org.apache.lucene.search
Class PhraseQuery

java.lang.Object
  extended by org.apache.lucene.search.Query
      extended by org.apache.lucene.search.PhraseQuery
All Implemented Interfaces:
Serializable, Cloneable

public class PhraseQuery
extends Query

A Query that matches documents containing a particular sequence of terms. A PhraseQuery is built by QueryParser for input like "new york".

This query may be combined with other terms or queries 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.
 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.
 void extractTerms(Set queryTerms)
          Expert: adds all terms occurring in this query to the terms set.
 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, getBoost, getSimilarity, mergeBooleanQueries, rewrite, setBoost, toString, weight
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

PhraseQuery

public PhraseQuery()
Constructs an empty phrase query.

Method Detail

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.


getSlop

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


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 -

getTerms

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


getPositions

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


createWeight

public Weight createWeight(Searcher searcher)
                    throws IOException
Description copied from class: Query
Expert: Constructs an appropriate Weight implementation for this query.

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

Overrides:
createWeight in class Query
Throws:
IOException

extractTerms

public void extractTerms(Set queryTerms)
Description copied from class: Query
Expert: adds all terms occurring in this query to the terms set. Only works if this query is in its rewritten form.

Overrides:
extractTerms in class Query
See Also:
Query.extractTerms(java.util.Set)

toString

public String toString(String f)
Prints a user-readable version of this query.

Specified by:
toString in class Query

equals

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

Overrides:
equals in class Query

hashCode

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

Overrides:
hashCode in class Query


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