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# UrlRegex

Provides the best known regex for validating and extracting URLs.
It builds on amazing work done by [Diego Perini](https://gist.github.com/dperini/729294)
and [Mathias Bynens](https://mathiasbynens.be/demo/url-regex).

Why do we need a gem for this regex?

- You don't need to follow changes and improvements of original regex.
- You can slightly customize the regex: a scheme can be optional, and you can get the regex for validation or parsing.

## Installation

Add this line to your application's Gemfile:

    gem 'url_regex'

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install url_regex

## Usage

Get the regex:

    UrlRegex.get(options)

where options are:

- `scheme_required` indicates that schema is required, defaults to `true`.

- `mode` can gets either `:validation`, `:parsing` or `:javascript`, defaults to `:validation`.

`:validation` asks to return the regex for validation, namely, with `\A` prefix, and with `\z` postfix.
That means, it matches whole text:

    UrlRegex.get(mode: :validation).match('https://www.google.com').nil?
    # => false
    UrlRegex.get(mode: :validation).match('link: https://www.google.com').nil?
    # => true

`:parsing` asks to return the regex for parsing:

    str = 'links: google.com https://google.com?t=1'
    str.scan(UrlRegex.get(mode: :parsing))
    # => ["https://google.com?t=1"]

    # schema is not required
    str.scan(UrlRegex.get(scheme_required: false, mode: :parsing))
    # => ["google.com", "https://google.com?t=1"]

`:javascript` asks to return the regex formatted for use in Javascript files or as `pattern` attribute values on HTML inputs. For this purpose, you'd use the `source` method on the Regexp object instance in order to produce a string that Javascript will understand. These examples make use of the Rails `text_field` method to generate HTML input elements.

    regex = UrlRegex.get(mode: :javascript)
    text_field(:site, :url, pattern: regex.source)
    # => <input type="text" id="site_url" name="site[url]" pattern="[javascript URL regex]" />

    regex = UrlRegex.get(scheme_required: false, mode: :javascript)
    text_field(:site, :url, pattern: regex.source)
    # => <input type="text" id="site_url" name="site[url]" pattern="[javascript URL regex with optional scheme]" />

`UrlRegex.get` returns regular Ruby's [Regex](http://ruby-doc.org/core-2.0.0/Regexp.html) object,
so you can use it as usual.

All regexes are case-insensitive.

## FAQ

Q: Hey, I want to parse HTML, but it doesn't work:

    str = '<a href="http://google.com?t=1">Link</a>'
    str.scan(UrlRegex.get(mode: :parsing))
    # => "http://google.com?t=1">Link</a>"

A: Well, you probably know that parsing HTML with regex is
[a bad idea](https://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags).
It requires matching corresponding open and close brackets, that makes the regex even more complicated.

Q: How can I speed up processing?

A: Generated regex depends only on options, so you can get the regex only once and cache it.

## Contributing

1. Fork it ( https://github.com/[my-github-username]/url_regex/fork )
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Add some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create a new Pull Request