/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.
*/
package org.apache.lucene.search;
import java.io.IOException;
// this is just one possible solution for "early termination" !
/**
* Abstract decorator class of a DocIdSetIterator
* implementation that provides on-demand filter/validation
* mechanism on an underlying DocIdSetIterator.
*/
public abstract class XFilteredDocIdSetIterator extends DocIdSetIterator {
protected DocIdSetIterator _innerIter;
private int doc;
/**
* Constructor.
* @param innerIter Underlying DocIdSetIterator.
*/
public XFilteredDocIdSetIterator(DocIdSetIterator innerIter) {
if (innerIter == null) {
throw new IllegalArgumentException("null iterator");
}
_innerIter = innerIter;
doc = -1;
}
/** Return the wrapped {@link DocIdSetIterator}. */
public DocIdSetIterator getDelegate() {
return _innerIter;
}
/**
* Validation method to determine whether a docid should be in the result set.
* @param doc docid to be tested
* @return true if input docid should be in the result set, false otherwise.
* @see #XFilteredDocIdSetIterator(DocIdSetIterator)
* @throws CollectionTerminatedException if the underlying iterator is exhausted.
*/
protected abstract boolean match(int doc);
@Override
public int docID() {
return doc;
}
@Override
public int nextDoc() throws IOException {
try {
while ((doc = _innerIter.nextDoc()) != NO_MORE_DOCS) {
if (match(doc)) {
return doc;
}
}
} catch (CollectionTerminatedException e) {
return doc = NO_MORE_DOCS;
}
return doc;
}
@Override
public int advance(int target) throws IOException {
doc = _innerIter.advance(target);
try {
if (doc != NO_MORE_DOCS) {
if (match(doc)) {
return doc;
} else {
while ((doc = _innerIter.nextDoc()) != NO_MORE_DOCS) {
if (match(doc)) {
return doc;
}
}
return doc;
}
}
} catch (CollectionTerminatedException e) {
return doc = NO_MORE_DOCS;
}
return doc;
}
@Override
public long cost() {
return _innerIter.cost();
}
}