| /* |
| * 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.solr.ltr.feature; |
| |
| import java.io.IOException; |
| import java.util.LinkedHashMap; |
| import java.util.Map; |
| |
| import org.apache.lucene.index.IndexableField; |
| import org.apache.lucene.index.LeafReaderContext; |
| import org.apache.lucene.index.NumericDocValues; |
| import org.apache.lucene.search.DocIdSetIterator; |
| import org.apache.lucene.search.IndexSearcher; |
| import org.apache.lucene.search.Query; |
| import org.apache.lucene.util.SmallFloat; |
| import org.apache.solr.request.SolrQueryRequest; |
| /** |
| * This feature returns the length of a field (in terms) for the current document. |
| * Example configuration: |
| * <pre>{ |
| "name": "titleLength", |
| "class": "org.apache.solr.ltr.feature.FieldLengthFeature", |
| "params": { |
| "field": "title" |
| } |
| }</pre> |
| * Note: since this feature relies on norms values that are stored in a single byte |
| * the value of the feature could have a lightly different value. |
| * (see also {@link org.apache.lucene.search.similarities.ClassicSimilarity}) |
| **/ |
| public class FieldLengthFeature extends Feature { |
| |
| private String field; |
| |
| public String getField() { |
| return field; |
| } |
| |
| public void setField(String field) { |
| this.field = field; |
| } |
| |
| @Override |
| public LinkedHashMap<String,Object> paramsToMap() { |
| final LinkedHashMap<String,Object> params = defaultParamsToMap(); |
| params.put("field", field); |
| return params; |
| } |
| |
| @Override |
| protected void validate() throws FeatureException { |
| if (field == null || field.isEmpty()) { |
| throw new FeatureException(getClass().getSimpleName()+ |
| ": field must be provided"); |
| } |
| } |
| |
| /** Cache of decoded bytes. */ |
| |
| private static final float[] NORM_TABLE = new float[256]; |
| |
| static { |
| NORM_TABLE[0] = 0; |
| for (int i = 1; i < 256; i++) { |
| NORM_TABLE[i] = SmallFloat.byte4ToInt((byte) i); |
| } |
| } |
| |
| /** |
| * Decodes the norm value, assuming it is a single byte. |
| * |
| */ |
| |
| private final float decodeNorm(long norm) { |
| return NORM_TABLE[(int) (norm & 0xFF)]; // & 0xFF maps negative bytes to |
| // positive above 127 |
| } |
| |
| public FieldLengthFeature(String name, Map<String,Object> params) { |
| super(name, params); |
| } |
| |
| @Override |
| public FeatureWeight createWeight(IndexSearcher searcher, boolean needsScores, |
| SolrQueryRequest request, Query originalQuery, Map<String,String[]> efi) |
| throws IOException { |
| |
| return new FieldLengthFeatureWeight(searcher, request, originalQuery, efi); |
| } |
| |
| |
| public class FieldLengthFeatureWeight extends FeatureWeight { |
| |
| public FieldLengthFeatureWeight(IndexSearcher searcher, |
| SolrQueryRequest request, Query originalQuery, Map<String,String[]> efi) { |
| super(FieldLengthFeature.this, searcher, request, originalQuery, efi); |
| } |
| |
| @Override |
| public FeatureScorer scorer(LeafReaderContext context) throws IOException { |
| NumericDocValues norms = context.reader().getNormValues(field); |
| if (norms == null){ |
| return new ValueFeatureScorer(this, 0f, |
| DocIdSetIterator.all(DocIdSetIterator.NO_MORE_DOCS)); |
| } |
| return new FieldLengthFeatureScorer(this, norms); |
| } |
| |
| public class FieldLengthFeatureScorer extends FeatureScorer { |
| |
| NumericDocValues norms = null; |
| |
| public FieldLengthFeatureScorer(FeatureWeight weight, |
| NumericDocValues norms) throws IOException { |
| super(weight, norms); |
| this.norms = norms; |
| |
| // In the constructor, docId is -1, so using 0 as default lookup |
| final IndexableField idxF = searcher.doc(0).getField(field); |
| if (idxF.fieldType().omitNorms()) { |
| throw new IOException( |
| "FieldLengthFeatures can't be used if omitNorms is enabled (field=" |
| + field + ")"); |
| } |
| } |
| |
| @Override |
| public float score() throws IOException { |
| |
| final long l = norms.longValue(); |
| final float numTerms = decodeNorm(l); |
| return numTerms; |
| } |
| |
| @Override |
| public float getMaxScore(int upTo) throws IOException { |
| return Float.POSITIVE_INFINITY; |
| } |
| } |
| } |
| |
| } |