Does node copying in a parameterized way, in order to deal with namespace preservation/inheritance. More...

#include <qcopyof_p.h>

Inheritance diagram for QPatternist::CopyOf:

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

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

	CopyOf (const Expression::Ptr &operand, const bool inheritNSS, const bool preserveNSS)

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

virtual ItemType::Ptr	expectedContextItemType () const

virtual SequenceType::List	expectedOperandTypes () const

Item	mapToItem (const Item &source, const DynamicContext::Ptr &context) const

virtual Properties	properties () const

virtual SequenceType::Ptr	staticType () const

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 Item	evaluateSingleton (const DynamicContext::Ptr &context) 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

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 ()

Private Types
typedef QExplicitlySharedDataPointer< const CopyOf >	ConstPtr

Properties
const bool	m_inheritNamespaces

const bool	m_preserveNamespaces

const QAbstractXmlNodeModel::NodeCopySettings	m_settings

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

Detailed Description

Does node copying in a parameterized way, in order to deal with namespace preservation/inheritance.

If someone tries to call evaluateEBV(), evaluateSingleton() or evaluateSequence() on us, we will infinitely loop. But apparently that's not possible because we're always a child of ElementConstructor, currently.

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

Definition at line 75 of file qcopyof_p.h.

Typedefs

◆ ConstPtr

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

private

Definition at line 110 of file qcopyof_p.h.

Constructors and Destructors

◆ CopyOf()

CopyOf::CopyOf	(	const Expression::Ptr &	operand,
		const bool	inheritNSS,
		const bool	preserveNSS
	)

Creats a CopyOf where it is checked that the expression operand conforms to the type reqType.

Definition at line 52 of file qcopyof.cpp.

                                        : SingleContainer(operand)
                                        , m_inheritNamespaces(inheritNSS)
                                        , m_preserveNamespaces(preserveNSS)
                                        , m_settings((m_inheritNamespaces ? QAbstractXmlNodeModel::InheritNamespaces : QAbstractXmlNodeModel::NodeCopySettings()) |
                                                     (m_preserveNamespaces ? QAbstractXmlNodeModel::PreserveNamespaces : QAbstractXmlNodeModel::NodeCopySettings()))
 {
 }

Functions

◆ accept()

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

virtual

Implements QPatternist::Expression.

Definition at line 103 of file qcopyof.cpp.

 {
     return visitor->visit(this);
 }

◆ compress()

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

virtual

compress() is the last stage performs in compiling an expression, done after the initial AST build and calling typeCheck(). compress() performs crucial simplifications, either by having drastic performance implications or that some expressions depend on it for proper behavior.

The default implementation performs a sparse conditional constant propagation. In short, a recursive process is performed in the AST which examines if the Expression's operands are constant values, and if so, performs a const fold(AST rewrite) into the result of evaluating the expression in question. This default behavior can be disabled by letting properties() return DisableElimination.

This compress() stage can be relative effective due to the design of XPath, in part because intrinsic functions are heavily used. Many Expressions override compress() and do optimizations specific to what they do. Also, many Expressions performs optimizations in their typeCheck().

Parameters

context the static context. Supplies compile time information, and is the channel for communicating error messages.

See also: Wikipedia, the free encyclopedia, Sparse conditional constant propagation; Wikipedia, the free encyclopedia, Intrinsic function; Wikipedia, the free encyclopedia, Compiler optimization

Reimplemented from QPatternist::Expression.

Definition at line 62 of file qcopyof.cpp.

 {
     /* We have zero effect if we have these settings. */
     if(m_inheritNamespaces && m_preserveNamespaces)
         return m_operand->compress(context);
     else
     {
         const ItemType::Ptr t(m_operand->staticType()->itemType());
         /* We have no effect on the empty sequence or atomic values. */
         if(BuiltinTypes::xsAnyAtomicType->xdtTypeMatches(t)
           || *t == *CommonSequenceTypes::Empty)
             return m_operand->compress(context);
         else
             return SingleContainer::compress(context);
     }
 }

◆ evaluateToSequenceReceiver()

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

virtual

Evaluates this Expression by sending its output to DynamicContext::outputReceiver().

