Class ScoreCachingWrappingScorer
- java.lang.Object
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- org.apache.lucene.search.DocIdSetIterator
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- org.apache.lucene.search.Scorer
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- org.apache.lucene.search.ScoreCachingWrappingScorer
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public class ScoreCachingWrappingScorer extends Scorer
AScorer
which wraps another scorer and caches the score of the current document. Successive calls toscore()
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 theCollector
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 aScorer
object, and might end up computing the score of a document more than once.
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Field Summary
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Fields inherited from class org.apache.lucene.search.DocIdSetIterator
NO_MORE_DOCS
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Constructor Summary
Constructors Constructor Description ScoreCachingWrappingScorer(Scorer scorer)
Creates a new instance by wrapping the given scorer.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
advance(int target)
Advances to the first beyond (see NOTE below) the current whose document number is greater than or equal to target.int
docID()
Returns the following: -1 orDocIdSetIterator.NO_MORE_DOCS
ifDocIdSetIterator.nextDoc()
orDocIdSetIterator.advance(int)
were not called yet.Similarity
getSimilarity()
Returns the Similarity implementation used by this scorer.int
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
score(Collector collector)
Scores and collects all matching documents.protected boolean
score(Collector collector, int max, int firstDocID)
Expert: Collects matching documents in a range.-
Methods inherited from class org.apache.lucene.search.Scorer
freq, visitScorers, visitSubScorers
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Constructor Detail
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ScoreCachingWrappingScorer
public ScoreCachingWrappingScorer(Scorer scorer)
Creates a new instance by wrapping the given scorer.
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Method Detail
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score
protected boolean score(Collector collector, int max, int firstDocID) throws IOException
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.NOTE: Because of backwards compatibility, this method is still declared as protected, but it is intended to be public, because it's called from other classes (like BooleanScorer). If you subclass
Scorer
, you should declare the overridden method as public to ease transition to Lucene 4.0, where it will be public.- 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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getSimilarity
public Similarity getSimilarity()
Description copied from class:Scorer
Returns the Similarity implementation used by this scorer.- Overrides:
getSimilarity
in classScorer
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score
public float score() throws IOException
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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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
public int nextDoc() throws IOException
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
public void score(Collector collector) throws IOException
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
public int advance(int target) throws IOException
Description copied from class:DocIdSetIterator
Advances to the first beyond (see NOTE below) the current whose document number is greater than or equal to target. Returns the current document number orDocIdSetIterator.NO_MORE_DOCS
if there are no more docs in the set.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: when
target ≤ current
implementations may opt not to advance beyond their currentDocIdSetIterator.docID()
.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.NOTE: after the iterator has exhausted you should not call this method, as it may result in unpredicted behavior.
- Specified by:
advance
in classDocIdSetIterator
- Throws:
IOException
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