Scala parser combinators for a language embedded in html or text (e.g. php)

Question

I’ve been playing with Scala parser combinators for some time and learned some ways to make it behave well and do most of the things I want using the built-in function.

But how do you create an embedded language (e.g. php or ruby ​​erb)? It requires that spaces are not ignored, outside the embedding of real code.

I managed to create a simple parser that matches the entire text to a given regular expression match, but I'm looking for a better, more beautiful way to do this. There is the possibility of using some already defined function that makes the necessary material.

The test language analyzes the text as follows:

now: [[ millis; ]]
and now: [[; millis; ]]

and is generated by the following code:

package test

import scala.util.parsing.combinator.RegexParsers
import scala.util.matching.Regex

sealed abstract class Statement
case class Print(s: String) extends Statement
case class Millis() extends Statement

object SimpleLang extends RegexParsers {

  def until(r: Regex): Parser[String] = new Parser[String]{
    def apply(in: Input) = {
      val source = in.source
      val offset = in.offset
      val start = offset
      (r.findFirstMatchIn( source.subSequence(offset, source.length) )) match {
        case Some(matched) => 
          Success(source.subSequence(offset, offset + matched.start).toString, in.drop(matched.start))
        case None => 
          Failure("string matching regex `"+ r +"' expected but `"+ in.first +"' found", in.drop(0))
      }
    }
  }

  def until(s: String): Parser[String] = until(java.util.regex.Pattern.quote(s).r)

  def interpret(stats: List[Statement]): Unit = stats match {
    case Print(s) :: rest => {
      print(s)
      interpret(rest)
    }
    case Millis() :: rest => {
      print(System.currentTimeMillis)
      interpret(rest)
    }
    case Nil => ()
  }

  def apply(input: String) : List[Statement] = parseAll(beginning, input) match {
    case Success(tree,_) => tree
    case e: NoSuccess => throw new RuntimeException("Syntax error: " + e)
  }

  /** GRAMMAR **/

  def beginning = (
    "[[" ~> stats |
    until("[[") ~ "[[" ~ stats ^^ { 
      case s ~ _ ~ ss => Print(s) :: ss
    }
  )

  def stats = rep1sep(stat, ";")

  def stat = (
    "millis" ^^^ { Millis() } |
    "]]" ~> ( (until("[[") <~ "[[") | until("\\z".r)) ^^ {
      case s => Print(s)
    }
  )

  def main(args: Array[String]){
    val tree = SimpleLang("now: [[ millis; ]]\nand now: [[; millis; ]]")
    println(tree)
    interpret(tree)
  }

}

Answer 1

Scala RegexParsers Regex Parser [ Char], .

override val skipWhitespace = false

whiteSpace ( ), .

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, , . CSS, , , javadoc.

Answer 2

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