Class UnionExpression

java.lang.Object
com.icl.saxon.expr.Expression
com.icl.saxon.expr.NodeSetExpression
com.icl.saxon.expr.UnionExpression
class UnionExpression extends NodeSetExpression
An expression representing a nodeset that is a union of two other NodeSets

  • Field Details

  • Constructor Details

    • UnionExpression

      public UnionExpression(Expression p1, Expression p2)
      Constructor
      Parameters:
      p1 - the left-hand operand
      p2 - the right-hand operand

  • Method Details

    • simplify

      public Expression simplify() throws XPathException
      Simplify an expression
      Overrides:
      simplify in class Expression
      Returns:
      the simplified expression
      Throws:
      XPathException

    • enumerate

      public NodeEnumeration enumerate(Context c, boolean sort) throws XPathException
      Evaluate the union expression. The result will always be sorted in document order, with duplicates eliminated
      Specified by:
      enumerate in class NodeSetExpression
      Parameters:
      c - The context for evaluation
      sort - Request the nodes in document order (they will be, regardless)
      Returns:
      a NodeSetValue representing the union of the two operands
      Throws:
      XPathException - when the expression does not return a nodeset.

    • getDependencies

      public int getDependencies()
      Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE
      Specified by:
      getDependencies in class Expression

    • 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

    • reduce

      public Expression reduce(int dependencies, Context context) throws XPathException
      Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
      Specified by:
      reduce in class Expression
      Parameters:
      dependencies - The dependencies to be removed
      context - The context to be used for the partial evaluation
      Returns:
      a new expression that does not have any of the specified dependencies
      Throws:
      XPathException

    • display

      public void display(int level)
      Diagnostic print of expression structure
      Specified by:
      display in class Expression