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https://issues.apache.org/jira/browse/LUCENE-7526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15616611#comment-15616611
]
ASF GitHub Bot commented on LUCENE-7526:
----------------------------------------
Github user Timothy055 commented on a diff in the pull request:
https://github.com/apache/lucene-solr/pull/105#discussion_r85611673
--- Diff:
lucene/highlighter/src/java/org/apache/lucene/search/uhighlight/CompositePostingsEnum.java
---
@@ -0,0 +1,165 @@
+/*
+ * 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.uhighlight;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.apache.lucene.index.PostingsEnum;
+import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.PriorityQueue;
+
+
+final class CompositePostingsEnum extends PostingsEnum {
+
+ private static final int NO_MORE_POSITIONS = -2;
+ private final BytesRef term;
+ private final int freq;
+ private final PriorityQueue<BoundsCheckingPostingsEnum> queue;
+
+
+ /**
+ * This class is used to ensure we don't over iterate the underlying
+ * postings enum by keeping track of the position relative to the
+ * frequency.
+ * Ideally this would've been an implementation of a PostingsEnum
+ * but it would have to delegate most methods and it seemed easier
+ * to just wrap the tweaked method.
+ */
+ private static final class BoundsCheckingPostingsEnum {
+
+
+ private final PostingsEnum postingsEnum;
+ private final int freq;
+ private int position;
+ private int nextPosition;
+ private int positionInc = 1;
+
+ private int startOffset;
--- End diff --
I thought the same, but unfortunately there's no way to check the current
position of the underlying PostingsEnum before calling nextPosition. Since we
call nextPosition the PostingsEnum has moved on before the highlighter calls
startOffset or endOffset.
> Improvements to UnifiedHighlighter OffsetStrategies
> ---------------------------------------------------
>
> Key: LUCENE-7526
> URL: https://issues.apache.org/jira/browse/LUCENE-7526
> Project: Lucene - Core
> Issue Type: Improvement
> Components: modules/highlighter
> Reporter: Timothy M. Rodriguez
> Assignee: David Smiley
> Priority: Minor
> Fix For: 6.4
>
>
> This ticket improves several of the UnifiedHighlighter FieldOffsetStrategies
> by reducing reliance on creating or re-creating TokenStreams.
> The primary changes are as follows:
> * AnalysisOffsetStrategy - split into two offset strategies
> ** MemoryIndexOffsetStrategy - the primary analysis mode that utilizes a
> MemoryIndex for producing Offsets
> ** TokenStreamOffsetStrategy - an offset strategy that avoids creating a
> MemoryIndex. Can only be used if the query distills down to terms and
> automata.
> * TokenStream removal
> ** MemoryIndexOffsetStrategy - previously a TokenStream was created to fill
> the memory index and then once consumed a new one was generated by
> uninverting the MemoryIndex back into a TokenStream if there were automata
> (wildcard/mtq queries) involved. Now this is avoided, which should save
> memory and avoid a second pass over the data.
> ** TermVectorOffsetStrategy - this was refactored in a similar way to avoid
> generating a TokenStream if automata are involved.
> ** PostingsWithTermVectorsOffsetStrategy - similar refactoring
> * CompositePostingsEnum - aggregates several underlying PostingsEnums for
> wildcard/mtq queries. This should improve relevancy by providing unified
> metrics for a wildcard across all it's term matches
> * Added a HighlightFlag for enabling the newly separated
> TokenStreamOffsetStrategy since it can adversely affect passage relevancy
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