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java.lang.Object org.apache.lucene.search.DocIdSetIterator org.apache.lucene.search.Scorer org.apache.lucene.search.ScoreCachingWrappingScorer
public class ScoreCachingWrappingScorer
A 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.
Field Summary |
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Fields inherited from class org.apache.lucene.search.DocIdSetIterator |
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NO_MORE_DOCS |
Constructor Summary | |
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ScoreCachingWrappingScorer(Scorer scorer)
Creates a new instance by wrapping the given scorer. |
Method Summary | |
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int |
advance(int target)
Advances to the first beyond the current whose document number is greater than or equal to target. |
int |
doc()
Deprecated. use docID() instead. |
int |
docID()
Returns the following: -1 or DocIdSetIterator.NO_MORE_DOCS if DocIdSetIterator.nextDoc() or
DocIdSetIterator.advance(int) were not called yet. |
Explanation |
explain(int doc)
Returns an explanation of the score for a document. |
Similarity |
getSimilarity()
Returns the Similarity implementation used by this scorer. |
boolean |
next()
Deprecated. use nextDoc() instead. |
int |
nextDoc()
Advances to the next document in the set and returns the doc it is currently on, or DocIdSetIterator.NO_MORE_DOCS if there are no more docs in the
set.NOTE: in 3.0 this method will become abstract, following the removal of DocIdSetIterator.next() . |
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. |
boolean |
skipTo(int target)
Deprecated. use advance(int) instead. |
Methods inherited from class org.apache.lucene.search.Scorer |
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score, score |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public ScoreCachingWrappingScorer(Scorer scorer)
Method Detail |
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protected boolean score(Collector collector, int max, int firstDocID) throws IOException
Scorer
firstDocID
is added to ensure that DocIdSetIterator.nextDoc()
was called before this method.
score
in class Scorer
collector
- The collector to which all matching documents are passed.max
- Do not score documents past this.firstDocID
- The first document ID (ensures DocIdSetIterator.nextDoc()
is called before
this method.
IOException
public Similarity getSimilarity()
Scorer
getSimilarity
in class Scorer
public Explanation explain(int doc) throws IOException
Scorer
DocIdSetIterator.next()
, DocIdSetIterator.skipTo(int)
and
Scorer.score(HitCollector)
methods should not be used.
explain
in class Scorer
doc
- The document number for the explanation.
IOException
public float score() throws IOException
Scorer
DocIdSetIterator.next()
or DocIdSetIterator.skipTo(int)
is called the first time, or when called from within
Collector.collect(int)
.
score
in class Scorer
IOException
public int doc()
docID()
instead.
DocIdSetIterator
DocIdSetIterator.docID()
instead. This method throws
UnsupportedOperationException
if called.
doc
in class DocIdSetIterator
public int docID()
DocIdSetIterator
DocIdSetIterator.NO_MORE_DOCS
if DocIdSetIterator.nextDoc()
or
DocIdSetIterator.advance(int)
were not called yet.
DocIdSetIterator.NO_MORE_DOCS
if the iterator has exhausted.
NOTE: in 3.0, this method will become abstract.
docID
in class DocIdSetIterator
public boolean next() throws IOException
nextDoc()
instead.
DocIdSetIterator
DocIdSetIterator.nextDoc()
instead. This method throws
UnsupportedOperationException
if called.
next
in class DocIdSetIterator
IOException
public int nextDoc() throws IOException
DocIdSetIterator
DocIdSetIterator.NO_MORE_DOCS
if there are no more docs in the
set.DocIdSetIterator.next()
. For backward compatibility it is implemented as:
public int nextDoc() throws IOException { return next() ? doc() : NO_MORE_DOCS; }NOTE: after the iterator has exhausted you should not call this method, as it may result in unpredicted behavior.
nextDoc
in class DocIdSetIterator
IOException
public void score(Collector collector) throws IOException
Scorer
score
in class Scorer
collector
- The collector to which all matching documents are passed.
Scorer.explain(int)
method should not be used.
IOException
public boolean skipTo(int target) throws IOException
advance(int)
instead.
DocIdSetIterator
DocIdSetIterator.advance(int)
instead. This method throws
UnsupportedOperationException
if called.
skipTo
in class DocIdSetIterator
IOException
public int advance(int target) throws IOException
DocIdSetIterator
DocIdSetIterator.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: certain implementations may return a different value (each time) if called several times in a row with the same target.
NOTE: this method may be called with 2147483647 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.
NOTE: in 3.0 this method will become abstract, following the removal
of DocIdSetIterator.skipTo(int)
.
advance
in class DocIdSetIterator
IOException
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