专用Scala字符串插值

Question

对于给定Map的常数

val ctt = Map("a" -> 1, "b" -> 2)

如何定义String插值器c在哪里

c"a" 

交付List(1)？

注意已经考虑过字符串插值但仍不清楚如何继续.

更新

c"a,b"
res: List(1,2)

c" a, b  "
res: List(1,2)

c"a,w"
res: List(1)

c"w"
res: List()

Answer 1

以下作品:

scala> val ctt = Map("a" -> 1, "b" -> 2)
ctt: scala.collection.immutable.Map[String,Int] = Map(a -> 1, b -> 2)

scala> implicit class CttHelper(val sc: StringContext) extends AnyVal {
     |   def c(args: Any*): Int = ctt(sc.parts.head)
     | }
defined class CttHelper

scala> c"a"
res0: Int = 1

或者您的更新版本:

implicit class CttHelper(val sc: StringContext) extends AnyVal {
  def c(args: Any*): List[Int] =
    sc.parts.head.split(',').map(_.trim).toList.flatMap(ctt.get)
}

然后:

scala> c"a,w"
res5: List[Int] = List(1)

scala> c"a,b"
res6: List[Int] = List(1, 2)

scala> c" a, b  "
res7: List[Int] = List(1, 2)

scala> c"a,w"
res8: List[Int] = List(1)

scala> c"w"
res9: List[Int] = List()

但是,您可能希望检查sc.parts具有单个元素,除非您确实想要对插值变量执行某些操作.