Code looks solid otherwise...at least where I work the style would be to favor functional idioms over for loops but I think that's just personal preference.
That has been removed from the Scala standard lib and is now distributed separately. I am unsure how well it will be maintained by the community. As the other commenter said, parboiled2 is a good choice using macros and it is lightning fast. A lighter weight, runtime choice that was released recently is fastparse[0].
https://wiki.scala-lang.org/display/SW/Parser+Combinators--G...
Code looks solid otherwise...at least where I work the style would be to favor functional idioms over for loops but I think that's just personal preference.