如何正确使用scala.util.matching.Regex？(How to use scala.util.matching.Regex correctly?)

如何正确使用scala.util.matching.Regex？(How to use scala.util.matching.Regex correctly?)

这可能看起来很明显，但我无法解释No match available error 。 下面，您可以找到我正在使用的简单匹配函数的定义。

函数内部的相同指令运行没有问题，但是调用函数会引发错误。 你能帮我找出错误吗？

import scala.util.matching.Regex def regexParsing(inputRecord:String, inputRegex:String, listOfFields:Seq[String], fieldsToRemove:Seq[String]): scala.collection.Map[String,Any] = { val logPattern = new Regex(inputRegex, listOfFields:_*) val result = logPattern.findAllIn(inputRecord) val resultMap = result.groupNames.map(a => Map(a.toString -> result.group(a))).reduce(_++_) return resultMap } val inputRecord = """s2222f""" val inputRegex = """(.*)""" val listOfFields = Seq("field") val fieldsToRemove = Seq("field1", "field2") // working val logPattern = new Regex(inputRegex, listOfFields:_*) val result = logPattern.findAllIn(inputRecord) val resultMap = result.groupNames.map(a => Map(a.toString -> result.group(a))).reduce(_++_) // not working regexParsing(inputRecord, inputRegex, listOfFields, fieldsToRemove)

This may look obvious but I couldn't explain the No match available error . Below, you find a definition of a simple matching function I am using.

The same instructions inside the function run without an issue, however calling the function raises the error. Can you help me pinpoint the mistake ?

import scala.util.matching.Regex def regexParsing(inputRecord:String, inputRegex:String, listOfFields:Seq[String], fieldsToRemove:Seq[String]): scala.collection.Map[String,Any] = { val logPattern = new Regex(inputRegex, listOfFields:_*) val result = logPattern.findAllIn(inputRecord) val resultMap = result.groupNames.map(a => Map(a.toString -> result.group(a))).reduce(_++_) return resultMap } val inputRecord = """s2222f""" val inputRegex = """(.*)""" val listOfFields = Seq("field") val fieldsToRemove = Seq("field1", "field2") // working val logPattern = new Regex(inputRegex, listOfFields:_*) val result = logPattern.findAllIn(inputRecord) val resultMap = result.groupNames.map(a => Map(a.toString -> result.group(a))).reduce(_++_) // not working regexParsing(inputRecord, inputRegex, listOfFields, fieldsToRemove)

最满意答案

试试2.12？ 推进迭代器的限制是最终解决的API中的问题。

$ scala Welcome to Scala 2.12.0-RC1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_101). Type in expressions for evaluation. Or try :help. scala> :pa // Entering paste mode (ctrl-D to finish) import scala.util.matching.Regex def regexParsing(inputRecord:String, inputRegex:String, listOfFields:Seq[String], fieldsToRemove:Seq[String]): scala.collection.Map[String,Any] = { val logPattern = new Regex(inputRegex, listOfFields:_*) val result = logPattern.findAllIn(inputRecord) val resultMap = result.groupNames.map(a => Map(a.toString -> result.group(a))).reduce(_++_) return resultMap } val inputRecord = """s2222f""" val inputRegex = """(.*)""" val listOfFields = Seq("field") val fieldsToRemove = Seq("field1", "field2") // working val logPattern = new Regex(inputRegex, listOfFields:_*) val result = logPattern.findAllIn(inputRecord) val resultMap = result.groupNames.map(a => Map(a.toString -> result.group(a))).reduce(_++_) // Exiting paste mode, now interpreting. import scala.util.matching.Regex regexParsing: (inputRecord: String, inputRegex: String, listOfFields: Seq[String], fieldsToRemove: Seq[String])scala.collection.Map[String,Any] inputRecord: String = s2222f inputRegex: String = (.*) listOfFields: Seq[String] = List(field) fieldsToRemove: Seq[String] = List(field1, field2) logPattern: scala.util.matching.Regex = (.*) result: scala.util.matching.Regex.MatchIterator = non-empty iterator resultMap: scala.collection.immutable.Map[String,String] = Map(field -> s2222f) scala> regexParsing(inputRecord, inputRegex, listOfFields, fieldsToRemove) res0: scala.collection.Map[String,Any] = Map(field -> s2222f) scala> :quit

Try 2.12? The restriction about advancing the iterator is a gotcha in the API that was finally addressed.

$ scala Welcome to Scala 2.12.0-RC1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_101). Type in expressions for evaluation. Or try :help. scala> :pa // Entering paste mode (ctrl-D to finish) import scala.util.matching.Regex def regexParsing(inputRecord:String, inputRegex:String, listOfFields:Seq[String], fieldsToRemove:Seq[String]): scala.collection.Map[String,Any] = { val logPattern = new Regex(inputRegex, listOfFields:_*) val result = logPattern.findAllIn(inputRecord) val resultMap = result.groupNames.map(a => Map(a.toString -> result.group(a))).reduce(_++_) return resultMap } val inputRecord = """s2222f""" val inputRegex = """(.*)""" val listOfFields = Seq("field") val fieldsToRemove = Seq("field1", "field2") // working val logPattern = new Regex(inputRegex, listOfFields:_*) val result = logPattern.findAllIn(inputRecord) val resultMap = result.groupNames.map(a => Map(a.toString -> result.group(a))).reduce(_++_) // Exiting paste mode, now interpreting. import scala.util.matching.Regex regexParsing: (inputRecord: String, inputRegex: String, listOfFields: Seq[String], fieldsToRemove: Seq[String])scala.collection.Map[String,Any] inputRecord: String = s2222f inputRegex: String = (.*) listOfFields: Seq[String] = List(field) fieldsToRemove: Seq[String] = List(field1, field2) logPattern: scala.util.matching.Regex = (.*) result: scala.util.matching.Regex.MatchIterator = non-empty iterator resultMap: scala.collection.immutable.Map[String,String] = Map(field -> s2222f) scala> regexParsing(inputRecord, inputRegex, listOfFields, fieldsToRemove) res0: scala.collection.Map[String,Any] = Map(field -> s2222f) scala> :quit