System.Xml.XmlTextReaderImpl.ParseDoctypeDecl C# (CSharp) Method

        private bool ParseDoctypeDecl()
        {
            if (_dtdProcessing == DtdProcessing.Prohibit)
            {
                ThrowWithoutLineInfo(_v1Compat ? SR.Xml_DtdIsProhibited : SR.Xml_DtdIsProhibitedEx);
            }

            // parse 'DOCTYPE'
            while (_ps.charsUsed - _ps.charPos < 8)
            {
                if (ReadData() == 0)
                {
                    Throw(SR.Xml_UnexpectedEOF, "DOCTYPE");
                }
            }
            if (!XmlConvert.StrEqual(_ps.chars, _ps.charPos, 7, "DOCTYPE"))
            {
                ThrowUnexpectedToken((!_rootElementParsed && _dtdInfo == null) ? "DOCTYPE" : "<!--");
            }
            if (!_xmlCharType.IsWhiteSpace(_ps.chars[_ps.charPos + 7]))
            {
                ThrowExpectingWhitespace(_ps.charPos + 7);
            }

            if (_dtdInfo != null)
            {
                Throw(_ps.charPos - 2, SR.Xml_MultipleDTDsProvided);  // position just before <!DOCTYPE
            }
            if (_rootElementParsed)
            {
                Throw(_ps.charPos - 2, SR.Xml_DtdAfterRootElement);
            }

            _ps.charPos += 8;

            EatWhitespaces(null);

            if (_dtdProcessing == DtdProcessing.Parse)
            {
                _curNode.SetLineInfo(_ps.LineNo, _ps.LinePos);

                ParseDtd();

                _nextParsingFunction = _parsingFunction;
                _parsingFunction = ParsingFunction.ResetAttributesRootLevel;
                return true;
            }
            // Skip DTD
            else
            {
                Debug.Assert(_dtdProcessing == DtdProcessing.Ignore);

                SkipDtd();
                return false;
            }
        }