gistfile1.rb

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