binary-search-party

binary-search-party

Asynchronous or Synchronous binary search. This can be useful for seraching through really useless databases like a pipermail archive. If you essentially just have a key value store and a list of keys that are known to be in order, you can efficiently search for a specific value using this module.

Installation

npm install binary-search-party

API

Synchronous

var search = require('binary-search-party')

var haystack = [1, 2, 3, 4, 5]
var needle = 4

var index = search(haystack, function (val) {
  if (val === needle) return 0
  if (val < needle) return -1
  if (val > needle) return +1
})
asssert(haystack[index] === needle)

Asynchronous

var search = require('binary-search-party')

var haystack = [1, 2, 3, 4, 5]
var needle = 4

search(haystack, function (val, callback) {
  if (val === needle) return callback(null, 0)
  if (val < needle) return callback(null, -1)
  if (val > needle) return callback(null, +1)
}, function (err, index) {
  if (err) throw err
  asssert(haystack[index] === needle)
})

Promised

var search = require('binary-search-party')

var haystack = [1, 2, 3, 4, 5]
var needle = 4

search(haystack, function (val) {
  if (val === needle) return Promise.from(null, 0)
  if (val < needle) return Promise.from(null, -1)
  if (val > needle) return Promise.from(null, +1)
}).done(function (index) {
  asssert(haystack[index] === needle)
})

N.B. You will get back the type of promise returned by calling the comparison function. This makes it easy to use your own promise library :)

N.B. If you pass an empty array, the comparison function can never be called so the result will be the literal number -1. If the array might be empty and you rely on the result being a promise you should assimilate the result into being a promise using something like Promise.from(search(arr, comparison))

License

MIT