efficient regex in scala

The super easy way to match RegEx in Scala is to use the matches method that is part of the string class.

def matches…is added by an implicit conversion from StringOps to String. Where needed, Strings are implicitly converted into instances of StringOps (indexed sequences)

val demoString = "Matchy McMatch"

val pattern = "^.*Mc.*$"
demoString.matches(pattern)

// true

For a more performant variety, lets consider this statement from the Scala Docs:

An instance of Regex represents a compiled regular expression pattern. Since compilation is expensive, frequently used Regexes should be constructed once, outside of loops and perhaps in a companion object. The canonical way to create a Regex is by using the method r, provided implicitly for strings

Once we construct a RegEx, strings can be tested using the standard Scala match expression:

val pattern = "^.*Mc.*$".r
demoString match {
  case pattern(_*) => true
  case _ => false
}

// true