Implements XPath 2.0's cast as expression. More...

#include <qcastas_p.h>

Inheritance diagram for QPatternist::CastAs:

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

	CastAs (const Expression::Ptr &source, const SequenceType::Ptr &targetType)

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

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

virtual SequenceType::List	expectedOperandTypes () const

virtual SequenceType::Ptr	staticType () const

SequenceType::Ptr	targetSequenceType () const

ItemType::Ptr	targetType () const

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

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

virtual Expression::List	operands () const

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

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

virtual Item::Iterator::Ptr	evaluateSequence (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

virtual ID	id () 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

virtual Properties	properties () 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 ()

Private Functions
Expression::Ptr	castToQName (const StaticContext::Ptr &context) const

Properties
const SequenceType::Ptr	m_targetType

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

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::SingleContainer
	SingleContainer (const Expression::Ptr &operand)

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

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

Protected Functions inherited from QPatternist::CastingPlatform< CastAs, true >
Item	cast (const Item &sourceValue, const ReportContext::Ptr &context) const

	CastingPlatform (const ReportContext::ErrorCode code=ReportContext::FORG0001)

void	checkTargetType (const ReportContext::Ptr &context) const

bool	prepareCasting (const ReportContext::Ptr &context, const ItemType::Ptr &sourceType)

Protected Variables inherited from QPatternist::SingleContainer
Expression::Ptr	m_operand

Detailed Description

Implements XPath 2.0's cast as expression.

Implements the casting expression, such as '3' cast as xs:integer. This class also implements constructor functions, which are created in the ConstructorFunctionsFactory.

CastAs uses CastingPlatform for carrying out the actual casting.

See also: XQuery 1.0 and XPath 2.0 Functions and Operators, 7 Casting; XML Path Language (XPath) 2.0, 3.10.2 Cast

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

Definition at line 79 of file qcastas_p.h.

Constructors and Destructors

◆ CastAs()

CastAs::CastAs	(	const Expression::Ptr &	source,
		const SequenceType::Ptr &	targetType
	)

Creates a cast expression for the type name via the schema type factory factory. This function is used by parser when creating 'cast to' expressions, and the ConstructorFunctionsFactory, when creating constructor functions.

Parameters

targetType	the type which the CastAs should cast to
source	the operand to evaluate and then cast from

Definition at line 62 of file qcastas.cpp.

                                              : SingleContainer(source),
                                                  m_targetType(tType)
 {
     Q_ASSERT(source);
     Q_ASSERT(tType);
     Q_ASSERT(!tType->cardinality().allowsMany());
     Q_ASSERT(tType->itemType()->isAtomicType());
 }

Functions

◆ accept()

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

virtual

Implements QPatternist::Expression.

Definition at line 199 of file qcastas.cpp.

 {
     return visitor->visit(this);
 }

◆ castToQName()

Expression::Ptr CastAs::castToQName ( const StaticContext::Ptr & context ) const

private

Performs casting to xs:QName. This case is special, and is always done at compile time.

Definition at line 162 of file qcastas.cpp.

Referenced by targetSequenceType(), and typeCheck().

 {
     /* Apply the whitespace facet by calling trimmed(). */
     /* We can assume m_operand is an Expression because this is a requirement
      * for casting to xs:QName. */
     const QString lexQName(m_operand->as<Literal>()->item().as<AtomicValue>()->stringValue().trimmed());
 
     const QXmlName
         expName(QNameConstructor::expandQName<StaticContext::Ptr,
                                               ReportContext::FORG0001,
                                               ReportContext::FONS0004>(lexQName,
                                                                        context,
                                                                        context->namespaceBindings(), this));
     return wrapLiteral(toItem(QNameValue::fromValue(context->namePool(), expName)), context, this);
 }

◆ compress()

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

virtual

If the target type is the same as the source type, it is rewritten to the operand.

Reimplemented from QPatternist::Expression.

Definition at line 153 of file qcastas.cpp.

 {
     /* Simplify casts to itself. */
     if(*m_targetType->itemType() == *m_operand->staticType()->itemType())
         return m_operand->compress(context);
     else
         return SingleContainer::compress(context);
 }

◆ evaluateSingleton()

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

virtual

Reimplemented from QPatternist::Expression.

Definition at line 72 of file qcastas.cpp.

 {
     Q_ASSERT(context);
     const Item val(m_operand->evaluateSingleton(context));
 
     if(val)
         return cast(val, context);
     else
     {
         /* No item supplied, let's handle the cardinality part. */
 
         if(m_targetType->cardinality().allowsEmpty())
             return Item();
         else
         {
             Q_ASSERT(context);
             context->error(QtXmlPatterns::tr("Type error in cast, expected %1, "
                                              "received %2.")
                            .arg(formatType(Cardinality::exactlyOne()))
                            .arg(formatType(Cardinality::empty())),
                            ReportContext::XPTY0004, this);
             return Item();
         }
     }
 }

◆ expectedOperandTypes()

SequenceType::List CastAs::expectedOperandTypes ( ) const

virtual

Returns a list of Sequence Types, describing the type of each of the expression's operands. Hence, this function has a relationship to the operands() function:

- The lengths of the lists returned by expectedOperandTypes()
and operands() should always be equal in length, since one
cannot describe the type of a non-existent operand(and all
operands must have type information).
- A significant difference between the two functions is that while
the type of objects in the list returned by operands() may vary
between compilations/static context, simply because the particular
Expression is part of different XPath expressions, the
types in the list returned by expectedOperandTypes is always the same
since the function/operator signature never changes.

