Removing special characters in multiline strings Scala

Question

Is there a way to remove special characters(\n, \b, \t, \f, \r) from a multi line string in Scala?

for a normal string

val someText = "some\nText\t"
someText.filter(_ >= ' ')       // returns "someText"

How do I achieve the same, in multi line string

val multLineStr = """some\nText\t"""
someText.filter(_ >= ' ')       // returns "some\nText\t"

I tried using regular expressions, couldn't remove the characters from the string.

val regex = new Regex("\\s")
regex.replaceAllIn(multLineStr, "")   // returns "some\nText\t"

`"""\n"""` is a combination of two chars, not a newline. Use `val regex = """\\[tn]""".r` — Wiktor Stribiżew, Feb 03 '20 at 11:51
The triple-quoted strings are "multiline" which means that they understand the rendered new line. In other words, for every rendered new line, a `\n` character is automatically inserted. And special characters are not treated as special anymore. — sarveshseri, Feb 03 '20 at 12:24
@diginoise, I wanted to replace "special chars" in triple quoted strings, although it's good to know another method to replace special chars in strings, thanks — chqdrian, Feb 03 '20 at 12:30
So, you are not after *removing* anything, but *defining* inside a string literal? — Wiktor Stribiżew, Feb 03 '20 at 12:32
I was after *removing* spec chars from the string, If you had *answered* my question, I would have accepted your solution @Wiktor Stribtizew. — chqdrian, Feb 03 '20 at 16:10

score 2 · Answer 1 · answered Feb 03 '20 at 11:52

It seems like you need add interpolation to this string:

val multLineStr = """some\nText\t"""
println(multLineStr.toList)
println(multLineStr.filter(_ >= ' '))

will print out:

List(s, o, m, e, \, n, T, e, x, t, \, t)
some\nText\t

and same with s interpolation before the multi-line string

val multLineStr = s"""some\nText\t"""
println(multLineStr.toList)
println(multLineStr.filter(_ >= ' '))

will give your desired result:

List(s, o, m, e, 
, T, e, x, t,   )
someText

score 1 · Accepted Answer · answered Feb 03 '20 at 14:19

As a side node, there exists StringContext.processEscapes method which

  /** Expands standard Scala escape sequences in a string.
   *  Escape sequences are:
   *   control: `\b`, `\t`, `\n`, `\f`, `\r`
   *   escape:  `\\`, `\"`, `\'`
   *
   *  @param  str  A string that may contain escape sequences
   *  @return The string with all escape sequences expanded.
   */
  def processEscapes(str: String): String

hence

assert(StringContext.processEscapes("""some\nText\t""") == "some\nText\t")

StringContext.processEscapes("""some\nText\t""").filter(_ >= ' ')
// res1: String = someText

Removing special characters in multiline strings Scala

2 Answers2