net.sf.saxon.tree.iter
Class ReverseArrayIterator<T extends Item>

java.lang.Object
  net.sf.saxon.tree.iter.ReverseArrayIterator<T>

All Implemented Interfaces:

LastPositionFinder<T>, SequenceIterator<T>, LookaheadIterator<T>, ReversibleIterator<T>, UnfailingIterator<T>

public class ReverseArrayIterator<T extends Item>
extends Object
implements UnfailingIterator<T>, ReversibleIterator<T>, LookaheadIterator<T>, LastPositionFinder<T>

ReverseArrayIterator is used to enumerate items held in an array in reverse order.

Author:

Michael H. Kay

Field Summary

Fields inherited from interface net.sf.saxon.om.SequenceIterator

GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

ReverseArrayIterator(T[] items, int start, int end)
Create an iterator a slice of an array

Method Summary

void	close() Close the iterator.
T	current() Get the current item in the sequence.
ReverseArrayIterator<T>	getAnother() Get another iterator over the same sequence of items, positioned at the start of the sequence.
int	getLength() Get the last position (that is, the number of items in the sequence).
int	getProperties() Get properties of this iterator, as a bit-significant integer.
SequenceIterator<T>	getReverseIterator() Get an iterator that processes the same items in reverse order.
boolean	hasNext() Determine whether there are more items to come.
T	next() Get the next item in the sequence.
int	position() Get the current position

Methods inherited from class java.lang.Object

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

Constructor Detail

ReverseArrayIterator

public ReverseArrayIterator(T[] items,
                            int start,
                            int end)

Create an iterator a slice of an array

Parameters:

items - The array of items

start - The first item in the array to be be used (this will be the last one in the resulting iteration). Zero-based.

end - The item after the last one in the array to be used (this will be the first one to be returned by the iterator). Zero-based.

Method Detail

hasNext

public boolean hasNext()

Determine whether there are more items to come. Note that this operation is stateless and it is not necessary (or usual) to call it before calling next(). It is used only when there is an explicit need to tell if we are at the last element.

Specified by:

hasNext in interface LookaheadIterator<T extends Item>

Returns:

true if there are more items in the sequence

next

public T next()

Description copied from interface: UnfailingIterator

Get the next item in the sequence.

Specified by:

next in interface SequenceIterator<T extends Item>

Specified by:

next in interface UnfailingIterator<T extends Item>

Returns:

the next Item. If there are no more nodes, return null.

current

public T current()

Description copied from interface: UnfailingIterator

Get the current item in the sequence.

Specified by:

current in interface SequenceIterator<T extends Item>

Specified by:

current in interface UnfailingIterator<T extends Item>

Returns:

the current item, that is, the item most recently returned by next()

position

public int position()

Description copied from interface: UnfailingIterator

Get the current position

Specified by:

position in interface SequenceIterator<T extends Item>

Specified by:

position in interface UnfailingIterator<T extends Item>

Returns:

the position of the current item (the item most recently returned by next()), starting at 1 for the first node

getLength

public int getLength()

Description copied from interface: LastPositionFinder

Get the last position (that is, the number of items in the sequence). This method is non-destructive: it does not change the state of the iterator. The result is undefined if the next() method of the iterator has already returned null. This method must not be called unless the result of getProperties() on the iterator includes the bit setting SequenceIterator.LAST_POSITION_FINDER

Specified by:

getLength in interface LastPositionFinder<T extends Item>

Returns:

the number of items in the sequence

close

public void close()

Description copied from interface: SequenceIterator

Close the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.

(Currently, closing an iterator is important only when the data is being "pushed" in another thread. Closing the iterator terminates that thread and means that it needs to do no additional work. Indeed, failing to close the iterator may cause the push thread to hang waiting for the buffer to be emptied.)

Specified by:

close in interface SequenceIterator<T extends Item>

getAnother

public ReverseArrayIterator<T> getAnother()

Description copied from interface: UnfailingIterator

Get another iterator over the same sequence of items, positioned at the start of the sequence. It must be possible to call this method at any time, whether none, some, or all of the items in the original iterator have been read. The method is non-destructive: it does not change the state of the original iterator.

Specified by:

getAnother in interface SequenceIterator<T extends Item>

Specified by:

getAnother in interface UnfailingIterator<T extends Item>

Returns:

a new iterator over the same sequence

getProperties

public int getProperties()

Get properties of this iterator, as a bit-significant integer.

Specified by:

getProperties in interface SequenceIterator<T extends Item>

Returns:

the properties of this iterator. This will be some combination of properties such as SequenceIterator.GROUNDED, SequenceIterator.LAST_POSITION_FINDER, and SequenceIterator.LOOKAHEAD. It is always acceptable to return the value zero, indicating that there are no known special properties. It is acceptable for the properties of the iterator to change depending on its state.

getReverseIterator

public SequenceIterator<T> getReverseIterator()

Get an iterator that processes the same items in reverse order. Since this iterator is processing the items backwards, this method returns an ArrayIterator that processes them forwards.

Specified by:

getReverseIterator in interface ReversibleIterator<T extends Item>

Returns:

a new ArrayIterator