package org.apache.lucene.facet.search;
import java.io.IOException;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.util.UnsafeByteArrayInputStream;
import org.apache.lucene.util.encoding.IntDecoder;
/**
* 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.
*/
/**
* A payload deserializer comes with its own working space (buffer). One need to
* define the {@link IndexReader} and {@link Term} in which the payload resides.
* The iterator then consumes the payload information of each document and
* decodes it into categories. A typical use case of this class is:
*
* <pre>
* IndexReader reader = [open your reader];
* Term t = new Term("field", "where-payload-exists");
* CategoryListIterator cli = new PayloadIntDecodingIterator(reader, t);
* if (!cli.init()) {
* // it means there are no payloads / documents associated with that term.
* // Usually a sanity check. However, init() must be called.
* }
* DocIdSetIterator disi = [you usually iterate on something else, such as a Scorer];
* int doc;
* while ((doc = disi.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
* cli.setdoc(doc);
* long category;
* while ((category = cli.nextCategory()) < Integer.MAX_VALUE) {
* }
* }
* </pre>
*
* @lucene.experimental
*/
public class PayloadIntDecodingIterator implements CategoryListIterator {
private final UnsafeByteArrayInputStream ubais;
private final IntDecoder decoder;
private final IndexReader indexReader;
private final Term term;
private final PayloadIterator pi;
private final int hashCode;
public PayloadIntDecodingIterator(IndexReader indexReader, Term term, IntDecoder decoder)
throws IOException {
this(indexReader, term, decoder, new byte[1024]);
}
public PayloadIntDecodingIterator(IndexReader indexReader, Term term, IntDecoder decoder,
byte[] buffer) throws IOException {
pi = new PayloadIterator(indexReader, term, buffer);
ubais = new UnsafeByteArrayInputStream();
this.decoder = decoder;
hashCode = indexReader.hashCode() ^ term.hashCode();
this.term = term;
this.indexReader = indexReader;
}
@Override
public boolean equals(Object other) {
if (!(other instanceof PayloadIntDecodingIterator)) {
return false;
}
PayloadIntDecodingIterator that = (PayloadIntDecodingIterator) other;
if (hashCode != that.hashCode) {
return false;
}
// Hash codes are the same, check equals() to avoid cases of hash-collisions.
return indexReader.equals(that.indexReader) && term.equals(that.term);
}
@Override
public int hashCode() {
return hashCode;
}
public boolean init() throws IOException {
return pi.init();
}
public long nextCategory() throws IOException {
return decoder.decode();
}
public boolean skipTo(int docId) throws IOException {
if (!pi.setdoc(docId)) {
return false;
}
// Initializing the decoding mechanism with the new payload data
ubais.reInit(pi.getBuffer(), 0, pi.getPayloadLength());
decoder.reInit(ubais);
return true;
}
}