/*
* 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.facet.sortedset;
import java.io.IOException;
import java.util.Map;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.SortedSetDocValues;
import org.apache.lucene.util.Accountable;
/** Wraps a {@link IndexReader} and resolves ords
* using existing {@link SortedSetDocValues} APIs without a
* separate taxonomy index. This only supports flat facets
* (dimension + label), and it makes faceting a bit
* slower, adds some cost at reopen time, but avoids
* managing the separate taxonomy index. It also requires
* less RAM than the taxonomy index, as it manages the flat
* (2-level) hierarchy more efficiently. In addition, the
* tie-break during faceting is now meaningful (in label
* sorted order).
*
* <p><b>NOTE</b>: creating an instance of this class is
* somewhat costly, as it computes per-segment ordinal maps,
* so you should create it once and re-use that one instance
* for a given {@link IndexReader}. */
public abstract class SortedSetDocValuesReaderState implements Accountable {
/** Holds start/end range of ords, which maps to one
* dimension (someday we may generalize it to map to
* hierarchies within one dimension). */
public static final class OrdRange {
/** Start of range, inclusive: */
public final int start;
/** End of range, inclusive: */
public final int end;
/** Start and end are inclusive. */
public OrdRange(int start, int end) {
this.start = start;
this.end = end;
}
}
/** Sole constructor. */
protected SortedSetDocValuesReaderState() {
}
/** Return top-level doc values. */
public abstract SortedSetDocValues getDocValues() throws IOException;
/** Indexed field we are reading. */
public abstract String getField();
/** Returns the {@link OrdRange} for this dimension. */
public abstract OrdRange getOrdRange(String dim);
/** Returns mapping from prefix to {@link OrdRange}. */
public abstract Map<String,OrdRange> getPrefixToOrdRange();
/** Returns top-level index reader. */
public abstract IndexReader getReader();
/** Number of unique labels. */
public abstract int getSize();
}