ptolemy.data
Class FunctionToken

java.lang.Object
  ptolemy.data.Token
      ptolemy.data.FunctionToken

All Implemented Interfaces:

java.io.Serializable

public class FunctionToken
extends Token

A token that contains a function. The function takes a fixed number of arguments, supplied as a list of tokens. Currently, no operations between function tokens (add, multiply, etc.) are supported.

Since:

Ptolemy II 2.1

Version:

$Id: FunctionToken.java 57040 2010-01-27 20:52:32Z cxh $

Author:

Xiaojun Liu, Steve Neuendorffer

See Also:

Serialized Form

Accepted Rating:

Red (liuxj)

Proposed Rating:

Yellow (liuxj)

Field Summary

private Function	_function
private FunctionType	_type

Fields inherited from class ptolemy.data.Token

NIL

Constructor Summary

FunctionToken(Function f, FunctionType type)
Create a new FunctionToken that applies the given function.

FunctionToken(java.lang.String init)
Create a new FunctionToken from the given string.

Method Summary

Token	apply(Token[] args) Apply this function to the given list of arguments.
Function	getFunction() Return the function of this token.
int	getNumberOfArguments() Return the number of arguments of the function.
Type	getType() Return the type of this token.
BooleanToken	isCloseTo(Token rightArgument, double epsilon) Test for closeness of the values of this Token and the argument Token.
BooleanToken	isEqualTo(Token rightArgument) Test for equality of the values of this Token and the argument Token.
java.lang.String	toString() Return a String representation of this function.

Methods inherited from class ptolemy.data.Token

add, addReverse, divide, divideReverse, isCloseTo, isNil, modulo, moduloReverse, multiply, multiplyReverse, notSupportedConversionMessage, notSupportedIncomparableConversionMessage, notSupportedIncomparableMessage, notSupportedMessage, notSupportedNullNilStringMessage, one, pow, subtract, subtractReverse, zero, zeroReturnType

Methods inherited from class java.lang.Object

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

Field Detail

_function

private Function _function

_type

private FunctionType _type

Constructor Detail

FunctionToken

public FunctionToken(Function f,
                     FunctionType type)

Create a new FunctionToken that applies the given function. The type of the function token will be the same as the given type.

Parameters:

f - The function.

type - The function type.

FunctionToken

public FunctionToken(java.lang.String init)
              throws IllegalActionException

Create a new FunctionToken from the given string.

Parameters:

init - The initialization string, for example function(x,y) 4+x+y.

Throws:

IllegalActionException - If an error occurs, or the string cannot be parsed into a function.

Method Detail

apply

public Token apply(Token[] args)
            throws IllegalActionException

Apply this function to the given list of arguments.

Parameters:

args - the arguments to which the function is applied

Returns:

The results of applying the arguments to this function.

Throws:

IllegalActionException - If the arguments are not compatible with this function, or an error occurs during evaluation.

getFunction

public Function getFunction()

Return the function of this token.

Returns:

A Function.

getNumberOfArguments

public int getNumberOfArguments()

Return the number of arguments of the function.

Returns:

The number of arguments of the function.

getType

public Type getType()

Return the type of this token.

Overrides:

getType in class Token

Returns:

A FunctionType.

isCloseTo

public BooleanToken isCloseTo(Token rightArgument,
                              double epsilon)

Test for closeness of the values of this Token and the argument Token. For function tokens, checking for closeness is the same as checking for equality.

Overrides:

isCloseTo in class Token

Parameters:

rightArgument - The token to compare to this token.

epsilon - This argument is ignored in this method.

Returns:

A true-valued token if the first argument is equal to this token.

isEqualTo

public BooleanToken isEqualTo(Token rightArgument)

Test for equality of the values of this Token and the argument Token. Two function tokens are equal if they correspond to the same expression, under renaming of any bound variables.

Overrides:

isEqualTo in class Token

Parameters:

rightArgument - The token to compare to this token.

Returns:

A token containing true if the value element of the first argument is equal to the value of this token.

toString

public java.lang.String toString()

Return a String representation of this function.

Overrides:

toString in class Token

Returns:

The String "present", unless this token is Token.NIL, in which case return the String "nil".