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.IndexOutput;
import org.apache.lucene.index.FieldInfo;
/**
* Extension of {@link PostingsConsumer} to support pluggable term dictionaries.
* <p>
* 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 start(IndexOutput termsOut) throws IOException;
/** Start a new term. Note that a matching call to {@link
* #finishTerm(TermStats)} is done, only if the term has at least one
* document. */
public abstract void startTerm() throws IOException;
/** Flush count terms starting at start "backwards", as a
* block. start is a negative offset from the end of the
* terms stack, ie bigger start means further back in
* the stack. */
public abstract void flushTermsBlock(int start, int count) throws IOException;
/** Finishes the current term. The provided {@link
* TermStats} contains the term's summary statistics. */
public abstract void finishTerm(TermStats stats) throws IOException;
/** Called when the writing switches to another field. */
public abstract void setField(FieldInfo fieldInfo);
@Override
public abstract void close() throws IOException;
}