com.sun.xacml.cond
Interface Function

All Known Implementing Classes:

FunctionBase, HigherOrderFunction

public interface Function

Interface that all functions in the system must implement.

Since:

1.0

Method Summary

void	checkInputs(List inputs) Checks that the given inputs are of the right types, in the right order, and are the right number for this function to evaluate.
void	checkInputsNoBag(List inputs) Checks that the given inputs are of the right types, in the right order, and are the right number for this function to evaluate.
EvaluationResult	evaluate(List inputs, EvaluationCtx context) Evaluates the Function using the given inputs.
URI	getIdentifier() Returns the identifier of this function as known by the factories.
URI	getReturnType() Provides the type of AttributeValue that this function returns from evaluate in a successful evaluation.
boolean	returnsBag() Tells whether this function will return a bag of values or just a single value.

Method Detail

evaluate

public EvaluationResult evaluate(List inputs,
                                 EvaluationCtx context)

Evaluates the Function using the given inputs. The List contains Evaluatables which are all of the correct type if the Function has been created as part of an Apply or TargetMatch, but which may otherwise be invalid. Each parameter should be evaluated by the Function, unless this is a higher-order function (in which case the Apply has already evaluated the inputs to check for any INDETERMINATE conditions), or the Function doesn't need to evaluate all inputs to determine a result (as in the case of the or function). The order of the List is significant, so a Function should have a very good reason if it wants to evaluate the inputs in a different order.

Note that if this is a higher-order function, like any-of, then the first argument in the List will actually be a Function object representing the function to apply to some bag. In this case, the second and any subsequent entries in the list are AttributeValue objects (no INDETERMINATE values are allowed, so the function is not given the option of dealing with attributes that cannot be resolved). A function needs to know if it's a higher-order function, and therefore whether or not to look for this case. Also, a higher-order function is responsible for checking that the inputs that it will pass to the Function provided as the first parameter are valid, ie. it must do a checkInputs on its sub-function when checkInputs is called on the higher-order function.

Parameters:

inputs - the List of inputs for the function

context - the representation of the request

Returns:

a result containing the AttributeValue computed when evaluating the function, or Status specifying some error condition

getIdentifier

public URI getIdentifier()

Returns the identifier of this function as known by the factories. In the case of the standard XACML functions, this will be one of the URIs defined in the standard namespace. This function must always return the complete namespace and identifier of this function.

Returns:

the function's identifier

getReturnType

public URI getReturnType()

Provides the type of AttributeValue that this function returns from evaluate in a successful evaluation.

Returns:

the type returned by this function

returnsBag

public boolean returnsBag()

Tells whether this function will return a bag of values or just a single value.

Returns:

true if evaluation will return a bag, false otherwise

checkInputs

public void checkInputs(List inputs)
                 throws IllegalArgumentException

Checks that the given inputs are of the right types, in the right order, and are the right number for this function to evaluate. If the function cannot accept the inputs for evaluation, an IllegalArgumentException is thrown.

Parameters:

inputs - a List of Evaluatables, with the first argument being a Function if this is a higher-order function

Throws:

IllegalArgumentException - if the inputs do match what the function accepts for evaluation

checkInputsNoBag

public void checkInputsNoBag(List inputs)
                      throws IllegalArgumentException

Checks that the given inputs are of the right types, in the right order, and are the right number for this function to evaluate. If the function cannot accept the inputs for evaluation, an IllegalArgumentException is thrown. Unlike the other checkInput method in this interface, this assumes that the parameters will never provide bags of values. This is useful if you're considering a target function which has a designator or selector in its input list, but which passes the values from the derived bags one at a time to the function, so the function doesn't have to deal with the bags that the selector or designator generates.

Parameters:

inputs - a List of Evaluatables, with the first argument being a Function if this is a higher-order function

Throws:

IllegalArgumentException - if the inputs do match what the function accepts for evaluation