net.sf.saxon.value

Class SingletonNode

Implemented Interfaces:
GroundedValue, Serializable, SequenceIterable, ValueRepresentation

public class SingletonNode
extends Value
implements GroundedValue

A value that is a sequence containing zero or one nodes

Field Summary

protected NodeInfo
node

Fields inherited from class net.sf.saxon.value.Value

EMPTY_CLASS_ARRAY, INDETERMINATE_ORDERING

Fields inherited from interface net.sf.saxon.om.ValueRepresentation

EMPTY_VALUE_ARRAY

Constructor Summary

SingletonNode(NodeInfo node)
Create a node-set containing zero or one nodes

Method Summary

Item
asItem()
Return the value in the form of an Item
Object
convertToJava(Class target, XPathContext context)
Convert to Java object (for passing to external functions)
boolean
effectiveBooleanValue()
Get the effective boolean value
int
getCardinality()
Determine the static cardinality
ItemType
getItemType(TypeHierarchy th)
Determine the data type of the items in the expression.
int
getLength()
Get the length of the sequence
NodeInfo
getNode()
Get the node that forms the node-set.
String
getStringValue()
Convert the value to a string, using the serialization rules.
Item
itemAt(int n)
Get the n'th item in the sequence (starting from 0).
SequenceIterator
iterate()
Return an enumeration of this nodeset value.
void
process(XPathContext context)
Process the instruction, without returning any tail calls
GroundedValue
subsequence(int start, int length)
Get a subsequence of the value

Methods inherited from class net.sf.saxon.value.Value

asItem, asItem, asIterator, asValue, checkPermittedContents, convertJavaObjectToXPath, convertToJava, convertToJava, effectiveBooleanValue, equals, fromItem, getCanonicalLexicalRepresentation, getCardinality, getItemType, getIterator, getLength, getSchemaComparable, getStringValue, getStringValueCS, itemAt, iterate, iterate, makeQNameValue, process, reduce, stringToNumber, toString

Field Details

node

protected NodeInfo node

Constructor Details

SingletonNode

public SingletonNode(NodeInfo node)
Create a node-set containing zero or one nodes
Parameters:
node - The node to be contained in the node-set, or null if the node-set is to be empty

Method Details

asItem

public Item asItem()
Return the value in the form of an Item
Overrides:
asItem in interface Value
Returns:
the value in the form of an Item

convertToJava

public Object convertToJava(Class target,
                            XPathContext context)
            throws XPathException
Convert to Java object (for passing to external functions)
Overrides:
convertToJava in interface Value

effectiveBooleanValue

public boolean effectiveBooleanValue()
Get the effective boolean value
Overrides:
effectiveBooleanValue in interface Value

getCardinality

public int getCardinality()
Determine the static cardinality
Overrides:
getCardinality in interface Value

getItemType

public ItemType getItemType(TypeHierarchy th)
Determine the data type of the items in the expression. This method determines the most precise type that it can, because it is called when testing that the node conforms to a required type.
Overrides:
getItemType in interface Value
Parameters:
th - the type hierarchy cache
Returns:
the most precise possible type of the node.

getLength

public int getLength()
            throws XPathException
Get the length of the sequence
Overrides:
getLength in interface Value

getNode

public NodeInfo getNode()
Get the node that forms the node-set. Return null if there is none.

getStringValue

public String getStringValue()
Convert the value to a string, using the serialization rules. For atomic values this is the same as a cast; for sequence values it gives a space-separated list. For QNames and NOTATIONS, or lists containing them, it fails.
Specified by:
getStringValue in interface ValueRepresentation
Overrides:
getStringValue in interface Value

itemAt

public Item itemAt(int n)
Get the n'th item in the sequence (starting from 0). This is defined for all SequenceValues, but its real benefits come for a SequenceValue stored extensionally (or for a MemoClosure, once all the values have been read)
Specified by:
itemAt in interface GroundedValue
Overrides:
itemAt in interface Value

iterate

public SequenceIterator iterate()
Return an enumeration of this nodeset value.
Overrides:
iterate in interface Value

process

public void process(XPathContext context)
            throws XPathException
Process the instruction, without returning any tail calls
Overrides:
process in interface Value
Parameters:
context - The dynamic context, giving access to the current node, the current variables, etc.

subsequence

public 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