org.apache.lucene.search.PrefixQuery Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.lucene.search;
import org.apache.lucene.index.Term;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.automaton.Automaton;
/** A Query that matches documents containing terms with a specified prefix. A PrefixQuery
* is built by QueryParser for input like app*.
*
* This query uses the {@link
* MultiTermQuery#CONSTANT_SCORE_REWRITE}
* rewrite method. */
public class PrefixQuery extends AutomatonQuery {
/** Constructs a query for terms starting with prefix. */
public PrefixQuery(Term prefix) {
// It's OK to pass unlimited maxDeterminizedStates: the automaton is born small and determinized:
super(prefix, toAutomaton(prefix.bytes()), Integer.MAX_VALUE, true);
if (prefix == null) {
throw new NullPointerException("prefix cannot be null");
}
}
/** Build an automaton accepting all terms with the specified prefix. */
public static Automaton toAutomaton(BytesRef prefix) {
Automaton automaton = new Automaton();
int lastState = automaton.createState();
for(int i=0;i