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 Summary

  Fields
  Modifier and Type
  Field
  Description
  `static final int`
  `NO_MORE_POSITIONS`

  ### Fields inherited from class org.apache.lucene.search.DocIdSetIterator

  `NO_MORE_DOCS`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `Spans()`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `TwoPhaseIterator`
  `asTwoPhaseIterator()`
  Optional method: Return a `TwoPhaseIterator` view of this `Scorer`.
  `abstract void`
  `collect(SpanCollector collector)`
  Collect postings data from the leaves of the current Spans.
  `protected void`
  `doCurrentSpans()`
  Called each time the scorer's SpanScorer is advanced during frequency calculation
  `protected void`
  `doStartCurrentDoc()`
  Called before the current doc's frequency is calculated
  `abstract int`
  `endPosition()`
  Returns the end position for the current start position, or -1 when `nextStartPosition()` was not yet called on the current doc.
  `abstract int`
  `nextStartPosition()`
  Returns the next start position for the current doc.
  `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`.
  `abstract int`
  `startPosition()`
  Returns the start position in the current doc, or -1 when `nextStartPosition()` was not yet called on the current doc.
  `String`
  `toString()`
  `abstract int`
  `width()`
  Return the width of the match, which is typically used to sloppy freq.

  ### Methods inherited from class org.apache.lucene.search.DocIdSetIterator

  `advance, all, cost, docID, docIDRunEnd, empty, intoBitSet, nextDoc, range, slowAdvance`

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- ## Field Details

  - ### NO_MORE_POSITIONS

    public static final int NO_MORE_POSITIONS
    See Also:
      - Constant Field Values

- ## 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:
      - `Scorer.twoPhaseIterator()`

  - ### 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`