org.apache.lucene.search.highlight

Class WeightedSpanTermExtractor

java.lang.Object

org.apache.lucene.search.highlight.WeightedSpanTermExtractor

public class WeightedSpanTermExtractor
extends Object

Class used to extract WeightedSpanTerms from a Query based on whether Terms from the Query are contained in a supplied TokenStream. In order to support additional, by default unsupported queries, subclasses can override extract(Query, float, Map) for extracting wrapped or delegate queries and extractUnknownQuery(Query, Map) to process custom leaf queries:

 
    WeightedSpanTermExtractor extractor = new WeightedSpanTermExtractor() {
        protected void extract(Query query, float boost, Map<String, WeightedSpanTerm>terms) throws IOException {
          if (query instanceof QueryWrapper) {
            extract(((QueryWrapper)query).getQuery(), boost, terms);
          } else {
            super.extract(query, boost, terms);
          }
        }

        protected void extractUnknownQuery(Query query, Map<String, WeightedSpanTerm> terms) throws IOException {
          if (query instanceOf CustomTermQuery) {
            Term term = ((CustomTermQuery) query).getTerm();
            terms.put(term.field(), new WeightedSpanTerm(1, term.text()));
          }
        }
    };
 }
 
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	WeightedSpanTermExtractor.PositionCheckingMap<K> This class makes sure that if both position sensitive and insensitive versions of the same term are added, the position insensitive one wins.

Constructor Summary

Constructors

Constructor and Description
WeightedSpanTermExtractor()
WeightedSpanTermExtractor(String defaultField)

Method Summary

Modifier and Type	Method and Description
protected void	collectSpanQueryFields(SpanQuery spanQuery, Set<String> fieldNames)
protected void	extract(Query query, float boost, Map<String,WeightedSpanTerm> terms) Fills a Map with WeightedSpanTerms using the terms from the supplied Query.
protected void	extractUnknownQuery(Query query, Map<String,WeightedSpanTerm> terms)
protected void	extractWeightedSpanTerms(Map<String,WeightedSpanTerm> terms, SpanQuery spanQuery, float boost) Fills a Map with WeightedSpanTerms using the terms from the supplied SpanQuery.
protected void	extractWeightedTerms(Map<String,WeightedSpanTerm> terms, Query query, float boost) Fills a Map with WeightedSpanTerms using the terms from the supplied Query.
protected boolean	fieldNameComparator(String fieldNameToCheck) Necessary to implement matches for queries against defaultField
boolean	getExpandMultiTermQuery()
protected LeafReaderContext	getLeafContext()
TokenStream	getTokenStream() Returns the tokenStream which may have been wrapped in a CachingTokenFilter.
Map<String,WeightedSpanTerm>	getWeightedSpanTerms(Query query, float boost, TokenStream tokenStream) Creates a Map of WeightedSpanTerms from the given Query and TokenStream.
Map<String,WeightedSpanTerm>	getWeightedSpanTerms(Query query, float boost, TokenStream tokenStream, String fieldName) Creates a Map of WeightedSpanTerms from the given Query and TokenStream.
Map<String,WeightedSpanTerm>	getWeightedSpanTermsWithScores(Query query, float boost, TokenStream tokenStream, String fieldName, IndexReader reader) Creates a Map of WeightedSpanTerms from the given Query and TokenStream.
boolean	isCachedTokenStream()
protected boolean	isQueryUnsupported(Class<? extends Query> clazz)
boolean	isUsePayloads()
protected boolean	mustRewriteQuery(SpanQuery spanQuery)
void	setExpandMultiTermQuery(boolean expandMultiTermQuery)
protected void	setMaxDocCharsToAnalyze(int maxDocCharsToAnalyze) A threshold of number of characters to analyze.
void	setUsePayloads(boolean usePayloads)
void	setWrapIfNotCachingTokenFilter(boolean wrap) By default, TokenStreams that are not of the type CachingTokenFilter are wrapped in a CachingTokenFilter to ensure an efficient reset - if you are already using a different caching TokenStream impl and you don't want it to be wrapped, set this to false.

Methods inherited from class java.lang.Object

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

Constructor Detail

WeightedSpanTermExtractor

public WeightedSpanTermExtractor()

WeightedSpanTermExtractor

public WeightedSpanTermExtractor(String defaultField)

Method Detail

extract

protected void extract(Query query,
                       float boost,
                       Map<String,WeightedSpanTerm> terms)
                throws IOException

Fills a Map with WeightedSpanTerms using the terms from the supplied Query.

Parameters:

query - Query to extract Terms from

terms - Map to place created WeightedSpanTerms in

Throws:

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

isQueryUnsupported

protected boolean isQueryUnsupported(Class<? extends Query> clazz)

extractUnknownQuery

protected void extractUnknownQuery(Query query,
                                   Map<String,WeightedSpanTerm> terms)
                            throws IOException

Throws:

IOException

extractWeightedSpanTerms

protected void extractWeightedSpanTerms(Map<String,WeightedSpanTerm> terms,
                                        SpanQuery spanQuery,
                                        float boost)
                                 throws IOException

Fills a Map with WeightedSpanTerms using the terms from the supplied SpanQuery.

Parameters:

terms - Map to place created WeightedSpanTerms in

spanQuery - SpanQuery to extract Terms from

Throws:

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

extractWeightedTerms

protected void extractWeightedTerms(Map<String,WeightedSpanTerm> terms,
                                    Query query,
                                    float boost)
                             throws IOException

Fills a Map with WeightedSpanTerms using the terms from the supplied Query.

Parameters:

terms - Map to place created WeightedSpanTerms in

query - Query to extract Terms from

Throws:

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

fieldNameComparator

protected boolean fieldNameComparator(String fieldNameToCheck)

Necessary to implement matches for queries against defaultField

getLeafContext

protected LeafReaderContext getLeafContext()
                                    throws IOException

Throws:

IOException

getWeightedSpanTerms

public Map<String,WeightedSpanTerm> getWeightedSpanTerms(Query query,
                                                         float boost,
                                                         TokenStream tokenStream)
                                                  throws IOException

Creates a Map of WeightedSpanTerms from the given Query and TokenStream.

Parameters:

query - that caused hit

tokenStream - of text to be highlighted

Returns:

Map containing WeightedSpanTerms

Throws:

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

getWeightedSpanTerms

public Map<String,WeightedSpanTerm> getWeightedSpanTerms(Query query,
                                                         float boost,
                                                         TokenStream tokenStream,
                                                         String fieldName)
                                                  throws IOException

Creates a Map of WeightedSpanTerms from the given Query and TokenStream.

Parameters:

query - that caused hit

tokenStream - of text to be highlighted

fieldName - restricts Term's used based on field name

Returns:

Map containing WeightedSpanTerms

Throws:

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

getWeightedSpanTermsWithScores

public Map<String,WeightedSpanTerm> getWeightedSpanTermsWithScores(Query query,
                                                                   float boost,
                                                                   TokenStream tokenStream,
                                                                   String fieldName,
                                                                   IndexReader reader)
                                                            throws IOException

Creates a Map of WeightedSpanTerms from the given Query and TokenStream. Uses a supplied IndexReader to properly weight terms (for gradient highlighting).

Parameters:

query - that caused hit

tokenStream - of text to be highlighted

fieldName - restricts Term's used based on field name

reader - to use for scoring

Returns:

Map of WeightedSpanTerms with quasi tf/idf scores

Throws:

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

collectSpanQueryFields

protected void collectSpanQueryFields(SpanQuery spanQuery,
                                      Set<String> fieldNames)

mustRewriteQuery

protected boolean mustRewriteQuery(SpanQuery spanQuery)

getExpandMultiTermQuery

public boolean getExpandMultiTermQuery()

setExpandMultiTermQuery

public void setExpandMultiTermQuery(boolean expandMultiTermQuery)

isUsePayloads

public boolean isUsePayloads()

setUsePayloads

public void setUsePayloads(boolean usePayloads)

isCachedTokenStream

public boolean isCachedTokenStream()

getTokenStream

public TokenStream getTokenStream()

Returns the tokenStream which may have been wrapped in a CachingTokenFilter. getWeightedSpanTerms* sets the tokenStream, so don't call this before.

setWrapIfNotCachingTokenFilter

public void setWrapIfNotCachingTokenFilter(boolean wrap)

By default, TokenStreams that are not of the type CachingTokenFilter are wrapped in a CachingTokenFilter to ensure an efficient reset - if you are already using a different caching TokenStream impl and you don't want it to be wrapped, set this to false. This setting is ignored when a term vector based TokenStream is supplied, since it can be reset efficiently.

setMaxDocCharsToAnalyze

protected final void setMaxDocCharsToAnalyze(int maxDocCharsToAnalyze)

A threshold of number of characters to analyze. When a TokenStream based on term vectors with offsets and positions are supplied, this setting does not apply.