org.apache.lucene.codecs.PostingsWriterBase Maven / Gradle / Ivy
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/*
* COPIED FROM APACHE LUCENE 4.7.2
*
* Git URL: [email protected]:apache/lucene.git, tag: releases/lucene-solr/4.7.2, path: lucene/core/src/java
*
* (see https://issues.apache.org/jira/browse/OAK-10786 for details)
*/
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.IOException;
import java.io.Closeable;
import org.apache.lucene.store.DataOutput;
import org.apache.lucene.store.IndexOutput;
import org.apache.lucene.index.FieldInfo;
/**
* Extension of {@link PostingsConsumer} to support pluggable term dictionaries.
*
* This class contains additional hooks to interact with the provided
* term dictionaries such as {@link BlockTreeTermsWriter}. If you want
* to re-use an existing implementation and are only interested in
* customizing the format of the postings list, extend this class
* instead.
*
* @see PostingsReaderBase
* @lucene.experimental
*/
// 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 PostingsWriterBase extends PostingsConsumer implements Closeable {
/** Sole constructor. (For invocation by subclass
* constructors, typically implicit.) */
protected PostingsWriterBase() {
}
/** Called once after startup, before any terms have been
* added. Implementations typically write a header to
* the provided {@code termsOut}. */
public abstract void init(IndexOutput termsOut) throws IOException;
/** Return a newly created empty TermState */
public abstract BlockTermState newTermState() throws IOException;
/** Start a new term. Note that a matching call to {@link
* #finishTerm(BlockTermState)} is done, only if the term has at least one
* document. */
public abstract void startTerm() throws IOException;
/** Finishes the current term. The provided {@link
* BlockTermState} contains the term's summary statistics,
* and will holds metadata from PBF when returned */
public abstract void finishTerm(BlockTermState state) throws IOException;
/**
* Encode metadata as long[] and byte[]. {@code absolute} controls whether
* current term is delta encoded according to latest term.
* Usually elements in {@code longs} are file pointers, so each one always
* increases when a new term is consumed. {@code out} is used to write generic
* bytes, which are not monotonic.
*
* NOTE: sometimes long[] might contain "don't care" values that are unused, e.g.
* the pointer to postings list may not be defined for some terms but is defined
* for others, if it is designed to inline some postings data in term dictionary.
* In this case, the postings writer should always use the last value, so that each
* element in metadata long[] remains monotonic.
*/
public abstract void encodeTerm(long[] longs, DataOutput out, FieldInfo fieldInfo, BlockTermState state, boolean absolute) throws IOException;
/**
* Sets the current field for writing, and returns the
* fixed length of long[] metadata (which is fixed per
* field), called when the writing switches to another field. */
// TODO: better name?
public abstract int setField(FieldInfo fieldInfo);
@Override
public abstract void close() throws IOException;
}