path: root/src/xmlpatterns/schema/qxsdschemahelper.cpp

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#include "qxsdschemahelper_p.h"

#include "qbuiltintypes_p.h"
#include "qvaluefactory_p.h"
#include "qxsdcomplextype_p.h"
#include "qxsdmodelgroup_p.h"
#include "qxsdsimpletype_p.h"
#include "qxsdtypechecker_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

/*
 * Calculates the effective total range minimum of the given @p particle as
 * described by the algorithm in the schema spec.
 */
static inline unsigned int effectiveTotalRangeMinimum(const XsdParticle::Ptr &particle)
{
    const XsdModelGroup::Ptr group = particle->term();

    if (group->compositor() == XsdModelGroup::ChoiceCompositor) {
        // @see http://www.w3.org/TR/xmlschema11-1/# cos-choice-range

        int minValue = -1;

        const XsdParticle::List particles = group->particles();
        if (particles.isEmpty())
            minValue = 0;

        for (int i = 0; i < particles.count(); ++i) {
            const XsdParticle::Ptr particle = particles.at(i);

            if (particle->term()->isElement() || particle->term()->isWildcard()) {
                if (minValue == -1) {
                    minValue = particle->minimumOccurs();
                } else {
                    minValue = qMin((unsigned int)minValue, particle->minimumOccurs());
                }
            } else if (particle->term()->isModelGroup()) {
                if (minValue == -1) {
                    minValue = effectiveTotalRangeMinimum(particle);
                } else {
                    minValue = qMin((unsigned int)minValue, effectiveTotalRangeMinimum(particle));
                }
            }
        }

        return (particle->minimumOccurs() * minValue);

    } else {
        // @see http://www.w3.org/TR/xmlschema11-1/# cos-seq-range

        unsigned int sum = 0;
        const XsdParticle::List particles = group->particles();
        for (int i = 0; i < particles.count(); ++i) {
            const XsdParticle::Ptr particle = particles.at(i);

            if (particle->term()->isElement() || particle->term()->isWildcard())
                sum += particle->minimumOccurs();
            else if (particle->term()->isModelGroup())
                sum += effectiveTotalRangeMinimum(particle);
        }

        return (particle->minimumOccurs() * sum);
    }
}

bool XsdSchemaHelper::isParticleEmptiable(const XsdParticle::Ptr &particle)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cos-group-emptiable

    if (particle->minimumOccurs() == 0)
        return true;

    if (!(particle->term()->isModelGroup()))
        return false;

    return (effectiveTotalRangeMinimum(particle) == 0);
}

bool XsdSchemaHelper::wildcardAllowsNamespaceName(const QString &nameSpace, const XsdWildcard::NamespaceConstraint::Ptr &constraint)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cvc-wildcard-namespace

    // 1
    if (constraint->variety() == XsdWildcard::NamespaceConstraint::Any)
        return true;

    // 2
    if (constraint->variety() == XsdWildcard::NamespaceConstraint::Not) { // 2.1
        if (!constraint->namespaces().contains(nameSpace)) // 2.2
            if (nameSpace != XsdWildcard::absentNamespace()) // 2.3
                return true;
    }

    // 3
    if (constraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration) {
        if (constraint->namespaces().contains(nameSpace))
            return true;
    }

    return false;
}

bool XsdSchemaHelper::wildcardAllowsExpandedName(const QXmlName &name, const XsdWildcard::Ptr &wildcard, const NamePool::Ptr &namePool)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cvc-wildcard-name

    // 1
    if (!wildcardAllowsNamespaceName(namePool->stringForNamespace(name.namespaceURI()), wildcard->namespaceConstraint()))
        return false;

    // 2, 3, 4
    //TODO: we have no disallowed namespace yet

    return true;
}

bool XsdSchemaHelper::isWildcardSubset(const XsdWildcard::Ptr &wildcard, const XsdWildcard::Ptr &otherWildcard)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cos-ns-subset
    // wildcard =^ sub
    // otherWildcard =^ super

    const XsdWildcard::NamespaceConstraint::Ptr constraint(wildcard->namespaceConstraint());
    const XsdWildcard::NamespaceConstraint::Ptr otherConstraint(otherWildcard->namespaceConstraint());

    // 1
    if (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Any)
        return true;

    // 2
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration) && (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {
        if (otherConstraint->namespaces().contains(constraint->namespaces()))
            return true;
    }

