System.Xml.Schema.XmlSchemaValidator.ValidateElementContext C# (CSharp) Méthode

        private object ValidateElementContext(XmlQualifiedName elementName, out bool invalidElementInContext)
        {
            object particle = null;
            int errorCode = 0;
            XmlQualifiedName head;
            XmlSchemaElement headElement = null;
            invalidElementInContext = false;

            if (_context.NeedValidateChildren)
            {
                if (_context.IsNill)
                {
                    SendValidationEvent(SR.Sch_ContentInNill, QNameString(_context.LocalName, _context.Namespace));
                    return null;
                }
                ContentValidator contentValidator = _context.ElementDecl.ContentValidator;
                if (contentValidator.ContentType == XmlSchemaContentType.Mixed && _context.ElementDecl.Presence == SchemaDeclBase.Use.Fixed)
                { //Mixed with default or fixed
                    SendValidationEvent(SR.Sch_ElementInMixedWithFixed, QNameString(_context.LocalName, _context.Namespace));
                    return null;
                }

                head = elementName;
                bool substitution = false;

                while (true)
                {
                    particle = _context.ElementDecl.ContentValidator.ValidateElement(head, _context, out errorCode);
                    if (particle != null)
                    { //Match found
                        break;
                    }
                    if (errorCode == -2)
                    { //ContentModel all group error
                        SendValidationEvent(SR.Sch_AllElement, elementName.ToString());
                        invalidElementInContext = true;
                        _processContents = _context.ProcessContents = XmlSchemaContentProcessing.Skip;
                        return null;
                    }
                    //Match not found; check for substitutionGroup
                    substitution = true;
                    headElement = GetSubstitutionGroupHead(head);
                    if (headElement == null)
                    {
                        break;
                    }
                    else
                    {
                        head = headElement.QualifiedName;
                    }
                }

                if (substitution)
                {
                    XmlSchemaElement matchedElem = particle as XmlSchemaElement;
                    if (matchedElem == null)
                    { //It matched an xs:any in that position
                        particle = null;
                    }
                    else if (matchedElem.RefName.IsEmpty)
                    { //It is not element ref but a local element
                        //If the head and matched particle are not hte same, then this is not substitutable, duped by a localElement with same QName
                        SendValidationEvent(SR.Sch_InvalidElementSubstitution, BuildElementName(elementName), BuildElementName(matchedElem.QualifiedName));
                        invalidElementInContext = true;
                        _processContents = _context.ProcessContents = XmlSchemaContentProcessing.Skip;
                    }
                    else
                    { //Correct substitution head found
                        particle = _compiledSchemaInfo.GetElement(elementName); //Re-assign correct particle
                        _context.NeedValidateChildren = true; //This will be reset to false once member match is not found
                    }
                }
                if (particle == null)
                {
                    ElementValidationError(elementName, _context, _eventHandler, _nsResolver, _sourceUriString, _positionInfo.LineNumber, _positionInfo.LinePosition, _schemaSet);
                    invalidElementInContext = true;
                    _processContents = _context.ProcessContents = XmlSchemaContentProcessing.Skip;
                }
            }
            return particle;
        }