re = /(?s)(?=OPERATION\s*\()(?:(?=.*?OPERATION\s*\((?!.*?\1)(.*\)(?!.*\2).*))(?=.*?\)(?!.*?\2)(.*)).)+?.*?(?=\1)(?:(?!OPERATION\s*\().)*(?=\2$)/
str = '1)"OPERATION(ASYNC_OPERATION,_RFID_ITEM_SERIAL);" 2)"OPERATION(CONCAT,~1261,01,OPERATION(ASYNC_OPERATION,_RFID_ITEM_ID);,21,OPERATION(ASYNC_OPERATION,_RFID_ITEM_SERIAL););"'
# Print the match result
str.scan(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