org.openanzo.glitter.expression
Class PolymorphicFunction

java.lang.Object
  org.openanzo.glitter.expression.PolymorphicFunction

All Implemented Interfaces:

Function, FunctionOnValues

Direct Known Subclasses:

PolymorphicEq, PolymorphicGe, PolymorphicGt, PolymorphicLe, PolymorphicLt, PolymorphicNe

public abstract class PolymorphicFunction
extends java.lang.Object
implements FunctionOnValues

Base class for functions that have different behavior (corresponding to different Functions) depending on the arguments given.

Author:

lee

Constructor Summary

PolymorphicFunction(FunctionOnValues[] functions)

Method Summary

RDFTerm	call(java.util.List<RDFTerm> arguments) See FunctionOnValues.call(List)
java.net.URI	getIdentifier() All of SPARQL's spec'ed out polymorphic functions are actually operators without a URI.
boolean	operatesOnTypeErrors()
boolean	operatesOnValues()

Methods inherited from class java.lang.Object

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

Constructor Detail

PolymorphicFunction

public PolymorphicFunction(FunctionOnValues[] functions)

Parameters:

functions - An ordered list of functions that implement this polymorphic function.

Method Detail

call

public RDFTerm call(java.util.List<RDFTerm> arguments)
             throws ExpressionEvaluationException

See FunctionOnValues.call(List)

Specified by:

call in interface FunctionOnValues

Parameters:

arguments - The (evaluated) RDF terms being passed to the function

Returns:

The return value of the first function that comprise this polymorphic function that does not result in an ExpressionEvaluationException when invoked.

Throws:

ExpressionEvaluationException - For invalid types, or other expression evalutaion problems

getIdentifier

public java.net.URI getIdentifier()

All of SPARQL's spec'ed out polymorphic functions are actually operators without a URI.

Specified by:

getIdentifier in interface Function

Returns:

The identifier for this function

operatesOnTypeErrors

public boolean operatesOnTypeErrors()

Specified by:

operatesOnTypeErrors in interface Function

Returns:

true if the function can process type errors as arguments; false if the function simply propagates type errors

operatesOnValues

public boolean operatesOnValues()

Specified by:

operatesOnValues in interface Function

Returns:

true if this function's arguments should be values evaluated in the context of the environment created from each set of bindings (solution); false if the function operates directly on the surface term (e.g. a hypothetical function isVariable would operate on terms and return false)