🗺 Mappemonde

A multidimensional (variadic keys) Map

This library expose a data structure similar to Map except it accept an arbitrary number of keys.

Gist

import { Mappemonde } from 'mappemonde';

const m = Mappemonde.byValue();
m.set(['foo', 42], 'bar');
m.get(['foo', 42]); // => 'bar'

Position vs Value

Mappemonde can work in two distinc modes: position or value. This define how items are identified:

• in value mode the order of the keys does not matter and you can even pass a Set as a list of keys.
• in position mode, the order does matter and you can't use a Set because Set are unordered.

You need to choose the mode you want to use when you create a Mappemonde:

const positionalMap = Mappemonde.byPosition();
const valueMap = Mappemonde.byValue();

API

Creating a Mappemonde

In both case you get back a Mappemonde instance

Mappemonde.byPosition();
// or
Mappemonde.byValue();
// or
Mappemonde.create('value');
Mappemonde.create('position');

Mappemonde instance

export interface Mappemonde<K extends Keys<any>, V> {
  get(keys: K): V | undefined;
  set(keys: K, value: V): void;
  has(keys: K): boolean;
  delete(keys: K): void;
  entries(): Array<[K, V]>;
  values(): Array<V>;
  keys(): Array<K>;
  cleanup(): void;
}

Typescript

This library is written in TypeScript and expose strict types !

import { Mappemonde } from 'mappemonde';

// keys should be number, value should be string
const m1 = Mappemonde.byValue<Array<number>, string>();

// keys should be of length 2 with first a string then a number
const m2 = Mappemonde.byPosition<[string, number], string>();

Cleanup

Internally this library uses a tree of Map. This mean that if you set, then delete an item you would end up with an empty Map, but Mappemonde prevent memory leaks by removing empty Map when they appear.

If this strategy doesn't work for you, you can change it using the cleanup option:

import { Mappemonde } from 'mappemonde';

// never cleanup
const m1 = Mappemonde.byValue({ cleanup: 'never' });
// you can call cleanup yourself
m1.cleanup();

// cleanup when you delete an item (default value)
const m2 = Mappemonde.byPosotion({ cleanup: 'onDelete' });

// cleanup every 10 delete
const m3 = Mappemonde.create('value', { cleanup: ['everyDelete', 10] });

// cleanup every 10 seconds
const m4 = Mappemonde.create('position', {
  cleanup: ['periodically', 10 * 1000],
});