Various api, documentation and code cleanups

14 files changed, 128 insertions, 54 deletions

diff --git a/src/xmlpatterns/schema/qnamespacesupport.cpp b/src/xmlpatterns/schema/qnamespacesupport.cpp
index 00698d6..349f451 100644
--- a/src/xmlpatterns/schema/qnamespacesupport.cpp
+++ b/src/xmlpatterns/schema/qnamespacesupport.cpp
@@ -33,9 +33,7 @@ NamespaceSupport::NamespaceSupport(const NamePool::Ptr &namePool)
     : m_namePool(namePool)
 {
     // the XML namespace
-    const QXmlName binding = namePool->allocateBinding(QLatin1String("xml"),
-                                                       QLatin1String("http://www.w3.org/XML/1998/namespace"));
-    m_ns.insert(binding.prefix(), binding.namespaceURI());
+    m_ns.insert(StandardPrefixes::xml, StandardNamespaces::xml);
 }
 
 void NamespaceSupport::setPrefix(const QXmlName::PrefixCode prefixCode, const QXmlName::NamespaceCode namespaceCode)
diff --git a/src/xmlpatterns/schema/qxsdparticlechecker.cpp b/src/xmlpatterns/schema/qxsdparticlechecker.cpp
index 1bdef00..7a09f8a 100644
--- a/src/xmlpatterns/schema/qxsdparticlechecker.cpp
+++ b/src/xmlpatterns/schema/qxsdparticlechecker.cpp
@@ -180,9 +180,9 @@ static bool derivedTermValid(const XsdTerm::Ptr &baseTerm, const XsdTerm::Ptr &d
             // check that the constraints of the derived element are more strict then the constraints of the base element
             const XsdElement::BlockingConstraints baseConstraints = element->disallowedSubstitutions();
             const XsdElement::BlockingConstraints derivedConstraints = derivedElement->disallowedSubstitutions();
-            if ((baseConstraints & XsdElement::RestrictionConstraint) && !(derivedConstraints & XsdElement::RestrictionConstraint) ||
-                (baseConstraints & XsdElement::ExtensionConstraint) && !(derivedConstraints & XsdElement::ExtensionConstraint) ||
-                (baseConstraints & XsdElement::SubstitutionConstraint) && !(derivedConstraints & XsdElement::SubstitutionConstraint)) {
+            if (((baseConstraints & XsdElement::RestrictionConstraint) && !(derivedConstraints & XsdElement::RestrictionConstraint)) ||
+                ((baseConstraints & XsdElement::ExtensionConstraint) && !(derivedConstraints & XsdElement::ExtensionConstraint)) ||
+                ((baseConstraints & XsdElement::SubstitutionConstraint) && !(derivedConstraints & XsdElement::SubstitutionConstraint))) {
                 errorMsg = QtXmlPatterns::tr("block constraints of derived element %1 must not be more weaker than in the base element").arg(formatKeyword(derivedElement->displayName(namePool)));
                 return false;
             }
diff --git a/src/xmlpatterns/schema/qxsdschemacontext.cpp b/src/xmlpatterns/schema/qxsdschemacontext.cpp
index 57736bd..65b2e52 100644
--- a/src/xmlpatterns/schema/qxsdschemacontext.cpp
+++ b/src/xmlpatterns/schema/qxsdschemacontext.cpp
@@ -67,7 +67,7 @@ QSourceLocation XsdSchemaContext::locationFor(const SourceLocationReflection *co
     return QSourceLocation();
 }
 
-void XsdSchemaContext::setUriResolver(QAbstractUriResolver *uriResolver)
+void XsdSchemaContext::setUriResolver(const QAbstractUriResolver *uriResolver)
 {
     m_uriResolver = uriResolver;
 }
diff --git a/src/xmlpatterns/schema/qxsdschemacontext_p.h b/src/xmlpatterns/schema/qxsdschemacontext_p.h
index cf52028..c3a9f15 100644
--- a/src/xmlpatterns/schema/qxsdschemacontext_p.h
+++ b/src/xmlpatterns/schema/qxsdschemacontext_p.h
@@ -115,7 +115,7 @@ namespace QPatternist
              * Sets the uri @p resolver that is used for resolving URIs in the
              * schema parser.
              */
-            void setUriResolver(QAbstractUriResolver *resolver);
+            void setUriResolver(const QAbstractUriResolver *resolver);
 
