Package net.sf.saxon.expr

Class FirstItemExpression.FirstItemExprElaborator

java.lang.Object

net.sf.saxon.expr.elab.Elaborator

net.sf.saxon.expr.elab.ItemElaborator

net.sf.saxon.expr.FirstItemExpression.FirstItemExprElaborator

Enclosing class:

FirstItemExpression

public static class FirstItemExpression.FirstItemExprElaborator
extends ItemElaborator

An elaborator for a "first-item" expression, typically written as X[1] or as head(X).

Constructor Summary

Constructors

Constructor	Description
FirstItemExprElaborator()

Method Summary

Modifier and Type	Method	Description
ItemEvaluator	elaborateForItem()	Get a function that evaluates the underlying expression in the form of a Item.

Methods inherited from class net.sf.saxon.expr.elab.ItemElaborator

eagerly, elaborateForBoolean, elaborateForPull, elaborateForPush, elaborateForUnicodeString

Methods inherited from class net.sf.saxon.expr.elab.Elaborator

elaborateForString, elaborateForUpdate, getConfiguration, getExpression, handleNullString, handleNullUnicodeString, handlePossiblyNullString, handlePossiblyNullUnicodeString, lazily, setExpression

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

FirstItemExprElaborator

public FirstItemExprElaborator()

Method Details

elaborateForItem

public ItemEvaluator elaborateForItem()

Description copied from class: Elaborator

Get a function that evaluates the underlying expression in the form of a Item. This must only be called for expressions whose result has cardinality zero or one.

Specified by:

elaborateForItem in class ItemElaborator

Returns:

an evaluator for the expression that returns an Item, or null to represent an empty sequence.