upsert-map

A Map with an upsert method that is like a "get or set" method. Also supports gc'ing empty upserts.

npm install upsert-map

Usage

const UpsertMap = require('upsert-map')

const map = new UpsertMap(() => new Set(), set => !set.size)

map.upsert(10).add(1)
map.upsert(10).add(2)
console.log(...m.values()) // new Set(1, 2)
map.get(10).delete(1)
map.get(10).delete(1)
console.log(...m.values()) // <empty>

API

m = new UpsertMap(createValue, isEmpty)

Make a new upsert map.

• createValue(key) should return a value to be upserted for a key.
• isEmpty(val) can optionally be added for auto gc of empty values.

val = m.upsert(key)

Returns the value for key if already exists, otherwise it is created and inserted into the map.

val = m.get(key)

Similar to Map.get

bool = m.has(key)

Similar to Map.has

m.delete(key)

Similar to Map.delete

size = m.size

Similar to Map.size

iterator = m.values()

Similar to Map.values()

iterator = m.keys()

Similar to Map.keys()

iterator = m[Symbol.iterator]()

Similar to MapSymbol.iterator

License

MIT