family-store

A storage-agnostic store with parents. If the store doesn't have a key, it asks its parents, who ask their parents, et cetera (breadth-first). Circular dependencies are okay.

example

const JSONStore = require('atomic-json-store')
const FamilyStore = require('family-store')

const one = new FamilyStore('one', JSONStore('one.json'))
const two = new FamilyStore('two', new Map)

one.inherit(two)
two.inherit(one)

two.set('host', 'two.com')
one.get('host') === 'two.com';
one.getOwn('host') === undefined;
one.getOwner('host').owner === two;

one.set('host', 'one.com')
one.set('port', 8080)

one.get('host') === 'one.com';
two.get('port') === 8080;

FamilyStore(name, storage, [options])

The storage should have the following synchronous interface:

• get(key)
• set(key, value)
• delete(key) or remove(key)
• keys() (array or iterable)
• clear() (optional, falls back to delete() all keys())

Options:

• inherit: array of parents to inherit() from

inherit(parent)

Add a parent store to inherit from. Returns false if it already inherits from parent or if parent is the store itself, otherwise true.

get(key) or getOwn(key)

Get a value with or without inheritance.

getOwner(key)

Returns an object with these properties:

• owner: the first found store that has a value for key
• value
• depth: traversal depth (0 if owner is the store itself)

set(key, value)

Set own value of key.

delete(key) or remove(key)

Delete own value of key.

clear()

Delete all own values.

keys() or ownKeys()

Returns an array of keys with or without inheritance.

pairs() or ownPairs()

Returns an array of [key, value] pairs with or without inheritance.

toJSON()

Get an object with all values, own and inherited.

equals(familyStore)

a.equals(b) is true if a.toJSON() deep equals b.toJSON().

traverse(function)

Breadth-first traversal, starting with the store itself. The function is called once for every store with the arguments storage, store and depth until the function returns a value other than undefined.

const a = new FamilyStore('a', storage())
const b = new FamilyStore('b', storage())
const c = new FamilyStore('c', storage())
const d = new FamilyStore('d', storage())

a.inherit(b)
a.inherit(c)

b.inherit(a)
b.inherit(d)

a.traverse(function(storage, store, depth){
  console.log('%s: %d', store.name, depth)
})

Gives:

a: 0
b: 1
c: 1
d: 2

install

With npm do:

npm install family-store

license

MIT © ironSource.