A step in a path expression that with an axis and a node test evaluates to a sequence of nodes from the context item. More...

#include <qaxisstep_p.h>

Inheritance diagram for QPatternist::AxisStep:

Public Functions
virtual ExpressionVisitorResult::Ptr	accept (const ExpressionVisitor::Ptr &visitor) const

QXmlNodeModelIndex::Axis	axis () const

	AxisStep (const QXmlNodeModelIndex::Axis axis, const ItemType::Ptr &nodeTest)

virtual Item::Iterator::Ptr	evaluateSequence (const DynamicContext::Ptr &) const

virtual Item	evaluateSingleton (const DynamicContext::Ptr &) const

virtual ItemType::Ptr	expectedContextItemType () const

virtual SequenceType::List	expectedOperandTypes () const

virtual ID	id () const

Item	mapToItem (const QXmlNodeModelIndex &node, const DynamicContext::Ptr &context) const

ItemType::Ptr	nodeTest () const

virtual PatternPriority	patternPriority () const

virtual Properties	properties () const

void	setAxis (const QXmlNodeModelIndex::Axis newAxis)

void	setNodeTest (const ItemType::Ptr &nev)

virtual SequenceType::Ptr	staticType () const

virtual Expression::Ptr	typeCheck (const StaticContext::Ptr &context, const SequenceType::Ptr &reqType)

Public Functions inherited from QPatternist::EmptyContainer
virtual Expression::List	operands () const

virtual void	setOperands (const Expression::List &)

Public Functions inherited from QPatternist::Expression
virtual const SourceLocationReflection *	actualReflection () const
	Returns `this`. More...

virtual void	announceFocusType (const ItemType::Ptr &itemType)

virtual Expression::Ptr	compress (const StaticContext::Ptr &context)

Properties	deepProperties () const
	Computes the union of properties for this Expression and all its descending children. More...

virtual Properties	dependencies () const

virtual QString	description () const

virtual bool	evaluateEBV (const DynamicContext::Ptr &context) const

virtual void	evaluateToSequenceReceiver (const DynamicContext::Ptr &context) const

	Expression ()

bool	has (const Property prop) const

bool	hasDependency (const Property prop) const

bool	is (const ID id) const

bool	isEvaluated () const

virtual ItemType::Ptr	newFocusType () const

virtual QList< QExplicitlySharedDataPointer< OptimizationPass > >	optimizationPasses () const

const Expression::Ptr &	rewrite (const Expression::Ptr &to, const StaticContext::Ptr &context) const
	Rewrites this Expression to `to`, and return `to`. More...

virtual	~Expression ()

Public Functions inherited from QSharedData
	QSharedData ()
	Constructs a QSharedData object with a reference count of 0. More...

	QSharedData (const QSharedData &)
	Constructs a QSharedData object with reference count 0. More...

Public Functions inherited from QPatternist::CppCastingHelper< Expression >
const TCastTarget *	as () const

TCastTarget *	as ()

Public Functions inherited from QPatternist::SourceLocationReflection
virtual QSourceLocation	sourceLocation () const

	SourceLocationReflection ()

virtual	~SourceLocationReflection ()

Static Public Functions
static QString	axisName (const QXmlNodeModelIndex::Axis axis)
	Prints the EBNF name corresponding to `axis`. More...

Static Public Functions inherited from QPatternist::Expression
static void	rewrite (Expression::Ptr &old, const Expression::Ptr &New, const StaticContext::Ptr &context)

Private Types
typedef QExplicitlySharedDataPointer< const AxisStep >	ConstPtr

Static Private Functions
static bool	isAlwaysEmpty (const QXmlNodeModelIndex::Axis axis, const QXmlNodeModelIndex::NodeKind nodeKind)

Properties
QXmlNodeModelIndex::Axis	m_axis

ItemType::Ptr	m_nodeTest

Static Private Attributes
static const QXmlNodeModelIndex::NodeKind	s_whenAxisNodeKindEmpty []

Additional Inherited Members
Public Types inherited from QPatternist::Expression
typedef QExplicitlySharedDataPointer< const Expression >	ConstPtr
	A smart pointer wrapping `const` Expression instances. More...

