Class GenerateId

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.GenerateId

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, InstructionInfo, Locator

public class GenerateId
extends SystemFunction

This class supports the generate-id() function

See Also:

• Serialized Form

Field Summary

Fields inherited from class SystemFunction

operation

Fields inherited from class FunctionCall

argument

Fields inherited from class 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

Constructors

Constructor	Description
GenerateId()

Method Summary

Modifier and Type	Method	Description
int	computeSpecialProperties()	Determine the special properties of this expression.
Item	evaluateItem(XPathContext c)	Evaluate the function in a string context
Expression	simplify(ExpressionVisitor visitor)	Simplify and validate.

Methods inherited from class SystemFunction

addContextDocumentArgument, addDocToPathMap, checkArguments, computeCardinality, copy, equals, getDetails, getErrorCodeForTypeErrors, getImplementationMethod, getItemType, getOperation, getRequiredType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault

Methods inherited from class FunctionCall

addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplifyArguments, toString, typeCheck

Methods inherited from class 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, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

GenerateId

public GenerateId()

Method Details

simplify

public Expression simplify(ExpressionVisitor visitor)
                    throws XPathException

Simplify and validate.

Overrides:

simplify in class FunctionCall

Parameters:

visitor - an expression visitor

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

computeSpecialProperties

public int computeSpecialProperties()

Determine the special properties of this expression. The generate-id() function is a special case: it is considered creative if its operand is creative, so that generate-id(f()) is not taken out of a loop

Overrides:

computeSpecialProperties in class SystemFunction

Returns:

the special properties, as a bit-significant integer

evaluateItem

public Item evaluateItem(XPathContext c)
                  throws XPathException

Evaluate the function in a string context

Overrides:

evaluateItem in class Expression

Parameters:

c - 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