/*
 * 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.
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package org.apache.lucene.index;

import java.util.List;

Common util methods for dealing with IndexReaders and IndexReaderContexts.
@lucene.internal
/** * Common util methods for dealing with {@link IndexReader}s and {@link IndexReaderContext}s. * * @lucene.internal */
public final class ReaderUtil { private ReaderUtil() {} // no instance
Walks up the reader tree and return the given context's top level reader context, or in other words the reader tree's root context.
/** * Walks up the reader tree and return the given context's top level reader * context, or in other words the reader tree's root context. */
public static IndexReaderContext getTopLevelContext(IndexReaderContext context) { while (context.parent != null) { context = context.parent; } return context; }
Returns index of the searcher/reader for document n in the array used to construct this searcher/reader.
/** * Returns index of the searcher/reader for document <code>n</code> in the * array used to construct this searcher/reader. */
public static int subIndex(int n, int[] docStarts) { // find // searcher/reader for doc n: int size = docStarts.length; int lo = 0; // search starts array int hi = size - 1; // for first element less than n, return its index while (hi >= lo) { int mid = (lo + hi) >>> 1; int midValue = docStarts[mid]; if (n < midValue) hi = mid - 1; else if (n > midValue) lo = mid + 1; else { // found a match while (mid + 1 < size && docStarts[mid + 1] == midValue) { mid++; // scan to last match } return mid; } } return hi; }
Returns index of the searcher/reader for document n in the array used to construct this searcher/reader.
/** * Returns index of the searcher/reader for document <code>n</code> in the * array used to construct this searcher/reader. */
public static int subIndex(int n, List<LeafReaderContext> leaves) { // find // searcher/reader for doc n: int size = leaves.size(); int lo = 0; // search starts array int hi = size - 1; // for first element less than n, return its index while (hi >= lo) { int mid = (lo + hi) >>> 1; int midValue = leaves.get(mid).docBase; if (n < midValue) hi = mid - 1; else if (n > midValue) lo = mid + 1; else { // found a match while (mid + 1 < size && leaves.get(mid + 1).docBase == midValue) { mid++; // scan to last match } return mid; } } return hi; } }