pt.ua.base
Class ImmutableList<T>

java.lang.Object
  pt.ua.base.ImmutableList<T>

public class ImmutableList<T>
extends java.lang.Object

Generic immutable list module.

This class follows DbC(tm) methodology. Where possible, contracts are implement with JML and native's Java assert.

Author:

Miguel Oliveira e Silva (mos@ua.pt)

Field Summary

T	head The list head element
int	size The list total number of elements.
ImmutableList<T>	tail The list tail list

Constructor Summary

ImmutableList()
Creates an empty list.

ImmutableList(T head, ImmutableList<T> tail)
Creates a new list by appending tail list to head element.

Method Summary

boolean	equals(ImmutableList<T> other) Queries equality with other list.
T	itemAt(int idx) Returns the element of the list at the idx position.
java.lang.String	toString() Returns a String with all list's elements separated with a space.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

size

public final int size

The list total number of elements.

head

public final T head

The list head element

tail

public final ImmutableList<T> tail

The list tail list

Constructor Detail

ImmutableList

public ImmutableList()

Creates an empty list.

ensures: size == 0
ensures: head == null
ensures: tail == null

ImmutableList

public ImmutableList(T head,
                     ImmutableList<T> tail)

Creates a new list by appending tail list to head element.

requires: tail != null

ensures: size == \old(size)+1
ensures: this.head == head
ensures: this.tail == tail

Parameters:

head - the element

tail - an immutable list

Method Detail

equals

public boolean equals(ImmutableList<T> other)

Queries equality with other list.

requires: other != null

Returns:

true if lists are equal, false otherwise

itemAt

public T itemAt(int idx)

Returns the element of the list at the idx position.

requires: idx >= 0 && idx < size

Parameters:

idx - the index

Returns:

the element

toString

public java.lang.String toString()

Returns a String with all list's elements separated with a space.

Overrides:

toString in class java.lang.Object

Returns:

the complete list as a string