Package net.sf.saxon.expr
Class LastItemExpression
- java.lang.Object
-
- net.sf.saxon.expr.Expression
-
- net.sf.saxon.expr.UnaryExpression
-
- net.sf.saxon.expr.SingleItemFilter
-
- net.sf.saxon.expr.LastItemExpression
-
- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,InstructionInfo
,org.xml.sax.Locator
public final class LastItemExpression extends SingleItemFilter
A LastItemExpression returns the last item in the sequence returned by a given base expression. The evaluation strategy is to read the input sequence with a one-item lookahead.- See Also:
- Serialized Form
-
-
Field Summary
-
Fields inherited from class net.sf.saxon.expr.UnaryExpression
operand
-
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
Constructors Constructor Description LastItemExpression(Expression base)
Constructor
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Expression
copy()
Copy an expression.Item
evaluateItem(XPathContext context)
Evaluate the expressionjava.lang.String
getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user.-
Methods inherited from class net.sf.saxon.expr.SingleItemFilter
computeCardinality, optimize, promote
-
Methods inherited from class net.sf.saxon.expr.UnaryExpression
computeSpecialProperties, displayOperator, equals, explain, getBaseExpression, getItemType, hashCode, iterateSubExpressions, replaceSubExpression, simplify, 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, getImplementationMethod, 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
-
-
-
-
Constructor Detail
-
LastItemExpression
public LastItemExpression(Expression base)
Constructor- Parameters:
base
- A sequence expression denoting sequence whose first item is to be returned
-
-
Method Detail
-
copy
public Expression copy()
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Returns:
- the copy of the original expression
-
evaluateItem
public Item evaluateItem(XPathContext context) throws XPathException
Evaluate the expression- 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
-
getExpressionName
public java.lang.String getExpressionName()
Description copied from class:Expression
Get a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionName
in classExpression
- Returns:
- a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.
-
-