             /**
              * Returns the uri resolver that is used for resolving URIs in the
@@ -145,7 +145,7 @@ namespace QPatternist
             NamePool::Ptr                                 m_namePool;
             QNetworkAccessManager*                        m_networkAccessManager;
             QUrl                                          m_baseURI;
-            QAbstractUriResolver*                         m_uriResolver;
+            const QAbstractUriResolver*                   m_uriResolver;
             QAbstractMessageHandler*                      m_messageHandler;
     };
 }
diff --git a/src/xmlpatterns/schema/qxsdschemadebugger_p.h b/src/xmlpatterns/schema/qxsdschemadebugger_p.h
index 8c12f0f..8966963 100644
--- a/src/xmlpatterns/schema/qxsdschemadebugger_p.h
+++ b/src/xmlpatterns/schema/qxsdschemadebugger_p.h
@@ -85,7 +85,7 @@ namespace QPatternist
             void dumpSchema(const XsdSchema::Ptr &schema);
 
         private:
-            NamePool::Ptr m_namePool;
+            const NamePool::Ptr m_namePool;
     };
 
 }
diff --git a/src/xmlpatterns/schema/qxsdschemahelper.cpp b/src/xmlpatterns/schema/qxsdschemahelper.cpp
index 752af89..ff169f7 100644
--- a/src/xmlpatterns/schema/qxsdschemahelper.cpp
+++ b/src/xmlpatterns/schema/qxsdschemahelper.cpp
@@ -409,7 +409,7 @@ bool XsdSchemaHelper::isValidlySubstitutable(const SchemaType::Ptr &type, const
     return false;
 }
 
-bool XsdSchemaHelper::isSimpleDerivationOk(const SchemaType::Ptr &derivedType, const SchemaType::Ptr baseType, const SchemaType::DerivationConstraints &constraints)
+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
 
@@ -453,7 +453,7 @@ bool XsdSchemaHelper::isSimpleDerivationOk(const SchemaType::Ptr &derivedType, c
     return false;
 }
 
-bool XsdSchemaHelper::isComplexDerivationOk(const SchemaType::Ptr &derivedType, const SchemaType::Ptr baseType, const SchemaType::DerivationConstraints &constraints)
+bool XsdSchemaHelper::isComplexDerivationOk(const SchemaType::Ptr &derivedType, const SchemaType::Ptr &baseType, const SchemaType::DerivationConstraints &constraints)
 {
     if (!derivedType)
         return false;
diff --git a/src/xmlpatterns/schema/qxsdschemahelper_p.h b/src/xmlpatterns/schema/qxsdschemahelper_p.h
index 1722b4c..918664e 100644
--- a/src/xmlpatterns/schema/qxsdschemahelper_p.h
+++ b/src/xmlpatterns/schema/qxsdschemahelper_p.h
@@ -55,12 +55,15 @@ namespace QPatternist
             /**
              * Checks whether the given @p nameSpace is allowed by the given namespace @p constraint.
              */
-            static bool wildcardAllowsNamespaceName(const QString &nameSpace, const XsdWildcard::NamespaceConstraint::Ptr &constraint);
+            static bool wildcardAllowsNamespaceName(const QString &nameSpace,
+                                                    const XsdWildcard::NamespaceConstraint::Ptr &constraint);
 
             /**
              * Checks whether the given @p name is allowed by the namespace constraint of the given @p wildcard.
              */
-            static bool wildcardAllowsExpandedName(const QXmlName &name, const XsdWildcard::Ptr &wildcard, const NamePool::Ptr &namePool);
+            static bool wildcardAllowsExpandedName(const QXmlName &name,
+                                                   const XsdWildcard::Ptr &wildcard,
+                                                   const NamePool::Ptr &namePool);
 
             /**
              * Checks whether the @p wildcard is a subset of @p otherWildcard.
@@ -75,25 +78,32 @@ namespace QPatternist
             /**
              * Returns the intersection of the given @p wildcard and @p otherWildcard.
              */
-            static XsdWildcard::Ptr wildcardIntersection(const XsdWildcard::Ptr &wildcard, const XsdWildcard::Ptr &otherWildcard);
+            static XsdWildcard::Ptr wildcardIntersection(const XsdWildcard::Ptr &wildcard,
+                                                         const XsdWildcard::Ptr &otherWildcard);
 
