@aintts/linked-list v0.1.0

@aintts/linked-list

Small double linked list (inspired by linked-list).

Install

npm:

npm install @aintts/linked-list

Use

import {List, Item} from '@aintts/linked-list'

const item1 = new Item()
const item2 = new Item()
const item3 = new Item()
const list = new List<Item>(item1, item2, item3)

list.head // => item1
list.head.next // => item2
list.head.next.next // => item3
list.head.next.prev // => item1
list.tail // => item3
list.tail.next // => `null`

Subclassing:

import {List, Item} from '@aintts/linked-list'

class Tokens<T extends Token> extends List<T> {
  join(delimiter: string) {
    return this.toArray().join(delimiter)
  }
}

class Token<T> extends Item {
  public value: T

  constructor(value: T) {
    super()
    this.value = value
  }

  toString() {
    return this.value
  }
}

const dogs = new Token('dogs')
const and = new Token('&')
const cats = new Token('cats')
const tokens = new Tokens<Token<string>>(dogs, and, cats)

console.log(tokens.join(' ')) // => 'dogs & cats'

and.prepend(cats)
and.append(dogs)

console.log(tokens.join(' ') + '!') // => 'cats & dogs!'

Note

Do not modify the property of an item or list directly. This disrupts the work of the event-emitter. If you want to change a property directly, you can use _dangerSet[PROPERTY], which will fire a single event instead of chaining events.

API

This package exports the following identifiers: List, Item. There is no default export.

List([items…])

new List()
new List(new Item(), new Item())

Create a new linked list.

List.from([items])

List.from()
List.from([])
List.from([new Item(), new Item()])

Create a new this and adds the given array of items. Ignores null or undefined values. Throws an error when a given item has no detach, append, or prepend methods.

List.of([items…])

List.of()
List.of(new Item(), new Item())

Creates a new linked list from the given arguments. Defers to List.from.

List#append(item)

const list = new List()
const item = new Item()

list.head === null // => true
item.list === null // => true

list.append(item)

list.head === item // => true
item.list === list // => true

Appends an item to a list. Throws an error when the given item has no detach, append, or prepend methods. Returns the given item.

List#prepend(item)

const list = new List()
const item = new Item()

list.prepend(item)

Prepends an item to a list. Throws an error when the given item has no detach, append, or prepend methods. Returns the given item.

List#toArray()

const item1 = new Item()
const item2 = new Item()
const list = new List(item1, item2)
const array = list.toArray()

array[0] === item1 // => true
array[1] === item2 // => true
array[0].next === item2 // => true
array[1].prev === item1 // => true

Returns the items in the list in an array.

List#head

const item = new Item()
const list = new List(item)

list.head === item // => true

The first item in a list, and null otherwise.

List#tail

const list = new List()
const item1 = new Item()
const item2 = new Item()

list.tail === null // => true

list.append(item1)
list.tail === null // => true, see note.

list.append(item2)
list.tail === item2 // => true

The last item in a list, and null otherwise. Note that a list with only one item has no tail, only a head.

List#size

const list = new List()
const item1 = new Item()
const item2 = new Item()

list.size === 0 // => true

list.append(item1)
list.size === 1 // => true

list.append(item2)
list.size === 2 // => true

The number of items in the list.

Item()

const item = new Item()

Creates a new linked list Item.

Item#append(item)

const item1 = new Item()
const item2 = new Item()

new List().append(item1)

item1.next === null // => true

item1.append(item2)
item1.next === item2 // => true

Adds the given item after the operated on item in a list. Throws an error when the given item has no detach, append, or prepend methods. Returns false when the operated on item is not attached to a list, otherwise the given item.

Item#prepend(item)

const item1 = new Item()
const item2 = new Item()

new List().append(item1)

item1.prev === null // => true

item1.prepend(item2)
item1.prev === item2 // => true

Adds the given item before the operated on item in a list. Throws an error when the given item has no detach, append, or prepend methods. Returns false when the operated on item is not attached to a list, otherwise the given item.

Item#detach()

const item = new Item()
const list = new List(item)

item.list === list // => true

item.detach()
item.list === null // => true

Removes the operated on item from its parent list. Removes references to it on its parent list, and prev and next items; relinking them when possible. Returns the operated on item. Even when it was already detached.

Item#next

const item1 = new Item()
const item2 = new Item()

new List(item1)

item1.next === null // => true
item2.next === null // => true

item1.append(item2)

item1.next === item2 // => true

item1.detach()

item1.next === null // => true

The items succeeding item, and null otherwise.

Item#prev

const item1 = new Item()
const item2 = new Item()

new List(item)

item1.prev === null // => true
item2.prev === null // => true

item1.append(item2)

item1.prev === item1 // => true

item2.detach()

item2.prev === null // => true

The items preceding item, and null otherwise.

Item#list

const item = new Item()
const list = new List()

item.list === null // => true

list.append(item)

item.list === list // => true

item.detach()

item.list === null // => true

The items parent list, and null otherwise.

License

MIT © Ikrom Alizoda