re = /^((19\d{2})|(20\d{2}))-(((02)-(0[1-9]|[1-2][0-9]))|(((0(1|[3-9]))|(1[0-2]))-(0[1-9]|[1-2][0-9]|30))|((01|03|05|07|08|10|12)-(31)))$/
str = '2000-12-31'
# 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