Class SingletonNode

java.lang.Object
net.sf.saxon.value.Value
net.sf.saxon.value.SingletonNode
All Implemented Interfaces:
Serializable, SequenceIterable, GroundedValue, ValueRepresentation

public class SingletonNode extends Value implements GroundedValue
A value that is a sequence containing zero or one nodes
See Also:
  • Field Details

  • Constructor Details

    • SingletonNode

      public SingletonNode(NodeInfo node)
      Create a node-set containing zero or one nodes
      Parameters:
      node - The node to be contained in the node-set, or null if the node-set is to be empty
  • Method Details

    • asItem

      public Item asItem()
      Return the value in the form of an Item
      Overrides:
      asItem in class Value
      Returns:
      the value in the form of an Item
    • process

      public void process(XPathContext context) throws XPathException
      Process the instruction, without returning any tail calls
      Overrides:
      process in class Value
      Parameters:
      context - The dynamic context, giving access to the current node, the current variables, etc.
      Throws:
      XPathException
    • getItemType

      public ItemType getItemType(TypeHierarchy th)
      Determine the data type of the items in the expression. This method determines the most precise type that it can, because it is called when testing that the node conforms to a required type.
      Overrides:
      getItemType in class Value
      Parameters:
      th - the type hierarchy cache
      Returns:
      the most precise possible type of the node.
    • getCardinality

      public int getCardinality()
      Determine the static cardinality
      Overrides:
      getCardinality in class Value
      Returns:
      the cardinality
    • getLength

      public int getLength() throws XPathException
      Get the length of the sequence
      Overrides:
      getLength in class Value
      Returns:
      the number of items in the sequence
      Throws:
      XPathException
    • itemAt

      public Item itemAt(int n)
      Get the n'th item in the sequence (starting from 0). This is defined for all SequenceValues, but its real benefits come for a SequenceValue stored extensionally (or for a MemoClosure, once all the values have been read)
      Specified by:
      itemAt in interface GroundedValue
      Overrides:
      itemAt in class Value
      Parameters:
      n - position of the required item, counting from zero.
      Returns:
      the n'th item in the sequence, where the first item in the sequence is numbered zero. If n is negative or >= the length of the sequence, returns null.
    • subsequence

      public GroundedValue subsequence(int start, int length)
      Get a subsequence of the value
      Specified by:
      subsequence in interface GroundedValue
      Parameters:
      start - the index of the first item to be included in the result, counting from zero. A negative value is taken as zero. If the value is beyond the end of the sequence, an empty sequence is returned
      length - the number of items to be included in the result. Specify Integer.MAX_VALUE to get the subsequence up to the end of the base sequence. If the value is negative, an empty sequence is returned. If the value goes off the end of the sequence, the result returns items up to the end of the sequence
      Returns:
      the required subsequence. If min is
    • getNode

      public NodeInfo getNode()
      Get the node that forms the node-set. Return null if there is none.
    • iterate

      public SequenceIterator iterate()
      Return an enumeration of this nodeset value.
      Specified by:
      iterate in class Value
      Returns:
      an iterator over the sequence of items
    • effectiveBooleanValue

      public boolean effectiveBooleanValue()
      Get the effective boolean value
      Overrides:
      effectiveBooleanValue in class Value
      Returns:
      the effective boolean value
    • getStringValue

      public String getStringValue()
      Convert the value to a string, using the serialization rules. For atomic values this is the same as a cast; for sequence values it gives a space-separated list. For QNames and NOTATIONS, or lists containing them, it fails.
      Specified by:
      getStringValue in interface ValueRepresentation
      Overrides:
      getStringValue in class Value