    // 3
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration) && (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Not)) {
        if (!constraint->namespaces().intersects(otherConstraint->namespaces()))
            return true;
    }

    // 4
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Not) && (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Not)) {
        if (constraint->namespaces().contains(otherConstraint->namespaces()))
            return true;
    }

    return false;
}

XsdWildcard::Ptr XsdSchemaHelper::wildcardUnion(const XsdWildcard::Ptr &wildcard, const XsdWildcard::Ptr &otherWildcard)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cos-aw-union

    XsdWildcard::Ptr unionWildcard(new XsdWildcard());

    const XsdWildcard::NamespaceConstraint::Ptr constraint(wildcard->namespaceConstraint());
    const XsdWildcard::NamespaceConstraint::Ptr otherConstraint(otherWildcard->namespaceConstraint());

    // 1
    if ((constraint->variety() == otherConstraint->variety()) &&
        (constraint->namespaces() == otherConstraint->namespaces())) {
        unionWildcard->namespaceConstraint()->setVariety(constraint->variety());
        unionWildcard->namespaceConstraint()->setNamespaces(constraint->namespaces());
        return unionWildcard;
    }

    // 2
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Any) || (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Any)) {
        unionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Any);
        return unionWildcard;
    }

    // 3
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration) && (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {
        unionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Enumeration);
        unionWildcard->namespaceConstraint()->setNamespaces(constraint->namespaces() + otherConstraint->namespaces());
        return unionWildcard;
    }

    // 4
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Not) && (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Not)) {
        if (constraint->namespaces() != otherConstraint->namespaces()) {
            unionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Not);
            unionWildcard->namespaceConstraint()->setNamespaces(QSet<QString>() << XsdWildcard::absentNamespace());
            return unionWildcard;
        }
    }

    // 5
    QSet<QString> sSet, negatedSet;
    bool matches5 = false;
    if (((constraint->variety() == XsdWildcard::NamespaceConstraint::Not) && !constraint->namespaces().contains(XsdWildcard::absentNamespace()))
        && (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {

        negatedSet = constraint->namespaces();
        sSet = otherConstraint->namespaces();
        matches5 = true;
    } else if (((otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Not) && !otherConstraint->namespaces().contains(XsdWildcard::absentNamespace()))
        && (constraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {

        negatedSet = otherConstraint->namespaces();
        sSet = constraint->namespaces();
        matches5 = true;
    }

    if (matches5) {
        if (sSet.contains(negatedSet.values().first()) && sSet.contains(XsdWildcard::absentNamespace())) { // 5.1
            unionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Any);
            return unionWildcard;
        }
        if (sSet.contains(negatedSet.values().first()) && !sSet.contains(XsdWildcard::absentNamespace())) { // 5.2
            unionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Not);
            unionWildcard->namespaceConstraint()->setNamespaces(QSet<QString>() << XsdWildcard::absentNamespace());
            return unionWildcard;
        }
        if (!sSet.contains(negatedSet.values().first()) && sSet.contains(XsdWildcard::absentNamespace())) { // 5.3
            return XsdWildcard::Ptr(); // not expressible
        }
        if (!sSet.contains(negatedSet.values().first()) && !sSet.contains(XsdWildcard::absentNamespace())) { // 5.4
            unionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Not);
            unionWildcard->namespaceConstraint()->setNamespaces(negatedSet);
            return unionWildcard;
        }
    }

    // 6
    bool matches6 = false;
    if (((constraint->variety() == XsdWildcard::NamespaceConstraint::Not) && constraint->namespaces().contains(XsdWildcard::absentNamespace()))
        && (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {

        negatedSet = constraint->namespaces();
        sSet = otherConstraint->namespaces();
        matches6 = true;
    } else if (((otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Not) && otherConstraint->namespaces().contains(XsdWildcard::absentNamespace()))
        && (constraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {

        negatedSet = otherConstraint->namespaces();
        sSet = constraint->namespaces();
        matches6 = true;
    }

    if (matches6) {
        if (sSet.contains(XsdWildcard::absentNamespace())) { // 6.1
            unionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Any);
            return unionWildcard;
        }
        if (!sSet.contains(XsdWildcard::absentNamespace())) { // 6.2
            unionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Not);
            unionWildcard->namespaceConstraint()->setNamespaces(QSet<QString>() += XsdWildcard::absentNamespace());
            return unionWildcard;
        }
    }

    return XsdWildcard::Ptr();
}

XsdWildcard::Ptr XsdSchemaHelper::wildcardIntersection(const XsdWildcard::Ptr &wildcard, const XsdWildcard::Ptr &otherWildcard)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cos-aw-intersect

    const XsdWildcard::NamespaceConstraint::Ptr constraint(wildcard->namespaceConstraint());
    const XsdWildcard::NamespaceConstraint::Ptr otherConstraint(otherWildcard->namespaceConstraint());

    const XsdWildcard::Ptr intersectionWildcard(new XsdWildcard());

