Class EmptyNodeSet


  • public final class EmptyNodeSet
    extends NodeSetValue
    A node-set value no nodes
    • 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)
        Returns:
        the value, unchanged
      • 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