Class DocIdSetIterator

This abstract class defines methods to iterate over a set of non-decreasing doc ids. Note that this class assumes it iterates on doc Ids, and therefore NO_MORE_DOCS is set to MaxValue in order to be used as a sentinel object. Implementations of this class are expected to consider MaxValue as an invalid value.

Inheritance

object

DocIdSetIterator

DocsEnum

FilteredDocIdSetIterator

FixedBitSet.FixedBitSetIterator

OpenBitSetIterator

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Lucene.Net.Search

Assembly: Lucene.Net.dll

Syntax

public abstract class DocIdSetIterator

Fields

NO_MORE_DOCS

When returned by NextDoc(), Advance(int) and DocID it means there are no more docs in the iterator.

Declaration

public const int NO_MORE_DOCS = 2147483647

Field Value

Type	Description
int

Properties

DocID

Returns the following:

• -1 or NO_MORE_DOCS if NextDoc() or Advance(int) were not called yet.
• NO_MORE_DOCS if the iterator has exhausted.
• Otherwise it should return the doc ID it is currently on.

@since 2.9

Declaration

public abstract int DocID { get; }

Property Value

Type	Description
int

Methods

Advance(int)

Advances to the first beyond the current whose document number is greater than or equal to target, and returns the document number itself. Exhausts the iterator and returns NO_MORE_DOCS if target is greater than the highest document number in the set.

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.

When target > current it behaves as if written:

int Advance(int target) 
{
    int doc;
    while ((doc = NextDoc()) < target) 
    {
    }
    return doc;
}

Some implementations are considerably more efficient than that.

NOTE: this method may be called with NO_MORE_DOCS for efficiency by some Scorers. If your implementation cannot efficiently determine that it should exhaust, it is recommended that you check for that value in each call to this method.

@since 2.9

Declaration

public abstract int Advance(int target)

Parameters

Type	Name	Description
int	target

Returns

Type	Description
int

GetCost()

Returns the estimated cost of this DocIdSetIterator.

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.

Declaration

public abstract long GetCost()

Returns

Type	Description
long

GetEmpty()

An empty DocIdSetIterator instance

Declaration

public static DocIdSetIterator GetEmpty()

Returns

Type	Description
DocIdSetIterator

NextDoc()

Advances to the next document in the set and returns the doc it is currently on, or NO_MORE_DOCS if there are no more docs in the set.

NOTE: after the iterator has exhausted you should not call this method, as it may result in unpredicted behavior.

@since 2.9

Declaration

public abstract int NextDoc()

Returns

Type	Description
int

SlowAdvance(int)

Slow (linear) implementation of Advance(int) relying on NextDoc() to advance beyond the target position.

Declaration

protected int SlowAdvance(int target)

Parameters

Type	Name	Description
int	target

Returns

Type	Description
int