org.wso2.balana.cond

Interface Function

All Superinterfaces:

Expression

All Known Implementing Classes:

AbsFunction, AddFunction, BagFunction, ComparisonFunction, ConditionBagFunction, ConditionSetFunction, DateMathFunction, DivideFunction, EqualFunction, FloorFunction, FunctionBase, GeneralBagFunction, GeneralSetFunction, HigherOrderFunction, IPInRangeFunction, LogicalFunction, MatchFunction, ModFunction, MultiplyFunction, NOfFunction, NotFunction, NumericConvertFunction, RoundFunction, SetFunction, StringComparingFunction, StringConversionFunction, StringCreationFunction, StringFunction, StringNormalizeFunction, SubStringFunction, SubtractFunction, TimeInRangeFunction, URLStringCatFunction, XACML3HigherOrderFunction, XPathFunction

public interface Function
extends Expression

Interface that all functions in the system must implement.

Since:

1.0

Author:

Seth Proctor

Method Summary

Modifier and Type	Method and Description
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.
String	encode() Encodes this Function into its XML form
void	encode(StringBuilder builder) Encodes this Function into its XML form and writes this out to the provided StringBuilder
EvaluationResult	evaluate(List<Evaluatable> 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.

Methods inherited from interface org.wso2.balana.cond.Expression

getType

Method Detail

evaluate

EvaluationResult evaluate(List<Evaluatable> 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 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 some argument (typically the first) in the List will actually be a Function object representing the function to apply to some bag. 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

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

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

boolean returnsBag()

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

Specified by:

returnsBag in interface Expression

Returns:

true if evaluation will return a bag, false otherwise

checkInputs

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

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

encode

String encode()

Encodes this Function into its XML form

Returns:

String

encode

void encode(StringBuilder builder)

Encodes this Function 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