parsii.eval

Interface Function

All Known Implementing Classes:

BinaryFunction, UnaryFunction

public interface Function

Defines a function which can be referenced and evaluated from within expressions.

Method Summary

Modifier and Type	Method and Description
double	eval(List<Expression> args) Executes the function with the given arguments.
int	getNumberOfArguments() Returns the number of expected arguments.
boolean	isNaturalFunction() A natural function returns the same output for the same input.

Method Detail

getNumberOfArguments

int getNumberOfArguments()

Returns the number of expected arguments.

If the function is called with a different number of arguments, an error will be created

In order to support functions with a variable number of arguments, a negative number can be returned. This will essentially disable the check.

Returns:

the number of arguments expected by this function or a negative number to indicate that this function accepts a variable number of arguments

eval

double eval(List<Expression> args)

Executes the function with the given arguments.

The arguments need to be evaluated first. This is not done externally to permit functions to perform lazy evaluations.

Parameters:

args - the arguments for this function. The length of the given list will exactly match getNumberOfArguments

Returns:

the result of the function evaluated with the given arguments

isNaturalFunction

boolean isNaturalFunction()

A natural function returns the same output for the same input.

All classical mathematical functions are "natural". A function which reads user input is not natural, as the function might return different results depending on the users input

Returns:

true if the function returns the same output for the same input, false otherwise