/*
 * 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.util;


import java.io.IOException;

import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.DocIdSetIterator;

This DocIdSet encodes the negation of another DocIdSet. It is cacheable and supports random-access if the underlying set is cacheable and supports random-access.
@lucene.internal
/** * This {@link DocIdSet} encodes the negation of another {@link DocIdSet}. * It is cacheable and supports random-access if the underlying set is * cacheable and supports random-access. * @lucene.internal */
public final class NotDocIdSet extends DocIdSet { private static final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(NotDocIdSet.class); private final int maxDoc; private final DocIdSet in;
Sole constructor.
/** Sole constructor. */
public NotDocIdSet(int maxDoc, DocIdSet in) { this.maxDoc = maxDoc; this.in = in; } @Override public Bits bits() throws IOException { final Bits inBits = in.bits(); if (inBits == null) { return null; } return new Bits() { @Override public boolean get(int index) { return !inBits.get(index); } @Override public int length() { return inBits.length(); } }; } @Override public long ramBytesUsed() { return BASE_RAM_BYTES_USED + in.ramBytesUsed(); } @Override public DocIdSetIterator iterator() throws IOException { final DocIdSetIterator inIterator = in.iterator(); return new DocIdSetIterator() { int doc = -1; int nextSkippedDoc = -1; @Override public int nextDoc() throws IOException { return advance(doc + 1); } @Override public int advance(int target) throws IOException { doc = target; if (doc > nextSkippedDoc) { nextSkippedDoc = inIterator.advance(doc); } while (true) { if (doc >= maxDoc) { return doc = NO_MORE_DOCS; } assert doc <= nextSkippedDoc; if (doc != nextSkippedDoc) { return doc; } doc += 1; nextSkippedDoc = inIterator.nextDoc(); } } @Override public int docID() { return doc; } @Override public long cost() { // even if there are few docs in this set, iterating over all documents // costs O(maxDoc) in all cases return maxDoc; } }; } }