Infi

A Kotlin List implementation to iterate around elements infinitely.

Add to your project:

In your root build.gradle file:

allprojects {
  repositories {
    ...
    maven { url 'jitpack.io' }
  }
}

and in your module build.gradle file: Latest version: 1.1.0

dependencies {
  implementation 'com.github.alraj-dev:infi:latest-version'
}

Demo:

Consider the following list:

val list = listOf(1, 2, 3, 4, 5)

In a normal case to loop around elements infinitely you do:

//Backwards
if(currentIndex == 0)
    currentIndex = list.lastIndex
else
    currentIndex--
	
//Forwards
if(currentIndex == list.lastIndex)
    currentIndex = 0
else
    currentIndex++

But with Infi, it is simple:

val list = infiOf(1, 2, 3, 4, 5)

use infiOf instead of listOf

//Backward by single element
list.previous()
//Forward by single element
list.next()

// go beyond single element
list.next(3)     // go to 3rd next element
list.previous(4) // go to 4th previous element

next(n: Int) - goes to the nth next element and returns it. (default n value is 1)

previous(n: Int) - goes to the nth previous element and returns it. (default n value is 1)

since this is a infinite loop list, increment or decrement beyond the element size, loops back just like a normal next or previous function.

list.next(17)      // Gets 2, loops around with the increment
list.previous(198) // Gets 3

The default element is the 0th element, to change the default element use with(). You can start looping from a specific index or element:

val list = infiOf(1, 2, 3, 4, 5).with(index = 2)

// By Index, use named parameter when Elements are Int
// Because both index parameter and element parameter will be Int
list.with(index = 3).next() // Gets 5
// By Element
list.with(4).next()         // Gets 5

with(index) - set the current index to the given index, so changes the current element and position to traverse from

with(element) - set the current index to the index of given element, so changes the current element and position to traverse from

other functions:

element() - returns the current element

index() - returns the current element's index

and all List functions available in Kotlin, since Infi extends List

open class Infi<E> : List<E>

MutableInfi:

class MutableInfi<E> : Infi<E>,MutableList<E>

Same as Infi but with Mutable property, you can use all MutableList functions available in Kotlin.

Exception

You get IndexOutOfBoundException() doing the following:

calling next() or previous(), when there is no element present.
calling index() or element() when there is no element.
calling with(index) when index is smaller than Zero or index is greater than elements size
calling with(element) when element is not present

alrajdev / infi