gistfile1.rb

# -*- coding: utf-8 -*-
require "addressable/uri"
require "uri"

def uri_valid?(uri)
  uri = Addressable::URI.parse(uri)
  # If it could not be parsed, it won't have a valid scheme
  %w{http https}.include?(uri.scheme)
rescue Addressable::URI::InvalidURIError
  false
end

urls = [
        "http://caius.name/",
        "http:/caius.name/",
        "http://ca]ius.name/",
        "http://cai;us.name/",
        "http://caius",
        "http://",
        "caius.name",
       ]

headers = %w(url uri-valid? uri-parse? add-valid?)
i = (headers | urls).map {|x| x.length }.max
headers.each do |h|
  printf " %-#{i}s", h
end
puts

urls.each do |u|
  printf " %-#{i+5}s", u

  if u =~ URI.regexp
    printf " %-#{i}s", "✓"
  else
    printf " %-#{i}s", "𐄂"
  end

  begin
    URI(u)
    printf " %-#{i}s", "✓"
  rescue URI::InvalidURIError => e
    printf " %-#{i}s", "𐄂"
  end

  if uri_valid?(u)
    printf " %-#{i}s", "✓"
  else
    printf " %-#{i}s", "𐄂"
  end

  puts
end

# url                 uri-valid?          uri-parse?          add-valid?
# http://caius.name/       ✓                   ✓                   ✓
# http:/caius.name/        ✓                   ✓                   ✓
# http://ca]ius.name/      ✓                   𐄂                   ✓
# http://cai;us.name/      ✓                   𐄂                   ✓
# http://caius             ✓                   ✓                   ✓
# http://                  ✓                   𐄂                   𐄂
# caius.name               𐄂                   ✓                   𐄂