Class Trace

  • All Implemented Interfaces:
    java.io.Serializable, javax.xml.transform.SourceLocator, Container, Expression, InstructionInfoProvider

    public class Trace
    extends SystemFunction
    This class supports the XPath 2.0 function trace(). The value is traced to the System.err stream, unless a TraceListener is in use, in which case the information is sent to the TraceListener
    See Also:
    Serialized Form
    • Constructor Detail

      • Trace

        public Trace()
    • Method Detail

      • simplify

        public Expression simplify​(StaticContext env)
                            throws XPathException
        Simplify the function call. This implementation saves the static namespace context, in case it is needed by the TraceListener.
        Specified by:
        simplify in interface Expression
        Overrides:
        simplify in class FunctionCall
        Parameters:
        env - the static context
        Returns:
        the simplified expression
        Throws:
        XPathException - if an error is discovered during expression rewriting
      • computeSpecialProperties

        public int computeSpecialProperties()
        Get the static properties of this expression (other than its type). The result is bit-significant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.
        Overrides:
        computeSpecialProperties in class SystemFunction
      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                          throws XPathException
        Evaluate the function
        Specified by:
        evaluateItem in interface Expression
        Overrides:
        evaluateItem in class ComputedExpression
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression