Class Sexpr

java.lang.Object
  |
  +--Sexpr

class Sexpr

extends java.lang.Object

Implements Lisp S-expressions. Every S-expression has car, cdr, and value fields; if isAtom is true, only the value field is used; if isAtom is false, only the car and cdr fields are used. The field isNull is true if the S-expression represents an empty list, while the field isNumeric tells whether the S-expression represents a numeric atom.

Field Summary
(package private)  Sexpr	car           The CAR of this S-expression; valid only for nonempty lists.
(package private)  Sexpr	cdr           The CDR of this S-expression; valid only for nonempty lists.
(package private)  boolean	isAtom           True if this S-expression represents an atom.
(package private)  boolean	isNull           True if this S-expression represents an empty list.
(package private)  boolean	isNumeric           True if this S-expression represents a numeric atom.
static Sexpr	NIL           The Lisp constant NIL.
static Sexpr	T           The Lisp constant T.
(package private)  java.lang.String	value           The value of this S-expression; valid only for atoms.

 

Constructor Summary
(package private)	Sexpr(int value)           Constructs a numeric S-expression.
(package private)	Sexpr(Sexpr car, Sexpr cdr)           Constructs an S-expression that is a list.
(package private)	Sexpr(java.lang.String value)           Constructs an atomic S-expression.

 

Method Summary
static void	main(java.lang.String[] args)           Unit testing for this class.
static Sexpr	parse(java.lang.String input)           Turns an input string into an S-expression.
java.lang.String	toString()           Turns this S-expression into a String.

 

Methods inherited from class java.lang.Object

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

 

Field Detail

car

Sexpr car

The CAR of this S-expression; valid only for nonempty lists.

cdr

Sexpr cdr

The CDR of this S-expression; valid only for nonempty lists.

isAtom

boolean isAtom

True if this S-expression represents an atom.

isNull

boolean isNull

True if this S-expression represents an empty list.

isNumeric

boolean isNumeric

True if this S-expression represents a numeric atom.

NIL

public static Sexpr NIL

The Lisp constant NIL.

T

public static Sexpr T

The Lisp constant T.

value

java.lang.String value

The value of this S-expression; valid only for atoms.

Sexpr

Sexpr(int value)

Constructs a numeric S-expression.

Parameters:

value - The integer value of the S-expression.

Sexpr

Sexpr(Sexpr car,
      Sexpr cdr)

Constructs an S-expression that is a list.

Parameters:

car - The car of the new S-expression.

Sexpr

Sexpr(java.lang.String value)

Constructs an atomic S-expression.

Parameters:

value - The String value of the S-expression.

main

public static void main(java.lang.String[] args)

Unit testing for this class.

parse

public static Sexpr parse(java.lang.String input)

Turns an input string into an S-expression.

toString

public java.lang.String toString()

Turns this S-expression into a String.

Overrides:

toString in class java.lang.Object