enum	ID { IDBooleanValue = 1, IDCountFN, IDEmptyFN, IDExistsFN, IDExpressionSequence, IDGeneralComparison, IDIfThenClause, IDIgnorableExpression, IDIntegerValue, IDPositionFN, IDStringValue, IDValueComparison, IDRangeVariableReference, IDContextItem, IDUserFunctionCallsite, IDExpressionVariableReference, IDAttributeConstructor, IDUpperCaseFN, IDLowerCaseFN, IDFirstItemPredicate, IDEmptySequence, IDReturnOrderBy, IDLetClause, IDForClause, IDPath, IDNamespaceConstructor, IDArgumentReference, IDGenericPredicate, IDAxisStep, IDFloat, IDCombineNodes, IDUnresolvedVariableReference, IDCardinalityVerifier }

typedef QList< Expression::Ptr >	List

typedef QFlags< Property >	Properties

enum	Property { UseContextItem = 1, DisableElimination = 1 << 1, IsEvaluated = 1 << 2, DisableTypingDeduction = 1 << 3, EmptynessFollowsChild = 1 << 4, RewriteToEmptyOnEmpty = 1 << 5, RequiresFocus = 1 << 6, AffectsOrderOnly = 1 << 7, RequiresContextItem = (1 << 8) \| RequiresFocus, CreatesFocusForLast = 1 << 9, LastOperandIsCollation = 1 << 10, DependsOnLocalVariable = (1 << 11) \| DisableElimination, EvaluationCacheRedundant = (1 << 12), IsNodeConstructor = 1 << 13, RequiresCurrentItem = 1 << 14 }

typedef QExplicitlySharedDataPointer< Expression >	Ptr
	A smart pointer wrapping mutable Expression instances. More...

typedef ::QAbstractXmlForwardIterator< Expression::Ptr >	QAbstractXmlForwardIterator

typedef QVector< Expression::Ptr >	Vector

Public Variables inherited from QSharedData
QAtomicInt	ref

Protected Functions inherited from QPatternist::EmptyContainer
virtual bool	compressOperands (const StaticContext::Ptr &context)

Protected Functions inherited from QPatternist::Expression
void	typeCheckOperands (const StaticContext::Ptr &context)

Protected Functions inherited from QPatternist::CppCastingHelper< Expression >
	CppCastingHelper ()

Detailed Description

A step in a path expression that with an axis and a node test evaluates to a sequence of nodes from the context item.

Author: Frans Englich frans.nosp@m..eng.nosp@m.lich@.nosp@m.noki.nosp@m.a.com

Definition at line 71 of file qaxisstep_p.h.

Typedefs

◆ ConstPtr

typedef QExplicitlySharedDataPointer<const AxisStep> QPatternist::AxisStep::ConstPtr

private

Definition at line 137 of file qaxisstep_p.h.

Constructors and Destructors

◆ AxisStep()

AxisStep::AxisStep	(	const QXmlNodeModelIndex::Axis	axis,
		const ItemType::Ptr &	nodeTest
	)

Definition at line 91 of file qaxisstep.cpp.

                                           : m_axis(a),
                                               m_nodeTest(nt)
 {
     Q_ASSERT(m_nodeTest);
     Q_ASSERT_X(BuiltinTypes::node->xdtTypeMatches(m_nodeTest), Q_FUNC_INFO,
                "We assume we're a node type.");
 }

Functions

◆ accept()

ExpressionVisitorResult::Ptr AxisStep::accept ( const ExpressionVisitor::Ptr & visitor ) const

virtual

Implements QPatternist::Expression.

Definition at line 199 of file qaxisstep.cpp.

 {
     return visitor->visit(this);
 }

◆ axis()

QXmlNodeModelIndex::Axis AxisStep::axis ( ) const

Returns: the axis this step is using.

Definition at line 204 of file qaxisstep.cpp.

Referenced by QPatternist::changeToTopAxis().

 {
     return m_axis;
 }

◆ axisName()

QString AxisStep::axisName ( const QXmlNodeModelIndex::Axis axis )

static

Prints the EBNF name corresponding to axis.

For instance, for QXmlNodeModelIndex::Child, "child" is returned.

Apart from being used in this class, it is used in the SDK.

Definition at line 209 of file qaxisstep.cpp.

Referenced by QPatternist::yyparse().

