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.FieldInfo;
import org.apache.lucene.index.Fields;
import org.apache.lucene.index.MergeState;
import org.apache.lucene.index.SegmentWriteState; // javadocs
import org.apache.lucene.index.Terms;
/**
* Abstract API that consumes terms, doc, freq, prox, offset and
* payloads postings. Concrete implementations of this
* actually do "something" with the postings (write it into
* the index in a specific format).
* <p>
* The lifecycle is:
* <ol>
* <li>FieldsConsumer is created by
* {@link PostingsFormat#fieldsConsumer(SegmentWriteState)}.
* <li>For each field, {@link #addField(FieldInfo)} is called,
* returning a {@link TermsConsumer} for the field.
* <li>After all fields are added, the consumer is {@link #close}d.
* </ol>
*
* @lucene.experimental
*/
public abstract class FieldsConsumer implements Closeable {
/** Sole constructor. (For invocation by subclass
* constructors, typically implicit.) */
protected FieldsConsumer() {
}
/** Add a new field */
public abstract TermsConsumer addField(FieldInfo field) throws IOException;
/** Called when we are done adding everything. */
public abstract void close() throws IOException;
/** Called during merging to merge all {@link Fields} from
* sub-readers. This must recurse to merge all postings
* (terms, docs, positions, etc.). A {@link
* PostingsFormat} can override this default
* implementation to do its own merging. */
public void merge(MergeState mergeState, Fields fields) throws IOException {
for (String field : fields) {
mergeState.fieldInfo = mergeState.fieldInfos.fieldInfo(field);
assert mergeState.fieldInfo != null : "FieldInfo for field is null: "+ field;
Terms terms = fields.terms(field);
if (terms != null) {
final TermsConsumer termsConsumer = addField(mergeState.fieldInfo);
termsConsumer.merge(mergeState, terms.iterator(null));
}
}
}
}