This function should not be confused with staticType(), which returns the static type of the expression itself, not its operands. The function call is an expression where this is clear: the type of the return value is not the same as the arguments' types. The static type of the operands supplied to the expression can be determined via the staticType() function of the instances returned by operands().

If the expression has no operands, an empty list should be returned.

Implements QPatternist::Expression.

Definition at line 187 of file qcastas.cpp.

 {
     SequenceType::List result;
 
     if(m_targetType->cardinality().allowsEmpty())
         result.append(CommonSequenceTypes::ZeroOrOneAtomicType);
     else
         result.append(CommonSequenceTypes::ExactlyOneAtomicType);
 
     return result;
 }

◆ staticType()

SequenceType::Ptr CastAs::staticType ( ) const

virtual

Returns: a SequenceType where the ItemType is this CastAs's target type, as per targetType(), and the Cardinality is inferred from the source operand to reflect whether this CastAs always will evaluate to exactly-one or zero-or-one values.

Implements QPatternist::Expression.

Definition at line 178 of file qcastas.cpp.

 {
     if(m_operand->staticType()->cardinality().allowsEmpty())
         return m_targetType;
     else
         return makeGenericSequenceType(m_targetType->itemType(),
                                        Cardinality::exactlyOne());
 }

◆ targetSequenceType()

SequenceType::Ptr QPatternist::CastAs::targetSequenceType ( ) const

inline

Definition at line 129 of file qcastas_p.h.

         {
             return m_targetType;
         }

◆ targetType()

ItemType::Ptr QPatternist::CastAs::targetType ( ) const

inline

Definition at line 124 of file qcastas_p.h.

         {
             return m_targetType->itemType();
         }

◆ typeCheck()

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

virtual

Overridden in order to check that casting to an abstract type is not attempted.

Reimplemented from QPatternist::Expression.

Definition at line 98 of file qcastas.cpp.

 {
     checkTargetType(context);
     const SequenceType::Ptr seqt(m_operand->staticType());
     ItemType::Ptr t(seqt->itemType());
 
     /* Special case xs:QName */
     if(BuiltinTypes::xsQName->xdtTypeMatches(m_targetType->itemType()))
     {
         /* Ok, We're casting to xs:QName. */
         if(m_operand->is(IDStringValue)) /* A valid combination, let's do the cast. */
             return castToQName(context)->typeCheck(context, reqType);
         else if(BuiltinTypes::xsQName->xdtTypeMatches(t))
             return m_operand->typeCheck(context, reqType);
         else if(seqt->cardinality().isEmpty() && m_targetType->cardinality().allowsEmpty())
             return EmptySequence::create(this, context);
         else if(!(seqt->cardinality().isEmpty() && !m_targetType->cardinality().allowsEmpty()))
         {
             context->error(QtXmlPatterns::tr("When casting to %1 or types "
                                              "derived from it, the source "
                                              "value must be of the same type, "
                                              "or it must be a string literal. "
                                              "Type %2 is not allowed.")
                            .arg(formatType(context->namePool(), BuiltinTypes::xsQName))
                            .arg(formatType(context->namePool(), seqt)),
                            ReportContext::XPTY0004, this);
             return Expression::Ptr(this);
         }
     }
 
     const Expression::Ptr me(SingleContainer::typeCheck(context, reqType));
     /* Type may have changed, such as that atomization has been applied. */
     t = m_operand->staticType()->itemType();
 
     if(m_targetType->itemType()->xdtTypeMatches(t) &&
        !BuiltinTypes::xsDayTimeDuration->xdtTypeMatches(t) &&
        !BuiltinTypes::xsYearMonthDuration->xdtTypeMatches(t))
     { /* At least casting is superflorous. */
         if(m_operand->staticType()->cardinality().isMatch(m_targetType->cardinality()))
             return m_operand; /* The whole cast expression is redundant. */
         else
         { /* Only cardinality check is needed, rewrite to CardinalityVerifier. */
             return Expression::Ptr(new CardinalityVerifier(m_operand,
                                                            m_targetType->cardinality(),
                                                            ReportContext::FORG0001));
         }
     }
 
     /* Let the CastingPlatform look up its AtomicCaster. */
     prepareCasting(context, t);
 
     return me;
 }

Properties

◆ m_targetType

const SequenceType::Ptr QPatternist::CastAs::m_targetType

private

Definition at line 140 of file qcastas_p.h.

Referenced by compress(), evaluateSingleton(), expectedOperandTypes(), staticType(), targetSequenceType(), targetType(), and typeCheck().

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

/src/xmlpatterns/expr/qcastas_p.h
/src/xmlpatterns/expr/qcastas.cpp

Public Functions

Private Functions

Properties

Additional Inherited Members

Detailed Description

Constructors and Destructors

◆ CastAs()

Functions

◆ accept()

◆ castToQName()

◆ compress()

◆ evaluateSingleton()

◆ expectedOperandTypes()

◆ staticType()

◆ targetSequenceType()

◆ targetType()

◆ typeCheck()

Properties

◆ m_targetType