org.terrier.querying.parser
Class PhraseQuery

java.lang.Object
  org.terrier.querying.parser.Query
      org.terrier.querying.parser.MultiTermQuery
          org.terrier.querying.parser.PhraseQuery

All Implemented Interfaces:

Serializable, Cloneable

public class PhraseQuery
extends MultiTermQuery

Models a phrase query, which can have a proximity requirement.

Author:

Vassilis Plachouras, Craig Macdonald

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.terrier.querying.parser.Query

Query.ForEachQueryNode

Field Summary

protected int

proximityDistance Indicates the distance, in number of blocks, that the phrase terms can appear in a document.

Fields inherited from class org.terrier.querying.parser.MultiTermQuery

prefix, suffix, v

Fields inherited from class org.terrier.querying.parser.Query

child, tmpSTQ

Constructor Summary

PhraseQuery()
A default constructor that calls the constructor of the super class.

PhraseQuery(int proxDistance)
Constructs a phrase query and sets the proximity distance

Method Summary

Object	clone() Deep copy this Query object
void	getTermsOf(Class<? extends Query> c, List<Query> alist, boolean req) Returns all the query terms, in subqueries that are instances of a given class
boolean	obtainControls(Set<String> allowed, Map<String,String> controls) This object cannot contain any controls, so this method will always return false.
void	obtainQueryTerms(MatchingQueryTerms terms) Stores the query terms of the phrase query in the given matching query terms structure.
void	obtainQueryTerms(MatchingQueryTerms terms, boolean required) Stores the query terms of the phrase query in the given matching query terms structure.
void	setProximityDistance(int prox) Sets the allowed distance, in blocks, between the phrase terms.
String	toString() Returns a string representation of the phrase query.

Methods inherited from class org.terrier.querying.parser.MultiTermQuery

add, add, apply, applyTermPipeline, getNumberOfTerms, getTerms, obtainAllOf, parseTree, replace

Methods inherited from class org.terrier.querying.parser.Query

setChild

Methods inherited from class java.lang.Object

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

Field Detail

proximityDistance

protected int proximityDistance

Indicates the distance, in number of blocks, that the phrase terms can appear in a document. A value of zero corresponds to phrase searching and it is the default value, while any higher value enables proximity searching.

Constructor Detail

PhraseQuery

public PhraseQuery()

A default constructor that calls the constructor of the super class.

PhraseQuery

public PhraseQuery(int proxDistance)

Constructs a phrase query and sets the proximity distance

Parameters:

proxDistance - int the distance, in number of blocks, that the phrase terms can appear in a document.

Method Detail

clone

public Object clone()

Deep copy this Query object

Overrides:

clone in class MultiTermQuery

setProximityDistance

public void setProximityDistance(int prox)

Sets the allowed distance, in blocks, between the phrase terms.

Parameters:

prox - the allowed distance between the phrase terms.

toString

public String toString()

Returns a string representation of the phrase query.

Overrides:

toString in class MultiTermQuery

Returns:

String the string representation of the phrase query.

obtainQueryTerms

public void obtainQueryTerms(MatchingQueryTerms terms)

Stores the query terms of the phrase query in the given matching query terms structure. The query terms are required to appear in the matched documents.

Overrides:

obtainQueryTerms in class MultiTermQuery

Parameters:

terms - MatchingQueryTerms the structure that stores the query terms for matching.

obtainQueryTerms

public void obtainQueryTerms(MatchingQueryTerms terms,
                             boolean required)

Stores the query terms of the phrase query in the given matching query terms structure. Whether the phrase is required to appear in the retrieved documents, depends on the value of the parameter required.

Overrides:

obtainQueryTerms in class MultiTermQuery

Parameters:

terms - MatchingQueryTerms the structure that stores the query terms for matching.

required - boolean indicates whether the phrase is required or not.

obtainControls

public boolean obtainControls(Set<String> allowed,
                              Map<String,String> controls)

This object cannot contain any controls, so this method will always return false.

Overrides:

obtainControls in class MultiTermQuery

Parameters:

allowed - The HashSet of control names that are allowed to be set.

controls - The Hashtable into which child objects much add found controls

Returns:

false

getTermsOf

public void getTermsOf(Class<? extends Query> c,
                       List<Query> alist,
                       boolean req)

Returns all the query terms, in subqueries that are instances of a given class

Overrides:

getTermsOf in class MultiTermQuery

Parameters:

c - Class a class of queries.

alist - ArrayList the list of query terms.

req - boolean indicates whether the subqueries are required or not.