org.apache.lucene.search

Class TermAutomatonQuery

java.lang.Object

org.apache.lucene.search.Query

org.apache.lucene.search.TermAutomatonQuery

public class TermAutomatonQuery
extends Query

A proximity query that lets you express an automaton, whose transitions are terms, to match documents. This is a generalization of other proximity queries like PhraseQuery, MultiPhraseQuery and SpanNearQuery. It is likely slow, since it visits any document having any of the terms (i.e. it acts like a disjunction, not a conjunction like PhraseQuery), and then it must merge-sort all positions within each document to test whether/how many times the automaton matches.

After creating the query, use createState(), setAccept(int, boolean), addTransition(int, int, java.lang.String) and addAnyTransition(int, int) to build up the automaton. Once you are done, call finish() and then execute the query.

This code is very new and likely has exciting bugs!

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary

Constructors

Constructor and Description
TermAutomatonQuery(String field)

Method Summary

Modifier and Type	Method and Description
void	addAnyTransition(int source, int dest) Adds a transition matching any term.
void	addTransition(int source, int dest, BytesRef term) Adds a transition to the automaton.
void	addTransition(int source, int dest, String term) Adds a transition to the automaton.
int	createState() Returns a new state; state 0 is always the initial state.
Weight	createWeight(IndexSearcher searcher, boolean needsScores)
boolean	equals(Object other) Returns true iff o is equal to this.
void	finish() Call this once you are done adding states/transitions.
void	finish(int maxDeterminizedStates) Call this once you are done adding states/transitions.
int	hashCode()
Query	rewrite(IndexReader reader)
void	setAccept(int state, boolean accept) Marks the specified state as accept or not.
String	toDot() Returns the dot (graphviz) representation of this automaton.
String	toString(String field)

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

classHash, sameClassAs, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

TermAutomatonQuery

public TermAutomatonQuery(String field)

Method Detail

createState

public int createState()

Returns a new state; state 0 is always the initial state.

setAccept

public void setAccept(int state,
                      boolean accept)

Marks the specified state as accept or not.

addTransition

public void addTransition(int source,
                          int dest,
                          String term)

Adds a transition to the automaton.

addTransition

public void addTransition(int source,
                          int dest,
                          BytesRef term)

Adds a transition to the automaton.

addAnyTransition

public void addAnyTransition(int source,
                             int dest)

Adds a transition matching any term.

finish

public void finish()

Call this once you are done adding states/transitions.

finish

public void finish(int maxDeterminizedStates)

Call this once you are done adding states/transitions.

Parameters:

maxDeterminizedStates - Maximum number of states created when determinizing the automaton. Higher numbers allow this operation to consume more memory but allow more complex automatons.

createWeight

public Weight createWeight(IndexSearcher searcher,
                           boolean needsScores)
                    throws IOException

Overrides:

createWeight in class Query

Throws:

IOException

toString

public String toString(String field)

Specified by:

toString in class Query

equals

public boolean equals(Object other)

Returns true iff o is equal to this.

Specified by:

equals in class Query

hashCode

public int hashCode()

Specified by:

hashCode in class Query

toDot

public String toDot()

Returns the dot (graphviz) representation of this automaton. This is extremely useful for visualizing the automaton.

rewrite

public Query rewrite(IndexReader reader)
              throws IOException

Overrides:

rewrite in class Query

Throws:

IOException