Package net.sf.saxon.tree.iter

Class ManualIterator

java.lang.Object

net.sf.saxon.tree.iter.ManualIterator

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, LastPositionFinder, FocusIterator, SequenceIterator, GroundedIterator, LookaheadIterator, ReversibleIterator

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

ManualIterator: a pseudo-iterator used while streaming. It has a current node and a current position which are set manually, and accepts a function callback which can be invoked to get the value of last(). Calling next() always returns null.

Constructor Summary

Constructors

Constructor	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	Description
Item	current()	Get the current value in the sequence (the one returned by the most recent call on next()).
int	getLength()	Get the last position (that is, the number of items in the sequence).
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()	Advance the current position by one.
boolean	isActuallyGrounded()	Ask if the iterator is actually grounded.
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)	Set (or reset) the context item
void	setLengthFinder(java.util.function.Supplier<java.lang.Integer> finder)	Set a callback function that can be invoked to get the value of last()
void	setPosition(int position)	Set the current position to a specific value
boolean	supportsGetLength()	Ask whether this iterator supports use of the getLength() method.
boolean	supportsHasNext()	Ask whether the iterator supports lookahead.

Methods inherited from class java.lang.Object

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

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

close

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)

Set (or reset) the context item

Parameters:

value - the context item

setLengthFinder

public void setLengthFinder(java.util.function.Supplier<java.lang.Integer> finder)

Set a callback function that can be invoked to get the value of last()

Parameters:

finder - the callback

incrementPosition

public void incrementPosition()

Advance the current position by one.

setPosition

public void setPosition(int position)

Set the current position to a specific value

Parameters:

position - the new current position

supportsHasNext

public boolean supportsHasNext()

Ask whether the iterator supports lookahead.

Specified by:

supportsHasNext in interface LookaheadIterator

Returns:

true (calling hasNext() is allowed, returns true if the value of position() is less than the value of length())

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

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().

supportsGetLength

public boolean supportsGetLength()

Ask whether this iterator supports use of the getLength() method. This method should always be called before calling getLength(), because an iterator that implements this interface may support use of getLength() in some situations and not in others

Specified by:

supportsGetLength in interface LastPositionFinder

Returns:

true if the getLength() method can be called to determine the length of the underlying sequence. This implementation always returns true (despite the fact that when streaming, a call to getLength() will actually fail)

getLength

public int getLength()

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 method calls the function supplied using setLengthFinder(Supplier) if available; otherwise it throws an UncheckedXPathException.

Specified by:

getLength in interface FocusIterator

Specified by:

getLength in interface LastPositionFinder

Returns:

the number of items in the sequence

Throws:

UncheckedXPathException - if no length finder function is available (or if it is available. but throws an exception)

isActuallyGrounded

public boolean isActuallyGrounded()

Description copied from interface: GroundedIterator

Ask if the iterator is actually grounded. This method must be called before calling GroundedIterator.materialize() or GroundedIterator.getResidue(), because the iterator might be grounded under some conditions and not others (usually when it delegates to another iterator)

Specified by:

isActuallyGrounded in interface GroundedIterator

Returns:

true if this iterator is grounded

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()

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. This method does not change the state of the iterator (in particular, it does not consume the iterator).

Specified by:

getResidue in interface GroundedIterator

Returns:

the corresponding Value