com.icl.saxon.expr

Class EmptyNodeSet

public final class EmptyNodeSet extends NodeSetValue

A node-set value no nodes
Method Summary
booleanasBoolean()
Evaluate as a boolean.
StringasString()
Convert to string value
NodeEnumerationenumerate()
Return an enumeration of this nodeset value.
booleanequals(Value other)
Test whether this nodeset "equals" another Value
Valueevaluate(Context context)
Evaluate the Node Set.
NodeSetValueevaluateAsNodeSet(Context context)
Evaluate an expression as a NodeSet.
intgetCount()
Count the nodes in the node-set.
NodeInfogetFirst()
Get the first node in the nodeset (in document order)
booleanisContextDocumentNodeSet()
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.
booleanisSorted()
Test whether the value is known to be sorted
booleannotEquals(Value other)
Test whether this nodeset "not-equals" another Value
voidsetSorted(boolean isSorted)
Set a flag to indicate whether the nodes are sorted.
NodeSetValuesort()
Sort the nodes into document order.

Method Detail

asBoolean

public boolean asBoolean()
Evaluate as a boolean.

Returns: false

asString

public String asString()
Convert to string value

Returns: an empty string

enumerate

public NodeEnumeration enumerate()
Return an enumeration of this nodeset value.

equals

public boolean equals(Value other)
Test whether this nodeset "equals" another Value

evaluate

public Value evaluate(Context context)
Evaluate the Node Set. This guarantees to return the result in sorted order.

Parameters: context The context for evaluation (not used)

evaluateAsNodeSet

public NodeSetValue evaluateAsNodeSet(Context context)
Evaluate an expression as a NodeSet.

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.

Returns: zero

getFirst

public NodeInfo getFirst()
Get the first node in the nodeset (in document order)

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.

isSorted

public boolean isSorted()
Test whether the value is known to be sorted

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

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.

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)

Returns: the same NodeSetValue, after sorting. (Historic)