FiFo

This module provides (double-ended) FIFO queues in an efficient manner.

FiFo is just a rewrite of the Erlang module queue in an Elixir way. The module includes implementations of the protocols Enumerable, Collectable, and Inspect.

Installation

First, add fi_fo to your mix.exs dependencies:

def deps do
  [{:fi_fo, "~> 0.1"}]
end

Then, update your dependencies:

$ mix deps.get

Documentation can be found at HexDocs.

Usage

Construct, write, and read: FiFo.new/0, FiFo.push/2, and FiFo.pop/1:

iex(1)> queue = FiFo.new()
#FiFo<[]>
iex(2)> queue = FiFo.push(queue, 1)
#FiFo<[1]>
iex(3)> queue = FiFo.push(queue, 2)
#FiFo<[1, 2]>
iex(4)> {{:ok, x}, queue} = FiFo.pop(queue)
{{:ok, 1}, #FiFo<[2]>}
iex(5)> {{:ok, x}, queue} = FiFo.pop(queue)
{{:ok, 2}, #FiFo<[]>}
iex(6)> FiFo.pop(queue)
{:error, #FiFo<[]>}

Create a queue from other data structures: FiFo.from_list/1, FiFo.from_range/1, and FiFo.from_erlange_queue:

iex(7)> FiFo.from_list([1, 2, 3, 4])
#FiFo<[1, 2, 3, 4]>
iex(8)> FiFo.from_range(1..10)
#FiFo<[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]>
iex(9)> FiFo.from_erlang_queue({[3, 2], [1]})
#FiFo<[1, 2, 3]>

Convert a queue to other data structures: FiFo.to_list/1 and FiFo.to_erlang_queue/1:

iex(10)> queue = FiFo.from_list([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
#FiFo<[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]>
iex(11)> FiFo.to_list(queue)
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
iex(12)> FiFo.to_erlang_queue(queue)
{[10, 9, 8, 7], [1, 2, 3, 4, 5, 6]}

Take and drop elements: FiFo.drop/2, FiFo.take/2, Enum.drop/1, and Enum.take/2:

iex(13)> FiFo.drop(queue, 3)
#FiFo<[4, 5, 6, 7, 8, 9, 10]>
iex(14)> FiFo.take(queue, 3)
{[1, 2, 3], #FiFo<[4, 5, 6, 7, 8, 9, 10]>}
iex(15)> Enum.drop(queue, 3)
[4, 5, 6, 7, 8, 9, 10]
iex(16)> Enum.take(queue, 3)
[1, 2, 3]