Parsing a delimited multiline string using scala StandardTokenParser - scala

Question

I have found a few similar questions but nothing that seems to directly address my needs here.
I am creating a DSL using Scala and have much of it already defined. However, part of the language needs to handle blocks of multi-line textual documentation that are collected and handled as individual entities by the parser. I would like to delimit these blocks in some way (say with something like {{ and }}) and just collect everything between the delimiters and return it as a DocString (a case class in my parser). These blocks will then be used to create additional end-user documentation along with the rest of the parsed file(s).
The parser is already structured as a StandardTokenParsers-derived class. I suppose I could convert it to a RegexParsers-derived class and just use regular expressions but that would be a major change and a lot of my grammar would have to be reworked. I am not sure if there would be any advantage to doing this (other than supporting the desired documentation blocks).
I have seen Using regex in StandardTokenParsers and found this. I am not sure either of those will actually handle what I need, however, or how to begin if they do.
If anyone has any ideas as to a viable way to proceed I would appreciate some pointers.
As an example, here is something I have tried (from Using regex in StandardTokenParsers):
object DModelParser extends StandardTokenParsers {
...
def modelElement: Parser[ModelElement] =
(other stuff, not important here) | docBlock
import scala.util.matching.Regex
import lexical.StringLit
def regexBlockMatch(r: Regex): Parser[String] = acceptMatch(
"string block matching regex " + r,
{case StringLit(s) if r.unapplySeq(s).isDefined => s})
val bmr = """\{\{((?s).*)\}\}""".r
def docBlockStr: Parser[String] = regexBlockMatch(bmr)
def docBlock: Parser[DocString] =
docBlockStr ^^ { s => new DocString(s) }
...
}
However, when passing it even a single line like the following:
{{ A block of docs }}
it fails to match causing the parser to stop parsing. I think the problem is in the case StringLit(s) in this case but I am not sure.
Edit
OK. StringLit was a problem. I forgot that this will only match strings in double quotes. So I tried replacing the string above with:
"{{ A block of docs }}"
and it works fine. However, the multi-line issue still remains. If I replace this with:
"{{ A block
of docs }}"
Then it still fails to parse. Again, I think it is the StringLit not working across line-feeds.
Edit
Another option occurred to me but I am not sure how to make it work in the parser. If I can read and match a line that only contains the opening delimiter then collect into a List[String] all the lines until a line that only contains the closing delimiter that would be sufficient. Is there a way to do this?
Edit 6/22/2015
I went a different direction and this seems to work for the examples I have tried so far:
// https://stackoverflow.com/questions/24771341/scala-regex-multiline-match-with-negative-lookahead
def docBlockRE = regex("""(?s).*?(?=}})""".r)
def docBlock: Parser[DocString] =
"{{" ~> docBlockRE <~ "}}" ^^ { case str => new DocString(str) }