In Scala is it possible to return more than one regex criteria from a string?-CodePudding

Sorry couldn't think of a better title. I'm new to Scala and I'm trying to parse out variables out of "{}". I want to be able to write regex that returns all variables out of he handle bars like example below. In some cases the sql string would have one "{}" in others it might have multiple.

val sql_str = "select * from {tbl} a left join {tbl2} b on a.id = b.id "

val r = """.*\{(.*)\}.*""".r

val result = sql_str match {
  case r(value) => value
  case _ => ""
}

For instance if I had the follow string:

select * from {tbl}

the result should be: tbl

for

select * from {tbl} a left join {tbl2} b on a.id = b.id

the result should be: tbl, tbl2

I tried searching for solution but couldn't find one. Thanks for any pointers you can provide.

CodePudding user response：

This is what I came up with. I don't think it's the greatest answer. If someone has an efficient way please share.

var sql_str = "select * from {tbl} a left join {tbl2} b on a.id = b.id"
var words = sql_str.split("\\s ")

var params = Array[String]()
val pattern = """.*\{(.*)\}.*""".r

words foreach(x=> if ((x match {case pattern(value)=> value case _=> ""})!="")  params=params: x )

params foreach(x=> print(x))

CodePudding user response：

"""\{(. ?)}""".r
  .findAllMatchIn(sql)
  .map(_.group(1))
  .foreach(println)

Or a bit less efficient, but, perhaps, somewhat simpler:

   """\{. ?}""".r
   .findAllIn(sql)
   .map(_.tail.init)
   .foreach(println)

This assumes, you don't have nested or unbalanced braces, and will not work very well on something like "foo {bar {bam} baz} {zap}}". If you want to handle those cases, regex is probably not the right tool, you'd be better off with a simple recursive function traversing the string while keeping track of the braces.