Package org.apache.lucene.queries.intervals

Class ExtendedIntervalIterator

java.lang.Object

org.apache.lucene.search.DocIdSetIterator

org.apache.lucene.queries.intervals.IntervalIterator

org.apache.lucene.queries.intervals.ExtendedIntervalIterator

class ExtendedIntervalIterator
extends IntervalIterator

Wraps an IntervalIterator and extends the bounds of its intervals Useful for specifying gaps in an ordered iterator; if you want to match `a b [2 spaces] c`, you can search for phrase(a, extended(b, 0, 2), c) An interval with prefix bounds extended by n will skip over matches that appear in positions lower than n

Field Summary

Fields

Modifier and Type	Field	Description
private int	after
private int	before
private IntervalIterator	in
private boolean	positioned

Fields inherited from class org.apache.lucene.queries.intervals.IntervalIterator

NO_MORE_INTERVALS

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

NO_MORE_DOCS

Constructor Summary

Constructors

Constructor	Description
ExtendedIntervalIterator(IntervalIterator in, int before, int after)	Create a new ExtendedIntervalIterator

Method Summary

Modifier and Type	Method	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 if DocIdSetIterator.nextDoc() or DocIdSetIterator.advance(int) were not called yet.
int	end()	The end of the current interval Returns -1 if IntervalIterator.nextInterval() has not yet been called and IntervalIterator.NO_MORE_INTERVALS once the iterator is exhausted.
int	gaps()	The number of gaps within the current interval Note that this returns the number of gaps between the immediate sub-intervals of this interval, and does not include the gaps inside those sub-intervals.
float	matchCost()	An indication of the average cost of iterating over all intervals in a document
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.
int	nextInterval()	Advance the iterator to the next interval
int	start()	The start of the current interval Returns -1 if IntervalIterator.nextInterval() has not yet been called and IntervalIterator.NO_MORE_INTERVALS once the iterator is exhausted.

Methods inherited from class org.apache.lucene.queries.intervals.IntervalIterator

toString, width

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

all, empty, range, slowAdvance

Methods inherited from class java.lang.Object

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

Field Detail

in

private final IntervalIterator in

before

private final int before

after

private final int after

positioned

private boolean positioned

Constructor Detail

ExtendedIntervalIterator

ExtendedIntervalIterator(IntervalIterator in,
                         int before,
                         int after)

Create a new ExtendedIntervalIterator

Parameters:

in - the iterator to wrap

before - the number of positions to extend before the delegated interval

after - the number of positions to extend beyond the delegated interval

Method Detail

start

public int start()

Description copied from class: IntervalIterator

The start of the current interval Returns -1 if IntervalIterator.nextInterval() has not yet been called and IntervalIterator.NO_MORE_INTERVALS once the iterator is exhausted.

Specified by:

start in class IntervalIterator

end

public int end()

Description copied from class: IntervalIterator

The end of the current interval Returns -1 if IntervalIterator.nextInterval() has not yet been called and IntervalIterator.NO_MORE_INTERVALS once the iterator is exhausted.

Specified by:

end in class IntervalIterator

gaps

public int gaps()

Description copied from class: IntervalIterator

The number of gaps within the current interval Note that this returns the number of gaps between the immediate sub-intervals of this interval, and does not include the gaps inside those sub-intervals. Should not be called before IntervalIterator.nextInterval(), or after it has returned IntervalIterator.NO_MORE_INTERVALS

Specified by:

gaps in class IntervalIterator

nextInterval

public int nextInterval()
                 throws java.io.IOException

Description copied from class: IntervalIterator

Advance the iterator to the next interval

Specified by:

nextInterval in class IntervalIterator

Returns:

the start of the next interval, or IntervalIterator.NO_MORE_INTERVALS if there are no more intervals on the current document

Throws:

java.io.IOException

matchCost

public float matchCost()

Description copied from class: IntervalIterator

An indication of the average cost of iterating over all intervals in a document

Specified by:

matchCost in class IntervalIterator

See Also:

TwoPhaseIterator.matchCost()

docID

public int docID()

Description copied from class: DocIdSetIterator

Returns the following:

• -1 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 java.io.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:

java.io.IOException

advance

public int advance(int target)
            throws java.io.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:

java.io.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