             /**
              * Returns whether the given @p type is validly substitutable for an @p otherType
              * under the given @p constraints.
              */
-            static bool isValidlySubstitutable(const SchemaType::Ptr &type, const SchemaType::Ptr &otherType, const SchemaType::DerivationConstraints &constraints);
+            static bool isValidlySubstitutable(const SchemaType::Ptr &type,
+                                               const SchemaType::Ptr &otherType,
+                                               const SchemaType::DerivationConstraints &constraints);
 
             /**
              * Returns whether the simple @p derivedType can be derived from the simple @p baseType
              * under the given @p constraints.
              */
-            static bool isSimpleDerivationOk(const SchemaType::Ptr &derivedType, const SchemaType::Ptr baseType, const SchemaType::DerivationConstraints &constraints);
+            static bool isSimpleDerivationOk(const SchemaType::Ptr &derivedType,
+                                             const SchemaType::Ptr &baseType,
+                                             const SchemaType::DerivationConstraints &constraints);
 
             /**
              * Returns whether the complex @p derivedType can be derived from the complex @p baseType
              * under the given @p constraints.
              */
-            static bool isComplexDerivationOk(const SchemaType::Ptr &derivedType, const SchemaType::Ptr baseType, const SchemaType::DerivationConstraints &constraints);
+            static bool isComplexDerivationOk(const SchemaType::Ptr &derivedType,
+                                              const SchemaType::Ptr &baseType,
+                                              const SchemaType::DerivationConstraints &constraints);
 
             /**
              * This method takes the two string based operands @p operand1 and @p operand2 and converts them to instances of type @p type.
@@ -111,41 +121,62 @@ namespace QPatternist
              * Returns whether the process content property of the @p derivedWildcard is valid
              * according to the process content property of its @p baseWildcard.
              */
-            static bool checkWildcardProcessContents(const XsdWildcard::Ptr &baseWildcard, const XsdWildcard::Ptr &derivedWildcard);
+            static bool checkWildcardProcessContents(const XsdWildcard::Ptr &baseWildcard,
+                                                     const XsdWildcard::Ptr &derivedWildcard);
 
             /**
              * Checks whether @[ member is a member of the substitution group with the given @p head.
              */
-            static bool foundSubstitutionGroupTransitive(const XsdElement::Ptr &head, const XsdElement::Ptr &member, QSet<XsdElement::Ptr> &visitedElements);
+            static bool foundSubstitutionGroupTransitive(const XsdElement::Ptr &head,
+                                                         const XsdElement::Ptr &member,
+                                                         QSet<XsdElement::Ptr> &visitedElements);
 
             /**
              * A helper method that iterates over the type hierarchy from @p memberType up to @p headType and collects all
              * @p derivationSet and @p blockSet constraints that exists on the way there.
              */
-            static void foundSubstitutionGroupTypeInheritance(const SchemaType::Ptr &headType, const SchemaType::Ptr &memberType,
-                                                              QSet<SchemaType::DerivationMethod> &derivationSet, NamedSchemaComponent::BlockingConstraints &blockSet);
+            static void foundSubstitutionGroupTypeInheritance(const SchemaType::Ptr &headType,
+                                                              const SchemaType::Ptr &memberType,
+                                                              QSet<SchemaType::DerivationMethod> &derivationSet,
+                                                              NamedSchemaComponent::BlockingConstraints &blockSet);
 
             /**
              * Checks if the @p member is transitive to @p head.
              */
-            static bool substitutionGroupOkTransitive(const XsdElement::Ptr &head, const XsdElement::Ptr &member, const NamePool::Ptr &namePool);
+            static bool substitutionGroupOkTransitive(const XsdElement::Ptr &head,
+                                                      const XsdElement::Ptr &member,
+                                                      const NamePool::Ptr &namePool);
 
             /**
              * Checks if @p derivedAttributeGroup is a valid restriction for @p attributeGroup.
              */
-            static bool isValidAttributeGroupRestriction(const XsdAttributeGroup::Ptr &derivedAttributeGroup, const XsdAttributeGroup::Ptr &attributeGroup, const XsdSchemaContext::Ptr &context, QString &errorMsg);
+            static bool isValidAttributeGroupRestriction(const XsdAttributeGroup::Ptr &derivedAttributeGroup,
+                                                         const XsdAttributeGroup::Ptr &attributeGroup,
+                                                         const XsdSchemaContext::Ptr &context,
+                                                         QString &errorMsg);
 