Reimplemented from QPatternist::Expression.

Definition at line 79 of file qcopyof.cpp.

 {
     /* Optimization: this completely breaks streaming. We get a call to
      * evaluateToSequenceReceiver() but we require heap allocations by calling
      * evaluateSequence(). */
 
     const Item::Iterator::Ptr it(m_operand->evaluateSequence(context));
     QAbstractXmlReceiver *const receiver = context->outputReceiver();
     Item next(it->next());
 
     while(next)
     {
         if(next.isNode())
         {
             const QXmlNodeModelIndex &asNode = next.asNode();
             asNode.model()->copyNodeTo(asNode, receiver, m_settings);
         }
         else
             receiver->item(next);
 
         next = it->next();
     }
 }

◆ expectedContextItemType()

ItemType::Ptr CopyOf::expectedContextItemType ( ) const

virtual

Returns the required type the context item must be an instance of.

If this Expression requires a focus, meaning its properties() function returns RequiresContextItem, it must return a type from this function. If any type is ok, BuiltinTypes::item should be returned.

In other words, this function must only be re-implemented if the focus is used. The default implementation performs an assert crash.

Reimplemented from QPatternist::Expression.

Definition at line 129 of file qcopyof.cpp.

 {
     return m_operand->expectedContextItemType();
 }

◆ expectedOperandTypes()

SequenceType::List CopyOf::expectedOperandTypes ( ) const

virtual

Returns: a list containing one CommonSequenceTypes::ZeroOrMoreItems

Implements QPatternist::Expression.

Definition at line 113 of file qcopyof.cpp.

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

◆ mapToItem()

Item QPatternist::CopyOf::mapToItem	(	const Item &	source,
		const DynamicContext::Ptr &	context
	)		const

inline

◆ properties()

Expression::Properties CopyOf::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 120 of file qcopyof.cpp.

 {
     /* We have the content of node constructors as children, but even though
      * createCopyOf() typically avoids creating us, we can still end up with an operand
      * that allows compression. We must always avoid that, because we don't have
      * implementation of evaluateSequence(), and so on. */
     return (m_operand->properties() & ~CreatesFocusForLast) | DisableElimination;
 }

◆ staticType()

SequenceType::Ptr CopyOf::staticType ( ) const

virtual

Returns: always the SequenceType passed in the constructor to this class. That is, the SequenceType that the operand must conform to.

Implements QPatternist::Expression.

Definition at line 108 of file qcopyof.cpp.

 {
     return m_operand->staticType();
 }

Properties

◆ m_inheritNamespaces

const bool QPatternist::CopyOf::m_inheritNamespaces

private

Definition at line 111 of file qcopyof_p.h.

Referenced by compress().

◆ m_preserveNamespaces

const bool QPatternist::CopyOf::m_preserveNamespaces

private

Definition at line 112 of file qcopyof_p.h.

Referenced by compress().

◆ m_settings

const QAbstractXmlNodeModel::NodeCopySettings QPatternist::CopyOf::m_settings

private

Definition at line 113 of file qcopyof_p.h.

Referenced by evaluateToSequenceReceiver().

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

/src/xmlpatterns/expr/qcopyof_p.h
/src/xmlpatterns/expr/qcopyof.cpp

Public Functions

Private Types

Properties

Additional Inherited Members

Detailed Description

Typedefs

◆ ConstPtr

Constructors and Destructors

◆ CopyOf()

Functions

◆ accept()

◆ compress()

◆ evaluateToSequenceReceiver()

◆ expectedContextItemType()

◆ expectedOperandTypes()

◆ mapToItem()

◆ properties()

◆ staticType()

Properties

◆ m_inheritNamespaces

◆ m_preserveNamespaces

◆ m_settings