Add 'passageSortComparator' option in FieldHighlighter

lucene/CHANGES.txt

@@ -298,6 +298,8 @@ Improvements
 * GITHUB#13385: Add Intervals.noIntervals() method to produce an empty IntervalsSource.
  (Aniketh Jain, Uwe Schindler, Alan Woodward))
 
+* GITHUB#13276: UnifiedHighlighter: new 'passageSortComparator' option to allow sorting other than offset order. (Seunghan Jung)
+
 Optimizations
 ---------------------
 

lucene/highlighter/src/java/org/apache/lucene/search/uhighlight/FieldHighlighter.java

@@ -40,6 +40,7 @@ public class FieldHighlighter {
  protected final int maxPassages;
  protected final int maxNoHighlightPassages;
  protected final PassageFormatter passageFormatter;
+ protected final Comparator<Passage> passageSortComparator;
 
  public FieldHighlighter(
  String field,
@@ -48,14 +49,16 @@ public FieldHighlighter(
  PassageScorer passageScorer,
  int maxPassages,
  int maxNoHighlightPassages,
- PassageFormatter passageFormatter) {
+ PassageFormatter passageFormatter,
+ Comparator<Passage> passageSortComparator) {
  this.field = field;
  this.fieldOffsetStrategy = fieldOffsetStrategy;
  this.breakIterator = breakIterator;
  this.passageScorer = passageScorer;
  this.maxPassages = maxPassages;
  this.maxNoHighlightPassages = maxNoHighlightPassages;
  this.passageFormatter = passageFormatter;
+ this.passageSortComparator = passageSortComparator;
  }
 
  public String getField() {
@@ -191,8 +194,7 @@ protected Passage[] highlightOffsetsEnums(OffsetsEnum off) throws IOException {
  maybeAddPassage(passageQueue, passageScorer, passage, contentLength);
 
  Passage[] passages = passageQueue.toArray(new Passage[passageQueue.size()]);
- // sort in ascending order
- Arrays.sort(passages, Comparator.comparingInt(Passage::getStartOffset));
+ Arrays.sort(passages, passageSortComparator);
  return passages;
  }
 

lucene/highlighter/src/java/org/apache/lucene/search/uhighlight/UnifiedHighlighter.java

@@ -21,6 +21,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Comparator;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -86,6 +87,7 @@
  * <li>{@link #getBreakIterator(String)}: Customize how the text is divided into passages.
  * <li>{@link #getScorer(String)}: Customize how passages are ranked.
  * <li>{@link #getFormatter(String)}: Customize how snippets are formatted.
+ * <li>{@link #getPassageSortComparator(String)}: Customize how snippets are formatted.
  * </ul>
  *
  * <p>This is thread-safe, notwithstanding the setters.
@@ -113,6 +115,8 @@ public class UnifiedHighlighter {
  private static final PassageScorer DEFAULT_PASSAGE_SCORER = new PassageScorer();
  private static final PassageFormatter DEFAULT_PASSAGE_FORMATTER = new DefaultPassageFormatter();
  private static final int DEFAULT_MAX_HIGHLIGHT_PASSAGES = -1;
+ private static final Comparator<Passage> DEFAULT_PASSAGE_SORT_COMPARATOR =
+ Comparator.comparingInt(Passage::getStartOffset);
 
  protected final IndexSearcher searcher; // if null, can only use highlightWithoutSearcher
 
@@ -151,6 +155,8 @@ public class UnifiedHighlighter {
 
  private int cacheFieldValCharsThreshold = DEFAULT_CACHE_CHARS_THRESHOLD;
 
+ private Comparator<Passage> passageSortComparator = DEFAULT_PASSAGE_SORT_COMPARATOR;
+
  /**
  * Constructs the highlighter with the given index searcher and analyzer.
  *
@@ -276,6 +282,7 @@ public static class Builder {
  private PassageFormatter formatter = DEFAULT_PASSAGE_FORMATTER;
  private int maxNoHighlightPassages = DEFAULT_MAX_HIGHLIGHT_PASSAGES;
  private int cacheFieldValCharsThreshold = DEFAULT_CACHE_CHARS_THRESHOLD;
+ private Comparator<Passage> passageSortComparator = DEFAULT_PASSAGE_SORT_COMPARATOR;
 