             /**
              * Checks if @p derivedAttributeUses are a valid restriction for @p attributeUses.
              */
-            static bool isValidAttributeUsesRestriction(const XsdAttributeUse::List &derivedAttributeUses, const XsdAttributeUse::List &attributeUses,
-                                                        const XsdWildcard::Ptr &derivedWildcard, const XsdWildcard::Ptr &wildcard, const XsdSchemaContext::Ptr &context, QString &errorMsg);
+            static bool isValidAttributeUsesRestriction(const XsdAttributeUse::List &derivedAttributeUses,
+                                                        const XsdAttributeUse::List &attributeUses,
+                                                        const XsdWildcard::Ptr &derivedWildcard,
+                                                        const XsdWildcard::Ptr &wildcard,
+                                                        const XsdSchemaContext::Ptr &context,
+                                                        QString &errorMsg);
 
             /**
              * Checks if @p derivedAttributeUses are a valid extension for @p attributeUses.
              */
-            static bool isValidAttributeUsesExtension(const XsdAttributeUse::List &derivedAttributeUses, const XsdAttributeUse::List &attributeUses,
-                                                      const XsdWildcard::Ptr &derivedWildcard, const XsdWildcard::Ptr &wildcard, const XsdSchemaContext::Ptr &context, QString &errorMsg);
+            static bool isValidAttributeUsesExtension(const XsdAttributeUse::List &derivedAttributeUses,
+                                                      const XsdAttributeUse::List &attributeUses,
+                                                      const XsdWildcard::Ptr &derivedWildcard,
+                                                      const XsdWildcard::Ptr &wildcard,
+                                                      const XsdSchemaContext::Ptr &context,
+                                                      QString &errorMsg);
+
+        private:
+            Q_DISABLE_COPY(XsdSchemaHelper)
     };
 }
 
diff --git a/src/xmlpatterns/schema/qxsdschemaparser.cpp b/src/xmlpatterns/schema/qxsdschemaparser.cpp
index 9f1e75d..cabc12e 100644
--- a/src/xmlpatterns/schema/qxsdschemaparser.cpp
+++ b/src/xmlpatterns/schema/qxsdschemaparser.cpp
@@ -5,6 +5,7 @@
 #include "qacceltreeresourceloader_p.h"
 #include "qautoptr_p.h"
 #include "qboolean_p.h"
+#include "qcommonnamespaces_p.h"
 #include "qderivedinteger_p.h"
 #include "qderivedstring_p.h"
 #include "qqnamevalue_p.h"
@@ -119,12 +120,28 @@ class TagValidationHandler
         void validate(XsdSchemaToken::NodeName token)
         {
             if (token == XsdSchemaToken::NoKeyword) {
-                m_parser->error(QtXmlPatterns::tr("can not process unknown element %1").arg(formatElement(m_parser->name().toString())));
+                const QList<XsdSchemaToken::NodeName> tokens = m_machine.possibleTransitions();
+
+                QStringList elementNames;
+                for (int i = 0; i < tokens.count(); ++i)
+                    elementNames.append(formatElement(XsdSchemaToken::toString(tokens.at(i))));
+
+                m_parser->error(QtXmlPatterns::tr("can not process unknown element %1, expected elements are: %2")
+                                                 .arg(formatElement(m_parser->name().toString()))
+                                                 .arg(elementNames.join(QLatin1String(", "))));
                 return;
             }
 
             if (!m_machine.proceed(token)) {
-                m_parser->error(QtXmlPatterns::tr("element %1 is not allowed in this scope").arg(formatElement(XsdSchemaToken::toString(token))));
+                const QList<XsdSchemaToken::NodeName> tokens = m_machine.possibleTransitions();
+
+                QStringList elementNames;
+                for (int i = 0; i < tokens.count(); ++i)
+                    elementNames.append(formatElement(XsdSchemaToken::toString(tokens.at(i))));
+
+                m_parser->error(QtXmlPatterns::tr("element %1 is not allowed in this scope, possible elements are: %2")
+                                                 .arg(formatElement(XsdSchemaToken::toString(token)))
+                                                 .arg(elementNames.join(QLatin1String(", "))));
                 return;
             }
         }
@@ -132,7 +149,14 @@ class TagValidationHandler
         void finalize() const
         {
             if (!m_machine.inEndState()) {
-                m_parser->error(QtXmlPatterns::tr("child element is missing in that scope"));
+                const QList<XsdSchemaToken::NodeName> tokens = m_machine.possibleTransitions();
+
+                QStringList elementNames;
+                for (int i = 0; i < tokens.count(); ++i)
+                    elementNames.append(formatElement(XsdSchemaToken::toString(tokens.at(i))));
+
+                m_parser->error(QtXmlPatterns::tr("child element is missing in that scope, possible child elements are: %1")
+                                                 .arg(elementNames.join(QLatin1String(", "))));
             }
         }
 
