Question

I am struggling to concatenate a message with two texts into a single text using regex in scala

original message = "part1 "+" part2"
original message = "part1 "   + " part2"
original message = "part 1 "+    " part2"

concatenated message = "part1 part2"

What I am using is this code below (to replace atleast the + sign with null)

val line:String = """"text1"+"text2"""" //My original String which is "text1"+"text2"
val temp_line:String = line.replaceAll("\\+","")
println(temp_line)

It works fine and results “text1″”text2”. Is there a way to get the output “text1 text2” using regex?

Please help. Thanks in advance

Answer 1

This is really not an ideal problem for regexes, but okay:

val Part = """"([^"]*)"(.*$)""".r    // Quotes, non quotes, quotes, then the rest
val Plus = """\s*\+\s*(.*)""".r      // Plus with optional spaces, then the rest

def parts(s: String, found: List[String] = Nil): String = s match {
  case Part(p,rest) => rest match {
    case "" => (p :: found).map(_.filter(c => !c.isWhitespace)).reverse.mkString(" ")
    case Plus(more) => parts(more, p :: found)
    case x => throw new IllegalArgumentException(s"$p :$x:")
  }
  case x => throw new IllegalArgumentException(s"|$x|")
}

This just takes the input string apart piece by piece; you can add printlns if you want to see how it works. (Note that + is a special character in regex, so you need to escape it to match it.)

scala> parts(""""part1 "+" part2"""")
res1: String = part1 part2

scala> parts(""""part1 "   + " part2"""")
res2: String = part1 part2

scala> parts(""""part 1 "+    " part2"""")
res3: String = part1 part2