scala regex group matching and replace

Question

val REGEX_OPEN_CURLY_BRACE = """\{""".r
val REGEX_CLOSED_CURLY_BRACE = """\}""".r
val REGEX_INLINE_DOUBLE_QUOTES = """\\\"""".r
val REGEX_NEW_LINE = """\\\n""".r

// Replacing { with '{' and } with '}'
str = REGEX_OPEN_CURLY_BRACE.replaceAllIn(str, """'{'""")
str = REGEX_CLOSED_CURLY_BRACE.replaceAllIn(str, """'}'""")
// Escape \" with '\"' and \n with '\n'
str = REGEX_INLINE_DOUBLE_QUOTES.replaceAllIn(str, """'\"'""")
str = REGEX_NEW_LINE.replaceAllIn(str, """'\n'""")

Is there a simpler way to group and replace all of these {,},\",\n?

Answer 1

You can use parenthesis to create a capture group, and $1 to refer to that capture group in the replacing string:

"""hello { \" world \" } \n""".replaceAll("""([{}]|\\["n])""", "'$1'")
// => java.lang.String = hello '{' '\"' world '\"' '}' '\n'

Answer 2

You can use regex groups like so:

scala> """([abc])""".r.replaceAllIn("a b c d e", """'$1'""")
res12: String = 'a' 'b' 'c' d e

The brackets in the regex allows you to match one of the characters between them. $1 is replaced by whatever is found between the parentheses in the regular expressions.

Answer 3

Consider this is your string :

var actualString = "Hi {  {  { string in curly brace }  }   } now quoted string :  \" this \" now next line \\\n second line text"

Solution :

var replacedString = Seq("\\{" -> "'{'", "\\}" -> "'}'", "\"" -> "'\"'", "\\\n" -> "'\\\n'").foldLeft(actualString) { _.replaceAll _ tupled (_) }

scala> var actualString = "Hi {  {  { string in curly brace }  }   } now quoted string :  \" this \" now next line \\\n second line text"
actualString: String =
Hi {  {  { string in curly brace }  }   } now quoted string :  " this " now next line \
 second line text

scala>      var replacedString = Seq("\\{" -> "'{'", "\\}" -> "'}'", "\"" -> "'\"'", "\\\n" -> "'\\\n'").foldLeft(actualString) { _.replaceAll _ tupled (_) }
replacedString: String =
Hi '{'  '{'  '{' string in curly brace '}'  '}'   '}' now quoted string :  '"' this '"' now next line \'
' second line text

Hope this will help :)