    // 1
    if ((constraint->variety() == otherConstraint->variety()) &&
        (constraint->namespaces() == otherConstraint->namespaces())) {
        intersectionWildcard->namespaceConstraint()->setVariety(constraint->variety());
        intersectionWildcard->namespaceConstraint()->setNamespaces(constraint->namespaces());
        return intersectionWildcard;
    }

    // 2
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Any) &&
        (otherConstraint->variety() != XsdWildcard::NamespaceConstraint::Any)) {
        intersectionWildcard->namespaceConstraint()->setVariety(otherConstraint->variety());
        intersectionWildcard->namespaceConstraint()->setNamespaces(otherConstraint->namespaces());
        return intersectionWildcard;
    }

    // 2
    if ((constraint->variety() != XsdWildcard::NamespaceConstraint::Any) &&
        (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Any)) {
        intersectionWildcard->namespaceConstraint()->setVariety(constraint->variety());
        intersectionWildcard->namespaceConstraint()->setNamespaces(constraint->namespaces());
        return intersectionWildcard;
    }

    // 3
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Not) &&
        (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {

        QSet<QString> set = otherConstraint->namespaces();
        set.subtract(constraint->namespaces());
        set.remove(XsdWildcard::absentNamespace());

        intersectionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Enumeration);
        intersectionWildcard->namespaceConstraint()->setNamespaces(set);

        return intersectionWildcard;
    }

    // 3
    if ((otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Not) &&
        (constraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {

        QSet<QString> set = constraint->namespaces();
        set.subtract(otherConstraint->namespaces());
        set.remove(XsdWildcard::absentNamespace());

        intersectionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Enumeration);
        intersectionWildcard->namespaceConstraint()->setNamespaces(set);

        return intersectionWildcard;
    }

    // 4
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration) &&
        (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Enumeration)) {

        QSet<QString> set = constraint->namespaces();
        set.intersect(otherConstraint->namespaces());

        intersectionWildcard->namespaceConstraint()->setVariety(XsdWildcard::NamespaceConstraint::Enumeration);
        intersectionWildcard->namespaceConstraint()->setNamespaces(set);

        return intersectionWildcard;
    }

    // 6
    if ((constraint->variety() == XsdWildcard::NamespaceConstraint::Not) &&
        (otherConstraint->variety() == XsdWildcard::NamespaceConstraint::Not)) {
        if (!(constraint->namespaces().contains(XsdWildcard::absentNamespace())) && otherConstraint->namespaces().contains(XsdWildcard::absentNamespace())) {
            return wildcard;
        }
        if (constraint->namespaces().contains(XsdWildcard::absentNamespace()) && !(otherConstraint->namespaces().contains(XsdWildcard::absentNamespace()))) {
            return otherWildcard;
        }
    }

    // 5 as not expressible return empty wildcard
    return XsdWildcard::Ptr();
}

static SchemaType::DerivationConstraints convertBlockingConstraints(const NamedSchemaComponent::BlockingConstraints &constraints)
{
    SchemaType::DerivationConstraints result = 0;

    if (constraints & NamedSchemaComponent::RestrictionConstraint)
        result |= SchemaType::RestrictionConstraint;
    if (constraints & NamedSchemaComponent::ExtensionConstraint)
        result |= SchemaType::ExtensionConstraint;

    return result;
}

bool XsdSchemaHelper::isValidlySubstitutable(const SchemaType::Ptr &type, const SchemaType::Ptr &otherType, const SchemaType::DerivationConstraints &constraints)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#key-val-sub-type

    // 1
    if (type->isComplexType() && otherType->isComplexType()) {
        SchemaType::DerivationConstraints keywords = constraints;
        if (otherType->isDefinedBySchema())
            keywords |= convertBlockingConstraints(XsdComplexType::Ptr(otherType)->prohibitedSubstitutions());

        return isComplexDerivationOk(type, otherType, keywords);
    }

    // 2
    if (type->isComplexType() && otherType->isSimpleType()) {
        return isComplexDerivationOk(type, otherType, constraints);
    }

