= Public Suffix List

{<img src="https://travis-ci.org/toddsundsted/Public-Suffix-List.svg?branch=master">}[https://travis-ci.org/toddsundsted/Public-Suffix-List]
{<img src="https://img.shields.io/badge/docs-available-brightgreen.svg">}[https://toddsundsted.github.io/Public-Suffix-List/]

== Description

The Public Suffix List (http://publicsuffix.org/) is "a cross-vendor
initiative to provide an accurate list of domain name suffixes". Such
a list is necessary because "there was and remains no algorithmic
method of finding the highest level at which a domain may be
registered for a particular top-level domain (the policies differ with
each registry)...". Public Suffix List is also a small Ruby library
designed to make the Public Suffix List (http://publicsuffix.org/)
easier to use.  Public Suffix List will transparently download the
latest list of top-level domains, parse the list, and optionally cache
the parsed data.

The public API is as simple as I could make it.  Instantiating the
PublicSuffixList class downloads, parses, and caches the data.  There
are three instance methods:

[*tld*(domain)] return the top-level domain name
[*cdn*(domain)] return the canonical domain name
[*split*(domain)] split the domain name into parts

== Features

* Transparent download of the TLD data file
* Optional caching of optimized, parsed TLD data
* Tiny API

== Synopsis

  require "public_suffix_list"

  # Downloads and parses the latest data file and returns "com".
  PublicSuffixList.new.tld("foobar.com")

  # Downloads and parses the latest data file and returns "foobar.com".
  PublicSuffixList.new.cdn("foobar.com")

  # Downloads and parses the latest data file, caches it in /tmp,
  # and returns ["abc", "xyz", "co.uk"].
  PublicSuffixList.new(cache_dir: "/tmp").split("abc.xyz.co.uk")

  # Loads the cached data in /tmp if it is less than 100 seconds old,
  # downloads, parses, and caches it if it is older, and returns
  # ["test", "parliament", "uk"].
  PublicSuffixList.new(cache_dir: "/tmp", cache_expiry_period: 100).split("test.parliament.uk")

  # You don't have to instantiate PublicSuffixList every time you
  # use it, of course...
  p = PublicSuffixList.new
  p.split("fee.fi.fo.com") # => ["fee.fi", "fo", "com"]
  p.cdn("fee.fi.fo.com")   # => "fo.com", "cdn" is "canonical domain name"
  p.tld("fee.fi.fo.com")   # => "com", "tld" is "top-level domain"

  # You can even use other data files, both local and remote
  # (as long as they conform to the Public Suffix List file format).
  PublicSuffixList.new(url: "spec/test.dat")

== Requirements

None that I am aware of.

== Install

Install the gem directly:

  gem install public-suffix-list

Or add it to your Gemfile and use bundler:

  gem 'public-suffix-list'

== License

Copyright (c) 2010-2019 Todd Sundsted

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.