escjava.prover
Class SNil

java.lang.Object
  escjava.prover.SExp
      escjava.prover.SList
          escjava.prover.SNil

final class SNil

extends SList

The single SNil instance represents the empty list of SExps.

Field Summary

private static SNil

single The single instance of this class, or null if it has not yet been allocated.

Constructor Summary

private

SNil() Instance creation is private so we can ensure that at most one instance of this class is ever created.

Method Summary

boolean	equals(java.lang.Object o)
static SNil	getNil()
boolean	isEmpty()
int	length()

Methods inherited from class escjava.prover.SList

addEnd, addFront, append, at, fromArray, getList, getPair, isList, main, make, make, make, make, make, make, make, make, make, prettyPrint, print, reverseD, setAt

Methods inherited from class escjava.prover.SExp

display, fancyMake, getAtom, getInteger, isAtom, isInteger, make, print, toString

Methods inherited from class java.lang.Object

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

Field Detail

single

private static SNil single

The single instance of this class, or null if it has not yet been allocated.

Constructor Detail

SNil

private SNil()

Instance creation is private so we can ensure that at most one instance of this class is ever created.

Method Detail

getNil

public static SNil getNil()

Returns:

the single SNil instance.

equals

public boolean equals(java.lang.Object o)

Returns:

true if the parameter is also the single instance of SNil.

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in class SList

Returns:

a flag indicating if we are we an empty list, which is always true since we are the nil instance.

length

public int length()

Specified by:

length in class SList

Returns:

our length, which is zero since we are the nil instance.