Question

How to split a string on multiple single‑character delimiters (and keep them) in Scala

Answer 1

import scala.util.matching.Regex

object SplitKeepDelims {

  def splitKeepDelims(s: String, delimiters: String): List[String] = {
    // Build regex: e.g. ",;|" → "([,;|])"
    val pattern = new Regex("([" + Regex.quote(delimiters) + "])")

    var result = List.empty[String]
    var lastEnd = 0

    for (m <- pattern.findAllMatchIn(s)) {
      val start = m.start
      val end   = m.end

      // Add text before delimiter
      if (start > lastEnd)
        result = result :+ s.substring(lastEnd, start)

      // Add the delimiter itself
      result = result :+ m.matched

      lastEnd = end
    }

    // Add remaining text after last delimiter
    if (lastEnd < s.length)
      result = result :+ s.substring(lastEnd)

    result
  }

  def main(args: Array[String]): Unit = {
    val input = "aa,bbb;cccc|ddddd"
    val parts = splitKeepDelims(input, ",;|")

    parts.foreach(p => print(s"[$p] "))
  }
}




/*
run:

[aa] [,] [bbb] [;] [cccc] [|] [ddddd] 

*/

 

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