Detect and replace URLs in text

Question

I want to detect and replace URLs in texts input by users. An example worth thousand words:

Here's a link to stackoverflow.com, so is http://stackoverflow.com.

=>

Here's a link to [stackoverflow.com](http://stackoverflow.com), so is [http://stackoverflow.com](http://stackoverflow.com).

All I found from Google is how to detect URLs and change them to <a> tags. Is there a way that I can detect URLs, and replace them with custom code blocks to generate something as the example above? Thanks a lot!

Answer 1

The tricky part of this is finding a regexp which will match all urls. eg this might work, from http://ryanangilly.com/post/8654404046/grubers-improved-regex-for-matching-urls-written

regexp = /\b((?:https?:\/\/|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}\/?)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s\`!()\[\]{};:\'\".,<>?«»“”‘’]))/i

Once you've got your regexp, then use gsub with a block, eg

text = "Here's a link to stackoverflow.com, so is http://stackoverflow.com."
=> "Here's a link to stackoverflow.com, so is http://stackoverflow.com."
text.gsub(regexp){|url| "FOO#{url}BAR"}
=> "Here's a link to stackoverflow.com, so is FOOhttp://stackoverflow.comBAR."

Note that this doesn't do anything with the first one in the text (that doesn't have the protocol), because it's not a url. if you were expecting it to pick up the first one too then that's going to be much harder for you.