Module org.apache.lucene.core

Package org.apache.lucene.search

Class BooleanWeight

java.lang.Object

org.apache.lucene.search.Weight

org.apache.lucene.search.BooleanWeight

All Implemented Interfaces:

SegmentCacheable

final class BooleanWeight
extends Weight

Expert: the Weight for BooleanQuery, used to normalize, score and explain these queries.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	BooleanWeight.WeightedBooleanClause

Nested classes/interfaces inherited from class org.apache.lucene.search.Weight

Weight.DefaultBulkScorer, Weight.DefaultScorerSupplier

Field Summary

Fields

Modifier and Type	Field	Description
(package private) final BooleanQuery	query
(package private) final ScoreMode	scoreMode
(package private) final Similarity	similarity	The Similarity implementation.
(package private) final ArrayList<BooleanWeight.WeightedBooleanClause>	weightedClauses

Fields inherited from class org.apache.lucene.search.Weight

parentQuery

Constructor Summary

Constructors

Constructor	Description
BooleanWeight(BooleanQuery query, IndexSearcher searcher, ScoreMode scoreMode, float boost)

Method Summary

Modifier and Type	Method	Description
int	count(LeafReaderContext context)	Counts the number of live documents that match a given Weight.parentQuery in a leaf.
Explanation	explain(LeafReaderContext context, int doc)	An explanation of the score computation for the named document.
boolean	isCacheable(LeafReaderContext ctx)
Matches	matches(LeafReaderContext context, int doc)	Returns Matches for a specific document, or null if the document does not match the parent query
private int	optCount(LeafReaderContext context, BooleanClause.Occur occur)	Return the number of matches of optional clauses, or -1 if unknown, or 0 if there are no optional clauses.
private int	reqCount(LeafReaderContext context)	Return the number of matches of required clauses, or -1 if unknown, or numDocs if there are no required clauses.
ScorerSupplier	scorerSupplier(LeafReaderContext context)	Get a ScorerSupplier, which allows knowing the cost of the Scorer before building it.

Methods inherited from class org.apache.lucene.search.Weight

bulkScorer, getQuery, scorer

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

similarity

final Similarity similarity

The Similarity implementation.

query

final BooleanQuery query

weightedClauses

final ArrayList<BooleanWeight.WeightedBooleanClause> weightedClauses

scoreMode

final ScoreMode scoreMode

Constructor Details

BooleanWeight

BooleanWeight(BooleanQuery query,
 IndexSearcher searcher,
 ScoreMode scoreMode,
 float boost)
       throws IOException

Throws:

IOException

Method Details

explain

public Explanation explain(LeafReaderContext context,
 int doc)
                    throws IOException

Description copied from class: Weight

An explanation of the score computation for the named document.

Specified by:

explain in class Weight

Parameters:

context - the readers context to create the Explanation for.

doc - the document's id relative to the given context's reader

Returns:

an Explanation for the score

Throws:

IOException - if an IOException occurs

matches

public Matches matches(LeafReaderContext context,
 int doc)
                throws IOException

Description copied from class: Weight

Returns Matches for a specific document, or null if the document does not match the parent query

A query match that contains no position information (for example, a Point or DocValues query) will return MatchesUtils.MATCH_WITH_NO_TERMS

Overrides:

matches in class Weight

Parameters:

context - the reader's context to create the Matches for

doc - the document's id relative to the given context's reader

Throws:

IOException

count

public int count(LeafReaderContext context)
          throws IOException

Description copied from class: Weight

Counts the number of live documents that match a given Weight.parentQuery in a leaf.

The default implementation returns -1 for every query. This indicates that the count could not be computed in sub-linear time.

Specific query classes should override it to provide other accurate sub-linear implementations (that actually return the count). Look at MatchAllDocsQuery.createWeight(IndexSearcher, ScoreMode, float) for an example

We use this property of the function to count hits in IndexSearcher.count(Query).

Overrides:

count in class Weight

Parameters:

context - the LeafReaderContext for which to return the count.

Returns:

integer count of the number of matches

Throws:

IOException - if there is a low-level I/O error

reqCount

private int reqCount(LeafReaderContext context)
              throws IOException

Return the number of matches of required clauses, or -1 if unknown, or numDocs if there are no required clauses.

Throws:

IOException

optCount

private int optCount(LeafReaderContext context,
 BooleanClause.Occur occur)
              throws IOException

Return the number of matches of optional clauses, or -1 if unknown, or 0 if there are no optional clauses.

Throws:

IOException

isCacheable

public boolean isCacheable(LeafReaderContext ctx)

Returns:

true if the object can be cached against a given leaf

scorerSupplier

public ScorerSupplier scorerSupplier(LeafReaderContext context)
                              throws IOException

Description copied from class: Weight

Get a ScorerSupplier, which allows knowing the cost of the Scorer before building it. A scorer supplier for the same LeafReaderContext instance may be requested multiple times as part of a single search call.

Note: It must return null if the scorer is null.

Specified by:

scorerSupplier in class Weight

Parameters:

context - the leaf reader context

Returns:

a ScorerSupplier providing the scorer, or null if scorer is null

Throws:

IOException - if an IOException occurs

See Also:

• Scorer
• Weight.DefaultScorerSupplier