    // 3
    if (type->isSimpleType() && otherType->isSimpleType()) {
        return isSimpleDerivationOk(type, otherType, constraints);
    }

    return false;
}

bool XsdSchemaHelper::isSimpleDerivationOk(const SchemaType::Ptr &derivedType, const SchemaType::Ptr &baseType, const SchemaType::DerivationConstraints &constraints)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cos-st-derived-ok

    // 1
    if (derivedType == baseType)
        return true;

    // 2.1
    if ((constraints & SchemaType::RestrictionConstraint) || derivedType->wxsSuperType()->derivationConstraints() & SchemaType::RestrictionConstraint) {
        return false;
    }

    // 2.2.1
    if (derivedType->wxsSuperType() == baseType)
        return true;

    // 2.2.2
    if (derivedType->wxsSuperType() != BuiltinTypes::xsAnyType) {
        if (isSimpleDerivationOk(derivedType->wxsSuperType(), baseType, constraints))
            return true;
    }

    // 2.2.3
    if (derivedType->category() == SchemaType::SimpleTypeList || derivedType->category() == SchemaType::SimpleTypeUnion) {
        if (baseType == BuiltinTypes::xsAnySimpleType)
            return true;
    }

    // 2.2.4
    if (baseType->category() == SchemaType::SimpleTypeUnion && baseType->isDefinedBySchema()) { // 2.2.4.1
        const AnySimpleType::List memberTypes = XsdSimpleType::Ptr(baseType)->memberTypes();
        for (int i = 0; i < memberTypes.count(); ++i) {
            if (isSimpleDerivationOk(derivedType, memberTypes.at(i), constraints)) { // 2.2.4.2
                if (XsdSimpleType::Ptr(baseType)->facets().isEmpty()) { // 2.2.4.3
                    return true;
                }
            }
        }
    }

    return false;
}

bool XsdSchemaHelper::isComplexDerivationOk(const SchemaType::Ptr &derivedType, const SchemaType::Ptr &baseType, const SchemaType::DerivationConstraints &constraints)
{
    if (!derivedType)
        return false;

    // @see http://www.w3.org/TR/xmlschema11-1/#cos-ct-derived-ok

    // 1
    if (derivedType != baseType) {
        if ((derivedType->derivationMethod() == SchemaType::DerivationRestriction) && (constraints & SchemaType::RestrictionConstraint))
            return false;
        if ((derivedType->derivationMethod() == SchemaType::DerivationExtension) && (constraints & SchemaType::ExtensionConstraint))
            return false;
    }

    // 2.1
    if (derivedType == baseType)
        return true;

    // 2.2
    if (derivedType->wxsSuperType() == baseType)
        return true;

    // 2.3
    bool isOk = true;
    if (derivedType->wxsSuperType() == BuiltinTypes::xsAnyType) { // 2.3.1
        isOk = false;
    } else { // 2.3.2
        if (!derivedType->wxsSuperType())
            return false;

        if (derivedType->wxsSuperType()->isComplexType()) { // 2.3.2.1
            isOk = isComplexDerivationOk(derivedType->wxsSuperType(), baseType, constraints);
        } else { // 2.3.2.2
            isOk = isSimpleDerivationOk(derivedType->wxsSuperType(), baseType, constraints);
        }
    }
    if (isOk)
        return true;

    return false;
}

bool XsdSchemaHelper::constructAndCompare(const DerivedString<TypeString>::Ptr &operand1,
                                          const AtomicComparator::Operator op,
                                          const DerivedString<TypeString>::Ptr &operand2,
                                          const SchemaType::Ptr &type,
                                          const ReportContext::Ptr &context,
                                          const SourceLocationReflection *const sourceLocationReflection)
{
    Q_ASSERT_X(type->category() == SchemaType::SimpleTypeAtomic, Q_FUNC_INFO,
               "We can only compare atomic values.");

