VariableReference (WSO2 Balana Core 1.1.15 API)

java.lang.Object
- org.wso2.balana.cond.VariableReference

All Implemented Interfaces:

Evaluatable, Expression
```
public class VariableReference
extends Object
implements Expression, 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

Constructors
Constructor and Description
`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

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`String`	`encode()` Encodes this `VariableReference` into its XML form
`void`	`encode(StringBuilder builder)` Encodes this `VariableReference` into its XML form and writes this out to the provided `StringBuilder`
`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 String encode()
```
    Encodes this VariableReference into its XML form
    
    Returns:
    
    String
  - encode
```
public void encode(StringBuilder builder)
```
    Encodes this VariableReference into its XML form and writes this out to the provided StringBuilder
    Specified by: encode in interface Expression Parameters: builder - string stream into which the XML-encoded data is written

Class VariableReference

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

VariableReference

VariableReference

VariableReference

Method Detail

getInstance

getVariableId

getReferencedDefinition

evaluate

getType

returnsBag

evaluatesToBag

getChildren

encode

encode