如何用SBT解析器匹配由可选空白包围的字符串

Question

我试图使用sbt解析器（http://www.scala-sbt.org/0.13/docs/parsing-input.html）解析sbt InputTask的命令行参数，但未能编写与以下伪regex匹配的解析器：

\w+(-n|--dry-run)\w+

import sbt.complete.Parser
import sbt.complete.DefaultParsers._

val dryRunOptions: Parser[String] = OptSpace ~> ("-n" | "--dry-run") <~ OptSpace
val dryRunParser: Parser[Boolean] = flag(dryRunOptions)

Parser(dryRunParser)("-n").result
Parser(dryRunParser)(" -n").result
Parser(dryRunParser)("-n ").result
Parser(dryRunParser)(" -n ").result

Parser(dryRunParser)("--dry-run").result
Parser(dryRunParser)(" --dry-run").result
Parser(dryRunParser)("--dry-run ").result
Parser(dryRunParser)(" --dry-run ").result

res0: Option[Boolean] = None
res1: Option[Boolean] = None
res2: Option[Boolean] = None
res3: Option[Boolean] = None

res4: Option[Boolean] = None
res5: Option[Boolean] = None
res6: Option[Boolean] = None
res7: Option[Boolean] = None

Answer 1

您正在以错误的方式检查解析器的正确性。在本例中，您应该使用.resultemtty.isvalid而不是.result，就像在这里的测试中一样。然后，您的代码工作正常：

import sbt.complete.Parser
import sbt.complete.DefaultParsers._

val dryRunOptions: Parser[String] = OptSpace ~> ("-n" | "--dry-run") <~ OptSpace
val dryRunParser: Parser[Boolean] = flag(dryRunOptions)

val test = Seq("-n", " -n", "-n ", " -n   ",
  "--dry-run", " --dry-run", "--dry-run ", " --dry-run   ")

test.foldLeft(true)((b:Boolean, input:String) =>
  b && Parser(dryRunParser)(input).resultEmpty.isValid)

结果是：

res0: Boolean = true