net.sf.saxon.expr

Class ValueTailIterator

java.lang.Object

net.sf.saxon.expr.ValueTailIterator

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, SequenceIterator, GroundedIterator, LookaheadIterator

public class ValueTailIterator
extends java.lang.Object
implements SequenceIterator, GroundedIterator, LookaheadIterator

ValueTailIterator iterates over a base sequence starting at an element other than the first. It is used in the case where the base sequence is "grounded", that is, it exists in memory and supports efficient direct addressing.

Constructor Summary

Constructors

Constructor and Description
ValueTailIterator(GroundedValue base, int start) Construct a ValueTailIterator

Method Summary

Modifier and Type	Method and Description
GroundedValue	getResidue() Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.
boolean	hasNext() Determine whether there are more items to come.
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.
boolean	supportsHasNext() Ask whether the hasNext() method can be called.

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, discharge

Constructor Detail

ValueTailIterator

public ValueTailIterator(GroundedValue base,
                         int start)

Construct a ValueTailIterator

Parameters:

base - The items to be filtered

start - The position of the first item to be included (zero-based)

Method Detail

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.

supportsHasNext

public boolean supportsHasNext()

Description copied from interface: LookaheadIterator

Ask whether the hasNext() method can be called. This method must be called before calling hasNext(), because some iterators implement this interface, but only support look-ahead under particular circumstances (this is usually because they delegate to another iterator)

Specified by:

supportsHasNext in interface LookaheadIterator

Returns:

true if the LookaheadIterator.hasNext() method is available

hasNext

public boolean hasNext()

Description copied from interface: LookaheadIterator

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.

This method must not be called unless the result of LookaheadIterator.supportsHasNext() is true.

Specified by:

hasNext in interface LookaheadIterator

Returns:

true if there are more items in the sequence

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

materialize

public GroundedValue materialize()

Return a Value containing all the items in the sequence returned by this SequenceIterator. This should be an "in-memory" value, not a Closure.

Specified by:

materialize in interface GroundedIterator

Returns:

the corresponding Value

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