QPatternist::DistinctIterator Class Reference

Filters another sequence by removing duplicates such that the items are unique. More...

#include <qdistinctiterator_p.h>

Inheritance diagram for QPatternist::DistinctIterator:

Public Functions
virtual const SourceLocationReflection *	actualReflection () const
virtual Item::Iterator::Ptr	copy () const
	Copies this QAbstractXmlForwardIterator and returns the copy. More...
virtual Item	current () const
	Returns the current item in the sequence. More...
	DistinctIterator (const Item::Iterator::Ptr &seq, const AtomicComparator::Ptr &comp, const Expression::ConstPtr &expression, const DynamicContext::Ptr &context)
virtual Item	next ()
	Returns the next item in the sequence, or a null object if the end has been reached. More...
AtomicComparator::Operator	operatorID () const
virtual xsInteger	position () const
	Returns the current position in the sequence represented by this. More...
Public Functions inherited from QAbstractXmlForwardIterator< T >
virtual qint64	count ()
	Determines the number of items this QAbstractXmlForwardIterator represents. More...
virtual bool	isEmpty ()
	Returns true if the sequence is empty. More...
virtual T	last ()
	Returns the item at the end of this QAbstractXmlForwardIterator. More...
	QAbstractXmlForwardIterator ()
	Default constructor. More...
virtual qint64	sizeHint () const
	Gives a hint to the size of the contained sequence. More...
virtual QList< T >	toList ()
	Performs a copy of this QAbstractXmlForwardIterator(with copy()), and returns its items in a QList. More...
virtual QAbstractXmlForwardIterator< T >::Ptr	toReversed ()
	Returns a reverse iterator for the sequence. More...
virtual	~QAbstractXmlForwardIterator ()
	Destructor. More...
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::SourceLocationReflection
virtual QString	description () const
virtual QSourceLocation	sourceLocation () const
	SourceLocationReflection ()
virtual	~SourceLocationReflection ()

Properties
const DynamicContext::Ptr	m_context
Item	m_current
const Expression::ConstPtr	m_expr
xsInteger	m_position
Item::List	m_processed
const Item::Iterator::Ptr	m_seq

Additional Inherited Members
Public Types inherited from QAbstractXmlForwardIterator< T >
typedef QList< QExplicitlySharedDataPointer< QAbstractXmlForwardIterator< T > > >	List
	A QList containing QAbstractXmlForwardIterator::Ptr instances. More...
typedef QExplicitlySharedDataPointer< QAbstractXmlForwardIterator< T > >	Ptr
	A smart pointer wrapping an instance of a QAbstractXmlForwardIterator subclass. More...
typedef QVector< QExplicitlySharedDataPointer< QAbstractXmlForwardIterator< T > > >	Vector
	A QVector containing QAbstractXmlForwardIterator::Ptr instances. More...
Public Variables inherited from QSharedData
QAtomicInt	ref
Protected Functions inherited from QPatternist::ComparisonPlatform< DistinctIterator, false >
const AtomicComparator::Ptr &	comparator () const
bool	compare (const Item &i1, const Item &i2, const AtomicComparator::Ptr &comp, const AtomicComparator::Operator op) const
	Compares i1 and i2 with operator op, using comparator comp. All input arguments must be valid, and not null. More...
	ComparisonPlatform ()
AtomicComparator::ComparisonResult	detailedFlexibleCompare (const Item &it1, const Item &it2, const DynamicContext::Ptr &context) const
	like flexibleCompare(), but returns the result as an AtomicComparator::Operator instead of bool. More...
AtomicComparator::Ptr	fetchComparator (const ItemType::Ptr &type1, const ItemType::Ptr &type2, const ReportContext::Ptr &context) const
bool	flexibleCompare (const Item &it1, const Item &it2, const DynamicContext::Ptr &context) const
	Compares it1 against it2, using comparator() and operatorID(). More...
void	prepareComparison (const AtomicComparator::Ptr &comparator)
void	useCaseInsensitiveComparator ()
Related Functions inherited from QAbstractXmlForwardIterator< T >
template<typename TResult , typename TSource , typename TMapper >
static QAbstractXmlForwardIterator< TResult >::Ptr	makeSequenceMappingIterator (const TMapper &mapper, const QExplicitlySharedDataPointer< QAbstractXmlForwardIterator< TSource > > &source, const DynamicContext::Ptr &context)
	An object generator for SequenceMappingIterator. More...
bool	qIsForwardIteratorEnd (const T &unit)
	The Callback QAbstractXmlForwardIterator uses for determining whether unit is the end of a sequence. More...

Detailed Description

Filters another sequence by removing duplicates such that the items are unique.

DistinctIterator takes an input sequence, and returns a sequence where each item is unique. Thus, DistinctIterator removes the duplicates of items in a sequence. DistinctIterator is central in the implementation of the fn:distinct-values() function.

