org.apache.lucene.search.spans
Class NearSpansOrdered

java.lang.Object
  extended by org.apache.lucene.search.spans.Spans
      extended by org.apache.lucene.search.spans.NearSpansOrdered

public class NearSpansOrdered
extends Spans

A Spans that is formed from the ordered subspans of a SpanNearQuery where the subspans do not overlap and have a maximum slop between them.

The formed spans only contains minimum slop matches.
The matching slop is computed from the distance(s) between the non overlapping matching Spans.
Successive matches are always formed from the successive Spans of the SpanNearQuery.

The formed spans may contain overlaps when the slop is at least 1. For example, when querying using

t1 t2 t3
with slop at least 1, the fragment:
t1 t2 t1 t3 t2 t3
matches twice:
t1 t2 .. t3      
      t1 .. t2 t3
Expert: Only public for subclassing. Most implementations should not need this class


Constructor Summary
NearSpansOrdered(SpanNearQuery spanNearQuery, IndexReader reader)
           
NearSpansOrdered(SpanNearQuery spanNearQuery, IndexReader reader, boolean collectPayloads)
           
 
Method Summary
 int doc()
          Returns the document number of the current match.
 int end()
          Returns the end position of the current match.
 Collection<byte[]> getPayload()
          Returns the payload data for the current span.
 Spans[] getSubSpans()
           
 boolean isPayloadAvailable()
          Checks if a payload can be loaded at this position.
 boolean next()
          Move to the next match, returning true iff any such exists.
 boolean skipTo(int target)
          Skips to the first match beyond the current, whose document number is greater than or equal to target.
 int start()
          Returns the start position of the current match.
 String toString()
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

NearSpansOrdered

public NearSpansOrdered(SpanNearQuery spanNearQuery,
                        IndexReader reader)
                 throws IOException
Throws:
IOException

NearSpansOrdered

public NearSpansOrdered(SpanNearQuery spanNearQuery,
                        IndexReader reader,
                        boolean collectPayloads)
                 throws IOException
Throws:
IOException
Method Detail

doc

public int doc()
Description copied from class: Spans
Returns the document number of the current match. Initially invalid.

Specified by:
doc in class Spans

start

public int start()
Description copied from class: Spans
Returns the start position of the current match. Initially invalid.

Specified by:
start in class Spans

end

public int end()
Description copied from class: Spans
Returns the end position of the current match. Initially invalid.

Specified by:
end in class Spans

getSubSpans

public Spans[] getSubSpans()

getPayload

public Collection<byte[]> getPayload()
                              throws IOException
Description copied from class: Spans
Returns the payload data for the current span. This is invalid until Spans.next() is called for the first time. This method must not be called more than once after each call of Spans.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.

Specified by:
getPayload in class Spans
Returns:
a List of byte arrays containing the data of this payload, otherwise null if isPayloadAvailable is false
Throws:
IOException

isPayloadAvailable

public boolean isPayloadAvailable()
Description copied from class: Spans
Checks if a payload can be loaded at this position.

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

Specified by:
isPayloadAvailable in class Spans
Returns:
true if there is a payload available at this position that can be loaded

next

public boolean next()
             throws IOException
Description copied from class: Spans
Move to the next match, returning true iff any such exists.

Specified by:
next in class Spans
Throws:
IOException

skipTo

public boolean skipTo(int target)
               throws IOException
Description copied from class: Spans
Skips to the first match beyond the current, whose document number is greater than or equal to target.

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.

Specified by:
skipTo in class Spans
Throws:
IOException

toString

public String toString()
Overrides:
toString in class Object


Copyright © 2000-2011 Apache Software Foundation. All Rights Reserved.