/*
 * 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.io.IOException;
import java.util.Arrays;

import org.apache.lucene.util.BytesRef;

Exposes PostingsEnum, merged from PostingsEnum API of sub-segments.
@lucene.experimental
/** * Exposes {@link PostingsEnum}, merged from {@link PostingsEnum} * API of sub-segments. * * @lucene.experimental */
public final class MultiPostingsEnum extends PostingsEnum { private final MultiTermsEnum parent; final PostingsEnum[] subPostingsEnums; private final EnumWithSlice[] subs; int numSubs; int upto; PostingsEnum current; int currentBase; int doc = -1;
Sole constructor.
Params:
  • parent – The MultiTermsEnum that created us.
  • subReaderCount – How many sub-readers are being merged.
/** Sole constructor. * @param parent The {@link MultiTermsEnum} that created us. * @param subReaderCount How many sub-readers are being merged. */
public MultiPostingsEnum(MultiTermsEnum parent, int subReaderCount) { this.parent = parent; subPostingsEnums = new PostingsEnum[subReaderCount]; this.subs = new EnumWithSlice[subReaderCount]; for (int i = 0; i < subs.length; i++) { subs[i] = new EnumWithSlice(); } }
Returns true if this instance can be reused by the provided MultiTermsEnum.
/** Returns {@code true} if this instance can be reused by * the provided {@link MultiTermsEnum}. */
public boolean canReuse(MultiTermsEnum parent) { return this.parent == parent; }
Re-use and reset this instance on the provided slices.
/** Re-use and reset this instance on the provided slices. */
public MultiPostingsEnum reset(final EnumWithSlice[] subs, final int numSubs) { this.numSubs = numSubs; for(int i=0;i<numSubs;i++) { this.subs[i].postingsEnum = subs[i].postingsEnum; this.subs[i].slice = subs[i].slice; } upto = -1; doc = -1; current = null; return this; }
How many sub-readers we are merging. @see #getSubs
/** How many sub-readers we are merging. * @see #getSubs */
public int getNumSubs() { return numSubs; }
Returns sub-readers we are merging.
/** Returns sub-readers we are merging. */
public EnumWithSlice[] getSubs() { return subs; } @Override public int freq() throws IOException { assert current != null; return current.freq(); } @Override public int docID() { return doc; } @Override public int advance(int target) throws IOException { assert target > doc; while(true) { if (current != null) { final int doc; if (target < currentBase) { // target was in the previous slice but there was no matching doc after it doc = current.nextDoc(); } else { doc = current.advance(target-currentBase); } if (doc == NO_MORE_DOCS) { current = null; } else { return this.doc = doc + currentBase; } } else if (upto == numSubs-1) { return this.doc = NO_MORE_DOCS; } else { upto++; current = subs[upto].postingsEnum; currentBase = subs[upto].slice.start; } } } @Override public int nextDoc() throws IOException { while(true) { if (current == null) { if (upto == numSubs-1) { return this.doc = NO_MORE_DOCS; } else { upto++; current = subs[upto].postingsEnum; currentBase = subs[upto].slice.start; } } final int doc = current.nextDoc(); if (doc != NO_MORE_DOCS) { return this.doc = currentBase + doc; } else { current = null; } } } @Override public int nextPosition() throws IOException { return current.nextPosition(); } @Override public int startOffset() throws IOException { return current.startOffset(); } @Override public int endOffset() throws IOException { return current.endOffset(); } @Override public BytesRef getPayload() throws IOException { return current.getPayload(); } // TODO: implement bulk read more efficiently than super
Holds a PostingsEnum along with the corresponding ReaderSlice.
/** Holds a {@link PostingsEnum} along with the * corresponding {@link ReaderSlice}. */
public final static class EnumWithSlice {
PostingsEnum for this sub-reader.
/** {@link PostingsEnum} for this sub-reader. */
public PostingsEnum postingsEnum;
ReaderSlice describing how this sub-reader fits into the composite reader.
/** {@link ReaderSlice} describing how this sub-reader * fits into the composite reader. */
public ReaderSlice slice; EnumWithSlice() { } @Override public String toString() { return slice.toString()+":"+ postingsEnum; } } @Override public long cost() { long cost = 0; for (int i = 0; i < numSubs; i++) { cost += subs[i].postingsEnum.cost(); } return cost; } @Override public String toString() { return "MultiDocsAndPositionsEnum(" + Arrays.toString(getSubs()) + ")"; } }