@@ -425,8 +449,8 @@ void XsdSchemaParser::parseSchema(ParserType parserType)
         const QString version = readAttribute(QString::fromLatin1("version"));
     }
 
-    if (hasAttribute(QString::fromLatin1("http://www.w3.org/XML/1998/namespace"), QString::fromLatin1("lang"))) {
-        const QString value = readAttribute(QString::fromLatin1("lang"), QString::fromLatin1("http://www.w3.org/XML/1998/namespace"));
+    if (hasAttribute(CommonNamespaces::XML, QString::fromLatin1("lang"))) {
+        const QString value = readAttribute(QString::fromLatin1("lang"), CommonNamespaces::XML);
 
         const QRegExp exp(QString::fromLatin1("[a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})*"));
         if (!exp.exactMatch(value)) {
@@ -750,7 +774,7 @@ void XsdSchemaParser::parseRedefine()
     if (url.isRelative()) {
         Q_ASSERT(m_documentURI.isValid());
 
-        url = m_documentURI.resolved(url); 
+        url = m_documentURI.resolved(url);
     }
 
     // we parse the schema given in the redefine tag into its own context
@@ -1176,8 +1200,8 @@ XsdDocumentation::Ptr XsdSchemaParser::parseDocumentation()
         }
     }
 
-    if (hasAttribute(QString::fromLatin1("http://www.w3.org/XML/1998/namespace"), QString::fromLatin1("lang"))) {
-        const QString value = readAttribute(QString::fromLatin1("lang"), QString::fromLatin1("http://www.w3.org/XML/1998/namespace"));
+    if (hasAttribute(CommonNamespaces::XML, QString::fromLatin1("lang"))) {
+        const QString value = readAttribute(QString::fromLatin1("lang"), CommonNamespaces::XML);
 
         const QRegExp exp(QString::fromLatin1("[a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})*"));
         if (!exp.exactMatch(value)) {
@@ -3948,7 +3972,7 @@ XsdAttribute::Ptr XsdSchemaParser::parseGlobalAttribute()
         error(QtXmlPatterns::tr("content of %1 attribute of %2 element must not be from namespace %3")
                                .arg(formatAttribute("name"))
                                .arg(formatElement("attribute"))
-                               .arg(formatURI(QLatin1String("http://www.w3.org/2001/XMLSchema-instance"))));
+                               .arg(formatURI(CommonNamespaces::XSI)));
         return attribute;
     }
     if (m_namePool->stringForLocalName(objectName.localName()) == QString::fromLatin1("xmlns")) {
@@ -4170,7 +4194,7 @@ XsdAttributeUse::Ptr XsdSchemaParser::parseLocalAttribute(const NamedSchemaCompo
                 error(QtXmlPatterns::tr("content of %1 attribute of %2 element must not be from namespace %3")
                                        .arg(formatAttribute("name"))
                                        .arg(formatElement("attribute"))
-                                       .arg(formatURI(QLatin1String("http://www.w3.org/2001/XMLSchema-instance"))));
+                                       .arg(formatURI(CommonNamespaces::XSI)));
                 return attributeUse;
             }
             if (m_namePool->stringForLocalName(objectName.localName()) == QString::fromLatin1("xmlns")) {
@@ -5858,7 +5882,7 @@ QString XsdSchemaParser::readXPathAttribute(const QString &attributeName, XPathT
 
     QXmlNamePool namePool(m_namePool.data());
 
