re = /^(\d{4})-((02-(0[1-9]|[12]\d))|((0[469]|11)-(0[1-9]|[12]\d|30))|((0[13578]|1[02])-(0[1-9]|[12]\d|3[01])))$/
str = ''
# Print the match result
str.match(re) do |match|
puts match.to_s
end
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html