https://github.com/mooreniemi/array_collapse
:boom: Array#collapse
https://github.com/mooreniemi/array_collapse
array c-extension ruby
Last synced: 10 months ago
JSON representation
:boom: Array#collapse
- Host: GitHub
- URL: https://github.com/mooreniemi/array_collapse
- Owner: mooreniemi
- License: mit
- Created: 2016-09-17T15:22:54.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2016-10-08T16:24:03.000Z (over 9 years ago)
- Last Synced: 2025-03-29T15:35:17.738Z (11 months ago)
- Topics: array, c-extension, ruby
- Language: Ruby
- Homepage:
- Size: 83 KB
- Stars: 32
- Watchers: 1
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
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README
# 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](http://mooreniemi.github.io/2016/09/15/flatten.html)
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](https://ruby-doc.org/core-2.2.0/Array.html#method-i-flatten)
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:
```ruby
gem 'array_collapse'
```
And then execute:
$ bundle
Or install it yourself as:
$ gem install array_collapse
## Usage
```ruby
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](https://github.com/mooreniemi/array_collapse). This project is
intended to be a safe, welcoming space for collaboration, and contributors
are expected to adhere to the [Contributor
Covenant](http://contributor-covenant.org) code of conduct.
## License
The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).