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 in order to be used as a sentinel object. Implementations of this class are expected to consider as an invalid value.

Inheritance
System.Object
DocIdSetIterator
DocsEnum
FilteredDocIdSetIterator
FixedBitSet.FixedBitSetIterator
OpenBitSetIterator
Namespace: Lucene.Net.Search
Assembly: Lucene.Net.dll
Syntax
public abstract class DocIdSetIterator : object

Fields

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NO_MORE_DOCS

When returned by NextDoc(), Advance(Int32) and DocID it means there are no more docs in the iterator.

Declaration
public const int NO_MORE_DOCS = null
Field Value
Type Description
System.Int32

Properties

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DocID

Returns the following:

@since 2.9

Declaration
public abstract int DocID { get; }
Property Value
Type Description
System.Int32

Methods

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Advance(Int32)

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
System.Int32 target
Returns
Type Description
System.Int32
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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
System.Int64
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GetEmpty()

An empty DocIdSetIterator instance

Declaration
public static DocIdSetIterator GetEmpty()
Returns
Type Description
DocIdSetIterator
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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
System.Int32
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SlowAdvance(Int32)

Slow (linear) implementation of Advance(Int32) relying on NextDoc() to advance beyond the target position.

Declaration
protected int SlowAdvance(int target)
Parameters
Type Name Description
System.Int32 target
Returns
Type Description
System.Int32