(1..REGEXP_MAX_NUM).each do |i|
        next unless conf["regexp#{i}"]
        key, regexp = conf["regexp#{i}"].split(/ /, 2)
        raise Fluent::ConfigError, "regexp#{i} does not contain 2 parameters" unless regexp
        raise Fluent::ConfigError, "regexp#{i} contains a duplicated key, #{key}" if regexp_and_conditions[key]