Implements the value instance of empty sequence: (). More...

#include <qemptysequence_p.h>

Inheritance diagram for QPatternist::EmptySequence:

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

	EmptySequence ()
	Creates an instance of EmptySequence. More...

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

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

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

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

virtual ID	id () const

virtual Properties	properties () const

virtual SequenceType::Ptr	staticType () const

virtual QString	stringValue () const

virtual ItemType::Ptr	type () const

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 ItemType::Ptr	expectedContextItemType () 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

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

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 Expression::Ptr	create (const Expression *const replacementFor, const StaticContext::Ptr &context)
	Creates an EmptySequence that is a replacement for `replacementFor`. More...

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

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)

virtual SequenceType::List	expectedOperandTypes () const

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

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

Detailed Description

Implements the value instance of empty sequence: ().

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

Definition at line 69 of file qemptysequence_p.h.

Constructors and Destructors

◆ EmptySequence()

QPatternist::EmptySequence::EmptySequence ( )

inline

Creates an instance of EmptySequence.

Note: In most cases create() should be used, since it takes care of adjusting source location annotations.

See also: create()

Definition at line 90 of file qemptysequence_p.h.

Referenced by create().

91 {

92 }

Functions

◆ accept()

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

virtual

Implements QPatternist::Expression.

Definition at line 97 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return visitor->visit(this);
 }

◆ create()

Expression::Ptr EmptySequence::create	(	const Expression *const	replacementFor,
		const StaticContext::Ptr &	context
	)

static

Creates an EmptySequence that is a replacement for replacementFor.

See also: EmptySequence()

Definition at line 52 of file qemptysequence.cpp.

Referenced by QPatternist::NodeComparison::compress(), QPatternist::ExpressionSequence::compress(), QPatternist::SubsequenceFN::compress(), QPatternist::Expression::constantPropagate(), QPatternist::GenericPredicate::create(), QPatternist::FunctionCall::typeCheck(), QPatternist::ValueComparison::typeCheck(), QPatternist::ForClause::typeCheck(), QPatternist::ArithmeticExpression::typeCheck(), QPatternist::IndexOfFN::typeCheck(), QPatternist::CastAs::typeCheck(), QPatternist::DocFN::typeCheck(), and QPatternist::DistinctValuesFN::typeCheck().

 {
     Q_ASSERT(replacementFor);
     Q_ASSERT(context);
 
     const Expression::Ptr retval(new EmptySequence());
     context->wrapExpressionWith(replacementFor, retval);
     return retval;
 }

◆ evaluateEBV()

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

virtual

Returns: always false.

Reimplemented from QPatternist::Expression.

Definition at line 87 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return false;
 }

◆ evaluateSequence()

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

virtual

Returns: always an empty iterator, an instance of EmptyIterator.

Reimplemented from QPatternist::Expression.

Definition at line 63 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return CommonValues::emptyIterator;
 }

◆ evaluateSingleton()

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

virtual

Returns: always null.

Reimplemented from QPatternist::Expression.

Definition at line 68 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return Item();
 }

◆ evaluateToSequenceReceiver()

void EmptySequence::evaluateToSequenceReceiver ( const DynamicContext::Ptr & ) const

virtual

Does nothing.

Reimplemented from QPatternist::Expression.

Definition at line 73 of file qemptysequence.cpp.

Referenced by EmptySequence().

74 {

75 }

◆ id()

Expression::ID EmptySequence::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 102 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return IDEmptySequence;
 }

◆ properties()

Expression::Properties EmptySequence::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 107 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return IsEvaluated;
 }

◆ staticType()

SequenceType::Ptr EmptySequence::staticType ( ) const

virtual

Returns: always CommonSequenceTypes::Empty

Implements QPatternist::Expression.

Definition at line 82 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return CommonSequenceTypes::Empty;
 }

◆ stringValue()

QString EmptySequence::stringValue ( ) const

virtual

Definition at line 92 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return QString();
 }

◆ type()

ItemType::Ptr EmptySequence::type ( ) const

virtual

Returns: always CommonSequenceTypes::Empty

Definition at line 77 of file qemptysequence.cpp.

Referenced by EmptySequence().

 {
     return CommonSequenceTypes::Empty;
 }

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

/src/xmlpatterns/expr/qemptysequence_p.h
/src/xmlpatterns/expr/qemptysequence.cpp

Public Functions

Static Public Functions

Additional Inherited Members

Detailed Description

Constructors and Destructors

◆ EmptySequence()

Functions

◆ accept()

◆ create()

◆ evaluateEBV()

◆ evaluateSequence()

◆ evaluateSingleton()

◆ evaluateToSequenceReceiver()

◆ id()

◆ properties()

◆ staticType()

◆ stringValue()

◆ type()