com.saxonica.ee.optim

Class MultiIndex.SelectedItemsIterator

java.lang.Object

com.saxonica.ee.optim.MultiIndex.SelectedItemsIterator

All Implemented Interfaces:

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

Enclosing class:

MultiIndex

public static class MultiIndex.SelectedItemsIterator
extends java.lang.Object
implements SequenceIterator, LastPositionFinder, LookaheadIterator

Iterator over a subset of the items in this IndexedValue, identified by an IntSet holding the positions of the items in the selected subset (zero-based)

Constructor Summary

Constructors

Constructor and Description
SelectedItemsIterator(GroundedValue indexedValue, IntSet selection)

Method Summary

Modifier and Type	Method and Description
int	getLength() Get the last position (that is, the number of items in the sequence).
boolean	hasNext() Determine whether there are more items to come.
Item	next() Get the next item in the sequence.
boolean	supportsGetLength() Ask whether this iterator supports use of the getLength() method.
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

SelectedItemsIterator

public SelectedItemsIterator(GroundedValue indexedValue,
                             IntSet selection)

Method Detail

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()

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 supportsHasNext() is true.

Specified by:

hasNext in interface LookaheadIterator

Returns:

true if there are more items in the sequence

next

public Item next()

Get the next item in the sequence. This method changes the state of the iterator, in particular it affects the result of subsequent calls of position() and current().

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.

Since:

8.4

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.

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 result is undefined if the next() method of the iterator has already returned null.

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

Specified by:

getLength in interface LastPositionFinder

Returns:

the number of items in the sequence