _preserveAdjacent = false;
            return true;
        }
        return false;
    }
}