    // we can not cast a xs:String to a xs:QName, so lets go the safe way
    if (type->name(context->namePool()) == BuiltinTypes::xsQName->name(context->namePool()))
        return false;

    const AtomicValue::Ptr value1 = ValueFactory::fromLexical(operand1->stringValue(), type, context, sourceLocationReflection);
    if (value1->hasError())
        return false;

    const AtomicValue::Ptr value2 = ValueFactory::fromLexical(operand2->stringValue(), type, context, sourceLocationReflection);
    if (value2->hasError())
        return false;

    return ComparisonFactory::compare(value1, op, value2, type, context, sourceLocationReflection);
}

bool XsdSchemaHelper::checkWildcardProcessContents(const XsdWildcard::Ptr &baseWildcard, const XsdWildcard::Ptr &derivedWildcard)
{
    if (baseWildcard->processContents() == XsdWildcard::Strict) {
        if (derivedWildcard->processContents() == XsdWildcard::Lax || derivedWildcard->processContents() == XsdWildcard::Skip) {
            return false;
        }
    } else if (baseWildcard->processContents() == XsdWildcard::Lax) {
        if (derivedWildcard->processContents() == XsdWildcard::Skip)
            return false;
    }

    return true;
}

bool XsdSchemaHelper::foundSubstitutionGroupTransitive(const XsdElement::Ptr &head, const XsdElement::Ptr &member, QSet<XsdElement::Ptr> &visitedElements)
{
    if (visitedElements.contains(member))
        return false;
    else
        visitedElements.insert(member);

    if (member->substitutionGroupAffiliations().isEmpty())
        return false;

    if (member->substitutionGroupAffiliations().contains(head)) {
        return true;
    } else {
        const XsdElement::List affiliations = member->substitutionGroupAffiliations();
        for (int i = 0; i < affiliations.count(); ++i) {
            if (foundSubstitutionGroupTransitive(head, affiliations.at(i), visitedElements))
                return true;
        }

        return false;
    }
}

void XsdSchemaHelper::foundSubstitutionGroupTypeInheritance(const SchemaType::Ptr &headType, const SchemaType::Ptr &memberType,
                                                             QSet<SchemaType::DerivationMethod> &derivationSet, NamedSchemaComponent::BlockingConstraints &blockSet)
{
    if (!memberType)
        return;

    if (memberType == headType)
        return;

    derivationSet.insert(memberType->derivationMethod());

    if (memberType->isComplexType()) {
        const XsdComplexType::Ptr complexType(memberType);
        blockSet |= complexType->prohibitedSubstitutions();
    }

    foundSubstitutionGroupTypeInheritance(headType, memberType->wxsSuperType(), derivationSet, blockSet);
}

bool XsdSchemaHelper::substitutionGroupOkTransitive(const XsdElement::Ptr &head, const XsdElement::Ptr &member, const NamePool::Ptr &namePool)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cos-equiv-derived-ok-rec

    // 1
    if ((member->name(namePool) == head->name(namePool)) && (member->type() == head->type()))
        return true;

    // 2.1
    if (head->disallowedSubstitutions() & NamedSchemaComponent::SubstitutionConstraint)
        return false;

    // 2.2
    {
        QSet<XsdElement::Ptr> visitedElements;
        if (!foundSubstitutionGroupTransitive(head, member, visitedElements))
            return false;
    }

    // 2.3
    {
        QSet<SchemaType::DerivationMethod> derivationSet;
        NamedSchemaComponent::BlockingConstraints blockSet;

        foundSubstitutionGroupTypeInheritance(head->type(), member->type(), derivationSet, blockSet);

        NamedSchemaComponent::BlockingConstraints checkSet(blockSet);
        checkSet |= head->disallowedSubstitutions();
        if (head->type()->isComplexType() && head->type()->isDefinedBySchema()) {
            const XsdComplexType::Ptr complexType(head->type());
            checkSet |= complexType->prohibitedSubstitutions();
        }

        if ((checkSet & NamedSchemaComponent::RestrictionConstraint) && derivationSet.contains(SchemaType::DerivationRestriction))
            return false;
        if ((checkSet & NamedSchemaComponent::ExtensionConstraint) && derivationSet.contains(SchemaType::DerivationExtension))
            return false;
        if (checkSet & NamedSchemaComponent::SubstitutionConstraint)
            return false;
    }

    return true;
}

bool XsdSchemaHelper::isValidAttributeGroupRestriction(const XsdAttributeGroup::Ptr &derivedAttributeGroup, const XsdAttributeGroup::Ptr &attributeGroup, const XsdSchemaContext::Ptr &context, QString &errorMsg)
{
    // @see http://www.w3.org/TR/xmlschema-1/#derivation-ok-restriction

    const XsdAttributeUse::List derivedAttributeUses = derivedAttributeGroup->attributeUses();
    const XsdAttributeUse::List baseAttributeUses = attributeGroup->attributeUses();

