Array#collapse

A C extension alternative to using flatten.compact or flatten.map. Slight performance improvement (just a constant factor better) than the common idioms, with exactly the same memory performance.

See this blog post for the background and a chart of memory performance.

In addition, collapse makes two other slightly different choices from core Ruby's flatten. 1. Attempting to flatten a recursive Array will error normally. collapse just drops the recursive reference, and continues on its merry way. 2. collapse doesn't accept a level argument. It's all or nothing.

Disclaimer

Should you use this? Needing to compile a native extension for a performance benefit that is not asymptotic is a trade-off I wouldn't always make myself.

Installation

Add this line to your application's Gemfile:

gem 'array_collapse'

And then execute:

$ bundle

Or install it yourself as:

$ gem install array_collapse

Usage

2.2.2 :001 > require 'array_collapse'
 => true
2.2.2 :002 > [1, 2, [3], nil].collapse {|e| e.nil? ? e : e * 2 }
 => [2, 4, 6]
2.2.2 :003 > [1, [2, [3, nil]]].collapse
 => [1, 2, 3]
2.2.2 :004 > a = [1, [2, [3]]]
 => [1, [2, [3]]]
2.2.2 :005 > a << a
 => [1, [2, [3]], [...]]
2.2.2 :006 > a.collapse {|e| e * 3 }
 => [3, 6, 9]
2.2.2 :007 > a.flatten
 => ArgumentError: tried to flatten recursive array

Contributing

Bug reports and pull requests are welcome on GitHub. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License