Package org.apache.lucene.search

Class SloppyPhraseMatcher

java.lang.Object

org.apache.lucene.search.PhraseMatcher

org.apache.lucene.search.SloppyPhraseMatcher

public final class SloppyPhraseMatcher
extends PhraseMatcher

Find all slop-valid position-combinations (matches) encountered while traversing/hopping the PhrasePositions.
The sloppy frequency contribution of a match depends on the distance:
- highest freq for distance=0 (exact match).
- freq gets lower as distance gets higher.
Example: for query "a b"~2, a document "x a b a y" can be matched twice: once for "a b" (distance=0), and once for "b a" (distance=2).
Possibly not all valid combinations are encountered, because for efficiency we always propagate the least PhrasePosition. This allows to base on PriorityQueue and move forward faster. As result, for example, document "a b c b a" would score differently for queries "a b c"~4 and "c b a"~4, although they really are equivalent. Similarly, for doc "a b c b a f g", query "c b"~2 would get same score as "g f"~2, although "c b"~2 could be matched twice. We may want to fix this in the future (currently not, for performance reasons).

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

Constructor Summary

Constructors

Constructor	Description
SloppyPhraseMatcher(PhraseQuery.PostingsAndFreq[] postings, int slop, ScoreMode scoreMode, Similarity.SimScorer scorer, float matchCost, boolean captureLeadMatch)

Method Summary

Modifier and Type	Method	Description
int	endOffset()
int	endPosition()
boolean	nextMatch()	Find the next match on the current document, returning false if there are none.
void	reset()	Called after PhraseMatcher.approximation() has been advanced
int	startOffset()
int	startPosition()

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

getMatchCost

Methods inherited from class java.lang.Object

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

Constructor Detail

SloppyPhraseMatcher

public SloppyPhraseMatcher(PhraseQuery.PostingsAndFreq[] postings,
                           int slop,
                           ScoreMode scoreMode,
                           Similarity.SimScorer scorer,
                           float matchCost,
                           boolean captureLeadMatch)

Method Detail

reset

public void reset()
           throws IOException

Description copied from class: PhraseMatcher

Called after PhraseMatcher.approximation() has been advanced

Specified by:

reset in class PhraseMatcher

Throws:

IOException

nextMatch

public boolean nextMatch()
                  throws IOException

Description copied from class: PhraseMatcher

Find the next match on the current document, returning false if there are none.

Specified by:

nextMatch in class PhraseMatcher

Throws:

IOException

startPosition

public int startPosition()

endPosition

public int endPosition()

startOffset

public int startOffset()
                throws IOException

Throws:

IOException

endOffset

public int endOffset()
              throws IOException

Throws:

IOException