    return isValidAttributeUsesRestriction(derivedAttributeUses, baseAttributeUses,
                                           derivedAttributeGroup->wildcard(), attributeGroup->wildcard(), context, errorMsg);
}

bool XsdSchemaHelper::isValidAttributeUsesRestriction(const XsdAttributeUse::List &derivedAttributeUses, const XsdAttributeUse::List &baseAttributeUses,
                                                      const XsdWildcard::Ptr &derivedWildcard, const XsdWildcard::Ptr &wildcard,  const XsdSchemaContext::Ptr &context, QString &errorMsg)
{
    const NamePool::Ptr namePool(context->namePool());

    QHash<QXmlName, XsdAttributeUse::Ptr> baseAttributeUsesLookup;
    for (int i = 0; i < baseAttributeUses.count(); ++i)
        baseAttributeUsesLookup.insert(baseAttributeUses.at(i)->attribute()->name(namePool), baseAttributeUses.at(i));

    QHash<QXmlName, XsdAttributeUse::Ptr> derivedAttributeUsesLookup;
    for (int i = 0; i < derivedAttributeUses.count(); ++i)
        derivedAttributeUsesLookup.insert(derivedAttributeUses.at(i)->attribute()->name(namePool), derivedAttributeUses.at(i));

    // 2
    for (int i = 0; i < derivedAttributeUses.count(); ++i) {
        const XsdAttributeUse::Ptr derivedAttributeUse = derivedAttributeUses.at(i);

        // prohibited attributes are no real attributes, so skip them in that test here
        if (derivedAttributeUse->useType() == XsdAttributeUse::ProhibitedUse)
            continue;

        if (baseAttributeUsesLookup.contains(derivedAttributeUse->attribute()->name(namePool))) {
            const XsdAttributeUse::Ptr baseAttributeUse(baseAttributeUsesLookup.value(derivedAttributeUse->attribute()->name(namePool)));

            // 2.1.1
            if (baseAttributeUse->isRequired() == true && derivedAttributeUse->isRequired() == false) {
                errorMsg = QtXmlPatterns::tr("Base attribute %1 is required but derived attribute is not.").arg(formatAttribute(baseAttributeUse->attribute()->displayName(namePool)));
                return false;
            }

            // 2.1.2
            if (!isSimpleDerivationOk(derivedAttributeUse->attribute()->type(), baseAttributeUse->attribute()->type(), SchemaType::DerivationConstraints())) {
                errorMsg = QtXmlPatterns::tr("Type of derived attribute %1 cannot be validly derived from type of base attribute.").arg(formatAttribute(derivedAttributeUse->attribute()->displayName(namePool)));
                return false;
            }

            // 2.1.3
            XsdAttributeUse::ValueConstraint::Ptr derivedConstraint;
            if (derivedAttributeUse->valueConstraint())
                derivedConstraint = derivedAttributeUse->valueConstraint();
            else if (derivedAttributeUse->attribute()->valueConstraint())
                derivedConstraint = XsdAttributeUse::ValueConstraint::fromAttributeValueConstraint(derivedAttributeUse->attribute()->valueConstraint());

            XsdAttributeUse::ValueConstraint::Ptr baseConstraint;
            if (baseAttributeUse->valueConstraint())
                baseConstraint = baseAttributeUse->valueConstraint();
            else if (baseAttributeUse->attribute()->valueConstraint())
                baseConstraint = XsdAttributeUse::ValueConstraint::fromAttributeValueConstraint(baseAttributeUse->attribute()->valueConstraint());

            bool ok = false;
            if (!baseConstraint || baseConstraint->variety() == XsdAttributeUse::ValueConstraint::Default)
                ok = true;

            if (derivedConstraint && baseConstraint) {
                const XsdTypeChecker checker(context, QVector<QXmlName>(), QSourceLocation(QUrl(QLatin1String("http://dummy.org")), 1, 1));
                if (derivedConstraint->variety() == XsdAttributeUse::ValueConstraint::Fixed && checker.valuesAreEqual(derivedConstraint->value(), baseConstraint->value(), baseAttributeUse->attribute()->type()))
                    ok = true;
            }

            if (!ok) {
                errorMsg = QtXmlPatterns::tr("Value constraint of derived attribute %1 does not match value constraint of base attribute.").arg(formatAttribute(derivedAttributeUse->attribute()->displayName(namePool)));
                return false;
            }
        } else {
            if (!wildcard) {
                errorMsg = QtXmlPatterns::tr("Derived attribute %1 does not exist in the base definition.").arg(formatAttribute(derivedAttributeUse->attribute()->displayName(namePool)));
                return false;
            }

