org.apache.lucene.search
Class ScoringRewrite<Q extends Query>

java.lang.Object
  org.apache.lucene.search.MultiTermQuery.RewriteMethod
      org.apache.lucene.search.ScoringRewrite<Q>

All Implemented Interfaces:

Serializable

public abstract class ScoringRewrite<Q extends Query>
extends MultiTermQuery.RewriteMethod

See Also:

Serialized Form

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Only public to be accessible by spans package.

Nested Class Summary

protected static interface

TermCollectingRewrite.TermCollector

Field Summary

static MultiTermQuery.RewriteMethod	CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE Like SCORING_BOOLEAN_QUERY_REWRITE except scores are not computed.
static ScoringRewrite<BooleanQuery>	SCORING_BOOLEAN_QUERY_REWRITE A rewrite method that first translates each term into BooleanClause.Occur.SHOULD clause in a BooleanQuery, and keeps the scores as computed by the query.

Constructor Summary

ScoringRewrite()

Method Summary

protected abstract void	addClause(Q topLevel, Term term, float boost) Add a MultiTermQuery term to the top-level query
protected void	collectTerms(IndexReader reader, MultiTermQuery query, TermCollectingRewrite.TermCollector collector)
protected abstract Q	getTopLevelQuery() Return a suitable top-level Query for holding all expanded terms.
Q	rewrite(IndexReader reader, MultiTermQuery query)

Methods inherited from class org.apache.lucene.search.MultiTermQuery.RewriteMethod

getTermsEnum

Methods inherited from class java.lang.Object

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

Field Detail

SCORING_BOOLEAN_QUERY_REWRITE

public static final ScoringRewrite<BooleanQuery> SCORING_BOOLEAN_QUERY_REWRITE

A rewrite method that first translates each term into BooleanClause.Occur.SHOULD clause in a BooleanQuery, and keeps the scores as computed by the query. Note that typically such scores are meaningless to the user, and require non-trivial CPU to compute, so it's almost always better to use MultiTermQuery.CONSTANT_SCORE_AUTO_REWRITE_DEFAULT instead.

NOTE: This rewrite method will hit BooleanQuery.TooManyClauses if the number of terms exceeds BooleanQuery.getMaxClauseCount().

See Also:

MultiTermQuery.setRewriteMethod(org.apache.lucene.search.MultiTermQuery.RewriteMethod)

CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE

public static final MultiTermQuery.RewriteMethod CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE

Like SCORING_BOOLEAN_QUERY_REWRITE except scores are not computed. Instead, each matching document receives a constant score equal to the query's boost.

NOTE: This rewrite method will hit BooleanQuery.TooManyClauses if the number of terms exceeds BooleanQuery.getMaxClauseCount().

See Also:

MultiTermQuery.setRewriteMethod(org.apache.lucene.search.MultiTermQuery.RewriteMethod)

Constructor Detail

ScoringRewrite

public ScoringRewrite()

Method Detail

rewrite

public Q rewrite(IndexReader reader,
                 MultiTermQuery query)
                        throws IOException

Specified by:

rewrite in class MultiTermQuery.RewriteMethod

Throws:

IOException

getTopLevelQuery

protected abstract Q getTopLevelQuery()
                                             throws IOException

Return a suitable top-level Query for holding all expanded terms.

Throws:

IOException

addClause

protected abstract void addClause(Q topLevel,
                                  Term term,
                                  float boost)
                           throws IOException

Add a MultiTermQuery term to the top-level query

Throws:

IOException

collectTerms

protected final void collectTerms(IndexReader reader,
                                  MultiTermQuery query,
                                  TermCollectingRewrite.TermCollector collector)
                           throws IOException

Throws:

IOException