sjm.engine
Class EmptyList

java.lang.Object
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  +--sjm.engine.Structure
        |
        +--sjm.engine.Fact
              |
              +--sjm.engine.EmptyList

public class EmptyList

extends Fact

The EmptyList is a list with no terms.

All lists except this one contain a head, which may be any term, and a tail, which is another list. This recursive defintion terminates with this singleton, the empty list.

Fields inherited from class sjm.engine.Fact

resolvent

Fields inherited from class sjm.engine.Structure

emptyList, functor, terms

Constructor Summary

protected

EmptyList() Constructs the empty list singleton.

Method Summary

boolean	isList() Return true, since an empty list is a list.
java.lang.String	listTailString() Returns a string representation of this list as a part of another list.
java.lang.String	toString() Returns a string representation of the empty list.

Methods inherited from class sjm.engine.Fact

copyForProof, dynamicAxiom, facts, head, resolvent, unify

Methods inherited from class sjm.engine.Structure

arity, canFindNextProof, equals, eval, functorAndArityEquals, headAndTail, list, list, list, listTermsToString, terms, unify, unify, unify, variables

Methods inherited from class java.lang.Object

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

Constructor Detail

EmptyList

protected EmptyList()

Constructs the empty list singleton.

Method Detail

isList

public boolean isList()

Return true, since an empty list is a list.

Overrides:

isList in class Structure

Returns:

true

listTailString

public java.lang.String listTailString()

Returns a string representation of this list as a part of another list. When the empty list represents itself as part of another list, it just returns "".

Overrides:

listTailString in class Structure

Returns:

an empty string

toString

public java.lang.String toString()

Returns a string representation of the empty list.

Overrides:

toString in class Structure

Returns:

a string representation of the empty list