net.sf.saxon.s9api

Class XdmValue

java.lang.Object

net.sf.saxon.s9api.XdmValue

All Implemented Interfaces:

java.lang.Iterable<XdmItem>

Direct Known Subclasses:

XdmEmptySequence, XdmItem

public class XdmValue
extends java.lang.Object
implements java.lang.Iterable<XdmItem>

An value in the XDM data model. A value is a sequence of zero or more items, each item being either an atomic value or a node.

An XdmValue is immutable.

A sequence consisting of a single item may be represented as an instance of XdmItem, which is a subtype of XdmValue. However, there is no guarantee that a sequence of length one will always be an instance of XdmItem.

Similarly, a zero-length sequence may be represented as an instance of XdmEmptySequence, but there is no guarantee that every sequence of length zero will always be an instance of XdmEmptySequence.

Since:

9.0

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	XdmValue()
	XdmValue(java.lang.Iterable<? extends XdmItem> items) Create an XdmValue as a sequence of XdmItem objects
protected	XdmValue(Sequence value)
	XdmValue(XdmSequenceIterator iterator) Create an XdmValue containing the items returned by an XdmSequenceIterator

Method Summary

Modifier and Type	Method and Description
XdmValue	append(XdmValue otherValue) Create a new XdmValue by concatenating the contents of this XdmValue and another XdmValue into a single sequence.
Sequence	getUnderlyingValue() Get the underlying implementation object representing the value.
XdmItem	itemAt(int n) Get the n'th item in the value, counting from zero.
XdmSequenceIterator	iterator() Get an iterator over the items in this value.
static XdmValue	makeSequence(java.lang.Iterable list) Make an XDM sequence from a Java Iterable.
static XdmValue	makeValue(java.lang.Object o) Make an XDM value from a Java object.
protected void	setValue(Sequence value)
int	size() Get the number of items in the sequence
java.lang.String	toString() Create a string representation of the value.
static XdmValue	wrap(Sequence value) Create an XdmValue that wraps an existing Saxon Sequence

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

XdmValue

protected XdmValue()

XdmValue

public XdmValue(java.lang.Iterable<? extends XdmItem> items)

Create an XdmValue as a sequence of XdmItem objects

Parameters:

items - a sequence of XdmItem objects. Note that if this is supplied as a list or similar collection, subsequent changes to the list/collection will have no effect on the XdmValue.

Since:

9.0.0.4

XdmValue

public XdmValue(XdmSequenceIterator iterator)
         throws SaxonApiException

Create an XdmValue containing the items returned by an XdmSequenceIterator

Parameters:

iterator - the iterator that supplies the values

Throws:

SaxonApiException - if an error occurs reading values from the supplied iterator

Since:

9.6

XdmValue

protected XdmValue(Sequence value)

Method Detail

setValue

protected void setValue(Sequence value)

wrap

public static XdmValue wrap(Sequence value)

Create an XdmValue that wraps an existing Saxon Sequence

Parameters:

value - the supplied Sequence (which may be a singleton Item),

Returns:

an XdmValue corresponding to the supplied Sequence. If the supplied value is null, an empty sequence is returned. If the supplied value is an atomic value, the result will be an instance of XdmAtomicValue. If the supplied value is a node, the result will be an instance of XdmNode. If the supplied value is a map, the result will be an instance of XdmMap. If the supplied value is an array, the result will be an instance of XdmArray. If the supplied value is a function item, the result will be an instance of XdmFunctionItem.

Throws:

SaxonApiUncheckedException - if the supplied Sequence is not yet fully evaluated, and evaluation of the underlying expression fails with a dynamic error.

Since:

9.5 (previously a protected method)

append

public XdmValue append(XdmValue otherValue)

Create a new XdmValue by concatenating the contents of this XdmValue and another XdmValue into a single sequence. The two input XdmValue objects are unaffected by this operation.

Note: creating a sequence of N values by successive calls on this method takes time proportional to N-squared.

Parameters:

otherValue - the value to be appended

Returns:

a new XdmValue containing the concatenation of the two input XdmValue objects

Since:

9.2

size

public int size()

Get the number of items in the sequence

Returns:

the number of items in the value, considered as a sequence. Note that for arrays and maps, the answer will be 1 (one) since arrays and maps are items.

Throws:

SaxonApiUncheckedException - if the value is lazily evaluated and the delayed evaluation fails with a dynamic error.

itemAt

public XdmItem itemAt(int n)
               throws java.lang.IndexOutOfBoundsException,
                      SaxonApiUncheckedException

Get the n'th item in the value, counting from zero.

Parameters:

n - the item that is required, counting the first item in the sequence as item zero

Returns:

the n'th item in the sequence making up the value, counting from zero

Throws:

java.lang.IndexOutOfBoundsException - if n is less than zero or greater than or equal to the number of items in the value

SaxonApiUncheckedException - if the value is lazily evaluated and the delayed evaluation fails with a dynamic error.

iterator

public XdmSequenceIterator iterator()
                             throws SaxonApiUncheckedException

Get an iterator over the items in this value.

Specified by:

iterator in interface java.lang.Iterable<XdmItem>

Returns:

an Iterator over the items in this value.

Throws:

SaxonApiUncheckedException - if the value is lazily evaluated and the delayed evaluation fails with a dynamic error.

getUnderlyingValue

public Sequence getUnderlyingValue()

Get the underlying implementation object representing the value. This method allows access to lower-level Saxon functionality, including classes and methods that offer no guarantee of stability across releases.

Returns:

the underlying implementation object representing the value

toString

public java.lang.String toString()

Create a string representation of the value. The is the result of serializing the value using the adaptive serialization method.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of the value

makeSequence

public static XdmValue makeSequence(java.lang.Iterable list)
                             throws java.lang.IllegalArgumentException

Make an XDM sequence from a Java Iterable. Each value delivered by the iterable is first converted to an XDM value using the makeValue(Object) method; if the result is anything other than a single XDM item, it is then wrapped in an XdmArray.

Returns:

the result of the conversion if successful

Throws:

java.lang.IllegalArgumentException - if conversion is not possible

makeValue

public static XdmValue makeValue(java.lang.Object o)
                          throws java.lang.IllegalArgumentException

Make an XDM value from a Java object. The supplied object may be any of the following:

• An instance of XdmValue (for example, an XdmNode or XdmAtomicValue or XdmArray or XdmMap), which is returned unchanged
• An instance of Sequence (for example, a NodeInfo or AtomicValue), which is wrapped as an XdmValue
• An instance of Map, which is converted to an XDM Map using the XdmMap.makeMap(java.util.Map) method
• A Java array, of any type, which is converted to an XDM Array using the XdmArray.makeArray(java.lang.Object[]) method
• A Java collection, more specifically Iterable, which is converted to an XDM sequence using the makeSequence(Iterable) method
• Any object that is convertible to an XDM atomic value using the method XdmAtomicValue.makeAtomicValue(Object)

Returns:

the result of the conversion if successful

Throws:

java.lang.IllegalArgumentException - if conversion is not possible