Class FilterExpression


class FilterExpression extends NodeSetExpression
A FilterExpression contains a base expression and a filter predicate, which may be an integer expression (positional filter), or a boolean expression (qualifier)
  • Constructor Details

    • FilterExpression

      public FilterExpression(Expression start, Expression filter)
      Constructor
      Parameters:
      start - A node-set expression denoting the absolute or relative set of nodes from which the navigation path should start.
      filter - An expression defining the filter predicate
  • 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 context, boolean sort) throws XPathException
      Evaluate the filter expression in a given context to return a Node Enumeration
      Specified by:
      enumerate in class NodeSetExpression
      Parameters:
      context - the evaluation context
      sort - true if the result must be in document order
      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
    • reduce

      public Expression reduce(int dep, 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:
      dep - 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
    • 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
    • display

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