Package org.apache.lucene.search

Class FieldComparator.RelevanceComparator

java.lang.Object
org.apache.lucene.search.FieldComparator<Float>
org.apache.lucene.search.FieldComparator.RelevanceComparator
All Implemented Interfaces:
LeafFieldComparator
Enclosing class:
FieldComparator<T>
public static final class FieldComparator.RelevanceComparator extends FieldComparator<Float> implements LeafFieldComparator
Sorts by descending relevance. NOTE: if you are sorting only by descending relevance and then secondarily by ascending docID, performance is faster using TopScoreDocCollector directly (which IndexSearcher.search(org.apache.lucene.search.Query, int) uses when no Sort is specified).

  • Constructor Details

    • RelevanceComparator

      public RelevanceComparator(int numHits)
      Creates a new comparator based on relevance for numHits.

  • Method Details

    • compare

      public int compare(int slot1, int slot2)
      Description copied from class: FieldComparator
      Compare hit at slot1 with hit at slot2.
      Specified by:
      compare in class FieldComparator<Float>
      Parameters:
      slot1 - first slot to compare
      slot2 - second slot to compare
      Returns:
      any N < 0 if slot2's value is sorted after slot1, any N > 0 if the slot2's value is sorted before slot1 and 0 if they are equal

    • compareBottom

      public int compareBottom(int doc) throws IOException
      Description copied from interface: LeafFieldComparator
      Compare the bottom of the queue with this doc. This will only invoked after setBottom has been called. This should return the same result as FieldComparator.compare(int,int)} as if bottom were slot1 and the new document were slot 2.

      For a search that hits many results, this method will be the hotspot (invoked by far the most frequently).

      Specified by:
      compareBottom in interface LeafFieldComparator
      Parameters:
      doc - that was hit
      Returns:
      any N < 0 if the doc's value is sorted after the bottom entry (not competitive), any N > 0 if the doc's value is sorted before the bottom entry and 0 if they are equal.
      Throws:
      IOException

    • copy

      public void copy(int slot, int doc) throws IOException
      Description copied from interface: LeafFieldComparator
      This method is called when a new hit is competitive. You should copy any state associated with this document that will be required for future comparisons, into the specified slot.
      Specified by:
      copy in interface LeafFieldComparator
      Parameters:
      slot - which slot to copy the hit to
      doc - docID relative to current reader
      Throws:
      IOException

    • getLeafComparator

      public LeafFieldComparator getLeafComparator(LeafReaderContext context)
      Description copied from class: FieldComparator
      Get a per-segment LeafFieldComparator to collect the given LeafReaderContext. All docIDs supplied to this LeafFieldComparator are relative to the current reader (you must add docBase if you need to map it to a top-level docID).
      Specified by:
      getLeafComparator in class FieldComparator<Float>
      Parameters:
      context - current reader context
      Returns:
      the comparator to use for this segment

    • setBottom

      public void setBottom(int bottom)
      Description copied from interface: LeafFieldComparator
      Set the bottom slot, ie the "weakest" (sorted last) entry in the queue. When LeafFieldComparator.compareBottom(int) is called, you should compare against this slot. This will always be called before LeafFieldComparator.compareBottom(int).
      Specified by:
      setBottom in interface LeafFieldComparator
      Parameters:
      bottom - the currently weakest (sorted last) slot in the queue

    • setTopValue

      public void setTopValue(Float value)
      Description copied from class: FieldComparator
      Record the top value, for future calls to LeafFieldComparator.compareTop(int). This is only called for searches that use searchAfter (deep paging), and is called before any calls to FieldComparator.getLeafComparator(LeafReaderContext).
      Specified by:
      setTopValue in class FieldComparator<Float>

    • setScorer

      public void setScorer(Scorable scorer)
      Description copied from interface: LeafFieldComparator
      Sets the Scorer to use in case a document's score is needed.
      Specified by:
      setScorer in interface LeafFieldComparator
      Parameters:
      scorer - Scorer instance that you should use to obtain the current hit's score, if necessary.

    • value

      public Float value(int slot)
      Description copied from class: FieldComparator
      Return the actual value in the slot.
      Specified by:
      value in class FieldComparator<Float>
      Parameters:
      slot - the value
      Returns:
      value in this slot

    • compareValues

      public int compareValues(Float first, Float second)
      Description copied from class: FieldComparator
      Returns a negative integer if first is less than second, 0 if they are equal and a positive integer otherwise. Default impl to assume the type implements Comparable and invoke .compareTo; be sure to override this method if your FieldComparator's type isn't a Comparable or if your values may sometimes be null
      Overrides:
      compareValues in class FieldComparator<Float>

    • compareTop

      public int compareTop(int doc) throws IOException
      Description copied from interface: LeafFieldComparator
      Compare the top value with this doc. This will only invoked after setTopValue has been called. This should return the same result as FieldComparator.compare(int,int)} as if topValue were slot1 and the new document were slot 2. This is only called for searches that use searchAfter (deep paging).
      Specified by:
      compareTop in interface LeafFieldComparator
      Parameters:
      doc - that was hit
      Returns:
      any N < 0 if the doc's value is sorted after the top entry (not competitive), any N > 0 if the doc's value is sorted before the top entry and 0 if they are equal.
      Throws:
      IOException