Class ScoreCachingWrappingScorer

A Scorer which wraps another scorer and caches the score of the current document. Successive calls to GetScore() will return the same result and will not invoke the wrapped Scorer's GetScore() method, unless the current document has changed.

This class might be useful due to the changes done to the ICollector interface, in which the score is not computed for a document by default, only if the collector requests it. Some collectors may need to use the score in several places, however all they have in hand is a Scorer object, and might end up computing the score of a document more than once.
Inheritance
object
DocIdSetIterator
DocsEnum
Scorer
ScoreCachingWrappingScorer
Inherited Members
Namespace: Lucene.Net.Search
Assembly: Lucene.Net.dll
Syntax
public class ScoreCachingWrappingScorer : Scorer

Constructors

ScoreCachingWrappingScorer(Scorer)

Creates a new instance by wrapping the given scorer.

Declaration
public ScoreCachingWrappingScorer(Scorer scorer)
Parameters
Type Name Description
Scorer scorer

Properties

DocID

Returns the following:

@since 2.9

Declaration
public override int DocID { get; }
Property Value
Type Description
int
Overrides

Freq

Returns term frequency in the current document, or 1 if the field was indexed with DOCS_ONLY. Do not call this before NextDoc() is first called, nor after NextDoc() returns NO_MORE_DOCS.

NOTE: if the DocsEnum was obtain with NONE, the result of this method is undefined.
Declaration
public override int Freq { get; }
Property Value
Type Description
int
Overrides

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 override int Advance(int target)
Parameters
Type Name Description
int target
Returns
Type Description
int
Overrides

GetChildren()

Returns child sub-scorers

Note

This API is experimental and might change in incompatible ways in the next release.

Declaration
public override ICollection<Scorer.ChildScorer> GetChildren()
Returns
Type Description
ICollection<Scorer.ChildScorer>
Overrides

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 override long GetCost()
Returns
Type Description
long
Overrides

GetScore()

Returns the score of the current document matching the query. Initially invalid, until NextDoc() or Advance(int) is called the first time, or when called from within Collect(int).

Declaration
public override float GetScore()
Returns
Type Description
float
Overrides

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 override int NextDoc()
Returns
Type Description
int
Overrides