Package org.apache.lucene.queries.spans

Class Spans

java.lang.Object
org.apache.lucene.search.DocIdSetIterator
org.apache.lucene.queries.spans.Spans
Direct Known Subclasses:
FilterSpans, NearSpansOrdered, NearSpansUnordered, TermSpans
public abstract class Spans extends DocIdSetIterator
Iterates through combinations of start/end positions per-doc. Each start/end position represents a range of term positions within the current document. These are enumerated in order, by increasing document number, within that by increasing start position and finally by increasing end position.

  • Field Details

  • Constructor Details

    • Spans

      public Spans()

  • Method Details

    • nextStartPosition

      public abstract int nextStartPosition() throws IOException
      Returns the next start position for the current doc. There is always at least one start/end position per doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.
      Throws:
      IOException

    • startPosition

      public abstract int startPosition()
      Returns the start position in the current doc, or -1 when nextStartPosition() was not yet called on the current doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.

    • endPosition

      public abstract int endPosition()
      Returns the end position for the current start position, or -1 when nextStartPosition() was not yet called on the current doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.

    • width

      public abstract int width()
      Return the width of the match, which is typically used to sloppy freq. It is only legal to call this method when the iterator is on a valid doc ID and positioned. The return value must be positive, and lower values means that the match is better.

    • collect

      public abstract void collect(SpanCollector collector) throws IOException
      Collect postings data from the leaves of the current Spans.

      This method should only be called after nextStartPosition(), and before NO_MORE_POSITIONS has been reached.

      Parameters:
      collector - a SpanCollector
      Throws:
      IOException
      WARNING: This API is experimental and might change in incompatible ways in the next release.

    • positionsCost

      public abstract float positionsCost()
      Return an estimation of the cost of using the positions of this Spans for any single document, but only after asTwoPhaseIterator() returned null. Otherwise this method should not be called. The returned value is independent of the current document.
      WARNING: This API is experimental and might change in incompatible ways in the next release.

    • asTwoPhaseIterator

      public TwoPhaseIterator asTwoPhaseIterator()
      Optional method: Return a TwoPhaseIterator view of this Scorer. A return value of null indicates that two-phase iteration is not supported.
      See Also:

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • doStartCurrentDoc

      protected void doStartCurrentDoc() throws IOException
      Called before the current doc's frequency is calculated
      Throws:
      IOException

    • doCurrentSpans

      protected void doCurrentSpans() throws IOException
      Called each time the scorer's SpanScorer is advanced during frequency calculation
      Throws:
      IOException