Class Weight
- Direct Known Subclasses:
BooleanQuery.BooleanWeight
,ConstantScoreQuery.ConstantWeight
,DisjunctionMaxQuery.DisjunctionMaxWeight
,SpanWeight
The purpose of Weight
is to ensure searching does not modify a
Query
, so that a Query
instance can be reused.
IndexSearcher
dependent state of the query should reside in the
Weight
.
AtomicReader
dependent state should reside in the Scorer
.
Since Weight
creates Scorer
instances for a given
AtomicReaderContext
(scorer(AtomicReaderContext, boolean, boolean, Bits)
)
callers must maintain the relationship between the searcher's top-level
IndexReaderContext
and the context used to create a Scorer
.
A Weight
is used in the following way:
- A
Weight
is constructed by a top-level query, given aIndexSearcher
(Query.createWeight(IndexSearcher)
). - The
getValueForNormalization()
method is called on theWeight
to compute the query normalization factorSimilarity.queryNorm(float)
of the query clauses contained in the query. - The query normalization factor is passed to
normalize(float, float)
. At this point the weighting is complete. - A
Scorer
is constructed byscorer(AtomicReaderContext, boolean, boolean, Bits)
.
- Since:
- 2.9
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionabstract Explanation
explain
(AtomicReaderContext context, int doc) An explanation of the score computation for the named document.abstract Query
getQuery()
The query that this concerns.abstract float
The value for normalization of contained query clauses (e.g.abstract void
normalize
(float norm, float topLevelBoost) Assigns the query normalization factor and boost from parent queries to this.abstract Scorer
scorer
(AtomicReaderContext context, boolean scoreDocsInOrder, boolean topScorer, Bits acceptDocs) Returns aScorer
which scores documents in/out-of order according toscoreDocsInOrder
.boolean
Returns true iff this implementation scores docs only out of order.
-
Constructor Details
-
Weight
public Weight()
-
-
Method Details
-
explain
An explanation of the score computation for the named document.- Parameters:
context
- the readers context to create theExplanation
for.doc
- the document's id relative to the given context's reader- Returns:
- an Explanation for the score
- Throws:
IOException
- if anIOException
occurs
-
getQuery
The query that this concerns. -
getValueForNormalization
The value for normalization of contained query clauses (e.g. sum of squared weights).- Throws:
IOException
-
normalize
public abstract void normalize(float norm, float topLevelBoost) Assigns the query normalization factor and boost from parent queries to this. -
scorer
public abstract Scorer scorer(AtomicReaderContext context, boolean scoreDocsInOrder, boolean topScorer, Bits acceptDocs) throws IOException Returns aScorer
which scores documents in/out-of order according toscoreDocsInOrder
.NOTE: even if
scoreDocsInOrder
is false, it is recommended to check whether the returnedScorer
indeed scores documents out of order (i.e., callscoresDocsOutOfOrder()
), as someScorer
implementations will always return documents in-order.
NOTE: null can be returned if no documents will be scored by this query.- Parameters:
context
- theAtomicReaderContext
for which to return theScorer
.scoreDocsInOrder
- specifies whether in-order scoring of documents is required. Note that if set to false (i.e., out-of-order scoring is required), this method can return whatever scoring mode it supports, as every in-order scorer is also an out-of-order one. However, an out-of-order scorer may not supportDocIdSetIterator.nextDoc()
and/orDocIdSetIterator.advance(int)
, therefore it is recommended to request an in-order scorer if use of these methods is required.topScorer
- if true,Scorer.score(Collector)
will be called; if false,DocIdSetIterator.nextDoc()
and/orDocIdSetIterator.advance(int)
will be called.acceptDocs
- Bits that represent the allowable docs to match (typically deleted docs but possibly filtering other documents)- Returns:
- a
Scorer
which scores documents in/out-of order. - Throws:
IOException
- if there is a low-level I/O error
-
scoresDocsOutOfOrder
public boolean scoresDocsOutOfOrder()Returns true iff this implementation scores docs only out of order. This method is used in conjunction withCollector
'sacceptsDocsOutOfOrder
andscorer(AtomicReaderContext, boolean, boolean, Bits)
to create a matchingScorer
instance for a givenCollector
, or vice versa.NOTE: the default implementation returns
false
, i.e. theScorer
scores documents in-order.
-