OOscheme
Class NEList

java.lang.Object
  OOscheme.NEList

All Implemented Interfaces:

IList, INEList

public class NEList
extends Object
implements INEList

Concrete implementation of the non-empty list interface, INEList. Contains two pieces of data:

• first: an Object representing the first data element
• rest: an IList object representing the rest of this non-emptylist.

When a class contains other objects that are isomorphic to itself, this class is called a composite.

Provides concrete code for

• a constructor to initialize this NEList to a given first and rest,
• the getFirst() method for accessing the first data element,
• the getRest() method for accesssing the rest of the list,
• the execute method: simply calls the nonEmptyCase method of the IListAlgo parameter, passing to this method itself as the host and the given input Object as the input.

Note the class is not public in order to hide from client code outside of the OOscheme package.

Since:

Copyright 2005 by DXN - All rights reserved

Author:

Dung X. Nguyen

Field Summary

private Object	_first The first data element of this NEList.
private IList	_rest The rest or "tail" of this NEList.

Constructor Summary

NEList(Object first, IList tail)
Initializes this NEList to a given first and rest.

Method Summary

Object	execute(IListAlgo algo, Object... inp) Calls the nonEmptyCase method of the IListAlgo parameter, passing to this method itself as the host parameter and the given input as the input parameter.
Object	getFirst() Returns the first data element of this NEList.
IList	getRest() Returns the rest of this NEList.

Methods inherited from class java.lang.Object

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

Field Detail

_first

private Object _first

The first data element of this NEList.

_rest

private IList _rest

The rest or "tail" of this NEList. Data Invariant: _rest != null;

Constructor Detail

NEList

public NEList(Object first,
              IList tail)

Initializes this NEList to a given first and rest.

Parameters:

first - the first data element of this NEList.

tail - != null, the rest of this NEList.

Method Detail

getFirst

public final Object getFirst()

Returns the first data element of this NEList. This method is marked as final to prevent all subclasses from overriding it. Finalizing a method also allows the compiler to generate more efficient calling code.

Specified by:

getFirst in interface INEList

Returns:

this INElist's first element.

getRest

public final IList getRest()

Returns the rest of this NEList. This method is marked as final to prevent all subclasses from overriding it. Finalizing a method also allows the compiler to generate more efficient calling code.

Specified by:

getRest in interface INEList

Returns:

this INElist's rest.

execute

public final Object execute(IListAlgo algo,
                            Object... inp)

Calls the nonEmptyCase method of the IListAlgo parameter, passing to this method itself as the host parameter and the given input as the input parameter. This method is marked as final to prevent all subclasses from overriding it. Finalizing a method also allows the compiler to generate more efficient calling code.

Specified by:

execute in interface IList

Parameters:

algo - the visitor, the algorithm to be executed.

inp - a variable number of input parameters to be used by the algorithm algo.

Returns:

an Object output from executing the algorithm algo; may be null.