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Public Member Functions | Static Public Member Functions
Lucene::FieldComparator Class Referenceabstract

A FieldComparator compares hits so as to determine their sort order when collecting the top results with TopFieldCollector. The concrete public FieldComparator classes here correspond to the SortField types. More...

#include <FieldComparator.h>

+ Inheritance diagram for Lucene::FieldComparator:

Public Member Functions

virtual ~FieldComparator ()
 
virtual String getClassName ()
 
boost::shared_ptr< FieldComparatorshared_from_this ()
 
virtual int32_t compare (int32_t slot1, int32_t slot2)=0
 Compare hit at slot1 with hit at slot2.
 
virtual void setBottom (int32_t slot)=0
 Set the bottom slot, ie the "weakest" (sorted last) entry in the queue. When compareBottom is called, you should compare against this slot. This will always be called before compareBottom.
 
virtual int32_t compareBottom (int32_t doc)=0
 Compare the bottom of the queue with doc. This will only invoked after setBottom has been called. This should return the same result as compare(int,int)} as if bottom were slot1 and the new document were slot 2.
 
virtual void copy (int32_t slot, int32_t doc)=0
 This method is called when a new hit is competitive. You should copy any state associated with this document that will be required for future comparisons, into the specified slot.
 
virtual void setNextReader (const IndexReaderPtr &reader, int32_t docBase)=0
 Set a new Reader. All doc correspond to the current Reader.
 
virtual void setScorer (const ScorerPtr &scorer)
 Sets the Scorer to use in case a document's score is needed.
 
virtual ComparableValue value (int32_t slot)=0
 Return the actual value in the slot.
 
- Public Member Functions inherited from Lucene::LuceneObject
virtual ~LuceneObject ()
 
virtual void initialize ()
 Called directly after instantiation to create objects that depend on this object being fully constructed.
 
virtual LuceneObjectPtr clone (const LuceneObjectPtr &other=LuceneObjectPtr())
 Return clone of this object.
 
virtual int32_t hashCode ()
 Return hash code for this object.
 
virtual bool equals (const LuceneObjectPtr &other)
 Return whether two objects are equal.
 
virtual int32_t compareTo (const LuceneObjectPtr &other)
 Compare two objects.
 
virtual String toString ()
 Returns a string representation of the object.
 
- Public Member Functions inherited from Lucene::LuceneSync
virtual ~LuceneSync ()
 
virtual SynchronizePtr getSync ()
 Return this object synchronize lock.
 
virtual LuceneSignalPtr getSignal ()
 Return this object signal.
 
virtual void lock (int32_t timeout=0)
 Lock this object using an optional timeout.
 
virtual void unlock ()
 Unlock this object.
 
virtual bool holdsLock ()
 Returns true if this object is currently locked by current thread.
 
virtual void wait (int32_t timeout=0)
 Wait for signal using an optional timeout.
 
virtual void notifyAll ()
 Notify all threads waiting for signal.
 

Static Public Member Functions

static String _getClassName ()
 

Additional Inherited Members

- Protected Member Functions inherited from Lucene::LuceneObject
 LuceneObject ()
 
- Protected Attributes inherited from Lucene::LuceneSync
SynchronizePtr objectLock
 
LuceneSignalPtr objectSignal
 

Detailed Description

A FieldComparator compares hits so as to determine their sort order when collecting the top results with TopFieldCollector. The concrete public FieldComparator classes here correspond to the SortField types.

This API is designed to achieve high performance sorting, by exposing a tight interaction with FieldValueHitQueue as it visits hits. Whenever a hit is competitive, it's enrolled into a virtual slot, which is an int ranging from 0 to numHits-1. The FieldComparator is made aware of segment transitions during searching in case any internal state it's tracking needs to be recomputed during these transitions.

A comparator must define these functions:

Constructor & Destructor Documentation

◆ ~FieldComparator()

virtual Lucene::FieldComparator::~FieldComparator ( )
virtual

Member Function Documentation

◆ _getClassName()

static String Lucene::FieldComparator::_getClassName ( )
inlinestatic

◆ compare()

virtual int32_t Lucene::FieldComparator::compare ( int32_t  slot1,
int32_t  slot2 
)
pure virtual

Compare hit at slot1 with hit at slot2.