 {
     const char *result = 0;
 
     switch(axis)
     {
         /* These must not be translated. */
         case QXmlNodeModelIndex::AxisAncestorOrSelf:    result = "ancestor-or-self";    break;
         case QXmlNodeModelIndex::AxisAncestor:          result = "ancestor";            break;
         case QXmlNodeModelIndex::AxisAttributeOrTop:    result = "attribute-or-top";    break;
         case QXmlNodeModelIndex::AxisAttribute:         result = "attribute";           break;
         case QXmlNodeModelIndex::AxisChildOrTop:        result = "child-or-top";        break;
         case QXmlNodeModelIndex::AxisChild:             result = "child";               break;
         case QXmlNodeModelIndex::AxisDescendantOrSelf:  result = "descendant-or-self";  break;
         case QXmlNodeModelIndex::AxisDescendant:        result = "descendant";          break;
         case QXmlNodeModelIndex::AxisFollowing:         result = "following";           break;
         case QXmlNodeModelIndex::AxisFollowingSibling:  result = "following-sibling";   break;
         case QXmlNodeModelIndex::AxisNamespace:         result = "namespace";           break;
         case QXmlNodeModelIndex::AxisParent:            result = "parent";              break;
         case QXmlNodeModelIndex::AxisPreceding:         result = "preceding";           break;
         case QXmlNodeModelIndex::AxisPrecedingSibling:  result = "preceding-sibling";   break;
         case QXmlNodeModelIndex::AxisSelf:              result = "self";                break;
     }
 
     Q_ASSERT_X(result, Q_FUNC_INFO, "An unknown axis type was apparently encountered.");
     return QString::fromLatin1(result);
 }

◆ evaluateSequence()

Item::Iterator::Ptr AxisStep::evaluateSequence ( const DynamicContext::Ptr & context ) const

virtual

Evaluate this Expression by iterating over it. This is a central function for evaluating expressions.

Expressions must always always return a valid QAbstractXmlForwardIterator and may never return 0. If an empty result is of interest to be returned, the EmptyIterator should be returned.

The default implementation returns a SingletonIterator over the item returned from evaluateSingleton().

Note: This function may raise an exception when calling, not only when QAbstractXmlForwardIterator::next() is called on the return value. This is because in some cases evaluateSingleton() is called directly.

Reimplemented from QPatternist::Expression.

Definition at line 114 of file qaxisstep.cpp.

 {
     /* If we don't have a focus, it's either a bug or our parent isn't a Path
      * that have advanced the focus iterator. Hence, attempt to advance the focus on our own. */
     if(!context->contextItem())
         context->focusIterator()->next();
 
     Q_ASSERT(context->contextItem());
 
     const QXmlNodeModelIndex::Iterator::Ptr source(context->contextItem().asNode().iterate(m_axis));
 
     return makeItemMappingIterator<Item>(ConstPtr(this), source, context);
 }

◆ evaluateSingleton()

Item AxisStep::evaluateSingleton ( const DynamicContext::Ptr & context ) const

virtual

Reimplemented from QPatternist::Expression.

Definition at line 128 of file qaxisstep.cpp.

 {
     /* If we don't have a focus, it's either a bug or our parent isn't a Path
      * that have advanced the focus iterator. Hence, attempt to advance the focus on our own. */
     if(!context->contextItem())
         context->focusIterator()->next();
 
     Q_ASSERT(context->contextItem());
 
     const QXmlNodeModelIndex::Iterator::Ptr it(context->contextItem().asNode().iterate(m_axis));
     QXmlNodeModelIndex next(it->next());
 
     while(!next.isNull())
     {
         const Item candidate(mapToItem(next, context));
 
         if(candidate)
             return candidate;
         else
             next = it->next();
     };
 
     return Item();
 }

◆ expectedContextItemType()

ItemType::Ptr AxisStep::expectedContextItemType ( ) const

virtual

Returns: always BuiltinTypes::node;

Reimplemented from QPatternist::Expression.

Definition at line 194 of file qaxisstep.cpp.

 {
     return BuiltinTypes::node;
 }

◆ expectedOperandTypes()

SequenceType::List AxisStep::expectedOperandTypes ( ) const

virtual

Returns: always an empty list since it has no operands.

Reimplemented from QPatternist::EmptyContainer.

Definition at line 182 of file qaxisstep.cpp.

 {
     SequenceType::List result;
     result.append(CommonSequenceTypes::ZeroOrMoreNodes);
     return result;
 }

◆ id()

Expression::ID AxisStep::id ( ) const

virtual

This property, which has no setter, returns an enum value that uniquely identifies this Expression. Patternist makes no use of C++'s dynamic_cast feature, but uses this polymorphic function instead.

