Scala: Regex Pattern Matching - regex

Question

I have the following input strings
"/horses/c132?XXX=abc-049#companyorg"
"/Goats/b-01?XXX=abc-721#"
"/CATS/001?XXX=abc-451#CompanyOrg"
I'd like to obtain the following as output
"horses", "c132", "abc-049#companyorg"
"Goats", "b-01", "abc-721#"
"CATS", "001", "abc-451#CompanyOrg"
I tried the following
StandardTokenParsers
import scala.util.parsing.combinator.syntactical._
val p = new StandardTokenParsers {
lexical.reserved ++= List("/", "?", "XXX=")
def p = "/" ~ opt(ident) ~ "/" ~ opt(ident) ~ "?" ~ "XXX=" ~ opt(ident)
}
p: scala.util.parsing.combinator.syntactical.StandardTokenParsers{def p: this.Parser[this.~[this.~[this.~[String,Option[String]],String],Option[String]]]} = $anon$1#6ca97ddf
scala> p.p(new p.lexical.Scanner("/horses/c132?XXX=abc-049#companyorg"))
warning: there was one feature warning; re-run with -feature for details
res3: p.ParseResult[p.~[p.~[p.~[String,Option[String]],String],Option[String]]] =
[1.1] failure: ``/'' expected but ErrorToken(illegal character) found
/horses/c132?XXX=abc-049#companyorg
^
RegEx
import scala.util.matching.regex
val p1 = "(/)(.*)(/)(.*)(?)(XXX)(=)(.*)".r
p1: scala.util.matching.Regex = (/)(.*)(/)(.*)(?)(XXX)(=)(.*)
scala> val p1(_,animal,_,id,_,_,_,company) = "/horses/c132?XXX=abc-049#companyorg"
scala.MatchError: /horses/c132?XXX=abc-049#companyorg (of class java.lang.String)
... 32 elided
Can someone please help? Thanks!

Answer 1

Your pattern looks like /(desired-group1)/(desired-group2)?XXX=(desired-group3).
So, regex would be
scala> val extractionPattern = """(/)(.*)(/)(.*)(\?XXX=)(.*)""".r
extractionPattern: scala.util.matching.Regex = (/)(.*)(/)(.*)(\?XXX=)(.*)
note - escape ? char.
How it is going to work is,
Full match `/horses/c132?XXX=abc-049#companyorg`
Group 1. `/`
Group 2. `horses`
Group 3. `/`
Group 4. `c132`
Group 5. `?XXX=`
Group 6. `abc-049#companyorg`
Now, apply the regex which gives you the group of all matches
scala> extractionPattern.findAllIn("""/horses/c132?XXX=abc-049#companyorg""")
.matchData.flatMap{m => m.subgroups}.toList
res15: List[String] = List(/, horses, /, c132, ?XXX=, abc-049#companyorg)
Since you only care care about 2nd, 4th and 6th match, only collect those.
So the solution would look like,
scala> extractionPattern.findAllIn("""/horses/c132?XXX=abc-049#companyorg""")
.matchData.map(_.subgroups)
.flatMap(matches => Seq(matches(1), matches(3), matches(4))).toList
res16: List[String] = List(horses, c132, ?XXX=)
When your input does not match regex, you get empty result
scala> extractionPattern.findAllIn("""/horses/c132""")
.matchData.map(_.subgroups)
.flatMap(matches => Seq(matches(1), matches(3), matches(4))).toList
res17: List[String] = List()
Working regex here - https://regex101.com/r/HuGRls/1/