net.sf.saxon.functions
Class Trace
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.FunctionCall
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.Trace
- All Implemented Interfaces:
- Serializable, SourceLocator, LocationProvider, SaxonLocator, CallableExpression, InstructionInfo, Locator
public class Trace
- extends SystemFunction
- implements CallableExpression
This class supports the XPath 2.0 function trace().
The value is traced to the registered output stream (defaulting to System.err),
unless a TraceListener is in use, in which case the information is sent to the TraceListener
- See Also:
- Serialized Form
Fields inherited from class net.sf.saxon.expr.Expression |
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD |
Constructor Summary |
Trace()
|
Methods inherited from class net.sf.saxon.functions.SystemFunction |
addContextDocumentArgument, addDocToPathMap, checkArguments, copy, equals, getDetails, getErrorCodeForTypeErrors, getImplementationMethod, getItemType, getOperation, getRequiredType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault |
Methods inherited from class net.sf.saxon.expr.FunctionCall |
addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheck |
Methods inherited from class net.sf.saxon.expr.Expression |
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError |
Trace
public Trace()
preEvaluate
public Expression preEvaluate(ExpressionVisitor visitor)
- preEvaluate: this method suppresses compile-time evaluation by doing nothing
- Overrides:
preEvaluate
in class FunctionCall
- Parameters:
visitor
- an expression visitor
- Returns:
- the result of the early evaluation, or the original expression, or potentially
a simplified expression
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
- Returns:
- the special properties, as a bit-significant integer
computeCardinality
public int computeCardinality()
- Get the static cardinality
- Overrides:
computeCardinality
in class SystemFunction
- Returns:
- the computed cardinality, as one of the values
StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.EXACTLY_ONE
, StaticProperty.ALLOWS_ONE_OR_MORE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
evaluateItem
public Item evaluateItem(XPathContext context)
throws XPathException
- Evaluate the function
- Overrides:
evaluateItem
in class Expression
- 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
traceItem
public static void traceItem(Item val,
String label,
PrintStream out)
iterate
public SequenceIterator iterate(XPathContext context)
throws XPathException
- Iterate over the results of the function
- Overrides:
iterate
in class Expression
- 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
call
public SequenceIterator call(SequenceIterator[] arguments,
XPathContext context)
throws XPathException
- Evaluate the expression
- Specified by:
call
in interface CallableExpression
- Parameters:
arguments
- the values of the arguments, supplied as SequenceIteratorscontext
- the dynamic evaluation context
- Returns:
- the result of the evaluation, in the form of a SequenceIterator
- Throws:
XPathException
- if a dynamic error occurs during the evaluation of the expression
Copyright (c) 2004-2011 Saxonica Limited. All rights reserved.