Returns: always IgnorableExpression.

Reimplemented from QPatternist::Expression.

Definition at line 242 of file qaxisstep.cpp.

 {
     return IDAxisStep;
 }

◆ isAlwaysEmpty()

bool AxisStep::isAlwaysEmpty	(	const QXmlNodeModelIndex::Axis	axis,
		const QXmlNodeModelIndex::NodeKind	nodeKind
	)

staticprivate

Returns: true when the axis axis and a node test testing node of type nodeKind always produces an empty sequence. One such example is attribute::comment().

Definition at line 86 of file qaxisstep.cpp.

 {
     return (s_whenAxisNodeKindEmpty[(1 >> axis) - 1] & nodeKind) != 0;
 }

◆ mapToItem()

Item AxisStep::mapToItem	(	const QXmlNodeModelIndex &	node,
		const DynamicContext::Ptr &	context
	)		const

inline

Returns node if it matches the node test this step is using, otherwise null.

Definition at line 100 of file qaxisstep.cpp.

Referenced by evaluateSingleton().

 {
     Q_ASSERT(!node.isNull());
     Q_ASSERT(Item(node).isNode());
     Q_ASSERT(Item(node));
     Q_UNUSED(context);
 
     if(m_nodeTest->itemMatches(Item(node)))
         return Item(node);
     else
         return Item();
 }

◆ nodeTest()

ItemType::Ptr QPatternist::AxisStep::nodeTest ( ) const

inline

Returns: the node test this step is using.

Definition at line 112 of file qaxisstep_p.h.

Referenced by QPatternist::yyparse().

         {
             return m_nodeTest;
         }

◆ patternPriority()

PatternPriority AxisStep::patternPriority ( ) const

virtual

By default 0.5 is returned.

Reimplemented from QPatternist::Expression.

Definition at line 237 of file qaxisstep.cpp.

 {
     return static_cast<const AnyNodeType *>(m_nodeTest.data())->patternPriority();
 }

◆ properties()

Expression::Properties AxisStep::properties ( ) const

virtual

Returns: a bitwise OR'd value of properties, describing the characteristics of the expression. These properties affects how this Expression is treated in for example type checking stages.

The default implementation returns 0. Override and let the function return a different value, if that's of interest.

An important decision when re-implementing properties() is whether to OR in the properties() of ones operands. For instance, if an operand has RequiresFocus set, that flag nost likely applies to the apparent as well, since it depends on its operand.

See also: deepProperties()

Returns: Expression::None, meaning no special properties

Reimplemented from QPatternist::Expression.

Definition at line 189 of file qaxisstep.cpp.

 {
     return RequiresContextItem | DisableElimination;
 }

◆ setAxis()

void QPatternist::AxisStep::setAxis ( const QXmlNodeModelIndex::Axis newAxis )

inline

Definition at line 157 of file qaxisstep_p.h.

Referenced by QPatternist::changeToTopAxis(), QPatternist::createPatternPath(), and QPatternist::yyparse().

     {
         m_axis = newAxis;
     }

◆ setNodeTest()

void QPatternist::AxisStep::setNodeTest ( const ItemType::Ptr & nev )

inline

Definition at line 117 of file qaxisstep_p.h.

Referenced by QPatternist::yyparse().

         {
             m_nodeTest = nev;
         }

◆ staticType()

SequenceType::Ptr AxisStep::staticType ( ) const

virtual

Returns: the static type of this Expression. For example, an 'and' expression have as static type xs:boolean

Implements QPatternist::Expression.

Definition at line 169 of file qaxisstep.cpp.

 {
     Cardinality cardinality;
 
     if(m_axis == QXmlNodeModelIndex::AxisSelf || m_axis == QXmlNodeModelIndex::AxisParent)
         cardinality = Cardinality::zeroOrOne();
     else
         cardinality = Cardinality::zeroOrMore();
 
     return makeGenericSequenceType(m_nodeTest,
                                    cardinality);
 }

◆ typeCheck()

Expression::Ptr AxisStep::typeCheck	(	const StaticContext::Ptr &	context,
		const SequenceType::Ptr &	reqType
	)

virtual

Rewrites to ParentNodeAxis, if possible.

Reimplemented from QPatternist::Expression.

Definition at line 153 of file qaxisstep.cpp.

 {
     if(m_axis == QXmlNodeModelIndex::AxisParent && *m_nodeTest == *BuiltinTypes::node)
     {
         /* We only rewrite parent::node() to ParentNodeAxis. */
         return rewrite(Expression::Ptr(new ParentNodeAxis()), context)->typeCheck(context, reqType);
     }
     /* TODO temporarily disabled
     else if(isAlwaysEmpty(m_axis, static_cast<const AnyNodeType *>(m_nodeTest.data())->nodeKind()))
         return EmptySequence::create(this, context);
         */
     else
         return EmptyContainer::typeCheck(context, reqType);
 }

Properties

◆ m_axis

QXmlNodeModelIndex::Axis QPatternist::AxisStep::m_axis

private

The reason this variable is mutable, is that in the case of XSL-T patterns, we do quite some reordering.

Definition at line 153 of file qaxisstep_p.h.

Referenced by axis(), evaluateSequence(), evaluateSingleton(), staticType(), and typeCheck().

◆ m_nodeTest

ItemType::Ptr QPatternist::AxisStep::m_nodeTest

private

Definition at line 154 of file qaxisstep_p.h.

Referenced by AxisStep(), mapToItem(), patternPriority(), staticType(), and typeCheck().

◆ s_whenAxisNodeKindEmpty

const QXmlNodeModelIndex::NodeKind AxisStep::s_whenAxisNodeKindEmpty

staticprivate

Initial value:

=
{
    QXmlNodeModelIndex::Attribute|QXmlNodeModelIndex::Text|QXmlNodeModelIndex::ProcessingInstruction|QXmlNodeModelIndex::Comment|QXmlNodeModelIndex::Namespace,   
    QXmlNodeModelIndex::Attribute|QXmlNodeModelIndex::Text|QXmlNodeModelIndex::ProcessingInstruction|QXmlNodeModelIndex::Comment|QXmlNodeModelIndex::Namespace,   
    QXmlNodeModelIndex::Document|QXmlNodeModelIndex::Attribute|QXmlNodeModelIndex::Text|QXmlNodeModelIndex::ProcessingInstruction|QXmlNodeModelIndex::Comment|QXmlNodeModelIndex::Namespace,
    QXmlNodeModelIndex::NodeKind(0),                         
    QXmlNodeModelIndex::NodeKind(0),                         
    QXmlNodeModelIndex::Document|QXmlNodeModelIndex::Attribute|QXmlNodeModelIndex::Text|QXmlNodeModelIndex::ProcessingInstruction|QXmlNodeModelIndex::Comment|QXmlNodeModelIndex::Namespace,    
    QXmlNodeModelIndex::Document,                                         
    QXmlNodeModelIndex::Document,                                         
    QXmlNodeModelIndex::Document,                                         
    QXmlNodeModelIndex::Document|QXmlNodeModelIndex::Attribute|QXmlNodeModelIndex::Namespace,         
    QXmlNodeModelIndex::Document|QXmlNodeModelIndex::Attribute|QXmlNodeModelIndex::Namespace,         
    QXmlNodeModelIndex::Document,                                         
    QXmlNodeModelIndex::NodeKind(0)                          
}

Note: The order is significant. It is of the same order as the values in QXmlNodeModelIndex::Axis is declared.

Definition at line 139 of file qaxisstep_p.h.

Referenced by isAlwaysEmpty(), and QPatternist::operator|().

The documentation for this class was generated from the following files:

/src/xmlpatterns/expr/qaxisstep_p.h
/src/xmlpatterns/expr/qaxisstep.cpp

Public Functions

Static Public Functions

Private Types

Static Private Functions

Properties

Static Private Attributes

Additional Inherited Members

Detailed Description

Typedefs

◆ ConstPtr

Constructors and Destructors

◆ AxisStep()

Functions

◆ accept()

◆ axis()

◆ axisName()

◆ evaluateSequence()

◆ evaluateSingleton()

◆ expectedContextItemType()

◆ expectedOperandTypes()

◆ id()

◆ isAlwaysEmpty()

◆ mapToItem()

◆ nodeTest()

◆ patternPriority()

◆ properties()

◆ setAxis()

◆ setNodeTest()

◆ staticType()

◆ typeCheck()

Properties

◆ m_axis

◆ m_nodeTest

◆ s_whenAxisNodeKindEmpty