regexp,uri,cgi,encode,decode

http://snippets.dzone.com/posts/show/5180
http://ruby-doc.org/stdlib/libdoc/uri/rdoc/classes/URI/Escape.html#M009386
http://ruby-doc.org/stdlib/libdoc/cgi/rdoc/classes/CGI.html#M000091

[^abc] Any single character but a, b, or c

 1 
   2  require 'cgi'
   3 
   4  # escape
   5  name = "ruby?"
   6  value = "yes"
   7  url = "http://example.com/?" + CGI.escape(name) + '=' + CGI.escape(value) + "&var=T"
   8  # url: http://example.com/?ruby%3F=yes&var=T
   9  html = %(<a href="#{CGI.escapeHTML(url)}">example</a>)
  10  # html: <a href="http://example.com/?ruby%3F=yes&amp;var=T">example</a>
  11 
  12  # unescape
  13  name_encoded = html.match(/http:([^"]+)/)[0]
  14  # name_encoded: http://example.com/?ruby%3F=yes&amp;var=T
  15  href = CGI.unescapeHTML(name_encoded)
  16  # href: http://example.com/?ruby%3F=yes&var=T
  17  query = href.match(/\?(.*)$/)[1]
  18  # query: ruby%3F=yes&var=T
  19  pairs = query.split('&')
  20  # pairs: ["ruby%3F=yes", "var=T"]
  21  name, value = pairs[0].split('=').map{|v| CGI.unescape(v)}
  22  # name, value: ["ruby?", "yes"]