inaccuratehititerator.java

Lucene Hack之通过缩小搜索结果集来提升性能

package org.apache.lucene.search;

/**
 * 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.
 */
import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * <p>
 * Rewritten by caocao (http://www.caocao.name)
 * 
 * <p>
 * Most of source code in InaccurateHitIterator came from HitIterator.
 */

/**
 * An iterator over {@link Hits} that provides lazy fetching of each document.
 * {@link Hits#iterator()} returns an instance of this class. Calls to
 * {@link #next()} return a {@link Hit} instance.
 * 
 * @author Jeremy Rayner
 */
public class InaccurateHitIterator implements Iterator {
	private InaccurateHits hits;

	private int hitNumber = 0;

	/**
	 * Constructed from {@link Hits#iterator()}.
	 */
	InaccurateHitIterator(InaccurateHits hits) {
		this.hits = hits;
	}

	/**
	 * @return true if current hit is less than the total number of {@link Hits}.
	 */
	public boolean hasNext() {
		return hitNumber < hits.length();
	}

	/**
	 * Returns a {@link Hit} instance representing the next hit in {@link Hits}.
	 * 
	 * @return Next {@link Hit}.
	 */
	public Object next() {
		if (hitNumber == hits.length())
			throw new NoSuchElementException();

		Object next = new InaccurateHit(hits, hitNumber);
		hitNumber++;
		return next;
	}

	/**
	 * Unsupported operation.
	 * 
	 * @throws UnsupportedOperationException
	 */
	public void remove() {
		throw new UnsupportedOperationException();
	}

	/**
	 * Returns the total number of hits.
	 */
	public int length() {
		return hits.length();
	}
}