require "uri"

p URI.escape("~url quote")
#=> "~url%20quote"
p URI.escape("~url quote", /./)
#=> "%7E%75%72%6C%20%71%75%6F%74%65"

p URI::UNSAFE
#=> /[^-_.!~*'()a-zA-Z¥d;\/?:@&=+$,\[\]]/n