richardstartin commented on a change in pull request #8016: URL: https://github.com/apache/pinot/pull/8016#discussion_r786580043
########## File path: pinot-segment-local/src/main/java/org/apache/pinot/segment/local/utils/nativefst/utils/RealTimeRegexpMatcher.java ########## @@ -0,0 +1,156 @@ +/** + * 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.pinot.segment.local.utils.nativefst.utils; + +import java.util.ArrayDeque; +import java.util.ArrayList; +import java.util.List; +import java.util.Queue; +import java.util.Set; +import org.apache.pinot.segment.local.utils.nativefst.automaton.Automaton; +import org.apache.pinot.segment.local.utils.nativefst.automaton.CharacterRunAutomaton; +import org.apache.pinot.segment.local.utils.nativefst.automaton.RegExp; +import org.apache.pinot.segment.local.utils.nativefst.automaton.State; +import org.apache.pinot.segment.local.utils.nativefst.automaton.Transition; +import org.apache.pinot.segment.local.utils.nativefst.mutablefst.MutableArc; +import org.apache.pinot.segment.local.utils.nativefst.mutablefst.MutableFST; +import org.apache.pinot.segment.local.utils.nativefst.mutablefst.MutableState; +import org.roaringbitmap.IntConsumer; + +public class RealTimeRegexpMatcher { + private final String _regexQuery; + private final MutableFST _fst; + private final Automaton _automaton; + private final IntConsumer _dest; + + public RealTimeRegexpMatcher(String regexQuery, MutableFST fst, IntConsumer dest) { + _regexQuery = regexQuery; + _fst = fst; + _dest = dest; + + _automaton = new RegExp(_regexQuery).toAutomaton(); + } + + public static void regexMatch(String regexQuery, MutableFST fst, IntConsumer dest) { + RealTimeRegexpMatcher matcher = new RealTimeRegexpMatcher(regexQuery, fst, dest); + matcher.regexMatchOnFST(); + } + + // Matches "input" string with _regexQuery Automaton. + public boolean match(String input) { + CharacterRunAutomaton characterRunAutomaton = new CharacterRunAutomaton(_automaton); + return characterRunAutomaton.run(input); + } + + /** + * This function runs matching on automaton built from regexQuery and the FST. + * FST stores key (string) to a value (Long). Both are state machines and state transition is based on + * a input character. + * + * This algorithm starts with Queue containing (Automaton Start Node, FST Start Node). + * Each step an entry is popped from the queue: + * 1) if the automaton state is accept and the FST Node is final (i.e. end node) then the value stored for that FST + * is added to the set of result. + * 2) Else next set of transitions on automaton are gathered and for each transition target node for that character + * is figured out in FST Node, resulting pair of (automaton state, fst node) are added to the queue. + * 3) This process is bound to complete since we are making progression on the FST (which is a DAG) towards final + * nodes. + */ + public void regexMatchOnFST() { Review comment: @mayankshriv the formatter leaves it up to the author for a few reasons: 1. it's difficult to make the tools enforce a guideline like this only within method bodies - the only tool available is RegexpMultiline which is a blunt instrument 2. it's expensive (in terms of build time) to apply the numerous RegexpMultiline rules necessary 3. A lot of the time, a line _here and there_ makes code more readable (though it usually indicates that the enclosing scope is too large and needs to be broken down), but this PR consistently takes this grey area to the extreme. For instance, consider the constructor below: what do the blank lines mean? Are they intentional? Why is initialising `_pathState` different to `_state`, `_node`, or `_fstArc`? As a peer reviewing this change set, I think it's inconsistent and a waste of screen space. ```java public Path(State state, MutableState node, MutableArc fstArc, List<Character> pathState) { _state = state; _node = node; _fstArc = fstArc; _pathState = pathState; _pathState.add(node.getLabel()); } ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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