org.apache.lucene.codecs.PostingsReaderBase Maven / Gradle / Ivy
package org.apache.lucene.codecs;
/*
* 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.io.Closeable;
import java.io.IOException;
import org.apache.lucene.index.PostingsEnum;
import org.apache.lucene.index.FieldInfo;
import org.apache.lucene.index.SegmentReadState;
import org.apache.lucene.store.DataInput;
import org.apache.lucene.store.IndexInput;
import org.apache.lucene.util.Accountable;
/** The core terms dictionaries (BlockTermsReader,
* BlockTreeTermsReader) interact with a single instance
* of this class to manage creation of {@link org.apache.lucene.index.PostingsEnum} and
* {@link org.apache.lucene.index.PostingsEnum} instances. It provides an
* IndexInput (termsIn) where this class may read any
* previously stored data that it had written in its
* corresponding {@link PostingsWriterBase} at indexing
* time.
* @lucene.experimental */
// TODO: maybe move under blocktree? but it's used by other terms dicts (e.g. Block)
// TODO: find a better name; this defines the API that the
// terms dict impls use to talk to a postings impl.
// TermsDict + PostingsReader/WriterBase == PostingsConsumer/Producer
public abstract class PostingsReaderBase implements Closeable, Accountable {
/** Sole constructor. (For invocation by subclass
* constructors, typically implicit.) */
protected PostingsReaderBase() {
}
/** Performs any initialization, such as reading and
* verifying the header from the provided terms
* dictionary {@link IndexInput}. */
public abstract void init(IndexInput termsIn, SegmentReadState state) throws IOException;
/** Return a newly created empty TermState */
public abstract BlockTermState newTermState() throws IOException;
/** Actually decode metadata for next term
* @see PostingsWriterBase#encodeTerm
*/
public abstract void decodeTerm(long[] longs, DataInput in, FieldInfo fieldInfo, BlockTermState state, boolean absolute) throws IOException;
/** Must fully consume state, since after this call that
* TermState may be reused. */
public abstract PostingsEnum postings(FieldInfo fieldInfo, BlockTermState state, PostingsEnum reuse, int flags) throws IOException;
/**
* Checks consistency of this reader.
*
* Note that this may be costly in terms of I/O, e.g.
* may involve computing a checksum value against large data files.
* @lucene.internal
*/
public abstract void checkIntegrity() throws IOException;
@Override
public abstract void close() throws IOException;
}