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: Class EmptyNodeSet

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com.icl.saxon.expr
Class EmptyNodeSet


java.lang.Object

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

        |

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

              |

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

                    |

                    +--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