Class ScoreCachingWrappingScorer
Scorer
which wraps another scorer and caches the score of the
current document. Successive calls to score()
will return the same
result and will not invoke the wrapped Scorer's score() method, unless the
current document has changed.This class might be useful due to the changes done to the
Collector
interface, in which the score is not computed for a document by default, only
if the collector requests it. Some collectors may need to use the score in
several places, however all they have in hand is a Scorer
object, and
might end up computing the score of a document more than once.-
Nested Class Summary
Nested classes/interfaces inherited from class org.apache.lucene.search.Scorer
Scorer.ChildScorer
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Field Summary
Fields inherited from class org.apache.lucene.index.DocsEnum
FLAG_FREQS, FLAG_NONE
Fields inherited from class org.apache.lucene.search.DocIdSetIterator
NO_MORE_DOCS
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Constructor Summary
ConstructorsConstructorDescriptionScoreCachingWrappingScorer
(Scorer scorer) Creates a new instance by wrapping the given scorer. -
Method Summary
Modifier and TypeMethodDescriptionint
advance
(int target) Advances to the first beyond the current whose document number is greater than or equal to target, and returns the document number itself.long
cost()
Returns the estimated cost of thisDocIdSetIterator
.int
docID()
Returns the following: -1 orDocIdSetIterator.NO_MORE_DOCS
ifDocIdSetIterator.nextDoc()
orDocIdSetIterator.advance(int)
were not called yet.int
freq()
Returns term frequency in the current document, or 1 if the field was indexed withFieldInfo.IndexOptions.DOCS_ONLY
.Returns child sub-scorersint
nextDoc()
Advances to the next document in the set and returns the doc it is currently on, orDocIdSetIterator.NO_MORE_DOCS
if there are no more docs in the set.
NOTE: after the iterator has exhausted you should not call this method, as it may result in unpredicted behavior.float
score()
Returns the score of the current document matching the query.void
Scores and collects all matching documents.boolean
Expert: Collects matching documents in a range.Methods inherited from class org.apache.lucene.index.DocsEnum
attributes
Methods inherited from class org.apache.lucene.search.DocIdSetIterator
empty, slowAdvance
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Constructor Details
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ScoreCachingWrappingScorer
Creates a new instance by wrapping the given scorer.
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Method Details
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score
Description copied from class:Scorer
Expert: Collects matching documents in a range. Hook for optimization. Note,firstDocID
is added to ensure thatDocIdSetIterator.nextDoc()
was called before this method.- Overrides:
score
in classScorer
- Parameters:
collector
- The collector to which all matching documents are passed.max
- Do not score documents past this.firstDocID
- The first document ID (ensuresDocIdSetIterator.nextDoc()
is called before this method.- Returns:
- true if more matching documents may remain.
- Throws:
IOException
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score
Description copied from class:Scorer
Returns the score of the current document matching the query. Initially invalid, untilDocIdSetIterator.nextDoc()
orDocIdSetIterator.advance(int)
is called the first time, or when called from withinCollector.collect(int)
.- Specified by:
score
in classScorer
- Throws:
IOException
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freq
Description copied from class:DocsEnum
Returns term frequency in the current document, or 1 if the field was indexed withFieldInfo.IndexOptions.DOCS_ONLY
. Do not call this beforeDocIdSetIterator.nextDoc()
is first called, nor afterDocIdSetIterator.nextDoc()
returnsDocIdSetIterator.NO_MORE_DOCS
.NOTE: if the
DocsEnum
was obtain withDocsEnum.FLAG_NONE
, the result of this method is undefined.- Specified by:
freq
in classDocsEnum
- Throws:
IOException
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docID
public int docID()Description copied from class:DocIdSetIterator
Returns the following:- -1 or
DocIdSetIterator.NO_MORE_DOCS
ifDocIdSetIterator.nextDoc()
orDocIdSetIterator.advance(int)
were not called yet. DocIdSetIterator.NO_MORE_DOCS
if the iterator has exhausted.- Otherwise it should return the doc ID it is currently on.
- Specified by:
docID
in classDocIdSetIterator
- -1 or
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nextDoc
Description copied from class:DocIdSetIterator
Advances to the next document in the set and returns the doc it is currently on, orDocIdSetIterator.NO_MORE_DOCS
if there are no more docs in the set.
NOTE: after the iterator has exhausted you should not call this method, as it may result in unpredicted behavior.- Specified by:
nextDoc
in classDocIdSetIterator
- Throws:
IOException
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score
Description copied from class:Scorer
Scores and collects all matching documents.- Overrides:
score
in classScorer
- Parameters:
collector
- The collector to which all matching documents are passed.- Throws:
IOException
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advance
Description copied from class:DocIdSetIterator
Advances to the first beyond the current whose document number is greater than or equal to target, and returns the document number itself. Exhausts the iterator and returnsDocIdSetIterator.NO_MORE_DOCS
if target is greater than the highest document number in the set.The behavior of this method is undefined when called with
target ≤ current
, or after the iterator has exhausted. Both cases may result in unpredicted behavior.When
target > current
it behaves as if written:int advance(int target) { int doc; while ((doc = nextDoc()) < target) { } return doc; }
Some implementations are considerably more efficient than that.NOTE: this method may be called with
DocIdSetIterator.NO_MORE_DOCS
for efficiency by some Scorers. If your implementation cannot efficiently determine that it should exhaust, it is recommended that you check for that value in each call to this method.- Specified by:
advance
in classDocIdSetIterator
- Throws:
IOException
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getChildren
Description copied from class:Scorer
Returns child sub-scorers- Overrides:
getChildren
in classScorer
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cost
public long cost()Description copied from class:DocIdSetIterator
Returns the estimated cost of thisDocIdSetIterator
.This is generally an upper bound of the number of documents this iterator might match, but may be a rough heuristic, hardcoded value, or otherwise completely inaccurate.
- Specified by:
cost
in classDocIdSetIterator
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