java.io.Serializable, javax.xml.transform.SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, org.xml.sax.Locatorpublic class ItemAt extends SystemFunction
The function takes two arguments: the first is an arbitrary sequence, the second is optional numeric. The function returns the same result as let $N := NUMBER return SEQUENCE[$N], including cases where the numeric argument is not a whole number.
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticPropertiesargumentoperation| Constructor | Description |
|---|---|
ItemAt() |
| Modifier and Type | Method | Description |
|---|---|---|
Item |
evaluateItem(XPathContext context) |
Evaluate the function to return the selected item.
|
Expression |
optimize(ExpressionVisitor visitor,
ItemType contextItemType) |
Perform optimisation of an expression and its subexpressions.
|
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, iterate, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeErroraddExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheckclone, finalize, getClass, notify, notifyAll, wait, wait, waitaddContextDocumentArgument, addDocToPathMap, checkArguments, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, makeSystemFunction, setDetails, useContextItemAsDefaultpublic Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.
optimize in class SystemFunctionvisitor - an expression visitorcontextItemType - the static type of "." at the point where this expression is invoked.
The parameter is set to null if it is known statically that the context item will be undefined.
If the type of the context item is not known statically, the argument is set to
Type.ITEM_TYPEXPathException - if an error is discovered during this phase
(typically a type error)public Item evaluateItem(XPathContext context) throws XPathException
evaluateItem in interface EvaluableItemevaluateItem in class Expressioncontext - The context in which the expression is to be evaluatedXPathException - if any dynamic error occurs evaluating the
expression