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Expert: Calculate query weights and build query scorers.
The purpose of Weight is to make it so that searching does not modify
a Query, so that a Query instance can be reused.
Searcher dependent state of the query should reside in the Weight.
IndexReader dependent state should reside in the Scorer.
A Weight
is used in the following way:
Weight
is constructed by a top-level query,
given a Searcher
(Query.createWeight(Searcher)
).
sumOfSquaredWeights()
method is called
on the Weight
to compute
the query normalization factor Similarity.queryNorm(float)
of the query clauses contained in the query.
normalize(float)
.
At this point the weighting is complete.
Scorer
is constructed by scorer(IndexReader)
.
Method Summary | |
Explanation |
explain(IndexReader reader,
int doc)
An explanation of the score computation for the named document. |
Query |
getQuery()
The query that this concerns. |
float |
getValue()
The weight for this query. |
void |
normalize(float norm)
Assigns the query normalization factor to this. |
Scorer |
scorer(IndexReader reader)
Constructs a scorer for this. |
float |
sumOfSquaredWeights()
The sum of squared weights of contained query clauses. |
Method Detail |
public Query getQuery()
public float getValue()
public float sumOfSquaredWeights() throws IOException
IOException
public void normalize(float norm)
public Scorer scorer(IndexReader reader) throws IOException
IOException
public Explanation explain(IndexReader reader, int doc) throws IOException
IOException
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