RosettaCodeData/Task/Execute-a-Markov-algorithm/Scala/execute-a-markov-algorithm-...

31 lines
987 B
Scala

import scala.io.Source
object MarkovAlgorithm {
val RulePattern = """(.*?)\s+->\s+(\.?)(.*)""".r
val CommentPattern = """#.*|\s*""".r
def rule(line: String) = line match {
case CommentPattern() => None
case RulePattern(pattern, terminal, replacement) => Some(pattern, replacement, terminal == ".")
case _ => error("Syntax error on line "+line)
}
def main(args: Array[String]) {
if (args.size != 2 ) {
println("Syntax: MarkovAlgorithm inputFile inputPattern")
exit(1)
}
val rules = (Source fromPath args(0) getLines () map rule).toList.flatten
def algorithm(input: String): String = rules find (input contains _._1) match {
case Some((pattern, replacement, true)) => input replaceFirst ("\\Q"+pattern+"\\E", replacement)
case Some((pattern, replacement, false)) => algorithm(input replaceFirst ("\\Q"+pattern+"\\E", replacement))
case None => input
}
println(args(1))
println(algorithm(args(1)))
}
}