-    QXmlQuery::QueryLanguage language;
+    QXmlQuery::QueryLanguage language = QXmlQuery::XPath20;
     switch (type) {
         case XPath20: language = QXmlQuery::XPath20; break;
         case XPathSelector: language = QXmlQuery::XmlSchema11IdentityConstraintSelector; break;
diff --git a/src/xmlpatterns/schema/qxsdstatemachine.cpp b/src/xmlpatterns/schema/qxsdstatemachine.cpp
index e40e55b..4f36f22 100644
--- a/src/xmlpatterns/schema/qxsdstatemachine.cpp
+++ b/src/xmlpatterns/schema/qxsdstatemachine.cpp
@@ -114,6 +114,20 @@ bool XsdStateMachine<TransitionType>::proceed(TransitionType transition)
 }
 
 template <typename TransitionType>
+QList<TransitionType> XsdStateMachine<TransitionType>::possibleTransitions() const
+{
+    // check that we are not in an invalid state
+    if (!m_transitions.contains(m_currentState)) {
+        return QList<TransitionType>();
+    }
+
+    // fetch the transition entry for the current state
+    const QHash<TransitionType, QVector<StateId> > &entry = m_transitions[m_currentState];
+
+    return entry.keys();
+}
+
+template <typename TransitionType>
 template <typename InputType>
 bool XsdStateMachine<TransitionType>::proceed(InputType input)
 {
@@ -259,7 +273,7 @@ typename XsdStateMachine<TransitionType>::StateId XsdStateMachine<TransitionType
     }
 
     // check if the NFA state set contains a Start or End
-    // state, in that case our new DFA state will be a 
+    // state, in that case our new DFA state will be a
     // Start or End state as well
     StateType type = InternalState;
     QSetIterator<StateId> it(nfaState);
diff --git a/src/xmlpatterns/schema/qxsdstatemachine_p.h b/src/xmlpatterns/schema/qxsdstatemachine_p.h
index 7988335..f0cf99d 100644
--- a/src/xmlpatterns/schema/qxsdstatemachine_p.h
+++ b/src/xmlpatterns/schema/qxsdstatemachine_p.h
@@ -113,6 +113,12 @@ namespace QPatternist
             bool proceed(TransitionType transition);
 
             /**
+             * Returns the list of transitions that are reachable from the current
+             * state.
+             */
+            QList<TransitionType> possibleTransitions() const;
+
+            /**
              * Continues execution of the machine with the given @p input.
              *
              * @note To use this method, inputEqualsTransition must be implemented
diff --git a/src/xmlpatterns/schema/qxsdvalidatedxmlnodemodel.cpp b/src/xmlpatterns/schema/qxsdvalidatedxmlnodemodel.cpp
index 8e1645a..33bca4e 100644
--- a/src/xmlpatterns/schema/qxsdvalidatedxmlnodemodel.cpp
+++ b/src/xmlpatterns/schema/qxsdvalidatedxmlnodemodel.cpp
@@ -20,7 +20,7 @@ QT_BEGIN_NAMESPACE
 using namespace QPatternist;
 
 XsdValidatedXmlNodeModel::XsdValidatedXmlNodeModel(const QAbstractXmlNodeModel *model)
-    : m_internalModel(const_cast<QAbstractXmlNodeModel*>(model))
+    : m_internalModel(model)
 {
 }
 
diff --git a/src/xmlpatterns/schema/qxsdvalidatedxmlnodemodel_p.h b/src/xmlpatterns/schema/qxsdvalidatedxmlnodemodel_p.h
index 579f41a..d52e369 100644
--- a/src/xmlpatterns/schema/qxsdvalidatedxmlnodemodel_p.h
+++ b/src/xmlpatterns/schema/qxsdvalidatedxmlnodemodel_p.h
@@ -134,11 +134,11 @@ namespace QPatternist
             virtual QVector<QXmlNodeModelIndex> attributes(const QXmlNodeModelIndex &element) const;
 
         private:
-            QAbstractXmlNodeModel::Ptr                        m_internalModel;
-            QHash<QXmlNodeModelIndex, XsdElement::Ptr>        m_assignedElements;
-            QHash<QXmlNodeModelIndex, XsdAttribute::Ptr>      m_assignedAttributes;
-            QHash<QXmlNodeModelIndex, SchemaType::Ptr>        m_assignedTypes;
-            QHash<QString, QSet<NamedSchemaComponent::Ptr> >  m_idIdRefBindings;
+            QExplicitlySharedDataPointer<const QAbstractXmlNodeModel> m_internalModel;
+            QHash<QXmlNodeModelIndex, XsdElement::Ptr>                m_assignedElements;
+            QHash<QXmlNodeModelIndex, XsdAttribute::Ptr>              m_assignedAttributes;
+            QHash<QXmlNodeModelIndex, SchemaType::Ptr>                m_assignedTypes;
+            QHash<QString, QSet<NamedSchemaComponent::Ptr> >          m_idIdRefBindings;
     };
 }
 
