net.sf.saxon.ma.zeno

Class ZenoChain<T>

java.lang.Object

net.sf.saxon.ma.zeno.ZenoChain<T>

Type Parameters:

T - the type of the items in the list

All Implemented Interfaces:

java.lang.Iterable<T>

public class ZenoChain<T>
extends java.lang.Object
implements java.lang.Iterable<T>

An implementation of sequences as a list-of-lists, where the sublists at the end of the master list tend to be small, and the sublists at the start tend to be larger (or the other way around if the list is built by prepending items rather than appending them). The number of sublists is of the order log(N) where N is the length of the sequence, giving logarithmic performance or better for appending items to either end of the sequence, or for getting the Nth item.

For a list built by appending to the end, the size of sublists goes as follows as the list grows: (1).. (32).. (32,1).. (32,32).. (64,1).. (64,32).. (64,32,1).. (64,32,32).. (64,64,1).. (64,64,32).. (128,32,1).. (128,64,1).. (128,64,32,1).. For a list of 20,000 items we get 10 sublists with sizes (8192, 4096, 4096, 2048, 1024, 256, 128, 64, 64, 32). The exact numbers don't matter, the important thing is that the number of sublists is log(N) with shorter sublists at the end of the sequence where append/prepend operations take place.

When two lists are concatenated, the two master lists are first concatenated, followed by a consolidation to combine short lists now appearing near the middle of the structure, to reduce the number of sublists.

The current implementation is a mutable structure, but it is designed to make creation of a mutable variant easy.

Constructor Summary

Constructors

Constructor and Description
ZenoChain() Create an empty sequence

Method Summary

Modifier and Type	Method and Description
ZenoChain<T>	add(T item) Append an item
ZenoChain<T>	addAll(java.lang.Iterable<? extends T> items) Append a sequence of items
ZenoChain<T>	concat(ZenoChain<T> other)
T	get(int n) Get the item at position n, zero-based
boolean	isEmpty() Ask if the list is empty
boolean	isSingleton() Ask if the list is a singleton
java.util.Iterator<T>	iterator() Iterate over the items
static void	main(java.lang.String[] args)
ZenoChain<T>	prepend(T item) Prepend an item
java.lang.String	show()
int	size() Get the size of the list
ZenoChain<T>	subList(int start, int end)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

ZenoChain

public ZenoChain()

Create an empty sequence

Method Detail

add

public ZenoChain<T> add(T item)

Append an item

Parameters:

item - the item to be appended

Returns:

the list after the append operation

prepend

public ZenoChain<T> prepend(T item)

Prepend an item

Parameters:

item - the item to be prepended

Returns:

the list after the prepend operation

addAll

public ZenoChain<T> addAll(java.lang.Iterable<? extends T> items)

Append a sequence of items

Parameters:

items - the sequence of items to be appended

Returns:

the concatenated sequence

concat

public ZenoChain<T> concat(ZenoChain<T> other)

get

public T get(int n)

Get the item at position n, zero-based

Parameters:

n - the requested index

Returns:

the item at position n

Throws:

java.lang.IndexOutOfBoundsException - if n is negative or beyond the end of the list

subList

public ZenoChain<T> subList(int start,
                            int end)

size

public int size()

Get the size of the list

Returns:

the size of the list

isEmpty

public boolean isEmpty()

Ask if the list is empty

Returns:

true if the size is zero

isSingleton

public boolean isSingleton()

Ask if the list is a singleton

Returns:

true if the size is one

iterator

public java.util.Iterator<T> iterator()

Iterate over the items

Specified by:

iterator in interface java.lang.Iterable<T>

Returns:

an iterator over the items

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

show

public java.lang.String show()

main

public static void main(java.lang.String[] args)