            QXmlName name = derivedAttributeUse->attribute()->name(namePool);

            // wildcards using XsdWildcard::absentNamespace, so we have to fix that here
            if (name.namespaceURI() == StandardNamespaces::empty)
                name.setNamespaceURI(namePool->allocateNamespace(XsdWildcard::absentNamespace()));

            if (!wildcardAllowsExpandedName(name, wildcard, namePool)) {
                errorMsg = QtXmlPatterns::tr("Derived attribute %1 does not match the wildcard in the base definition.").arg(formatAttribute(derivedAttributeUse->attribute()->displayName(namePool)));
                return false;
            }
        }
    }

    // 3
    for (int i = 0; i < baseAttributeUses.count(); ++i) {
        const XsdAttributeUse::Ptr baseAttributeUse = baseAttributeUses.at(i);

        if (baseAttributeUse->isRequired()) {
            if (derivedAttributeUsesLookup.contains(baseAttributeUse->attribute()->name(namePool))) {
                if (!derivedAttributeUsesLookup.value(baseAttributeUse->attribute()->name(namePool))->isRequired()) {
                    errorMsg = QtXmlPatterns::tr("Base attribute %1 is required but derived attribute is not.").arg(formatAttribute(baseAttributeUse->attribute()->displayName(namePool)));
                    return false;
                }
            } else {
                errorMsg = QtXmlPatterns::tr("Base attribute %1 is required but missing in derived definition.").arg(formatAttribute(baseAttributeUse->attribute()->displayName(namePool)));
                return false;
            }
        }
    }

    // 4
    if (derivedWildcard) {
        if (!wildcard) {
            errorMsg = QtXmlPatterns::tr("Derived definition contains an %1 element that does not exists in the base definition").arg(formatElement("anyAttribute."));
            return false;
        }

        if (!isWildcardSubset(derivedWildcard, wildcard)) {
            errorMsg = QtXmlPatterns::tr("Derived wildcard is not a subset of the base wildcard.");
            return false;
        }

        if (!checkWildcardProcessContents(wildcard, derivedWildcard)) {
            errorMsg = QtXmlPatterns::tr("%1 of derived wildcard is not a valid restriction of %2 of base wildcard").arg(formatKeyword("processContents")).arg(formatKeyword("processContents."));
            return false;
        }
    }

    return true;
}

bool XsdSchemaHelper::isValidAttributeUsesExtension(const XsdAttributeUse::List &derivedAttributeUses, const XsdAttributeUse::List &attributeUses,
                                                    const XsdWildcard::Ptr &derivedWildcard, const XsdWildcard::Ptr &wildcard, const XsdSchemaContext::Ptr &context, QString &errorMsg)
{
    // @see http://www.w3.org/TR/xmlschema11-1/#cos-ct-extends

    const NamePool::Ptr namePool(context->namePool());

    // 1.2
    QHash<QXmlName, XsdAttribute::Ptr> lookupHash;
    for (int i = 0; i < derivedAttributeUses.count(); ++i)
        lookupHash.insert(derivedAttributeUses.at(i)->attribute()->name(namePool), derivedAttributeUses.at(i)->attribute());

    for (int i = 0; i < attributeUses.count(); ++i) {
        const QXmlName attributeName = attributeUses.at(i)->attribute()->name(namePool);
        if (!lookupHash.contains(attributeName)) {
            errorMsg = QtXmlPatterns::tr("Attribute %1 from base type is missing in derived type.").arg(formatKeyword(namePool->displayName(attributeName)));
            return false;
        }

        if (lookupHash.value(attributeName)->type() != attributeUses.at(i)->attribute()->type()) {
            errorMsg = QtXmlPatterns::tr("Type of derived attribute %1 differs from type of base attribute.").arg(formatKeyword(namePool->displayName(attributeName)));
            return false;
        }
    }

    // 1.3
    if (wildcard) {
        if (!derivedWildcard) {
            errorMsg = QtXmlPatterns::tr("Base definition contains an %1 element that is missing in the derived definition").arg(formatElement("anyAttribute."));
            return false;
        }
    }

    return true;
}

QT_END_NAMESPACE