diff --git a/src/xmlpatterns/schema/qxsdvalidatinginstancereader.cpp b/src/xmlpatterns/schema/qxsdvalidatinginstancereader.cpp
index 12fc477..8cb34d4 100644
--- a/src/xmlpatterns/schema/qxsdvalidatinginstancereader.cpp
+++ b/src/xmlpatterns/schema/qxsdvalidatinginstancereader.cpp
@@ -15,6 +15,7 @@
 #include "qacceltreeresourceloader_p.h"
 #include "qbase64binary_p.h"
 #include "qboolean_p.h"
+#include "qcommonnamespaces_p.h"
 #include "qderivedinteger_p.h"
 #include "qduration_p.h"
 #include "qgenericstaticcontext_p.h"
@@ -64,14 +65,14 @@ namespace QPatternist
     }
 }
 
-XsdValidatingInstanceReader::XsdValidatingInstanceReader(const XsdValidatedXmlNodeModel *model, const QUrl &documentUri, const XsdSchemaContext::Ptr &context)
+XsdValidatingInstanceReader::XsdValidatingInstanceReader(XsdValidatedXmlNodeModel *model, const QUrl &documentUri, const XsdSchemaContext::Ptr &context)
     : XsdInstanceReader(model, context)
-    , m_model(const_cast<XsdValidatedXmlNodeModel*>(model))
+    , m_model(model)
     , m_namePool(m_context->namePool())
-    , m_xsiNilName(m_namePool->allocateQName(QLatin1String("http://www.w3.org/2001/XMLSchema-instance"), QLatin1String("nil")))
-    , m_xsiTypeName(m_namePool->allocateQName(QLatin1String("http://www.w3.org/2001/XMLSchema-instance"), QLatin1String("type")))
-    , m_xsiSchemaLocationName(m_namePool->allocateQName(QLatin1String("http://www.w3.org/2001/XMLSchema-instance"), QLatin1String("schemaLocation")))
-    , m_xsiNoNamespaceSchemaLocationName(m_namePool->allocateQName(QLatin1String("http://www.w3.org/2001/XMLSchema-instance"), QLatin1String("noNamespaceSchemaLocation")))
+    , m_xsiNilName(m_namePool->allocateQName(CommonNamespaces::XSI, QLatin1String("nil")))
+    , m_xsiTypeName(m_namePool->allocateQName(CommonNamespaces::XSI, QLatin1String("type")))
+    , m_xsiSchemaLocationName(m_namePool->allocateQName(CommonNamespaces::XSI, QLatin1String("schemaLocation")))
+    , m_xsiNoNamespaceSchemaLocationName(m_namePool->allocateQName(CommonNamespaces::XSI, QLatin1String("noNamespaceSchemaLocation")))
     , m_documentUri(documentUri)
 {
     m_idRefsType = m_context->schemaTypeFactory()->createSchemaType(m_namePool->allocateQName(CommonNamespaces::WXS, QLatin1String("IDREFS")));
@@ -152,7 +153,7 @@ bool XsdValidatingInstanceReader::read()
 
 void XsdValidatingInstanceReader::error(const QString &msg) const
 {
-    const_cast<XsdSchemaContext*>(m_context.data())->error(msg, XsdSchemaContext::XSDError, sourceLocation());
+    m_context.data()->error(msg, XsdSchemaContext::XSDError, sourceLocation());
 }
 
 bool XsdValidatingInstanceReader::loadSchema(const QString &targetNamespace, const QUrl &location)
diff --git a/src/xmlpatterns/schema/qxsdvalidatinginstancereader_p.h b/src/xmlpatterns/schema/qxsdvalidatinginstancereader_p.h
index 799ab44..28f3c3f 100644
--- a/src/xmlpatterns/schema/qxsdvalidatinginstancereader_p.h
+++ b/src/xmlpatterns/schema/qxsdvalidatinginstancereader_p.h
@@ -59,7 +59,7 @@ namespace QPatternist
              * @param documentUri The uri of the document the model is from.
              * @param context The context that is used to report errors etc.
              */
-            XsdValidatingInstanceReader(const XsdValidatedXmlNodeModel *model, const QUrl &documentUri, const XsdSchemaContext::Ptr &context);
+            XsdValidatingInstanceReader(XsdValidatedXmlNodeModel *model, const QUrl &documentUri, const XsdSchemaContext::Ptr &context);
 
             /**
              * Adds a new @p schema to the pool of schemas that shall be used