Package net.sf.saxon.expr.elab

Class ItemElaborator

java.lang.Object

net.sf.saxon.expr.elab.Elaborator

net.sf.saxon.expr.elab.ItemElaborator

Direct Known Subclasses:

Abs.AbsElaborator, AccessorFn.AccessorFnElaborator, ArithmeticExpression.ArithmeticElaborator, AttributeGetter.AttributeGetterElaborator, BaseUri_1.BaseUriFnElaborator, CastExpression.CastExprElaborator, Ceiling.CeilingElaborator, ContextItemExpression.ContextItemElaborator, Count.CountFnElaborator, DateTimeConstructor.DateTimeFnElaborator, FirstItemExpression.FirstItemExprElaborator, Floor.FloorElaborator, IdentityComparison.IdentityComparisonElaborator, LastItemExpression.LastItemExprElaborator, NamespaceUriFn_1.NamespaceUriFnElaborator, NegateExpression.NegateElaborator, NodeName_1.NodeNameFnElaborator, Number_1.NumberFnElaborator, ParseQNameFn.QNameFnElaborator, PositionAndLast.Last.LastFnElaborator, PositionAndLast.Position.PositionFnElaborator, QNameFn.QNameFnElaborator, Root_1.RootFnElaborator, RootExpression.RootExprElaborator, Round.RoundElaborator, RoundHalfToEven.RoundHalfToEvenElaborator, SingletonIntersectExpression.SingletonIntersectElaborator, StringLength_1.StringLengthFnElaborator, SubscriptExpression.SubscriptExprElaborator, Substring.SubstringFnElaborator, Sum.SumFnElaborator, Translate.TranslateFnElaborator, ValueComparison.ValueComparisonElaborator

public abstract class ItemElaborator
extends Elaborator

An ItemElaborator is an abstract superclass for use by expressions that deliver zero or one items as their result. A concrete subclass must implement the elaborateForItem() method; other evaluation methods are implemented (by default) by calling elaborateForItem().

Constructor Summary

Constructors

Constructor	Description
ItemElaborator()

Method Summary

Modifier and Type	Method	Description
SequenceEvaluator	eagerly()	Get a function that evaluates the underlying expression eagerly
BooleanEvaluator	elaborateForBoolean()	Get a function that evaluates the underlying expression in the form of a boolean, this being the effective boolean value of the expression.
abstract ItemEvaluator	elaborateForItem()	Get a function that evaluates the underlying expression in the form of a Item.
PullEvaluator	elaborateForPull()	Get a function that evaluates the underlying expression in the form of a SequenceIterator
PushEvaluator	elaborateForPush()	Get a function that evaluates the underlying expression in push mode, by writing events to an Outputter
UnicodeStringEvaluator	elaborateForUnicodeString(boolean zeroLengthWhenAbsent)	Get a function that evaluates the underlying expression in the form of a unicode string, this being the result of applying fn:string() to the result of the expression.

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 Detail

ItemElaborator

public ItemElaborator()

Method Detail

eagerly

public SequenceEvaluator eagerly()

Description copied from class: Elaborator

Get a function that evaluates the underlying expression eagerly

Overrides:

eagerly in class Elaborator

Returns:

an evaluator for the expression that returns a GroundedValue. The class SequenceEvaluator is declared to return a Sequence not a GroundedValue; we can't specialize it because it's a limitation of C# delegates, but the result can safely be cast to GroundedValue.

elaborateForPull

public PullEvaluator elaborateForPull()

Description copied from class: Elaborator

Get a function that evaluates the underlying expression in the form of a SequenceIterator

Specified by:

elaborateForPull in class Elaborator

Returns:

an evaluator for the expression that returns a SequenceIterator

elaborateForPush

public PushEvaluator elaborateForPush()

Description copied from class: Elaborator

Get a function that evaluates the underlying expression in push mode, by writing events to an Outputter

Specified by:

elaborateForPush in class Elaborator

Returns:

an evaluator for the expression in push mode

elaborateForItem

public abstract 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 Elaborator

Returns:

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

elaborateForBoolean

public BooleanEvaluator elaborateForBoolean()

Description copied from class: Elaborator

Get a function that evaluates the underlying expression in the form of a boolean, this being the effective boolean value of the expression.

Specified by:

elaborateForBoolean in class Elaborator

Returns:

an evaluator for the expression that returns a boolean.

elaborateForUnicodeString

public UnicodeStringEvaluator elaborateForUnicodeString(boolean zeroLengthWhenAbsent)

Description copied from class: Elaborator

Get a function that evaluates the underlying expression in the form of a unicode string, this being the result of applying fn:string() to the result of the expression.

Specified by:

elaborateForUnicodeString in class Elaborator

Parameters:

zeroLengthWhenAbsent - if true, then when the result of the expression is an empty sequence, the result of the StringEvaluator should be a zero-length string. If false, the return value should be null. For an expression or function that never returns an empty sequence (for example, a call on string() or normalize-space()), the argument has no effect.

Returns:

an evaluator for the expression that returns a string.