Scala 使用简化的正则表达式读取、写入和拒绝记录

Question

我正在处理日志文件以使用 scala 解析 read/written/rejected 记录并将它们转换为地图。这些值出现在不同的行中 - "read" 后跟下一行的 "written"，然后是 "rejected"..

我使用的代码片段是

val log_text =
  """
    |server.net|Wed Apr  8 05:44:24 2018|acct_reformat.000||finish|
    |            120 records (              7200 bytes) read
    |            100 records (              6000 bytes) written
    |             20 records (              1200 bytes) rejected|
    |server.net|Wed Apr  8 05:44:24 2018|acct_reformat_rfm_logs
  """.stripMargin

val read_pat = """(\d+) (records) (.*)""".r
val write_pat = """(?s)records .*? (\d+) (records)(.*)""".r
val reject_pat = """(?s).* (\d+) (records)""".r

val read_recs  = read_pat.findAllIn(log_text).matchData.map( m=> m.subgroups(0) ).take(1).mkString
val write_recs = write_pat.findAllIn(log_text).matchData.map( m=> m.subgroups(0) ).take(1).mkString
val reject_recs = reject_pat.findAllIn(log_text).matchData.map( m=> m.subgroups(0) ).take(1).mkString

val log_summ = List("Read",read_recs,"Write",write_recs,"Reject",reject_recs).sliding(2,2).map( p => p match { case List(x,y) => (x,y)}).toMap

结果是

log_summ: scala.collection.immutable.Map[String,String] = Map(Read -> 120, Write -> 100, Reject -> 20)

不知怎的，我觉得，我正在以 roundabout/redundant 的方式来做。有没有更好的方法来完成这个？。

Answer 1

我觉得不错。只有三件事需要改进：

1) IntelliJ 是你的朋友。它立即给你两个意图：

m.subgroups(0) -> m.subgroups.head
map(p => p match { case List(x, y) => (x, y) }) -> map { case List(x, y) => (x, y) }

2) 干燥。不要重复read/write/reject相关代码三次。只要把它放在某个地方一次。例如：

case class Processor(name: String, patternString: String) {
  lazy val pattern: Regex = patternString.r
}

val processors = Seq(
  Processor("Read", """(\d+) (records) (.*)"""),
  Processor("Write", """(?s)records .*? (\d+) (records)(.*)"""),
  Processor("Reject", """(?s).* (\d+) (records)"""),
)

def read_recs(processor: Processor) = processor.pattern.findAllIn(log_text).matchData.map(m => m.subgroups.head).take(1).mkString

3) List[Tuple2] 可以通过简单的 toMap

转换为 Map

val log_summ = processors.map(processor => processor.name -> read_recs(processor)).toMap

Answer 2

鉴于 read/write/reject 文本的相似性，您可以将多个 Regex 匹配模式简化为一个通用模式，并使用 zip 生成您的 Map，如下所示：

val pattern = """(\d+) records .*""".r

val keys = List("Read", "Write", "Reject")

val values = pattern.findAllIn(log_text).matchData.map(_.subgroups(0)).toList
// values: List[String] = List(120, 100, 20)

val log_summ = (keys zip values).toMap
// log_summ: scala.collection.immutable.Map[String,String] =
//   Map(Read -> 120, Write -> 100, Reject -> 20)

Answer 3

如果您愿意将日志的措辞用于 Map 键，则可以一次性完成。

val Pattern = raw"(\d+) records .*\) ([^|]+)".r.unanchored

log_text.split("\n").flatMap{
  case Pattern(num, typ) => Some(typ -> num)
  case _ => None
}.toMap
//res0: immutable.Map[String,String] = Map(read -> 120, written -> 100, rejected -> 20)

Scala 使用简化的正则表达式读取、写入和拒绝记录

scala getting read,write and reject records with simplified regex

scala

scala-collections