## com.icl.saxon.expr
Class EmptyNodeSet

    java.lang.Object
      |
      +--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

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`

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.

  Specified by:
    `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

  Specified by:
    `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

  Specified by:
    `asString` in class `NodeSetValue`
  Returns:
    an empty string

### asBoolean

    public boolean asBoolean()

  Evaluate as a boolean.

  Specified by:
    `asBoolean` in class `NodeSetValue`
  Returns:
    false

### getCount

    public int getCount()

  Count the nodes in the node-set.

  Specified by:
    `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)

  Specified by:
    `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)

  Specified by:
    `getFirst` in class `NodeSetValue`
  Returns:
    null

### equals

    public boolean equals(Value other)

  Test whether this nodeset "equals" another Value

  Overrides:
    `equals` in class `NodeSetValue`
  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`
  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.

  Specified by:
    `enumerate` in class `NodeSetValue`