net.sf.saxon.tree.iter

Class ManualIterator

java.lang.Object

net.sf.saxon.tree.iter.ManualIterator

All Implemented Interfaces:

LastPositionFinder, FocusIterator, SequenceIterator, GroundedIterator, LookaheadIterator, ReversibleIterator, UnfailingIterator

Direct Known Subclasses:

ManualGroupIterator, ManualRegexIterator

public class ManualIterator
extends java.lang.Object
implements FocusIterator, UnfailingIterator, ReversibleIterator, LastPositionFinder, GroundedIterator, LookaheadIterator

ManualIterator: a pseudo-iterator used while streaming. It has a current node and a current position which are set manually. Calling last() is an error. Calling next() always returns null.

Field Summary

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

ATOMIZING, GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

Constructors

Constructor and Description
ManualIterator() Create an uninitialized ManualIterator: this is only usable after the context item, position, and size (if required) have been initialized using setter methods.
ManualIterator(Item value) Create a ManualIterator supplying the context item, and setting the value of both "position()" and "last()" implicitly to 1.
ManualIterator(Item value, int position) Create a ManualIterator initializing the context item and position.

Method Summary

Modifier and Type	Method and Description
void	close() Close the iterator.
Item	current() Get the current value in the sequence (the one returned by the most recent call on next()).
int	getLength() Get the position of the last item in the sequence
int	getProperties() Get properties of this iterator, as a bit-significant integer.
GroundedValue	getResidue() Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.
ManualIterator	getReverseIterator() Get a new SequenceIterator that returns the same items in reverse order.
boolean	hasNext() Determine whether there are more items to come.
void	incrementPosition()
GroundedValue	materialize() Return a Value containing all the items in the sequence returned by this SequenceIterator
Item	next() Get the next item in the sequence.
int	position() Return the current position in the sequence.
void	setContextItem(Item value)
void	setLastPositionFinder(LastPositionFinder finder)
void	setPosition(int position)

Methods inherited from class java.lang.Object

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

Constructor Detail

ManualIterator

public ManualIterator()

Create an uninitialized ManualIterator: this is only usable after the context item, position, and size (if required) have been initialized using setter methods.

ManualIterator

public ManualIterator(Item value,
                      int position)

Create a ManualIterator initializing the context item and position. The value of "last()" for such an iterator is unknown unless a LastPositionFinder is supplied.

Parameters:

value - the context item. May be null if the value is to be initialized later.

position - the context position

ManualIterator

public ManualIterator(Item value)

Create a ManualIterator supplying the context item, and setting the value of both "position()" and "last()" implicitly to 1.

Parameters:

value - the context item

Method Detail

setContextItem

public void setContextItem(Item value)

setLastPositionFinder

public void setLastPositionFinder(LastPositionFinder finder)

incrementPosition

public void incrementPosition()

setPosition

public void setPosition(int position)

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

Returns:

true if there are more items

next

public Item next()

Description copied from interface: SequenceIterator

Get the next item in the sequence. This method changes the state of the iterator.

Specified by:

next in interface SequenceIterator

Specified by:

next in interface UnfailingIterator

Returns:

the next item, or null if there are no more items. Once a call on next() has returned null, no further calls should be made. The preferred action for an iterator if subsequent calls on next() are made is to return null again, and all implementations within Saxon follow this rule.

current

public Item current()

Description copied from interface: FocusIterator

Get the current value in the sequence (the one returned by the most recent call on next()). This will be null before the first call of next(). This method does not change the state of the iterator.

Specified by:

current in interface FocusIterator

Returns:

the current item, the one most recently returned by a call on next(). Returns null if next() has not been called, or if the end of the sequence has been reached.

position

public int position()

Return the current position in the sequence.

Specified by:

position in interface FocusIterator

Returns:

0 before the first call on next(); 1 before the second call on next(); -1 after the second call on next().

getLength

public int getLength()
              throws XPathException

Description copied from interface: FocusIterator

Get the position of the last item in the sequence

Specified by:

getLength in interface LastPositionFinder

Specified by:

getLength in interface FocusIterator

Returns:

the position of the last item

Throws:

XPathException - if a failure occurs reading 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

getReverseIterator

public ManualIterator getReverseIterator()

Description copied from interface: ReversibleIterator

Get a new SequenceIterator that returns the same items in reverse order. If this SequenceIterator is an AxisIterator, then the returned SequenceIterator must also be an AxisIterator.

Specified by:

getReverseIterator in interface ReversibleIterator

Returns:

an iterator over the items in reverse order

materialize

public GroundedValue materialize()

Return a Value containing all the items in the sequence returned by this SequenceIterator

Specified by:

materialize in interface GroundedIterator

Returns:

the corresponding Value. If the value is a closure or a function call package, it will be evaluated and expanded.

getResidue

public GroundedValue getResidue()
                         throws XPathException

Description copied from interface: GroundedIterator

Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position. This should be an "in-memory" value, not a Closure.

Specified by:

getResidue in interface GroundedIterator

Returns:

the corresponding Value

Throws:

XPathException - in the cases of subclasses (such as the iterator over a MemoClosure) which cause evaluation of expressions while materializing the value.

getProperties

public int getProperties()

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

Specified by:

getProperties in interface SequenceIterator

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.