jpountz commented on a change in pull request #1351: LUCENE-9280: Collectors to skip noncompetitive documents URL: https://github.com/apache/lucene-solr/pull/1351#discussion_r410688437
########## File path: lucene/core/src/java/org/apache/lucene/search/FilteringFieldComparator.java ########## @@ -0,0 +1,350 @@ +/* + * 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. + */ +package org.apache.lucene.search; + +import org.apache.lucene.document.LongPoint; +import org.apache.lucene.document.IntPoint; +import org.apache.lucene.document.DoublePoint; +import org.apache.lucene.document.FloatPoint; +import org.apache.lucene.index.LeafReaderContext; +import org.apache.lucene.index.PointValues; +import org.apache.lucene.util.DocIdSetBuilder; + +import java.io.IOException; +import java.util.Arrays; + +/** + * Decorates a wrapped FieldComparator to add a functionality to skip over non-competitive docs. + * FilteringFieldComparator provides two additional functions for a FieldComparator: + * 1) {@code competitiveIterator()} that returns an iterator over + * competitive docs that are stronger than already collected docs. + * 2) {@code setCanUpdateIterator()} that notifies the comparator when it is ok to start updating its internal iterator. + * This method is called from a collector to inform the comparator to start updating its iterator. + */ +public abstract class FilteringFieldComparator<T> extends FieldComparator<T> { + final FieldComparator<T> in; + protected DocIdSetIterator iterator = null; + + public FilteringFieldComparator(FieldComparator<T> in) { + this.in = in; + } + + protected abstract void setCanUpdateIterator() throws IOException; + + @Override + public int compare(int slot1, int slot2) { + return in.compare(slot1, slot2); + } + + @Override + public T value(int slot) { + return in.value(slot); + } + + @Override + public void setTopValue(T value) { + in.setTopValue(value); + } + + @Override + public int compareValues(T first, T second) { + return in.compareValues(first, second); + } + + /** + * Returns an iterator over competitive documents + */ + public DocIdSetIterator competitiveIterator() { + if (iterator == null) return null; + return new DocIdSetIterator() { + private int doc; + @Override + public int nextDoc() throws IOException { + return doc = iterator.nextDoc(); + } + + @Override + public int docID() { + return doc; + } + + @Override + public long cost() { + return iterator.cost(); + } + + @Override + public int advance(int target) throws IOException { + return doc = iterator.advance(target); + } + }; + } + + /** + * Try to wrap a given field comparator to add to it a functionality to skip over non-competitive docs. + * If for the given comparator the skip functionality is not implemented, return the comparator itself. + */ + public static FieldComparator<?> wrapToFilteringComparator(FieldComparator<?> comparator, boolean reverse) { + if (comparator instanceof FieldComparator.LongComparator){ + return new FilteringFieldComparator.FilteringLongComparator((FieldComparator.LongComparator) comparator, reverse); + } + if (comparator instanceof FieldComparator.IntComparator){ + return new FilteringFieldComparator.FilteringIntComparator((FieldComparator.IntComparator) comparator, reverse); + } + if (comparator instanceof FieldComparator.DoubleComparator){ + return new FilteringFieldComparator.FilteringDoubleComparator((FieldComparator.DoubleComparator) comparator, reverse); + } + if (comparator instanceof FieldComparator.FloatComparator){ + return new FilteringFieldComparator.FilteringFloatComparator((FieldComparator.FloatComparator) comparator, reverse); + } + return comparator; + } + + /** + * A wrapper over {@code NumericComparator} that adds a functionality to filter non-competitive docs. + */ + public static abstract class FilteringNumericComparator<T extends Number> extends FilteringFieldComparator<T> implements LeafFieldComparator { Review comment: I know some existing comparators do this but it'd be cleaner to not implement FieldComparator and LeafFieldComparator in the same class? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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