com.atlassian.jira.util

Class Window<T>

java.lang.Object

com.atlassian.jira.util.Window<T>

All Implemented Interfaces:

Iterable<T>

@Immutable
public class Window<T>
extends Object
implements Iterable<T>

A type of collection that contains another collection - underlying collection - and limits your view over it. The subcollection that can be seen is called the visible part. It's more flexible than List.subList(int, int) because it allows more operations and also can tell whether either start or end is obstructed.

Method Summary

Modifier and Type	Method and Description
Window<T>	dropUntil(Predicate<T> predicate) Drop elements that don't match the predicate.
Window<T>	dropUntilElement(T expected) Drop all the elements before the requested element.
static <T> Window<T>	empty() Create a window over an empty collection.
T	first() Returns the first element of the visible part or the only element if the visible part has only one.
Window<T>	focusElement(T expected, int radius) Drop elements from beginning and end until there are number of elements on both sides of the requested element.
List<T>	get() Returns the visible part
boolean	hasElementsAfter() Returns true if there are elements after the end of the visible part of the underlying collection
boolean	hasElementsBefore() Returns true if there are elements before the start of the visible part of the underlying collection
boolean	isEmpty() Checks whether the visible part is empty
Iterator<T>	iterator()
Window<T>	keepUntil(Predicate<T> predicate) Keep only elements that match the predicate.
Window<T>	keepUntilElement(T expected) Drop all elements after the requested element.
T	last() Returns the last element of the visible part or the only element if the visible part is has only one.
static <T> Window<T>	of(Collection<T> coll) Create a window over a whole collection
Window<T>	reverse() Return a copy of the window where all the elements are in reverse order.
Window<T>	shrinkFromEnd(int size) Drop elements from the start until the new visible part is of the requested size
Window<T>	shrinkFromStart(int size) Drop elements from the beginning until the new visible part is of the requested size
int	size() Returns the size of the visible part
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

Method Detail

of

public static <T> Window<T> of(Collection<T> coll)

Create a window over a whole collection

Parameters:

coll - the underlying collection

empty

public static <T> Window<T> empty()

Create a window over an empty collection.

size

public int size()

Returns the size of the visible part

hasElementsAfter

public boolean hasElementsAfter()

Returns true if there are elements after the end of the visible part of the underlying collection

hasElementsBefore

public boolean hasElementsBefore()

Returns true if there are elements before the start of the visible part of the underlying collection

first

public T first()

Returns the first element of the visible part or the only element if the visible part has only one.

Throws:

IndexOutOfBoundsException - if there are no elements

last

public T last()

Returns the last element of the visible part or the only element if the visible part is has only one.

Throws:

IndexOutOfBoundsException - if there are no elements

keepUntil

public Window<T> keepUntil(Predicate<T> predicate)

Keep only elements that match the predicate. The new visible part ends at the first element that doesn't match.

dropUntil

public Window<T> dropUntil(Predicate<T> predicate)

Drop elements that don't match the predicate. The new visible part start from the first matching element.

dropUntilElement

public Window<T> dropUntilElement(T expected)

Drop all the elements before the requested element.

Parameters:

expected - requested element

Returns:

a new window which includes the requested element

Throws:

IllegalArgumentException - if the requested element is not in the current visible part

keepUntilElement

public Window<T> keepUntilElement(T expected)

Drop all elements after the requested element.

Parameters:

expected - requested element

Returns:

a new window which includes the requested element

Throws:

IllegalArgumentException - if the requested element is not in the current visible part

focusElement

public Window<T> focusElement(T expected,
                              int radius)

Drop elements from beginning and end until there are number of elements on both sides of the requested element.

Parameters:

expected - the element that should be surrounded

radius - number of elements before and after

Throws:

IllegalArgumentException - if the requested element is not the visible part

IllegalArgumentException - if radius is less than zero

shrinkFromStart

public Window<T> shrinkFromStart(int size)

Drop elements from the beginning until the new visible part is of the requested size

Parameters:

size - requested size

Returns:

a new window over the same collection or the same window if is larger than the visible part

shrinkFromEnd

public Window<T> shrinkFromEnd(int size)

Drop elements from the start until the new visible part is of the requested size

Parameters:

size - requested size

Returns:

a new window over the same collection or the same window if is larger than the visible part

get

public List<T> get()

Returns the visible part

Returns:

A fresh, mutable list

isEmpty

public boolean isEmpty()

Checks whether the visible part is empty

Returns:

true if the visible part is empty

reverse

public Window<T> reverse()

Return a copy of the window where all the elements are in reverse order. The elements in resulting visible part are identical with the original

Returns:

A new window over the same collection

toString

public String toString()

Overrides:

toString in class Object

iterator

public Iterator<T> iterator()

Specified by:

iterator in interface Iterable<T>