org.apache.lucene.search

Class FilteredDocIdSetIterator

java.lang.Object

org.apache.lucene.search.DocIdSetIterator

org.apache.lucene.search.FilteredDocIdSetIterator

public abstract class FilteredDocIdSetIterator
extends DocIdSetIterator

Abstract decorator class of a DocIdSetIterator implementation that provides on-demand filter/validation mechanism on an underlying DocIdSetIterator. See FilteredDocIdSet.

Field Summary

Fields

Modifier and Type	Field and Description
protected DocIdSetIterator	_innerIter

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

NO_MORE_DOCS

Constructor Summary

Constructors

Constructor and Description
FilteredDocIdSetIterator(DocIdSetIterator innerIter) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
int	advance(int target) Advances to the first beyond the current whose document number is greater than or equal to target, and returns the document number itself.
long	cost() Returns the estimated cost of this DocIdSetIterator.
int	docID() Returns the following: -1 or DocIdSetIterator.NO_MORE_DOCS if DocIdSetIterator.nextDoc() or DocIdSetIterator.advance(int) were not called yet.
protected abstract boolean	match(int doc) Validation method to determine whether a docid should be in the result set.
int	nextDoc() Advances to the next document in the set and returns the doc it is currently on, or DocIdSetIterator.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.

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

empty, slowAdvance

Methods inherited from class java.lang.Object

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

Field Detail

_innerIter

protected DocIdSetIterator _innerIter

Constructor Detail

FilteredDocIdSetIterator

public FilteredDocIdSetIterator(DocIdSetIterator innerIter)

Constructor.

Parameters:

innerIter - Underlying DocIdSetIterator.

Method Detail

match

protected abstract boolean match(int doc)

Validation method to determine whether a docid should be in the result set.

Parameters:

doc - docid to be tested

Returns:

true if input docid should be in the result set, false otherwise.

See Also:

FilteredDocIdSetIterator(DocIdSetIterator)

docID

public int docID()

Description copied from class: DocIdSetIterator

Returns the following:

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

Specified by:

docID in class DocIdSetIterator

nextDoc

public int nextDoc()
            throws IOException

Description copied from class: DocIdSetIterator

Advances to the next document in the set and returns the doc it is currently on, or DocIdSetIterator.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.

Specified by:

nextDoc in class DocIdSetIterator

Throws:

IOException

advance

public int advance(int target)
            throws IOException

Description copied from class: DocIdSetIterator

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 DocIdSetIterator.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 DocIdSetIterator.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.

Specified by:

advance in class DocIdSetIterator

Throws:

IOException

cost

public long cost()

Description copied from class: DocIdSetIterator

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.

Specified by:

cost in class DocIdSetIterator