如何为统一的diff语法编写解析器

Question

我应该使用RegexParsers,StandardTokenParsers还是完全适合解析这种语法？语法示例可以在这里找到.

Answer 1

我用的是正则表达式.它简化了一些事情,并使其余部分成为标准.

def process(src: scala.io.Source) {
  import scala.util.matching.Regex

  val FilePattern = """(.*) ''(.*)''"""
  val OriginalFile = new Regex("--- "+FilePattern, "path", "timestamp")
  val NewFile = new Regex("+++ "+FilePattern, "path", "timestamp")
  val Chunk = new Regex("""@@ -(\d+),(\d+) +(\d+),(\d+) @@""", "orgStarting", "orgSize", "newStarting", "newSize")
  val AddedLine = """+(.*)""".r
  val RemovedLine = """-(.*)""".r
  val UnchangedLine = """ (.*)""".r

  src.getLines() foreach {
    case OriginalFile(path, timestamp) => println("Original file: "+path)
    case NewFile(path, timestamp) => println("New file: "+path)
    case Chunk(l1, s1, l2, s2) => println("Modifying %d lines at line %d, to %d lines at %d" format (s1, l1, s2, l2))
    case AddedLine(line) => println("Adding line "+line)
    case RemovedLine(line) => println("Removing line "+line)
    case UnchangedLine(line) => println("Keeping line "+line)
  }
}