  /**
  * Constructor for UH builder which accepts {@link IndexSearcher} and {@link Analyzer} objects.
@@ -402,6 +409,11 @@ public Builder withCacheFieldValCharsThreshold(int value) {
  return this;
  }
 
+ public Builder withPassageSortComparator(Comparator<Passage> value) {
+ this.passageSortComparator = value;
+ return this;
+ }
+
  public UnifiedHighlighter build() {
  return new UnifiedHighlighter(this);
  }
@@ -463,6 +475,7 @@ public UnifiedHighlighter(Builder builder) {
  this.formatter = builder.formatter;
  this.maxNoHighlightPassages = builder.maxNoHighlightPassages;
  this.cacheFieldValCharsThreshold = builder.cacheFieldValCharsThreshold;
+ this.passageSortComparator = builder.passageSortComparator;
  }
 
  /** Extracts matching terms */
@@ -614,6 +627,11 @@ protected PassageFormatter getFormatter(String field) {
  return formatter;
  }
 
+ /** Returns the {@link Comparator} to use for finally sorting passages. */
+ protected Comparator<Passage> getPassageSortComparator(String field) {
+ return passageSortComparator;
+ }
+
  /**
  * Returns the number of leading passages (as delineated by the {@link BreakIterator}) when no
  * highlights could be found. If it's less than 0 (the default) then this defaults to the {@code
@@ -1119,7 +1137,8 @@ protected FieldHighlighter getFieldHighlighter(
  getScorer(field),
  maxPassages,
  getMaxNoHighlightPassages(field),
- getFormatter(field));
+ getFormatter(field),
+ getPassageSortComparator(field));
  }
 
  protected FieldHighlighter newFieldHighlighter(
@@ -1129,15 +1148,17 @@ protected FieldHighlighter newFieldHighlighter(
  PassageScorer passageScorer,
  int maxPassages,
  int maxNoHighlightPassages,
- PassageFormatter passageFormatter) {
+ PassageFormatter passageFormatter,
+ Comparator<Passage> passageSortComparator) {
  return new FieldHighlighter(
  field,
  fieldOffsetStrategy,
  breakIterator,
  passageScorer,
  maxPassages,
  maxNoHighlightPassages,
- passageFormatter);
+ passageFormatter,
+ passageSortComparator);
  }
 
  protected UHComponents getHighlightComponents(String field, Query query, Set<Term> allTerms) {

lucene/highlighter/src/test/org/apache/lucene/search/uhighlight/visibility/TestUnifiedHighlighterExtensibility.java

@@ -20,6 +20,7 @@
 import java.io.IOException;
 import java.text.BreakIterator;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -129,6 +130,11 @@ protected PassageFormatter getFormatter(String field) {
  return super.getFormatter(field);
  }
 
+ @Override
+ protected Comparator<Passage> getPassageSortComparator(String field) {
+ return super.getPassageSortComparator(field);
+ }
+
  @Override
  public Analyzer getIndexAnalyzer() {
  return super.getIndexAnalyzer();
@@ -186,7 +192,8 @@ protected FieldHighlighter getFieldHighlighter(
  getScorer(field),
  maxPassages,
  getMaxNoHighlightPassages(field),
- getFormatter(field));
+ getFormatter(field),
+ getPassageSortComparator(field));
  }
 
  @Override
@@ -240,7 +247,7 @@ public Object format(Passage[] passages, String content) {
  public void testFieldHiglighterExtensibility() {
  final String fieldName = "fieldName";
  FieldHighlighter fieldHighlighter =
- new FieldHighlighter(fieldName, null, null, null, 1, 1, null) {
+ new FieldHighlighter(fieldName, null, null, null, 1, 1, null, null) {
  @Override
  protected Passage[] highlightOffsetsEnums(OffsetsEnum offsetsEnums) throws IOException {
  return super.highlightOffsetsEnums(offsetsEnums);
@@ -262,15 +269,17 @@ protected static class CustomFieldHighlighter extends FieldHighlighter {
  PassageScorer passageScorer,
  int maxPassages,
  int maxNoHighlightPassages,
- PassageFormatter passageFormatter) {
+ PassageFormatter passageFormatter,
+ Comparator<Passage> passageSortComparator) {
  super(
  field,
  fieldOffsetStrategy,
  breakIterator,
  passageScorer,
  maxPassages,
  maxNoHighlightPassages,
- passageFormatter);
+ passageFormatter,
+ passageSortComparator);
  }
 
  @Override