System.Xml.Schema.Compiler.IsValidRestriction C# (CSharp) Méthode

        private bool IsValidRestriction(XmlSchemaParticle derivedParticle, XmlSchemaParticle baseParticle) {
            if (derivedParticle == baseParticle) {
                return true;
            }
            else if (derivedParticle == null || derivedParticle == XmlSchemaParticle.Empty) {
                return IsParticleEmptiable(baseParticle);
            }
            else if (baseParticle == null || baseParticle == XmlSchemaParticle.Empty) {
                return false;
            }
            if (derivedParticle is XmlSchemaElement) { //check for derived element being head of substitutionGroup
                XmlSchemaElement derivedElem = (XmlSchemaElement)derivedParticle;
                derivedParticle = CannonicalizeElement(derivedElem);
            }
            if (baseParticle is XmlSchemaElement) {
                XmlSchemaElement baseElem = (XmlSchemaElement)baseParticle;
                XmlSchemaParticle newBaseParticle;
                newBaseParticle = CannonicalizeElement(baseElem);
                if (newBaseParticle is XmlSchemaChoice) { //Base Element is subs grp head.
                    return IsValidRestriction(derivedParticle, newBaseParticle);
                }
                else if (derivedParticle is XmlSchemaElement) {
                    return IsElementFromElement((XmlSchemaElement)derivedParticle, baseElem);
                }
                else {
                    restrictionErrorMsg = Res.GetString(Res.Sch_ForbiddenDerivedParticleForElem);
                    return false;
                }
            }
            else if (baseParticle is XmlSchemaAny) {
                if (derivedParticle is XmlSchemaElement) {
                    return IsElementFromAny((XmlSchemaElement)derivedParticle, (XmlSchemaAny)baseParticle);
                }
                else if (derivedParticle is XmlSchemaAny) {
                    return IsAnyFromAny((XmlSchemaAny)derivedParticle, (XmlSchemaAny)baseParticle);
                }
                else {
                    return IsGroupBaseFromAny((XmlSchemaGroupBase)derivedParticle, (XmlSchemaAny)baseParticle);
                }
            }
            else if (baseParticle is XmlSchemaAll) {
                if (derivedParticle is XmlSchemaElement) {
                    return IsElementFromGroupBase((XmlSchemaElement)derivedParticle, (XmlSchemaGroupBase)baseParticle);
                }
                else if (derivedParticle is XmlSchemaAll) {
                    if(IsGroupBaseFromGroupBase((XmlSchemaGroupBase)derivedParticle, (XmlSchemaGroupBase)baseParticle, true)) {
                        return true;    
                    }
                }
                else if (derivedParticle is XmlSchemaSequence) {
                    if(IsSequenceFromAll((XmlSchemaSequence)derivedParticle, (XmlSchemaAll)baseParticle)) {
                        return true;
                    }
                    restrictionErrorMsg = Res.GetString(Res.Sch_SeqFromAll, derivedParticle.LineNumber.ToString(NumberFormatInfo.InvariantInfo), derivedParticle.LinePosition.ToString(NumberFormatInfo.InvariantInfo), baseParticle.LineNumber.ToString(NumberFormatInfo.InvariantInfo), baseParticle.LinePosition.ToString(NumberFormatInfo.InvariantInfo));
                }
                else if (derivedParticle is XmlSchemaChoice || derivedParticle is XmlSchemaAny) {
                    restrictionErrorMsg = Res.GetString(Res.Sch_ForbiddenDerivedParticleForAll);
                }
                return false;
            }
            else if (baseParticle is XmlSchemaChoice ) {
                if (derivedParticle is XmlSchemaElement) {
                    return IsElementFromGroupBase((XmlSchemaElement)derivedParticle, (XmlSchemaGroupBase)baseParticle);
                }
                else if (derivedParticle is XmlSchemaChoice) {
                    XmlSchemaChoice baseChoice = baseParticle as XmlSchemaChoice;
                    XmlSchemaChoice derivedChoice = derivedParticle as XmlSchemaChoice;
                    if (baseChoice.Parent == null || derivedChoice.Parent == null) { //using parent property to indicate this choice was created on the fly for substitutionGroup
                        return IsChoiceFromChoiceSubstGroup(derivedChoice, baseChoice);
                    }
                    if(IsGroupBaseFromGroupBase(derivedChoice, baseChoice, false)) {
                        return true;
                    }
                }
                else if (derivedParticle is XmlSchemaSequence) {
                    if(IsSequenceFromChoice((XmlSchemaSequence)derivedParticle, (XmlSchemaChoice)baseParticle)) {
                        return true;
                    }
                    restrictionErrorMsg = Res.GetString(Res.Sch_SeqFromChoice, derivedParticle.LineNumber.ToString(NumberFormatInfo.InvariantInfo), derivedParticle.LinePosition.ToString(NumberFormatInfo.InvariantInfo), baseParticle.LineNumber.ToString(NumberFormatInfo.InvariantInfo), baseParticle.LinePosition.ToString(NumberFormatInfo.InvariantInfo));
                }
                else {
                    restrictionErrorMsg = Res.GetString(Res.Sch_ForbiddenDerivedParticleForChoice); 
                }
                return false;
            }
            else if (baseParticle is XmlSchemaSequence) {
                if (derivedParticle is XmlSchemaElement) {
                    return IsElementFromGroupBase((XmlSchemaElement)derivedParticle, (XmlSchemaGroupBase)baseParticle);
                }
                else if (derivedParticle is XmlSchemaSequence || (derivedParticle is XmlSchemaAll && ((XmlSchemaGroupBase)derivedParticle).Items.Count ==1)) {
                    if (IsGroupBaseFromGroupBase((XmlSchemaGroupBase)derivedParticle, (XmlSchemaGroupBase)baseParticle, true)) {
                        return true;    
                    }
                }
                else {
                    restrictionErrorMsg = Res.GetString(Res.Sch_ForbiddenDerivedParticleForSeq); 
                }
                return false;
            }
            else {
                Debug.Assert(false);
            }

            return false;
        }