+++ /dev/null
-package org.apache.lucene.search.highlight;
-/**
- * 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.
- */
-
-import java.io.IOException;
-import java.util.HashSet;
-import java.util.Iterator;
-
-import org.apache.lucene.index.IndexReader;
-import org.apache.lucene.index.Term;
-import org.apache.lucene.search.BooleanClause;
-import org.apache.lucene.search.BooleanQuery;
-import org.apache.lucene.search.FilteredQuery;
-import org.apache.lucene.search.Query;
-import org.apache.lucene.util.StringHelper;
-
-/**
- * Utility class used to extract the terms used in a query, plus any weights.
- * This class will not find terms for MultiTermQuery, TermRangeQuery and PrefixQuery classes
- * so the caller must pass a rewritten query (see Query.rewrite) to obtain a list of
- * expanded terms.
- *
- */
-public final class QueryTermExtractor
-{
-
- /**
- * Extracts all terms texts of a given Query into an array of WeightedTerms
- *
- * @param query Query to extract term texts from
- * @return an array of the terms used in a query, plus their weights.
- */
- public static final WeightedTerm[] getTerms(Query query)
- {
- return getTerms(query,false);
- }
-
- /**
- * Extracts all terms texts of a given Query into an array of WeightedTerms
- *
- * @param query Query to extract term texts from
- * @param reader used to compute IDF which can be used to a) score selected fragments better
- * b) use graded highlights eg changing intensity of font color
- * @param fieldName the field on which Inverse Document Frequency (IDF) calculations are based
- * @return an array of the terms used in a query, plus their weights.
- */
- public static final WeightedTerm[] getIdfWeightedTerms(Query query, IndexReader reader, String fieldName)
- {
- WeightedTerm[] terms=getTerms(query,false, fieldName);
- int totalNumDocs=reader.numDocs();
- for (int i = 0; i < terms.length; i++)
- {
- try
- {
- int docFreq=reader.docFreq(new Term(fieldName,terms[i].term));
- // docFreq counts deletes
- if(totalNumDocs < docFreq) {
- docFreq = totalNumDocs;
- }
- //IDF algorithm taken from DefaultSimilarity class
- float idf=(float)(Math.log((float)totalNumDocs/(double)(docFreq+1)) + 1.0);
- terms[i].weight*=idf;
- }
- catch (IOException e)
- {
- //ignore
- }
- }
- return terms;
- }
-
- /**
- * Extracts all terms texts of a given Query into an array of WeightedTerms
- *
- * @param query Query to extract term texts from
- * @param prohibited <code>true</code> to extract "prohibited" terms, too
- * @param fieldName The fieldName used to filter query terms
- * @return an array of the terms used in a query, plus their weights.
- */
- public static final WeightedTerm[] getTerms(Query query, boolean prohibited, String fieldName)
- {
- HashSet<WeightedTerm> terms=new HashSet<WeightedTerm>();
- if(fieldName!=null)
- {
- fieldName= StringHelper.intern(fieldName);
- }
- getTerms(query,terms,prohibited,fieldName);
- return terms.toArray(new WeightedTerm[0]);
- }
-
- /**
- * Extracts all terms texts of a given Query into an array of WeightedTerms
- *
- * @param query Query to extract term texts from
- * @param prohibited <code>true</code> to extract "prohibited" terms, too
- * @return an array of the terms used in a query, plus their weights.
- */
- public static final WeightedTerm[] getTerms(Query query, boolean prohibited)
- {
- return getTerms(query,prohibited,null);
- }
-
- //fieldname MUST be interned prior to this call
- private static final void getTerms(Query query, HashSet<WeightedTerm> terms,boolean prohibited, String fieldName)
- {
- try
- {
- if (query instanceof BooleanQuery)
- getTermsFromBooleanQuery((BooleanQuery) query, terms, prohibited, fieldName);
- else
- if(query instanceof FilteredQuery)
- getTermsFromFilteredQuery((FilteredQuery)query, terms,prohibited, fieldName);
- else
- {
- HashSet<Term> nonWeightedTerms=new HashSet<Term>();
- query.extractTerms(nonWeightedTerms);
- for (Iterator<Term> iter = nonWeightedTerms.iterator(); iter.hasNext();)
- {
- Term term = iter.next();
- if((fieldName==null)||(term.field()==fieldName))
- {
- terms.add(new WeightedTerm(query.getBoost(),term.text()));
- }
- }
- }
- }
- catch(UnsupportedOperationException ignore)
- {
- //this is non-fatal for our purposes
- }
- }
-
- /**
- * extractTerms is currently the only query-independent means of introspecting queries but it only reveals
- * a list of terms for that query - not the boosts each individual term in that query may or may not have.
- * "Container" queries such as BooleanQuery should be unwrapped to get at the boost info held
- * in each child element.
- * Some discussion around this topic here:
- * http://www.gossamer-threads.com/lists/lucene/java-dev/34208?search_string=introspection;#34208
- * Unfortunately there seemed to be limited interest in requiring all Query objects to implement
- * something common which would allow access to child queries so what follows here are query-specific
- * implementations for accessing embedded query elements.
- */
- private static final void getTermsFromBooleanQuery(BooleanQuery query, HashSet<WeightedTerm> terms, boolean prohibited, String fieldName)
- {
- BooleanClause[] queryClauses = query.getClauses();
- for (int i = 0; i < queryClauses.length; i++)
- {
- if (prohibited || queryClauses[i].getOccur()!=BooleanClause.Occur.MUST_NOT)
- getTerms(queryClauses[i].getQuery(), terms, prohibited, fieldName);
- }
- }
- private static void getTermsFromFilteredQuery(FilteredQuery query, HashSet<WeightedTerm> terms, boolean prohibited, String fieldName)
- {
- getTerms(query.getQuery(),terms,prohibited,fieldName);
- }
-
-}
fnp / pylucene.git / blobdiff