I would like to create a function that creates regex matching an arbitrary string given at the input. For example, when I feed it with 123$ it should match literally "123$" and not 123 at the end of the string.
def convert( xs: String ) = (xs map ( x => "\\"+x)).mkString val text = """ 123 \d+ 567 """ val x = """\d+""" val p1 = x.r val p2 = convert(x).r println( p1.toString ) \d+ // regex to match number println( ( p1 findAllIn text ).toList ) List(123, 567) // ok, numbers are matched println( p2.toString ) \\\d\+ // regex to match "backshash d plus" println( ( p2 findAllIn text ).toList ) List() // nothing matched :( So the last findAllIn should find \d+ in text, but it doesn't. What's wrong here?
Best Answer
You can use Java's Pattern class to escape strings as regular expressions. See http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#quote%28java.lang.String%29
For example:
scala> Pattern.quote("123$").r.findFirstIn("123$")res3: Option[String] = Some(123$)Just to bring more attention to Harold L's comment above, if you want to do this with a Scala library you can use:
import scala.util.matching.RegexRegex.quote("123$").r.findFirstIn("123$")