See also

XQuery 1.0 and XPath 2.0 Functions and Operators, 15.1.6 fn:distinct-values

Author

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

Definition at line 83 of file qdistinctiterator_p.h.

Constructors and Destructors

DistinctIterator()

DistinctIterator::DistinctIterator	(	const Item::Iterator::Ptr &	seq,
		const AtomicComparator::Ptr &	comp,
		const Expression::ConstPtr &	expression,
		const DynamicContext::Ptr &	context
	)

Creates a DistinctIterator.

Parameters

comp	the AtomicComparator to be used for comparing values. This may be null, meaning the IndexOfIterator iterator will dynamically determine what comparator to use
seq	the sequence whose duplicates should be filtered out
context	the usual context, used for error reporting and by AtomicComparators.
expression	the Expression that this DistinctIterator is evaluating for. It is used for error reporting, via actualReflection().

Definition at line 49 of file qdistinctiterator.cpp.

Referenced by copy().

                                  : m_seq(seq)
                                  , m_context(context)
                                  , m_expr(expression)
                                  , m_position(0)
{
    Q_ASSERT(seq);
    prepareComparison(comp);
}

Functions

actualReflection()

const SourceLocationReflection * DistinctIterator::actualReflection ( ) const

virtual

Implements QPatternist::SourceLocationReflection.

Definition at line 107 of file qdistinctiterator.cpp.

{
    return m_expr.data();
}

copy()

Item::Iterator::Ptr DistinctIterator::copy ( ) const

virtual

Copies this QAbstractXmlForwardIterator and returns the copy.

Warning

This function is not part of the public interface.

A copy and the original instance are completely independent of each other. Because evaluating an QAbstractXmlForwardIterator modifies it, one should always use a copy when an QAbstractXmlForwardIterator needs to be used several times.

Reimplemented from QAbstractXmlForwardIterator< T >.

Definition at line 102 of file qdistinctiterator.cpp.

{
    return Item::Iterator::Ptr(new DistinctIterator(m_seq->copy(), comparator(), m_expr, m_context));
}

current()

Item DistinctIterator::current ( ) const

virtual

Returns the current item in the sequence.

If this function is called before the first call to next(), a null object is returned. If the end of the sequence has been reached, a null object is returned.

Implements QAbstractXmlForwardIterator< T >.

Definition at line 92 of file qdistinctiterator.cpp.

{
    return m_current;
}

next()

Item DistinctIterator::next ( )

virtual

Returns the next item in the sequence, or a null object if the end has been reached.

Implements QAbstractXmlForwardIterator< T >.

Definition at line 62 of file qdistinctiterator.cpp.

{
    if(m_position == -1)
        return Item();

    const Item nitem(m_seq->next());
    if(!nitem)
    {
        m_position = -1;
        m_current.reset();
        return Item();
    }

    const Item::List::const_iterator end(m_processed.constEnd());
    Item::List::const_iterator it(m_processed.constBegin());

    for(; it != end; ++it)
    {
        if(flexibleCompare(*it, nitem, m_context))
        {
            return next();
        }
    }

    m_current = nitem;
    ++m_position;
    m_processed.append(nitem);
    return nitem;
}

operatorID()

AtomicComparator::Operator QPatternist::DistinctIterator::operatorID ( ) const

inline

Definition at line 109 of file qdistinctiterator_p.h.

        {
            return AtomicComparator::OperatorEqual;
        }

position()

xsInteger DistinctIterator::position ( ) const

virtual

Returns the current position in the sequence represented by this.

The first position is 1, not 0. If next() hasn't been called, 0 is returned. If this has reached the end, -1 is returned.

Implements QAbstractXmlForwardIterator< T >.

Definition at line 97 of file qdistinctiterator.cpp.

{
    return m_position;
}

Properties

m_context

const DynamicContext::Ptr QPatternist::DistinctIterator::m_context

private

Definition at line 116 of file qdistinctiterator_p.h.

Referenced by copy(), and next().

m_current

Item QPatternist::DistinctIterator::m_current

private

Definition at line 118 of file qdistinctiterator_p.h.

Referenced by current(), and next().

m_expr

const Expression::ConstPtr QPatternist::DistinctIterator::m_expr

private

Definition at line 117 of file qdistinctiterator_p.h.

Referenced by actualReflection(), and copy().

m_position

xsInteger QPatternist::DistinctIterator::m_position

private

Definition at line 119 of file qdistinctiterator_p.h.

Referenced by next(), and position().

m_processed

Item::List QPatternist::DistinctIterator::m_processed

private

Definition at line 120 of file qdistinctiterator_p.h.

Referenced by next().

m_seq

const Item::Iterator::Ptr QPatternist::DistinctIterator::m_seq

private

Definition at line 115 of file qdistinctiterator_p.h.

Referenced by copy(), and next().

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

• /src/xmlpatterns/iterators/qdistinctiterator_p.h
• /src/xmlpatterns/iterators/qdistinctiterator.cpp