Qex

A :queue wrapper with improvements in API and addition of Protocol implementations

Protocols

Inspect, Collectable and Enumerable are implemented, use Qex with IO.inspect and Enum functions!

Function signatures

Parameters are re-ordered to better suit Elixir's awesome |>

Installation

The package can be installed as:

1. Add :qex to your list of dependencies in mix.exs:

   def deps do
     [
       {:qex, "~> 0.5"}
     ]
   end
   

2. Run mix deps.get

How to use

Read the docs

Protocols

iex> inspect Qex.new
"#Qex<[]>"

iex> Enum.count Qex.new(1..5)
5

iex> Enum.empty? Qex.new
true

iex> Enum.map Qex.new([1, 2, 3]), &(&1 + 1)
[2, 3, 4]

iex> inspect Enum.into(1..5, %Qex{})
"#Qex<[1, 2, 3, 4, 5]>"

# Leverages :queue.member/2 under the hood for performance
iex> Enum.member? Qex.new(1..10_000), 9_999
true

Create a new queue from a range

iex> inspect Qex.new(1..3)
"#Qex<[1, 2, 3]>"

Create a new queue from a list

iex> inspect Qex.new([1, 2, 3])
"#Qex<[1, 2, 3]>"

Add an element to the back of the queue

iex> q = Qex.new([:mid])
iex> Enum.to_list Qex.push(q, :back)
[:mid, :back]

Add an element to the front of the queue

iex> q = Qex.new([:mid])
iex> Enum.to_list Qex.push_front(q, :front)
[:front, :mid]

Get and remove an element from the front of the queue

iex> q = Qex.new([:front, :mid])
iex> {{:value, item}, _q} = Qex.pop(q)
iex> item
:front

iex> q = Qex.new
iex> {empty, _q} = Qex.pop(q)
iex> empty
:empty

Get and remove an element from the back of the queue

iex> q = Qex.new([:mid, :back])
iex> {{:value, item}, _q} = Qex.pop_back(q)
iex> item
:back

iex> q = Qex.new
iex> {empty, _q} = Qex.pop_back(q)
iex> empty
:empty

Reverse a queue

iex> q = Qex.new(1..3)
iex> Enum.to_list q
[1, 2, 3]
iex> Enum.to_list Qex.reverse(q)
[3, 2, 1]

Split a queue into two, the front n items are put in the first queue

iex> q = Qex.new 1..5
iex> {q1, q2} = Qex.split(q, 3)
iex> Enum.to_list q1
[1, 2, 3]
iex> Enum.to_list q2
[4, 5]

Join two queues together

iex> q1 = Qex.new 1..3
iex> q2 = Qex.new 4..5
iex> Enum.to_list Qex.join(q1, q2)
[1, 2, 3, 4, 5]

Return the first item

iex> q1 = Qex.new 1..3
iex> Qex.first(q1)
{:value, 1}
iex> q2 = Qex.new []
iex> Qex.first(q2)
:empty

iex> q1 = Qex.new 1..3
iex> Qex.first!(q1)
1

Return the last item

iex> q1 = Qex.new 1..3
iex> Qex.last(q1)
{:value, 3}
iex> q2 = Qex.new []
iex> Qex.last(q2)
:empty

iex> q1 = Qex.new 1..3
iex> Qex.last!(q1)
3

Why not "Queue"?

The name is taken... Hex link

Copyright and License

Copyright (c) 2022 Po Chen

This work is free. You can redistribute it and/or modify it under the terms of the MIT License. See the LICENSE.md file for more details.