A Map with an upsert method and gc support
npm install upsert-mapA Map with an upsert method that is like a "get or set" method.
Also supports gc'ing empty upserts.
``
npm install upsert-map
` js
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()) //
`
#### 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 Map[Symbol.iterator]()
MIT