org.basex.query.iter
Class Iter

java.lang.Object
  org.basex.query.iter.Iter

Direct Known Subclasses:

FTIter, NodeIter, RangeIter, SeqIter

public abstract class Iter
extends Object

Iterator interface.

Author:

Workgroup DBIS, University of Konstanz 2005-10, ISC License, Christian Gruen

Field Summary

static Iter

EMPTY Empty iterator.

Constructor Summary

Iter()

Method Summary

Item	finish() Returns a sequence from all iterator values.
Item	get(long i) Returns the specified item.
abstract Item	next() Returns the next item or null if no other items are found.
boolean	reset() Resets the iterator and returns true.
boolean	reverse() Reverses the iterator and returns true.
int	size() Returns the number of entries.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static final Iter EMPTY

Empty iterator.

Constructor Detail

Iter

public Iter()

Method Detail

next

public abstract Item next()
                   throws QueryException

Returns the next item or null if no other items are found.

Returns:

resulting item

Throws:

QueryException - query exception

get

public Item get(long i)

Returns the specified item. Note: null is returned if the item cannot be retrieved, so the returned value has to be checked.

Parameters:

i - value offset

Returns:

specified item

size

public int size()

Returns the number of entries. Note: -1 is returned if the number cannot be retrieved, so the returned value has to be checked. If this method is implemented, get(long) has to be implemented as well.

Returns:

number of entries

reset

public boolean reset()

Resets the iterator and returns true. Note: false is returned if the iterator cannot be reset, so the returned value has to be checked.

Returns:

true if operator could be reset

reverse

public boolean reverse()

Reverses the iterator and returns true. Note: false is returned if the iterator cannot be reset, so the returned value has to be checked.

Returns:

true if operator could be reversed

finish

public Item finish()
            throws QueryException

Returns a sequence from all iterator values. Should be called before next().

Returns:

sequence

Throws:

QueryException - query exception