/*
* 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,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.search;
import java.io.IOException;
/**
* A supplier of {@link Scorer}. This allows to get an estimate of the cost before
* building the {@link Scorer}.
*/
public abstract class ScorerSupplier {
/**
* Get the {@link Scorer}. This may not return {@code null} and must be called
* at most once.
* @param randomAccess A hint about the expected usage of the {@link Scorer}.
* If {@link DocIdSetIterator#advance} or {@link TwoPhaseIterator} will be
* used to check whether given doc ids match, then pass {@code true}.
* Otherwise if the {@link Scorer} will be mostly used to lead the iteration
* using {@link DocIdSetIterator#nextDoc()}, then {@code false} should be
* passed. Under doubt, pass {@code false} which usually has a better
* worst-case.
*/
public abstract Scorer get(boolean randomAccess) throws IOException;
/**
* Get an estimate of the {@link Scorer} that would be returned by {@link #get}.
* This may be a costly operation, so it should only be called if necessary.
* @see DocIdSetIterator#cost
*/
public abstract long cost();
}