A reference to a variable declared with declare variable or let. More...

#include <qexpressionvariablereference_p.h>

Inheritance diagram for QPatternist::ExpressionVariableReference:

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

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

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

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

	ExpressionVariableReference (const VariableSlotID slot, const VariableDeclaration *varDecl)

virtual ID	id () const

const Expression::Ptr &	sourceExpression () const

virtual SequenceType::Ptr	staticType () const

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

const VariableDeclaration *	variableDeclaration () const

Public Functions inherited from QPatternist::VariableReference
virtual Properties	properties () const

VariableSlotID	slot () const

	VariableReference (const VariableSlotID slot)

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 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 ()

Properties
const VariableDeclaration *	m_varDecl

Additional Inherited Members
Public Types inherited from QPatternist::VariableReference
typedef QList< VariableReference::Ptr >	List

typedef QExplicitlySharedDataPointer< VariableReference >	Ptr

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::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

A reference to a variable declared with declare variable or let.

It's also used by variable bindings in case branches of the typeswitch expression.

This AST node is only used up until the typeCheck() stage. Therefore it has no functions for evaluation, such as evaluateSequence().

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

Definition at line 76 of file qexpressionvariablereference_p.h.

Constructors and Destructors

◆ ExpressionVariableReference()

ExpressionVariableReference::ExpressionVariableReference	(	const VariableSlotID	slot,
		const VariableDeclaration *	varDecl
	)

Definition at line 49 of file qexpressionvariablereference.cpp.

                                                                                              : VariableReference(slotP)
                                                                                                   , m_varDecl(varDecl)
 {
 }

Functions

◆ accept()

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

virtual

Implements QPatternist::Expression.

Definition at line 83 of file qexpressionvariablereference.cpp.

 {
     return visitor->visit(this);
 }

◆ evaluateEBV()

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

virtual

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 55 of file qexpressionvariablereference.cpp.

 {
     return context->expressionVariable(slot())->evaluateEBV(context);
 }

◆ evaluateSequence()

Item::Iterator::Ptr ExpressionVariableReference::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 65 of file qexpressionvariablereference.cpp.

 {
     return context->expressionVariable(slot())->evaluateSequence(context);
 }

◆ evaluateSingleton()

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

virtual

Reimplemented from QPatternist::Expression.

Definition at line 60 of file qexpressionvariablereference.cpp.

 {
     return context->expressionVariable(slot())->evaluateSingleton(context);
 }

◆ id()

Expression::ID ExpressionVariableReference::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 78 of file qexpressionvariablereference.cpp.

 {
     return IDExpressionVariableReference;
 }

◆ sourceExpression()

const Expression::Ptr & QPatternist::ExpressionVariableReference::sourceExpression ( ) const

inline

Definition at line 98 of file qexpressionvariablereference_p.h.

Referenced by QPatternist::checkVariableCircularity().

     {
         return m_varDecl->expression();
     }

◆ staticType()

SequenceType::Ptr ExpressionVariableReference::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 88 of file qexpressionvariablereference.cpp.

 {
     return m_varDecl->expression()->staticType();
 }

◆ typeCheck()

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

virtual

This implementation guarantees to never rewrite away this Expression, but at most rewrite it as a child of another expression(that presumably have a type checking role). It is therefore always safe to override this function and call this implementation and not worry about that this Expression becomes deleted.

Many Expressions override typeCheck() and performs optimizations, as opposed to doing it in the compress() stage. This is due to that the design of those Expressions often are tied to that certain simplifications are done at the typeCheck() stage of the compilation process or that it in some other way is related to what the typeCheck() do. Also, the earlier the AST can be simplified, the better the chances are for subsequent optimizations.

It is important that the super class's typeCheck() is called before doing any custom type checking, since the call can change the children(notably, the childrens' static types). For example, if the Expression, MyExpression in the example, does not match the required type, typeCheck returns the Expression wrapped in for example ItemVerifier, CardinalityVerifier, or both.

typeCheck() may be called many times. typeCheck() must either raise an error if this Expression is an invalid expression. Thus, it is guaranteed that an Expression is valid after typeCheck() is called.

Parameters

context	supplies information, such as namespace bindings and available function signatures, that can be needed at compilation time. `context` is guaranteed by the caller to never null.
reqType	the static type that this Expression must match when evaluated. `reqType` is guaranteed by the caller to never null.

Returns: an Expression that can be this Expression, or another expression, which somehow is necessary for making this Expression conforming to reqType

Reimplemented from QPatternist::Expression.

Definition at line 69 of file qexpressionvariablereference.cpp.

 {
     if(m_varDecl->canSourceRewrite)
         return m_varDecl->expression()->typeCheck(context, reqType);
     else
         return VariableReference::typeCheck(context, reqType);
 }

◆ variableDeclaration()

const VariableDeclaration * QPatternist::ExpressionVariableReference::variableDeclaration ( ) const

inline

Definition at line 103 of file qexpressionvariablereference_p.h.

Referenced by QPatternist::checkVariableCircularity().

     {
         return m_varDecl;
     }

Properties

◆ m_varDecl

const VariableDeclaration* QPatternist::ExpressionVariableReference::m_varDecl

private

Definition at line 95 of file qexpressionvariablereference_p.h.

Referenced by sourceExpression(), staticType(), typeCheck(), and variableDeclaration().

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

/src/xmlpatterns/expr/qexpressionvariablereference_p.h
/src/xmlpatterns/expr/qexpressionvariablereference.cpp

Public Functions

Properties

Additional Inherited Members

Detailed Description

Constructors and Destructors

◆ ExpressionVariableReference()

Functions

◆ accept()

◆ evaluateEBV()

◆ evaluateSequence()

◆ evaluateSingleton()

◆ id()

◆ sourceExpression()

◆ staticType()

◆ typeCheck()

◆ variableDeclaration()

Properties

◆ m_varDecl