net.sf.saxon.om

Class AbstractItem

java.lang.Object

net.sf.saxon.om.AbstractItem

All Implemented Interfaces:

PullEvent, GroundedValue, Item, Sequence

Direct Known Subclasses:

AbstractFunctionItem, AtomicValue, HashTrieMap, ObjectValue

public abstract class AbstractItem
extends Object
implements Item, GroundedValue

Abstract superclass for items

Constructor Summary

Constructors

Constructor and Description
AbstractItem()

Method Summary

Methods

Modifier and Type	Method and Description
int	getLength() Get the size of the value (the number of items)
Item	head() Get the first item in the sequence.
Item	itemAt(int n) Get the n'th item in the value, counting from 0
UnfailingIterator	iterate() Get an iterator over all the items in the sequence
GroundedValue	reduce() Reduce the sequence to its simplest form.
GroundedValue	subsequence(int start, int length) Get a subsequence of the value

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.Item

getStringValue, getStringValueCS

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

effectiveBooleanValue, getStringValue, getStringValueCS

Constructor Detail

AbstractItem

public AbstractItem()

Method Detail

itemAt

public Item itemAt(int n)

Get the n'th item in the value, counting from 0

Specified by:

itemAt in interface GroundedValue

Parameters:

n - the index of the required item, with 0 representing the first item in the sequence

Returns:

the n'th item if it exists, or null otherwise

subsequence

public final GroundedValue subsequence(int start,
                        int length)

Get a subsequence of the value

Specified by:

subsequence in interface GroundedValue

Parameters:

start - the index of the first item to be included in the result, counting from zero. A negative value is taken as zero. If the value is beyond the end of the sequence, an empty sequence is returned

length - the number of items to be included in the result. Specify Integer.MAX_VALUE to get the subsequence up to the end of the base sequence. If the value is negative, an empty sequence is returned. If the value goes off the end of the sequence, the result returns items up to the end of the sequence

Returns:

the required subsequence. If min is

getLength

public final int getLength()

Get the size of the value (the number of items)

Specified by:

getLength in interface GroundedValue

Returns:

the number of items in the sequence

head

public Item head()

Get the first item in the sequence.

Specified by:

head in interface GroundedValue

Specified by:

head in interface Item

Specified by:

head in interface Sequence

Returns:

the first item in the sequence if there is one, or null if the sequence is empty

Throws:

XPathException - in the situation where the sequence is evaluated lazily, and evaluation of the first item causes a dynamic error.

iterate

public UnfailingIterator iterate()

Get an iterator over all the items in the sequence

Specified by:

iterate in interface GroundedValue

Specified by:

iterate in interface Sequence

Returns:

an iterator over all the items

reduce

public GroundedValue reduce()

Reduce the sequence to its simplest form. If the value is an empty sequence, the result will be EmptySequence.getInstance(). If the value is a single atomic value, the result will be an instance of AtomicValue. If the value is a single item of any other kind, the result will be an instance of SingletonItem. Otherwise, the result will typically be unchanged.

Specified by:

reduce in interface GroundedValue

Returns:

the simplified sequence