Package 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
,SourceLocator
,Container
,Expression
,InstructionInfoProvider
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:
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Nested Class Summary
Nested Classes -
Field Summary
FieldsFields 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.ComputedExpression
locationId, staticProperties
Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
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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
(StaticContext env) preEvaluate: this method suppresses compile-time evaluation by doing nothingsimplify
(StaticContext env) Simplify the function call.Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, checkArguments, display, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, main, makeSystemFunction, setDetails, useContextItemAsDefault
Methods inherited from class net.sf.saxon.expr.FunctionCall
checkArgumentCount, getArguments, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, optimize, promote, replaceSubExpression, setArguments, setFunctionNameCode, simplifyArguments, typeCheck
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
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Field Details
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resolver
NamespaceResolver resolver
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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.- Specified by:
simplify
in interfaceExpression
- Overrides:
simplify
in classFunctionCall
- Parameters:
env
- the static context- 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
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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
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computeCardinality
public int computeCardinality()Get the static cardinality- Overrides:
computeCardinality
in classSystemFunction
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evaluateItem
Evaluate the function- Specified by:
evaluateItem
in interfaceExpression
- Overrides:
evaluateItem
in classComputedExpression
- 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 interfaceExpression
- Overrides:
iterate
in classComputedExpression
- 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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