com.icl.saxon.expr

Class EmptyNodeSet


public final class EmptyNodeSet
extends NodeSetValue

A node-set value no nodes

Field Summary

Fields inherited from class com.icl.saxon.expr.Value

ANY, BOOLEAN, NODESET, NUMBER, OBJECT, STRING

Fields inherited from class com.icl.saxon.expr.Expression

staticContext

Method Summary

boolean
asBoolean()
Evaluate as a boolean.
String
asString()
Convert to string value
NodeEnumeration
enumerate()
Return an enumeration of this nodeset value.
boolean
equals(Value other)
Test whether this nodeset "equals" another Value
Value
evaluate(Context context)
Evaluate the Node Set.
NodeSetValue
evaluateAsNodeSet(Context context)
Evaluate an expression as a NodeSet.
int
getCount()
Count the nodes in the node-set.
NodeInfo
getFirst()
Get the first node in the nodeset (in document order)
boolean
isContextDocumentNodeSet()
Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node.
boolean
isSorted()
Test whether the value is known to be sorted
boolean
notEquals(Value other)
Test whether this nodeset "not-equals" another Value
void
setSorted(boolean isSorted)
Set a flag to indicate whether the nodes are sorted.
NodeSetValue
sort()
Sort the nodes into document order.

Methods inherited from class com.icl.saxon.expr.NodeSetValue

asBoolean, asNumber, asString, compare, conversionPreference, convertToJava, display, enumerate, enumerate, equals, evaluate, evaluateAsNodeSet, getCount, getDataType, getFirst, isSorted, notEquals, setSorted, sort

Methods inherited from class com.icl.saxon.expr.Value

asBoolean, asNumber, asString, compare, conversionPreference, convertToJava, equals, evaluate, getDependencies, inverse, notEquals, numericCompare, reduce, simplify, stringToNumber

Methods inherited from class com.icl.saxon.expr.Expression

containsReferences, display, enumerate, evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsNumber, evaluateAsString, getDataType, getDependencies, getStaticContext, indent, isContextDocumentNodeSet, make, outputStringValue, reduce, setStaticContext, simplify, usesCurrent

Method Details

asBoolean

public boolean asBoolean()
Evaluate as a boolean.
Overrides:
asBoolean in interface NodeSetValue
Returns:
false

asString

public String asString()
Convert to string value
Overrides:
asString in interface NodeSetValue
Returns:
an empty string

enumerate

public NodeEnumeration enumerate()
Return an enumeration of this nodeset value.
Overrides:
enumerate in interface NodeSetValue

equals

public boolean equals(Value other)
Test whether this nodeset "equals" another Value
Overrides:
equals in interface NodeSetValue

evaluate

public Value evaluate(Context context)
Evaluate the Node Set. This guarantees to return the result in sorted order.
Overrides:
evaluate in interface NodeSetValue
Parameters:
context - The context for evaluation (not used)

evaluateAsNodeSet

public NodeSetValue evaluateAsNodeSet(Context context)
Evaluate an expression as a NodeSet.
Overrides:
evaluateAsNodeSet in interface NodeSetValue
Parameters:
context - The context in which the expression is to be evaluated
Returns:
the value of the expression, evaluated in the current context

getCount

public int getCount()
Count the nodes in the node-set.
Overrides:
getCount in interface NodeSetValue
Returns:
zero

getFirst

public NodeInfo getFirst()
Get the first node in the nodeset (in document order)
Overrides:
getFirst in interface NodeSetValue
Returns:
null

isContextDocumentNodeSet

public boolean isContextDocumentNodeSet()
Determine, in the case of an expression whose data type is Value.NODESET, whether all the nodes in the node-set are guaranteed to come from the same document as the context node. Used for optimization.
Overrides:
isContextDocumentNodeSet in interface Expression

isSorted

public boolean isSorted()
Test whether the value is known to be sorted
Overrides:
isSorted in interface NodeSetValue
Returns:
true if the value is known to be sorted in document order, false if it is not known whether it is sorted.

notEquals

public boolean notEquals(Value other)
Test whether this nodeset "not-equals" another Value
Overrides:
notEquals in interface NodeSetValue

setSorted

public void setSorted(boolean isSorted)
Set a flag to indicate whether the nodes are sorted. Used when the creator of the node-set knows that they are already in document order.
Overrides:
setSorted in interface NodeSetValue
Parameters:
isSorted - true if the caller wishes to assert that the nodes are in document order and do not need to be further sorted

sort

public NodeSetValue sort()
Sort the nodes into document order. This does nothing if the nodes are already known to be sorted; to force a sort, call setSorted(false)
Overrides:
sort in interface NodeSetValue
Returns:
the same NodeSetValue, after sorting. (Historic)