persistent-hash-trie
v0.4.2
Published
Pure string:val storage, using structural sharing
Downloads
55
Readme
persistent-hash-trie
Pure string:val storage, using structural sharing.
Why
This module forms a possible basis for effecient persistent datastructures; such as those found in Clojure's PersistentHashMap and PersistentVector.
Install
npm install persistent-hash-trie
Docs
Trie
var p = require('persistent-hash-trie')
var trie = p.Trie()
assoc
Returns a new Trie with the new key:value keys added.
var trie1 = p.Trie()
var trie2 = p.assoc(trie1, 'key', { value: true })
dissoc
Returns a new Trie without a specific key
var trie1 = p.assoc(p.Trie(), 'key', 'val')
var trie2 = p.dissoc(trie2, 'key')
get
Retrieves a value from a Trie.
var trie = p.assoc(p.Trie(), 'key', 'val')
p.get(trie, 'key') //= 'val'
has
Returns true
or false
, depending on whether the value is in the Trie.
var trie = p.assoc(p.Trie(), 'key', 'val')
p.has(trie, 'key') //= true
p.has(trie, 'not-in-here') //= false
transient
Returns a mutable copy of a Trie, in the form of a js object.
var trie = p.assoc(p.Trie(), 'key', 'val')
p.transient(trie) //= { key: 'val' }
Extending assoc/dissoc/get/has
The hashing and equality functions used on the keys can be overidden by passing an opts object to assoc
, dissoc
, get
and has
.
var im = require('persistent-hash-trie')
var opts = {
eq: function(a, b){ return a === b},
hash: function(key){ return parseInt(key, 10) }
}
var vector = p.assoc(p.Trie(), 3, 'my-val', opts)
var val = p.get(vector, 3, opts)
var vector2 = p.dissoc(vector, 3, opts)
p.has(vector2, 3, opts) // false
Running tests and benchmarks
npm test
and npm run-script benchmark
are your friends.