Parameters
slot1first slot to compare
slot2second slot to compare
Returns
any N < 0 if slot2's value is sorted after slot1, any N > 0 if the slot2's value is sorted before slot1 and 0 if they are equal

Implemented in Lucene::NumericComparator< TYPE >, Lucene::NumericComparator< double >, Lucene::NumericComparator< int32_t >, Lucene::NumericComparator< int64_t >, Lucene::NumericComparator< uint8_t >, Lucene::DoubleComparator, Lucene::IntComparator, Lucene::LongComparator, Lucene::RelevanceComparator, Lucene::StringComparatorLocale, Lucene::StringOrdValComparator, and Lucene::StringValComparator.

◆ compareBottom()

virtual int32_t Lucene::FieldComparator::compareBottom ( int32_t  doc)
pure virtual

Compare the bottom of the queue with doc. This will only invoked after setBottom has been called. This should return the same result as compare(int,int)} as if bottom were slot1 and the new document were slot 2.

For a search that hits many results, this method will be the hotspot (invoked by far the most frequently).

Parameters
docthat was hit
Returns
any N < 0 if the doc's value is sorted after the bottom entry (not competitive), any N > 0 if the doc's value is sorted before the bottom entry and 0 if they are equal.

Implemented in Lucene::NumericComparator< TYPE >, Lucene::NumericComparator< double >, Lucene::NumericComparator< int32_t >, Lucene::NumericComparator< int64_t >, Lucene::NumericComparator< uint8_t >, Lucene::DocComparator, Lucene::DoubleComparator, Lucene::IntComparator, Lucene::LongComparator, Lucene::RelevanceComparator, Lucene::StringComparatorLocale, Lucene::StringOrdValComparator, and Lucene::StringValComparator.

◆ copy()

virtual void Lucene::FieldComparator::copy ( int32_t  slot,
int32_t  doc 
)
pure virtual

This method is called when a new hit is competitive. You should copy any state associated with this document that will be required for future comparisons, into the specified slot.

Parameters
slotwhich slot to copy the hit to
docdocID relative to current reader

Implemented in Lucene::NumericComparator< TYPE >, Lucene::NumericComparator< double >, Lucene::NumericComparator< int32_t >, Lucene::NumericComparator< int64_t >, Lucene::NumericComparator< uint8_t >, Lucene::DocComparator, Lucene::RelevanceComparator, Lucene::StringComparatorLocale, Lucene::StringOrdValComparator, and Lucene::StringValComparator.

◆ getClassName()

virtual String Lucene::FieldComparator::getClassName ( )
inlinevirtual

◆ setBottom()

virtual void Lucene::FieldComparator::setBottom ( int32_t  slot)
pure virtual

Set the bottom slot, ie the "weakest" (sorted last) entry in the queue. When compareBottom is called, you should compare against this slot. This will always be called before compareBottom.

Parameters
slotthe currently weakest (sorted last) slot in the queue

Implemented in Lucene::NumericComparator< TYPE >, Lucene::NumericComparator< double >, Lucene::NumericComparator< int32_t >, Lucene::NumericComparator< int64_t >, Lucene::NumericComparator< uint8_t >, Lucene::StringComparatorLocale, Lucene::StringOrdValComparator, and Lucene::StringValComparator.

◆ setNextReader()

virtual void Lucene::FieldComparator::setNextReader ( const IndexReaderPtr reader,
int32_t  docBase 
)
pure virtual

◆ setScorer()

virtual void Lucene::FieldComparator::setScorer ( const ScorerPtr scorer)
virtual

Sets the Scorer to use in case a document's score is needed.

Parameters
scorerScorer instance that you should use to obtain the current hit's score, if necessary.

Reimplemented in Lucene::RelevanceComparator.

◆ shared_from_this()

boost::shared_ptr< FieldComparator > Lucene::FieldComparator::shared_from_this ( )
inline

◆ value()

virtual ComparableValue Lucene::FieldComparator::value ( int32_t  slot)
pure virtual

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

clucene.sourceforge.net