Package org.apache.lucene.search
Interface LeafFieldComparator
- All Known Implementing Classes:
DoubleComparator.DoubleLeafComparator
,FieldComparator.RelevanceComparator
,FieldComparator.TermOrdValComparator
,FieldComparator.TermValComparator
,FloatComparator.FloatLeafComparator
,IntComparator.IntLeafComparator
,LongComparator.LongLeafComparator
,NumericComparator.NumericLeafComparator
,SimpleFieldComparator
public interface LeafFieldComparator
Expert: comparator that gets instantiated on each leaf from a top-level
FieldComparator
instance.
A leaf comparator must define these functions:
setBottom(int)
This method is called byFieldValueHitQueue
to notify the FieldComparator of the current weakest ("bottom") slot. Note that this slot may not hold the weakest value according to your comparator, in cases where your comparator is not the primary one (ie, is only used to break ties from the comparators before it).compareBottom(int)
Compare a new hit (docID) against the "weakest" (bottom) entry in the queue.compareTop(int)
Compare a new hit (docID) against the top value previously set by a call toFieldComparator.setTopValue(T)
.copy(int, int)
Installs a new hit into the priority queue. TheFieldValueHitQueue
calls this method when a new hit is competitive.
- See Also:
- WARNING: This API is experimental and might change in incompatible ways in the next release.
-
Method Summary
Modifier and TypeMethodDescriptionint
compareBottom
(int doc) Compare the bottom of the queue with this doc.int
compareTop
(int doc) Compare the top value with this doc.default DocIdSetIterator
Returns a competitive iteratorvoid
copy
(int slot, int doc) This method is called when a new hit is competitive.void
setBottom
(int slot) Set the bottom slot, ie the "weakest" (sorted last) entry in the queue.default void
Informs this leaf comparator that hits threshold is reached.void
Sets the Scorer to use in case a document's score is needed.
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Method Details
-
setBottom
Set the bottom slot, ie the "weakest" (sorted last) entry in the queue. WhencompareBottom(int)
is called, you should compare against this slot. This will always be called beforecompareBottom(int)
.- Parameters:
slot
- the currently weakest (sorted last) slot in the queue- Throws:
IOException
-
compareBottom
Compare the bottom of the queue with this doc. This will only invoked after setBottom has been called. This should return the same result asFieldComparator.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:
doc
- that was hit- Returns:
- any
N < 0
if the doc's value is sorted after the bottom entry (not competitive), anyN > 0
if the doc's value is sorted before the bottom entry and0
if they are equal. - Throws:
IOException
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compareTop
Compare the top value with this doc. This will only invoked after setTopValue has been called. This should return the same result asFieldComparator.compare(int,int)
} as if topValue were slot1 and the new document were slot 2. This is only called for searches that use searchAfter (deep paging).- Parameters:
doc
- that was hit- Returns:
- any
N < 0
if the doc's value is sorted after the top entry (not competitive), anyN > 0
if the doc's value is sorted before the top entry and0
if they are equal. - Throws:
IOException
-
copy
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:
slot
- which slot to copy the hit todoc
- docID relative to current reader- Throws:
IOException
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setScorer
Sets the Scorer to use in case a document's score is needed.- Parameters:
scorer
- Scorer instance that you should use to obtain the current hit's score, if necessary.- Throws:
IOException
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competitiveIterator
Returns a competitive iterator- Returns:
- an iterator over competitive docs that are stronger than already collected docs or
null
if such an iterator is not available for the current comparator or segment. - Throws:
IOException
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setHitsThresholdReached
Informs this leaf comparator that hits threshold is reached. This method is called from a collector when hits threshold is reached.- Throws:
IOException
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