org.apache.lucene.search

Class PhraseQuery

Implemented Interfaces:
Cloneable, java.io.Serializable

public class PhraseQuery
extends Query

A Query that matches documents containing a particular sequence of terms. This may be combined with other terms with a BooleanQuery.
See Also:
Serialized Form

Constructor Summary

PhraseQuery()
Constructs an empty phrase query.

Method Summary

void
add(Term term)
Adds a term to the end of the query phrase.
void
add(Term term, int position)
Adds a term to the end of the query phrase.
protected Weight
createWeight(Searcher searcher)
Expert: Constructs an appropriate Weight implementation for this query.
boolean
equals(Object o)
Returns true iff o is equal to this.
int[]
getPositions()
Returns the relative positions of terms in this phrase.
int
getSlop()
Returns the slop.
Term[]
getTerms()
Returns the set of terms in this phrase.
int
hashCode()
Returns a hash code value for this object.
void
setSlop(int s)
Sets the number of other words permitted between words in query phrase.
String
toString(String f)
Prints a user-readable version of this query.

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

clone, combine, createWeight, getBoost, getSimilarity, mergeBooleanQueries, rewrite, setBoost, toString, toString, weight

Constructor Details

PhraseQuery

public PhraseQuery()
Constructs an empty phrase query.

Method Details

add

public void add(Term term)
Adds a term to the end of the query phrase. The relative position of the term is the one immediately after the last term added.

add

public void add(Term term,
                int position)
Adds a term to the end of the query phrase. The relative position of the term within the phrase is specified explicitly. This allows e.g. phrases with more than one term at the same position or phrases with gaps (e.g. in connection with stopwords).
Parameters:
term -
position -

createWeight

protected Weight createWeight(Searcher searcher)
Expert: Constructs an appropriate Weight implementation for this query.

Only implemented by primitive queries, which re-write to themselves.

Overrides:
createWeight in interface Query

equals

public boolean equals(Object o)
Returns true iff o is equal to this.

getPositions

public int[] getPositions()
Returns the relative positions of terms in this phrase.

getSlop

public int getSlop()
Returns the slop. See setSlop().

getTerms

public Term[] getTerms()
Returns the set of terms in this phrase.

hashCode

public int hashCode()
Returns a hash code value for this object.

setSlop

public void setSlop(int s)
Sets the number of other words permitted between words in query phrase. If zero, then this is an exact phrase search. For larger values this works like a WITHIN or NEAR operator.

The slop is in fact an edit-distance, where the units correspond to moves of terms in the query phrase out of position. For example, to switch the order of two words requires two moves (the first move places the words atop one another), so to permit re-orderings of phrases, the slop must be at least two.

More exact matches are scored higher than sloppier matches, thus search results are sorted by exactness.

The slop is zero by default, requiring exact matches.


toString

public String toString(String f)
Prints a user-readable version of this query.
Overrides:
toString in interface Query

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