Package org.apache.lucene.search.spans

Class Spans

  • Direct Known Subclasses:
    NearSpansOrdered, NearSpansUnordered, TermSpans
    public abstract class Spans
extends java.lang.Object
    Expert: an enumeration of span matches. Used to implement span searching. Each span represents a range of term positions within a document. Matches are enumerated in order, by increasing document number, within that by increasing start position and finally by increasing end position.

    • Constructor Summary

      Constructors 
      Constructor Description
      Spans()  

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      abstract long cost()
      Returns the estimated cost of this spans.
      abstract int doc()
      Returns the document number of the current match.
      abstract int end()
      Returns the end position of the current match.
      abstract java.util.Collection<byte[]> getPayload()
      Returns the payload data for the current span.
      abstract boolean isPayloadAvailable()
      Checks if a payload can be loaded at this position.
      abstract boolean next()
      Move to the next match, returning true iff any such exists.
      abstract boolean skipTo​(int target)
      Skips to the first match beyond the current, whose document number is greater than or equal to target.
      abstract int start()
      Returns the start position of the current match.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • Spans

        public Spans()

    • Method Detail

      • next

        public abstract boolean next()
                      throws java.io.IOException
        Move to the next match, returning true iff any such exists.
        Throws:
        java.io.IOException

      • skipTo

        public abstract boolean skipTo​(int target)
                        throws java.io.IOException
        Skips to the first match beyond the current, whose document number is greater than or equal to target.

        The behavior of this method is undefined when called with target ≤ current, or after the iterator has exhausted. Both cases may result in unpredicted behavior.

        Returns true iff there is such a match.

        Behaves as if written: 

           boolean skipTo(int target) {
     do {
       if (!next())
         return false;
     } while (target > doc());
     return true;
   }
        Most implementations are considerably more efficient than that.
        Throws:
        java.io.IOException

      • doc

        public abstract int doc()
        Returns the document number of the current match. Initially invalid.

      • start

        public abstract int start()
        Returns the start position of the current match. Initially invalid.

      • end

        public abstract int end()
        Returns the end position of the current match. Initially invalid.

      • getPayload

        public abstract java.util.Collection<byte[]> getPayload()
                                                 throws java.io.IOException
        Returns the payload data for the current span. This is invalid until next() is called for the first time. This method must not be called more than once after each call of next(). However, most payloads are loaded lazily, so if the payload data for the current position is not needed, this method may not be called at all for performance reasons. An ordered SpanQuery does not lazy load, so if you have payloads in your index and you do not want ordered SpanNearQuerys to collect payloads, you can disable collection with a constructor option.

        Note that the return type is a collection, thus the ordering should not be relied upon.
        Returns:
        a List of byte arrays containing the data of this payload, otherwise null if isPayloadAvailable is false
        Throws:
        java.io.IOException - if there is a low-level I/O error

      • isPayloadAvailable

        public abstract boolean isPayloadAvailable()
                                    throws java.io.IOException
        Checks if a payload can be loaded at this position.

        Payloads can only be loaded once per call to next().

        Returns:
        true if there is a payload available at this position that can be loaded
        Throws:
        java.io.IOException

      • cost

        public abstract long cost()
        Returns the estimated cost of this spans.

        This is generally an upper bound of the number of documents this iterator might match, but may be a rough heuristic, hardcoded value, or otherwise completely inaccurate.