/*
 * 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.
 */

/**
 * Faceted search.
 *
 * <p>This module provides multiple methods for computing facet counts and value aggregations:
 *
 * <ul>
 *   <li>Taxonomy-based methods rely on a separate taxonomy index to map hierarchical facet paths to
 *       global int ordinals for fast counting at search time; these methods can compute counts
 *       (({@link org.apache.lucene.facet.taxonomy.FastTaxonomyFacetCounts}, {@link
 *       org.apache.lucene.facet.taxonomy.TaxonomyFacetCounts}) aggregate long or double values
 *       {@link org.apache.lucene.facet.taxonomy.TaxonomyFacetIntAssociations}, {@link
 *       org.apache.lucene.facet.taxonomy.TaxonomyFacetFloatAssociations}. Add {@link
 *       org.apache.lucene.facet.FacetField} or {@link
 *       org.apache.lucene.facet.taxonomy.AssociationFacetField} to your documents at index time to
 *       use taxonomy-based methods.
 *   <li>Sorted-set doc values method does not require a separate taxonomy index, and computes
 *       counts based on sorted set doc values fields ({@link
 *       org.apache.lucene.facet.sortedset.SortedSetDocValuesFacetCounts}). Add {@link
 *       org.apache.lucene.facet.sortedset.SortedSetDocValuesFacetField} to your documents at index
 *       time to use sorted set facet counts.
 *   <li>Range faceting {@link org.apache.lucene.facet.range.LongRangeFacetCounts}, {@link
 *       org.apache.lucene.facet.range.DoubleRangeFacetCounts} compute counts for a dynamic numeric
 *       range from a provided {@link org.apache.lucene.search.LongValuesSource} (previously indexed
 *       numeric field, or a dynamic expression such as distance).
 * </ul>
 *
 * <p>At search time you first run your search, but pass a {@link
 * org.apache.lucene.facet.FacetsCollector} to gather all hits (and optionally, scores for each
 * hit). Then, instantiate whichever facet methods you'd like to use to compute aggregates. Finally,
 * all methods implement a common {@link org.apache.lucene.facet.Facets} base API that you use to
 * obtain specific facet counts.
 *
 * <p>The various {@link org.apache.lucene.facet.FacetsCollector#search} utility methods are useful
 * for doing an "ordinary" search (sorting by score, or by a specified Sort) but also collecting
 * into a {@link org.apache.lucene.facet.FacetsCollector} for subsequent faceting.
 */
package org.apache.lucene.facet;
