org.jboss.security.xacml.sunxacml.cond
Class VariableReference

java.lang.Object
  org.jboss.security.xacml.sunxacml.cond.VariableReference

All Implemented Interfaces:

Evaluatable, Expression

public class VariableReference
extends Object
implements Evaluatable

This class supports the VariableReferenceType type introuced in XACML 2.0. It allows an expression to reference a variable definition. If there is no such definition then the Policy is invalid. A reference can be included anywwhere in an expression where the referenced expression would be valid.

Since:

2.0

Author:

Seth Proctor

Constructor Summary

VariableReference(String variableId)
Simple constructor that takes only the identifier.

VariableReference(String variableId, VariableManager manager)
Constructor that takes the reference identifier and a manager.

VariableReference(VariableDefinition definition)
Constructor that takes the definition referenced by this class.

Method Summary

void	encode(OutputStream output) Encodes this class into its XML representation and writes this encoding to the given OutputStream with no indentation.
void	encode(OutputStream output, Indenter indenter) Encodes this class into its XML representation and writes this encoding to the given OutputStream with indentation.
EvaluationResult	evaluate(EvaluationCtx context) Evaluates the referenced expression using the given context, and either returns an error or a resulting value.
boolean	evaluatesToBag() Deprecated. As of 2.0, you should use the returnsBag method from the super-interface Expression.
List	getChildren() Always returns an empty list since references never have children in the policy tree.
static VariableReference	getInstance(Node root, PolicyMetaData metaData, VariableManager manager) Returns a new instance of the VariableReference class based on a DOM node.
VariableDefinition	getReferencedDefinition() Returns the VariableDefinition referenced by this class, or null if the definition cannot be resolved.
URI	getType() Returns the type of the referenced expression.
String	getVariableId() Returns the reference identifier.
boolean	returnsBag() Tells whether evaluation will return a bag or a single value.

Methods inherited from class java.lang.Object

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

Constructor Detail

VariableReference

public VariableReference(String variableId)

Simple constructor that takes only the identifier. This is provided for tools that want to build policies only for the sake of encoding or displaying them. This constructor will not create a reference that can be followed to its associated definition, so it cannot be used in evaluation.

Parameters:

variableId - the reference identifier

VariableReference

public VariableReference(VariableDefinition definition)

Constructor that takes the definition referenced by this class. If you're building policies programatically, this is typically the form you use. It does make the connection from reference to definition, so this will result in an evaluatable reference.

Parameters:

definition - the definition this class references

VariableReference

public VariableReference(String variableId,
                         VariableManager manager)

Constructor that takes the reference identifier and a manager. This is typically only used by parsing code, since the manager is used to handle out-of-order definitions and circular references.

Parameters:

variableId - the reference identifier

manager - a VariableManager used to handle the dependencies between references and definitions during parsing

Method Detail

getInstance

public static VariableReference getInstance(Node root,
                                            PolicyMetaData metaData,
                                            VariableManager manager)
                                     throws ParsingException

Returns a new instance of the VariableReference class based on a DOM node. The node must be the root of an XML VariableReferenceType.

Parameters:

root - the DOM root of a VariableReferenceType XML type

metaData - the meta-data associated with the containing policy

manager - the VariableManager used to connect this reference to its definition

Throws:

ParsingException - if the VariableReferenceType is invalid

getVariableId

public String getVariableId()

Returns the reference identifier.

Returns:

the reference's identifier

getReferencedDefinition

public VariableDefinition getReferencedDefinition()

Returns the VariableDefinition referenced by this class, or null if the definition cannot be resolved.

Returns:

the referenced definition or null

evaluate

public EvaluationResult evaluate(EvaluationCtx context)

Evaluates the referenced expression using the given context, and either returns an error or a resulting value. If this doesn't reference an evaluatable expression (eg, a single Function) then this will throw an exception.

Specified by:

evaluate in interface Evaluatable

Parameters:

context - the representation of the request

Returns:

the result of evaluation

getType

public URI getType()

Returns the type of the referenced expression.

Specified by:

getType in interface Expression

Returns:

the attribute return type of the referenced expression

Throws:

ProcessingException - if the type couldn't be resolved

returnsBag

public boolean returnsBag()

Tells whether evaluation will return a bag or a single value.

Specified by:

returnsBag in interface Expression

Returns:

true if evaluation will return a bag, false otherwise

Throws:

ProcessingException - if the return type couldn't be resolved

evaluatesToBag

public boolean evaluatesToBag()

Deprecated. As of 2.0, you should use the returnsBag method from the super-interface Expression.

Tells whether evaluation will return a bag or a single value.

Specified by:

evaluatesToBag in interface Evaluatable

Returns:

true if evaluation will return a bag, false otherwise

Throws:

ProcessingException - if the return type couldn't be resolved

getChildren

public List getChildren()

Always returns an empty list since references never have children in the policy tree. Note that the referenced definition may still have children, so tools may want to treat these as children of this reference, but must take care since circular references could create a tree of infinite depth.

Specified by:

getChildren in interface Evaluatable

Returns:

an empty List

encode

public void encode(OutputStream output)

Encodes this class into its XML representation and writes this encoding to the given OutputStream with no indentation.

Specified by:

encode in interface Expression

Parameters:

output - a stream into which the XML-encoded data is written

encode

public void encode(OutputStream output,
                   Indenter indenter)

Encodes this class into its XML representation and writes this encoding to the given OutputStream with indentation.

Specified by:

encode in interface Expression

Parameters:

output - a stream into which the XML-encoded data is written

indenter - an object that creates indentation strings