Implements the functions fn:exists() and fn:empty(). More...

#include <qsequencefns_p.h>

Inheritance diagram for QPatternist::Existence< Id >:

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

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

Public Functions inherited from QPatternist::FunctionCall
virtual ExpressionVisitorResult::Ptr	accept (const ExpressionVisitor::Ptr &visitor) const

virtual SequenceType::List	expectedOperandTypes () const

virtual ID	id () const

virtual Expression::Properties	properties () const

virtual void	setSignature (const FunctionSignature::Ptr &sign)

virtual FunctionSignature::Ptr	signature () const

virtual SequenceType::Ptr	staticType () const

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

Public Functions inherited from QPatternist::UnlimitedContainer
virtual bool	compressOperands (const StaticContext::Ptr &)

virtual Expression::List	operands () const

virtual void	setOperands (const Expression::List &list)

	UnlimitedContainer (const Expression::List &operands=Expression::List())

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

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

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

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

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

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 ()

Additional Inherited Members
Public Types inherited from QPatternist::FunctionCall
typedef QExplicitlySharedDataPointer< FunctionCall >	Ptr

Public Types inherited from QPatternist::UnlimitedContainer
enum	CardinalityComputation { ProductOfCardinality, UnionOfCardinality }

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

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

Public Variables inherited from QSharedData
QAtomicInt	ref

Protected Functions inherited from QPatternist::UnlimitedContainer
template<CardinalityComputation suppliedCard>
SequenceType::Ptr	operandsUnionType () const

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

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

Protected Variables inherited from QPatternist::UnlimitedContainer
Expression::List	m_operands

Detailed Description

template<const Expression::ID Id>
class QPatternist::Existence< Id >

Implements the functions fn:exists() and fn:empty().

Existence is a template value class. Appropriate implementations are achieved by instantiating it with either IDExistsFN or IDEmptyFN.

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

Definition at line 132 of file qsequencefns_p.h.

Functions

◆ compress()

template<const Expression::ID Id>

virtual Expression::Ptr QPatternist::Existence< Id >::compress ( const StaticContext::Ptr & context )

inlinevirtual

Attempts to rewrite to false or true by looking at the static cardinality of its operand.

Reimplemented from QPatternist::Expression.

Definition at line 147 of file qsequencefns_p.h.

         {
             // RVCT doesn't like using template parameter in trinary operator when the trinary operator result is
             // passed directly into another constructor. 
             Q_ASSERT(Id == IDExistsFN || Id == IDEmptyFN);
 
             const Expression::Ptr me(FunctionCall::compress(context));
 
             if(me != this)
                 return me;
 
             // RVCT doesn't like using template parameter in trinary operator when the trinary operator result is
             // passed directly into another constructor. 
             Expression::ID tempId = Id;
             const Cardinality myCard((tempId == IDExistsFN) ? Cardinality::oneOrMore() : Cardinality::empty());
 
             const Cardinality card(m_operands.first()->staticType()->cardinality());
             if(myCard.isMatch(card))
             { /* Since the dynamic type always is narrower than the static type or equal, and that the
                  static type is in scope, it means we will always be true. */
                 return wrapLiteral(CommonValues::BooleanTrue, context, this);
             }
             else
             {
                 /* Is it even possible to hit? */
                 if(myCard.canMatch(card))
                 {
                     return me;
                 }
                 else
                 { /* We can never hit. */
                     return wrapLiteral(CommonValues::BooleanFalse, context, this);
                 }
             }
         }

◆ evaluateEBV()

template<const Expression::ID Id>

virtual bool QPatternist::Existence< Id >::evaluateEBV ( const DynamicContext::Ptr & context ) const

inlinevirtual

Determines the Effective Boolean Value of the expression.

The Effective Boolean Value of a value is not necessarily the same as converting the value to a new value of type xs:boolean.

Note that this function cannot return the empty sequence, evaluateSingleton() must be overridden in order to be able to do that.

The default implementation results in a type error. Hence, this function must be overridden if such behavior is not of interest.

See also: XML Path Language (XPath) 2.0, 2.4.3 Effective Boolean Value

Reimplemented from QPatternist::Expression.

Definition at line 135 of file qsequencefns_p.h.

         {
             if(Id == IDExistsFN)
                 return !m_operands.first()->evaluateSequence(context)->isEmpty();
             else
                 return m_operands.first()->evaluateSequence(context)->isEmpty();
         }

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

/src/xmlpatterns/functions/qsequencefns_p.h

Public Functions

Additional Inherited Members

Detailed Description

template<const Expression::ID Id> class QPatternist::Existence< Id >

Functions

◆ compress()

◆ evaluateEBV()

template<const Expression::ID Id>
class QPatternist::Existence< Id >