Package 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
,EvaluableItem
,SequenceIterable
,InstructionInfo
,Locator
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:
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Field Summary
Fields inherited from class net.sf.saxon.functions.SystemFunction
operation
Fields inherited from class net.sf.saxon.expr.FunctionCall
argument
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
Get the static cardinalityint
Get the static properties of this expression (other than its type).evaluateItem
(XPathContext context) Evaluate the functioniterate
(XPathContext context) Iterate over the results of the functionpreEvaluate
(ExpressionVisitor visitor) preEvaluate: this method suppresses compile-time evaluation by doing nothingsimplify
(ExpressionVisitor visitor) Simplify the function call.Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, addDocToPathMap, checkArguments, copy, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault
Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionName, simplifyArguments, toString, typeCheck
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
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Constructor Details
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Trace
public Trace()
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Method Details
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simplify
Simplify the function call. This implementation saves the static namespace context, in case it is needed by the TraceListener.- Overrides:
simplify
in classFunctionCall
- Parameters:
visitor
- an expression visitor- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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preEvaluate
preEvaluate: this method suppresses compile-time evaluation by doing nothing- Overrides:
preEvaluate
in classFunctionCall
- Parameters:
visitor
- an expression visitor- Returns:
- the result of the early evaluation, or the original expression, or potentially a simplified expression
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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 classSystemFunction
- Returns:
- the special properties, as a bit-significant integer
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computeCardinality
public int computeCardinality()Get the static cardinality- Overrides:
computeCardinality
in classSystemFunction
- 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
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evaluateItem
Evaluate the function- Specified by:
evaluateItem
in interfaceEvaluableItem
- Overrides:
evaluateItem
in classExpression
- 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
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iterate
Iterate over the results of the function- Specified by:
iterate
in interfaceSequenceIterable
- Overrides:
iterate
in classExpression
- 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
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