net.sf.saxon.functions
Class Trace
java.lang.Object
net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.FunctionCall
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.Trace
- All Implemented Interfaces:
- Serializable, Expression
public class Trace
- extends SystemFunction
This class supports the XPath 2.0 function trace().
At present the value is simply traced to the System.err stream
- See Also:
- Serialized Form
Constructor Summary |
Trace()
|
Methods inherited from class net.sf.saxon.expr.ComputedExpression |
computeDependencies, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSpecialProperties, markTailFunctionCalls, setLineNumber, typeError |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Trace
public Trace()
preEvaluate
public Expression preEvaluate(StaticContext env)
- preEvaluate: this method suppresses compile-time evaluation by doing nothing
- Overrides:
preEvaluate
in class FunctionCall
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 ComputedExpression
computeCardinality
public int computeCardinality()
- Get the static cardinality
- Overrides:
computeCardinality
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
iterate
public SequenceIterator iterate(XPathContext context)
throws XPathException
- Iterate over the results of the function
- Specified by:
iterate
in interface Expression
- Overrides:
iterate
in class ComputedExpression
- Parameters:
context
- supplies the context for evaluation
- Returns:
- a SequenceIterator that can be used to iterate over the result
of the expression
- Throws:
XPathException
- if any dynamic error occurs evaluating the
expression