org.apache.lucene.search.highlight
Class SpanScorer

java.lang.Object
  org.apache.lucene.search.highlight.SpanScorer

All Implemented Interfaces:

Scorer

public class SpanScorer
extends Object
implements Scorer

Scorer implementation which scores text fragments by the number of unique query terms found. This class converts appropriate Querys to SpanQuerys and attempts to score only those terms that participated in generating the 'hit' on the document.

Constructor Summary

SpanScorer(Query query, String field, CachingTokenFilter cachingTokenFilter)

SpanScorer(Query query, String field, CachingTokenFilter cachingTokenFilter, IndexReader reader)

SpanScorer(Query query, String field, CachingTokenFilter cachingTokenFilter, IndexReader reader, String defaultField)
As above, but with ability to pass in an IndexReader

SpanScorer(Query query, String field, CachingTokenFilter cachingTokenFilter, String defaultField)

SpanScorer(WeightedSpanTerm[] weightedTerms)

Method Summary

float	getFragmentScore() Called when the highlighter has no more tokens for the current fragment - the scorer returns the weighting it has derived for the most recent fragment, typically based on the tokens passed to getTokenScore().
float	getMaxTermWeight()
float	getTokenScore(Token token) Called for each token in the current fragment
WeightedSpanTerm	getWeightedSpanTerm(String token) Retrieve the WeightedSpanTerm for the specified token.
static boolean	isHighlightCnstScrRngQuery()
void	reset() If you call Highlighter#getBestFragment() more than once you must reset the SpanScorer between each call.
static void	setHighlightCnstScrRngQuery(boolean highlight) Turns highlighting of ConstantScoreRangeQuery on/off.
void	startFragment(TextFragment newFragment) called when a new fragment is started for consideration

Methods inherited from class java.lang.Object

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

Constructor Detail

SpanScorer

public SpanScorer(Query query,
                  String field,
                  CachingTokenFilter cachingTokenFilter)
           throws IOException

Parameters:

query - Query to use for highlighting

field - Field to highlight - pass null to ignore fields

tokenStream - of source text to be highlighted

Throws:

IOException

SpanScorer

public SpanScorer(Query query,
                  String field,
                  CachingTokenFilter cachingTokenFilter,
                  IndexReader reader)
           throws IOException

Parameters:

query - Query to use for highlighting

field - Field to highlight - pass null to ignore fields

tokenStream - of source text to be highlighted

reader -

Throws:

IOException

SpanScorer

public SpanScorer(Query query,
                  String field,
                  CachingTokenFilter cachingTokenFilter,
                  IndexReader reader,
                  String defaultField)
           throws IOException

As above, but with ability to pass in an IndexReader

Throws:

IOException

SpanScorer

public SpanScorer(Query query,
                  String field,
                  CachingTokenFilter cachingTokenFilter,
                  String defaultField)
           throws IOException

Parameters:

defaultField - - The default field for queries with the field name unspecified

Throws:

IOException

SpanScorer

public SpanScorer(WeightedSpanTerm[] weightedTerms)

Parameters:

weightedTerms -

Method Detail

getFragmentScore

public float getFragmentScore()

Description copied from interface: Scorer

Called when the highlighter has no more tokens for the current fragment - the scorer returns the weighting it has derived for the most recent fragment, typically based on the tokens passed to getTokenScore().

Specified by:

getFragmentScore in interface Scorer

getMaxTermWeight

public float getMaxTermWeight()

Returns:

The highest weighted term (useful for passing to GradientFormatter to set top end of coloring scale.

getTokenScore

public float getTokenScore(Token token)

Description copied from interface: Scorer

Called for each token in the current fragment

Specified by:

getTokenScore in interface Scorer

Parameters:

token - The token to be scored

Returns:

a score which is passed to the Highlighter class to influence the mark-up of the text (this return value is NOT used to score the fragment)

getWeightedSpanTerm

public WeightedSpanTerm getWeightedSpanTerm(String token)

Retrieve the WeightedSpanTerm for the specified token. Useful for passing Span information to a Fragmenter.

Parameters:

token -

Returns:

WeightedSpanTerm for token

isHighlightCnstScrRngQuery

public static boolean isHighlightCnstScrRngQuery()

Returns:

whether ConstantScoreRangeQuerys are set to be highlighted

reset

public void reset()

If you call Highlighter#getBestFragment() more than once you must reset the SpanScorer between each call.

setHighlightCnstScrRngQuery

public static void setHighlightCnstScrRngQuery(boolean highlight)

Turns highlighting of ConstantScoreRangeQuery on/off. ConstantScoreRangeQuerys cannot be highlighted if you rewrite the query first. Must be called before SpanScorer construction.

Parameters:

highlightCnstScrRngQuery -

startFragment

public void startFragment(TextFragment newFragment)

Description copied from interface: Scorer

called when a new fragment is started for consideration

Specified by:

startFragment in interface Scorer