Package org.apache.xpath.operations

Class VariableSafeAbsRef

java.lang.Object
org.apache.xpath.Expression
org.apache.xpath.operations.Variable
org.apache.xpath.operations.VariableSafeAbsRef
All Implemented Interfaces:
Serializable, SourceLocator, PathComponent, ExpressionNode, XPathVisitable
public class VariableSafeAbsRef
extends Variable
This is a "smart" variable reference that is used in situations where an absolute path is optimized into a variable reference, but may be used in some situations where the document context may have changed. For instance, in select="document(doc/@href)//name[//salary > 7250]", the root in the predicate will be different for each node in the set. While this is easy to detect statically in this case, in other cases static detection would be very hard or impossible. So, this class does a dynamic check to make sure the document context of the referenced variable is the same as the current document context, and, if it is not, execute the referenced variable's expression with the current context instead.
See Also:
Serialized Form

  • Constructor Details

    • VariableSafeAbsRef

      public VariableSafeAbsRef()

  • Method Details

    • execute

      public XObject execute​(XPathContext xctxt, boolean destructiveOK) throws TransformerException
      Dereference the variable, and return the reference value. Note that lazy evaluation will occur. If a variable within scope is not found, a warning will be sent to the error listener, and an empty nodeset will be returned.
      Overrides:
      execute in class Variable
      Parameters:
      xctxt - The runtime execution context.
      destructiveOK - true if a "safe" object doesn't need to be returned.
      Returns:
      The evaluated variable, or an empty nodeset if not found.
      Throws:
      TransformerException