More-maps NPM | npm.io

More Maps

A collection of additional map-like data structures. Including a bidirectional map, a multi map, and a bidirectional multi map.

Installation

 $ npm i more-maps

Usage

BidirectionalMap

A map that allows bidirectional lookup between keys and values. It extends the built-in Map class.

import { BidirectionalMap } from "more-maps"

const map = new BidirectionalMap<string, number>()

map.set("one", 1)
map.set("two", 2)

console.log(map.get("one")) // 1
console.log(map.reverse.get(2)) // "two"

console.log(map.reverse.reverse === map) // true

Be aware that if you set the same value twice to a different key, the second key will overwrite the first one in the reverse map. So make sure they do not conflict. If you want to avoid this, use the BidirectionalMultiMap.

MultiMap

A map that allows multiple values per key. It stores the values in an array. It provides methods to add, retrieve, and delete values.

import { MultiMap } from "more-maps"

const map = new MultiMap<string, number>()

map.add("one", 1)
map.add("one", 2)
map.add("one", 3)
map.add("two", 4)

console.log(map.getAll("one")) // [1, 2, 3]
console.log(map.get("one")) // 1
console.log(map.get("two")) // 4

map.delete("one", 2)
console.log(map.getAll("one")) // [1, 3]

map.delete("one")
console.log(map.getAll("one")) // []
console.log(map.get("one")) // undefined

BidirectionalMultiMap

A bidirectional version of the MultiMap. It allows bidirectional lookup between keys and values, and also supports adding and deleting values.

import { BidirectionalMultiMap } from "more-maps"

const map = new BidirectionalMultiMap<string, number>()

map.add("one", 1)
map.add("one", 2)
map.add("two", 3)
map.add("three", 2)

console.log(map.getAll("one")) // [1, 2]
console.log(map.reverse.getAll(2)) // ["one", "three"]

map.delete("one", 2)
console.log(map.getAll("one")) // [1]
console.log(map.reverse.getAll(2)) // ["three"]