org.apache.lucene.search
Class Scorer
public abstract class Scorer
Expert: Common scoring functionality for different types of queries.
A Scorer
either iterates over documents matching a query,
or provides an explanation of the score for a query for a given document.
Document scores are computed using a given Similarity
implementation.
abstract int | doc() - Returns the current document number matching the query.
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abstract Explanation | explain(int doc) - Returns an explanation of the score for a document.
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Similarity | getSimilarity() - Returns the Similarity implementation used by this scorer.
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abstract boolean | next() - Advances to the next document matching the query.
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abstract float | score() - Returns the score of the current document matching the query.
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void | score(HitCollector hc) - Scores and collects all matching documents.
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protected boolean | score(HitCollector hc, int max) - Expert: Collects matching documents in a range.
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abstract boolean | skipTo(int target) - Skips to the first match beyond the current whose document number is
greater than or equal to a given target.
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Scorer
protected Scorer(Similarity similarity)
Constructs a Scorer.
similarity
- The Similarity
implementation used by this scorer.
doc
public abstract int doc()
Returns the current document number matching the query.
Initially invalid, until
next()
is called the first time.
explain
public abstract Explanation explain(int doc)
throws IOException
doc
- The document number for the explanation.
getSimilarity
public Similarity getSimilarity()
Returns the Similarity implementation used by this scorer.
next
public abstract boolean next()
throws IOException
Advances to the next document matching the query.
- true iff there is another document matching the query.
When this method is used the explain(int)
method should not be used.
score
public abstract float score()
throws IOException
Returns the score of the current document matching the query.
Initially invalid, until
next()
or
skipTo(int)
is called the first time.
score
public void score(HitCollector hc)
throws IOException
Scores and collects all matching documents.
score
protected boolean score(HitCollector hc,
int max)
throws IOException
Expert: Collects matching documents in a range. Hook for optimization.
Note that
next()
must be called once before this method is called
for the first time.
- true if more matching documents may remain.
skipTo
public abstract boolean skipTo(int target)
throws IOException
Skips to the first match beyond the current whose document number is
greater than or equal to a given target.
When this method is used the
explain(int)
method should not be used.
target
- The target document number.
- true iff there is such a match.
Behaves as if written:
boolean skipTo(int target) {
do {
if (!next())
return false;
} while (target > doc());
return true;
}
Most implementations are considerably more efficient than that.
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