def splitAndKeep(text: String, delims: Set[Char]): List[String] = {
if (text.isEmpty) return Nil
val buf = scala.collection.mutable.ListBuffer[String]()
var start = 0
for (i <- 1 until text.length) {
val prev = text(i - 1)
val curr = text(i)
val prevIsDelim = delims.contains(prev)
val currIsDelim = delims.contains(curr)
val shouldSplit =
(prevIsDelim != currIsDelim) || // text ↔ delim
(prevIsDelim && currIsDelim && prev != curr) // delim type changed
if (shouldSplit) {
buf += text.substring(start, i)
start = i
}
}
// Add final segment
buf += text.substring(start)
buf.toList
}
val s = "aa==bbb---cccc++++ddddd"
val delimiters = Set('=', '-', '+')
println(splitAndKeep(s, delimiters))
/*
run:
List(aa, ==, bbb, ---, cccc, ++++, ddddd)
*/
