Qt 4.8
Public Functions | List of all members
QPatternist::ReverseFN Class Reference

Implements the function fn:reverse(). More...

#include <qsequencefns_p.h>

Inheritance diagram for QPatternist::ReverseFN:
QPatternist::FunctionCall QPatternist::UnlimitedContainer QPatternist::Expression QSharedData QPatternist::CppCastingHelper< Expression > QPatternist::SourceLocationReflection

Public Functions

virtual Item::Iterator::Ptr evaluateSequence (const DynamicContext::Ptr &context) const
 
virtual SequenceType::Ptr staticType () const
 
virtual Expression::Ptr typeCheck (const StaticContext::Ptr &context, const SequenceType::Ptr &reqType)
 
- 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
 
- 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 SourceLocationReflectionactualReflection () 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 bool evaluateEBV (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::Ptrrewrite (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< FunctionCallPtr
 
- Public Types inherited from QPatternist::UnlimitedContainer
enum  CardinalityComputation { ProductOfCardinality, UnionOfCardinality }
 
- Public Types inherited from QPatternist::Expression
typedef QExplicitlySharedDataPointer< const ExpressionConstPtr
 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::PtrList
 
typedef QFlags< PropertyProperties
 
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< ExpressionPtr
 A smart pointer wrapping mutable Expression instances. More...
 
typedef ::QAbstractXmlForwardIterator< Expression::PtrQAbstractXmlForwardIterator
 
typedef QVector< Expression::PtrVector
 
- 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

Implements the function fn:reverse().

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

Definition at line 281 of file qsequencefns_p.h.

Functions

◆ evaluateSequence()

Item::Iterator::Ptr ReverseFN::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 197 of file qsequencefns.cpp.

198 {
199  return m_operands.first()->evaluateSequence(context)->toReversed();
200 }
T & first()
Returns a reference to the first item in the list.
Definition: qlist.h:282
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const

◆ staticType()

SequenceType::Ptr ReverseFN::staticType ( ) const
virtual

Formally speaking, the type inference is:

statEnv |-  (FN-URI,"reverse")(Type) : prime(Type) * quantifier(Type)
       @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_reverse">XQuery 1.0
       and XPath 2.0 Formal Semantics, 7.2.12 The fn:reverse function</a>
       @returns the static type of the function's first argument.

Reimplemented from QPatternist::FunctionCall.

Definition at line 211 of file qsequencefns.cpp.

212 {
213  return m_operands.first()->staticType();
214 }
T & first()
Returns a reference to the first item in the list.
Definition: qlist.h:282
virtual SequenceType::Ptr staticType() const =0

◆ typeCheck()

Expression::Ptr ReverseFN::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
contextsupplies 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.
reqTypethe 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::FunctionCall.

Definition at line 202 of file qsequencefns.cpp.

204 {
206  return FunctionCall::typeCheck(context, reqType);
207  else
208  return m_operands.first()->typeCheck(context, reqType);
209 }
virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context, const SequenceType::Ptr &reqType)
virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context, const SequenceType::Ptr &reqType)
Definition: qexpression.cpp:70
virtual Cardinality cardinality() const =0
T & first()
Returns a reference to the first item in the list.
Definition: qlist.h:282
virtual SequenceType::Ptr staticType() const =0

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