| package org.apache.lucene.search; |
| |
| /* |
| * 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.Collection; |
| import java.util.Collections; |
| |
| /** A Scorer for queries with a required subscorer |
| * and an excluding (prohibited) sub {@link Scorer}. |
| * <br> |
| * This <code>Scorer</code> implements {@link Scorer#advance(int)}, |
| * and it uses the advance() on the given scorers. |
| */ |
| class ReqExclScorer extends Scorer { |
| |
| private final Scorer reqScorer; |
| // approximations of the scorers, or the scorers themselves if they don't support approximations |
| private final DocIdSetIterator reqApproximation; |
| private final DocIdSetIterator exclApproximation; |
| // two-phase views of the scorers, or null if they do not support approximations |
| private final TwoPhaseIterator reqTwoPhaseIterator; |
| private final TwoPhaseIterator exclTwoPhaseIterator; |
| |
| /** Construct a <code>ReqExclScorer</code>. |
| * @param reqScorer The scorer that must match, except where |
| * @param exclScorer indicates exclusion. |
| */ |
| public ReqExclScorer(Scorer reqScorer, Scorer exclScorer) { |
| super(reqScorer.weight); |
| this.reqScorer = reqScorer; |
| reqTwoPhaseIterator = reqScorer.asTwoPhaseIterator(); |
| if (reqTwoPhaseIterator == null) { |
| reqApproximation = reqScorer; |
| } else { |
| reqApproximation = reqTwoPhaseIterator.approximation(); |
| } |
| exclTwoPhaseIterator = exclScorer.asTwoPhaseIterator(); |
| if (exclTwoPhaseIterator == null) { |
| exclApproximation = exclScorer; |
| } else { |
| exclApproximation = exclTwoPhaseIterator.approximation(); |
| } |
| } |
| |
| @Override |
| public int nextDoc() throws IOException { |
| return toNonExcluded(reqApproximation.nextDoc()); |
| } |
| |
| /** Confirms whether or not the given {@link TwoPhaseIterator} |
| * matches on the current document. */ |
| private static boolean matches(TwoPhaseIterator it) throws IOException { |
| return it == null || it.matches(); |
| } |
| |
| /** Confirm whether there is a match given the current positions of the |
| * req and excl approximations. This method has 2 important properties: |
| * - it only calls matches() on excl if the excl approximation is on |
| * the same doc ID as the req approximation |
| * - it does NOT call matches() on req if the excl approximation is exact |
| * and is on the same doc ID as the req approximation */ |
| private static boolean matches(int doc, int exclDoc, |
| TwoPhaseIterator reqTwoPhaseIterator, |
| TwoPhaseIterator exclTwoPhaseIterator) throws IOException { |
| assert exclDoc >= doc; |
| if (doc == exclDoc && matches(exclTwoPhaseIterator)) { |
| return false; |
| } |
| return matches(reqTwoPhaseIterator); |
| } |
| |
| /** Advance to the next non-excluded doc. */ |
| private int toNonExcluded(int doc) throws IOException { |
| int exclDoc = exclApproximation.docID(); |
| for (;; doc = reqApproximation.nextDoc()) { |
| if (doc == NO_MORE_DOCS) { |
| return NO_MORE_DOCS; |
| } |
| if (exclDoc < doc) { |
| exclDoc = exclApproximation.advance(doc); |
| } |
| if (matches(doc, exclDoc, reqTwoPhaseIterator, exclTwoPhaseIterator)) { |
| return doc; |
| } |
| } |
| } |
| |
| @Override |
| public int docID() { |
| return reqScorer.docID(); |
| } |
| |
| @Override |
| public int freq() throws IOException { |
| return reqScorer.freq(); |
| } |
| |
| @Override |
| public long cost() { |
| return reqScorer.cost(); |
| } |
| |
| @Override |
| public float score() throws IOException { |
| return reqScorer.score(); // reqScorer may be null when next() or skipTo() already return false |
| } |
| |
| @Override |
| public Collection<ChildScorer> getChildren() { |
| return Collections.singleton(new ChildScorer(reqScorer, "MUST")); |
| } |
| |
| @Override |
| public int advance(int target) throws IOException { |
| return toNonExcluded(reqApproximation.advance(target)); |
| } |
| |
| @Override |
| public TwoPhaseIterator asTwoPhaseIterator() { |
| if (reqTwoPhaseIterator == null) { |
| return null; |
| } |
| return new TwoPhaseIterator(reqApproximation) { |
| |
| @Override |
| public boolean matches() throws IOException { |
| final int doc = reqApproximation.docID(); |
| // check if the doc is not excluded |
| int exclDoc = exclApproximation.docID(); |
| if (exclDoc < doc) { |
| exclDoc = exclApproximation.advance(doc); |
| } |
| return ReqExclScorer.matches(doc, exclDoc, reqTwoPhaseIterator, exclTwoPhaseIterator); |
| } |
| |
| @Override |
| public float matchCost() { |
| return reqTwoPhaseIterator.matchCost(); // TODO: also use cost of exclApproximation.advance() |
| } |
| }; |
| } |
| } |