javanna commented on a change in pull request #581: LUCENE-3041: QueryVisitor URL: https://github.com/apache/lucene-solr/pull/581#discussion_r260325064
########## File path: lucene/core/src/java/org/apache/lucene/search/QueryVisitor.java ########## @@ -0,0 +1,80 @@ +/* + * 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 java.util.Set; + +import org.apache.lucene.index.Term; + +/** + * Allows recursion through a query tree + * + * @see Query#visit(QueryVisitor) + */ +public abstract class QueryVisitor { + + /** + * Called by leaf queries that match on a specific term + * + * @param query the leaf query + * @param term the term the query will match on + */ + public void consumesTerm(Query query, Term term) { } + + /** + * Called by leaf queries that do not match on terms + * @param query the query + */ + public void visitLeaf(Query query) { } Review comment: Not knowing all the internals of this and their potential future usages, I am looking at the API mainly and I have a couple of questions: - should all compound queries have their corresponding `visit` method which calls `getSubVisitor` for each of their sub-query? - when should `visitLeaf` be used compared to `consumeTerms`? I understand from the javadocs above that there are queries which are not compound queries but don't hold terms either. If so what would query visitors generally do in their `visitLeaf` impl? I think I am getting to whether `consumesTerm` and `visitLeaf` could be combined together somehow. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
