listFW

Class NEList

java.lang.Object

listFW.NEList

All Implemented Interfaces:

IList

public class NEList
extends java.lang.Object
implements IList

Represents non-empty lists. 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.

Author:

D. X. Nguyen, S. B. Wong

Field Summary

Fields

Modifier and Type	Field and Description
private java.lang.Object	_first The first data element.
private IList	_rest The rest or "tail" of this NEList.

Constructor Summary

Constructors

Constructor and Description
NEList(java.lang.Object f, IList r) Initializes this NEList to a given first and a given rest.

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.Object	execute(IListAlgo algo, java.lang.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.
java.lang.Object	getFirst() Returns the first data element of this NEList.
IList	getRest() Returns the first data element of this NEList.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

_first

private java.lang.Object _first

The first data element.

_rest

private IList _rest

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

Constructor Detail

NEList

public NEList(java.lang.Object f,
      IList r)

Initializes this NEList to a given first and a given rest.

Parameters:

f - the first element of this NEList.

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

Method Detail

getFirst

public final java.lang.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.

getRest

public final IList getRest()

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.

execute

public final java.lang.Object execute(IListAlgo algo,
                       java.lang.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 - an extrinsic operation (algorithm) on this IList.

inp - a variable number of input parameters needed by algo to perform the computation.

Returns:

an Object representing the output of the computation.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object