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: Class EmptyNodeSet

com.icl.saxon.expr
Class EmptyNodeSet


java.lang.Object

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  +--com.icl.saxon.expr.Expression

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        +--com.icl.saxon.expr.Value

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              +--com.icl.saxon.expr.NodeSetValue

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                    +--com.icl.saxon.expr.EmptyNodeSet


public final class EmptyNodeSet
extends NodeSetValue

A node-set value no nodes


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
 
Constructor Summary
EmptyNodeSet()
           
 
Method Summary
 boolean asBoolean()
          Evaluate as a boolean.
 java.lang.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
asNumber, compare, conversionPreference, convertToJava, display, enumerate, getDataType
 
Methods inherited from class com.icl.saxon.expr.Value
getDependencies, inverse, numericCompare, reduce, simplify, stringToNumber
 
Methods inherited from class com.icl.saxon.expr.Expression
containsReferences, evaluateAsBoolean, evaluateAsNumber, evaluateAsString, getStaticContext, indent, make, outputStringValue, setStaticContext, usesCurrent
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

EmptyNodeSet


public EmptyNodeSet()
Method Detail

evaluate


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

evaluateAsNodeSet


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

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 class 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

isSorted


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

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 class Expression

asString


public java.lang.String asString()
Convert to string value
Overrides:
asString in class NodeSetValue
Returns:
an empty string

asBoolean


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

getCount


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

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

getFirst


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

equals


public boolean equals(Value other)
Test whether this nodeset "equals" another Value
Overrides:
equals in class NodeSetValue
Following copied from class: com.icl.saxon.expr.Value
Returns:
a boolean giving the value of the expression, evaluated in the current context

notEquals


public boolean notEquals(Value other)
Test whether this nodeset "not-equals" another Value
Overrides:
notEquals in class NodeSetValue
Following copied from class: com.icl.saxon.expr.Value
Returns:
a boolean giving the value of the expression, evaluated in the current context

enumerate


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